A method for delivering an agent to the pulmonary system, in a single, breath-activated step or a single breath, comprises administering from a receptacle enclosing a mass of particles, to a subject's respiratory tract, particles which have a tap density of less than 0.4 g/cm.sup.3 and deliver at least about 50% of the mass of particles. The particles are capable of carrying agents. The agent is (1) part of the spray-drying pre-mixture and thereby incorporated into the particles, (2) added to separately-prepared particles so that the agent is in chemical association with the particles or (3) blended so that the agent is mixed with, and co-delivered with the particles.Respirable compositions comprising carrier particles having a tap density of less than 0.4 g/cm.sup.3 and a composition comprising an agent are also disclosed. Methods of delivering these respirable compositions are also included.

Description of the Invention

SUMMARY OF THE INVENTION

The invention is related to methods of delivery of an agent (for example, a therapeutic agent, a prophylactic agent, a diagnostic agent, a prognostic agent) to the pulmonary system. The invention is also related to methods of delivery of a bioactive agent to the pulmonary system.

In one embodiment, the invention is drawn to a method of delivering an agent to the pulmonary system, in a single, breath-activated step comprising: a) providing particles comprising an agent; and b) administering the particles, from a receptacle having a mass of the particles, to a subject's respiratory tract, wherein the particles deliver at least about 50% of the mass of particles.

In another embodiment, the invention is drawn to a method of delivering an agent to the pulmonary system, in a single, breath comprising: a) providing particles comprising an agent; and b) administering the particles, from a receptacle having a mass of the particles, to a subject's respiratory tract, wherein the particles deliver at least about 5 milligrams of an agent. In other embodiments, the particles deliver at least about 7 milligrams of an agent, at least about 10 milligrams of an agent, at least about 15 milligrams of an agent, at least about 20 milligrams of an agent or at least about 25 milligrams of an agent. Higher amounts of agent can also be delivered, for example, the particles can deliver at least about 35, at least about 40 or at least about 50 milligrams of an agent.

In another embodiment, the invention is drawn to a method of delivering an agent to the pulmonary system comprising: a) providing carrier particles having a tap density of less than 0.4 g/cm.sup.3; b) providing a composition which comprises at least one agent; c) mixing the carrier particles in a) and the composition in b) to form a respirable composition; and d) administering the respirable composition in c) to the respiratory tract of a subject. As used herein, the term "respirable composition" refers to a composition which is suitable for delivery to the respiratory tract of a subject.

The invention is also drawn to respirable compositions which are capable of being delivered to the pulmonary system. The respirable compositions of the invention preferably include carrier particles having a tap density less than 0.4 g/cm.sup.3 and a composition comprising an agent. In one embodiment, the carrier particles which are included in the respirable compositions can be prepared separately without an agent and then mixed with a composition containing an agent.

In one embodiment, the particles of the invention are administered from a receptacle having, holding, containing or enclosing a mass of particles. Receptacles which have a volume of at least about 0.37cm.sup.3 can be employed in the invention. Larger receptacles having a volume of at least about 0.48 cm.sup.3, 0.67 cm.sup.3 or 0.95 cm.sup.3 can also be employed. The receptacles preferably have a design suitable for use in a dry powder inhaler.

In another embodiment, the energy holding the particles of the dry powder in an aggregated state is such that a patient's breath, over a reasonable physiological range of inhalation flow rates, is sufficient to deaggregate the powder contained in the receptacle into respirable particles. The deaggregated particles can penetrate via the patient's breath into and deposit in the airways and/or deep lung with high efficiency.

In a preferred embodiment of the invention, the particles have a tap density of less than about 0.4 g/cm.sup.3, preferably around 0.1 g/cm.sup.3 or less. In another embodiment, the particles have a mass median geometric diameter (MMGD) larger than 5 .mu.m, preferably around about 10 .mu.m or larger. In yet another embodiment, the particles have a mass median aerodynamic diameter (MMAD) ranging from about 1 .mu.m to about 5 .mu.m.

In one embodiment, the carrier particles have about a 10 micron diameter and a density of about 0.001 g/cm.sup.3 and an aerodynamic diameter of about 0.3 microns, preferably about 0.001 to about 0.3 microns (about 10 to about 300 nanometers) or about 0.001 to about 0.2 microns. The carrier particles are not considered respirable in this range. Submicron particles are capable of conferring sufficient density to bring the non-respirable carrier particles into the respirable range. In one embodiment, the density of the submicron particles are, for example, about 1 g/cm.sup.3. Such carrier particles are designed to ensure that a therapeutic amount of nanometer-sized agent would not adversely affect aerodynamic performance of the carrier particle when the agent is adhered to the surface, adsorbed on to the surface or chemically associated with the carrier particle. For example, to address this concern, carrier particles are designed with about a 10 .mu.m diameter and a very low density (of about 0.001 g/cm.sup.3) which by itself might produce particles with a much smaller aerodynamic size (for example, 0.3 .mu.m) that fall below the 1-5 .mu.m respirable range. However, upon inclusion of enough nanometer-sized submicron particles (for example, about 10-200 nm) which have a greater density (for example, about 1 g/cm.sup.3) and comprise agent, the resulting particles would be engineered to fall within the size and porosity range required. In this way, larger loads of agent are accomodated. While not being bound to one explanation, it is believed that because of the small particle size of the micronized particles, the number of particle-particle contact points within a given volume is large relative to the powders made of larger particles. Powders with small particle size require large energies to be dispersed into an aerosol cloud. The effect of the large energy requirement of such powders is that both a large device and a small dose mass is necessary.

The invention has numerous advantages. For example, a large single dose of an agent (for example, a therapeutic agent, a prophylactic agent, a diagnostic agent, a prognostic agent) can be administered to the pulmonary system via a DPI with high efficiency. The invention employs a simple, cost-effective device for pulmonary delivery which increases efficiency and minimizes wasted drug. Since dosage frequency can be reduced by the delivery method of the invention, patient compliance to treatment or prophylaxis protocols is expected to improve. Pulmonary delivery advantageously can eliminate the need for injection. For example, the requirement for daily insulin injections can be avoided. Also, the enhancing properties of the particles themselves can result in a dose advantage where the amount of agent needed to achieve the therapeutic, prophylactic, diagnostic or prognostic effect is actually reduced. Examples 5-9 disclose such an effect with L-Dopa. This dose advantage can produce at least a 2-fold increase in bioavailability (for example, plasma level bioavailablity) as well as in therapeutical advantages in comparison with other modes of administration, especially oral administration. Still further, the combination of a highly efficient delivery and a dose advantage potentiate an agent's effectiveness beyond presently known levels. Also, the fact that the particles can be used as carriers for a variety of agents underscores the broad applicability of the instant invention.

DETAILED DESCRIPTION OF THE INVENTION

The features and other details of the invention, either as steps of the invention or as combination of parts of the invention, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular embodiments of the invention are shown by way of illustration and not as limitations of the invention. The principle feature of this invention may be employed in various embodiments without departing from the scope of the invention. This application also is related to U.S. patent application Ser. No. 09/665,252 entitled Pulmonary Delivery in Treating Disorders of the Central Nervous System filed Sep. 19, 2000 and to its Continuation-in-Part application Ser. No. 09/877,734 with the same title and inventors filed on even date as the instant application. The entire teachings of said applications are incorporated in their entirety by reference herein.

The invention is related to methods of delivery to the pulmonary system of subject particles. The invention is also related to respirable compositions which comprise carrier particles and which are capable of being delivered to the pulmonary system.

In one embodiment, the particles of the invention comprise an agent. As used herein, the term "agent" includes, but is not limited to, therapeutic agents, prophylactic agents, diagnostic agents and prognostic agents. The invention is also related to agents which themselves comprise particles delivered by this method. Depending upon the intended use, the agent may be in the form of, but not limited to, a dry powder (for example, a particulate powder), particles (such as, but not limited to, micronized particles, submicron particles, nanometer-sized particles, liposomes, microspheres, microparticles, micelles, and beads), crystals, a liquid solution, a suspension or an emulsion. The term "agent" includes bioactive agents. As used herein, the term "bioactive" refers to having an effect on a living organism, for example, a mammal and in particular a human subject. Agents in the form of particles or particulate powders may be prepared by milling, filtering, evaporating, extracting, and spray drying as well as other techniques known to those skilled in the art. In one embodiment, the agent is non-crystalline, for example, the agent does not have a crystalline structure or does not comprise crystals.

Some examples of suitable bioactive agents include drugs (for example, hydrophobic drugs, hydrophilic drugs), pharmaceutical formulations, vitamins, pharmaceutical adjuvants, proteins, peptides, polypeptides, hormones, amino acids, nucleic acids, vaccine formulations, inactivated viruses, phospholipids, surfactants and any combinations thereof. Other examples of agents include synthetic compounds, inorganic compounds and organic compounds.

This invention also relates to the preparation of unique particles by spray drying. The unique properties of the particles which give them their excellent respirability, flowability and dispersibility are maintained whether the agent is (1) part of the spray-drying pre-mixture and thereby incorporated into the particles, (2) added to separately-prepared particles so that the agent is adhered onto or in chemical association with the particles or (3) blended so that the agent is mixed with, and co-delivered with the particles. The chemical association includes, but is not limited to, ionic interactions, attraction of charged particles and/or agent, dipole-dipole interactions, Van der Waals forces, covalent interactions, adsorption and hydrogen bonding.

Unlike particles known in the art, the dry particles of the instant invention are versatile. For example, the particles of the invention can incorporate an agent, carry an agent or co-deliver an agent or any combination thereof. In one embodiment, the co-delivered particles may be described as escorts that accompany at least one agent to the desired deposition site in the lung. For example, lactose is an approved, commercially-available carrier. However, lactose cannot be efficiently delivered to the deep lung. The particles of the instant invention do reach the deep lung and are capable of escorting, accompanying and/or co-delivering the desired agent to its desired deposition site. Several examples are provided herein. In this respect, the particles of the instant invention, when used as carriers, have advantages and offer options that other carriers, including lactose, do not.

The particles of the invention are capable of carrying surprisingly high loads of agent. The particles of the invention are also highly dispersible and are capable of targeting regions in the respiratory system. Compositions used in the methods of the invention comprising dry particles carrying surprisingly high loads of agent are also capable of targeting to particular regions of the respiratory system, for example, upper airways, central airways and/or deep lung.

By considering the individual properties of the particles of the invention and agent, the compositions may be optimized for successful pulmonary administration. Compositions comprising highly-dispersible particles can optionally include additional particles and/or agents. It is understood that compositions comprising the particles of the invention include particles with or without agent. If present, the agent may be, among other things, (1) incorporated into the particles, (2) adsorbed, adhered onto or in chemical association with the particles, and/or (3) blended so that the agent is mixed with, and co-delivered with the particles.

As described herein, compositions comprising the particles of the invention, especially highly dispersible particles as defined herein, can further comprise an agent. In one embodiment, compositions comprising the particles of the invention comprise at least one additional agent. As indicated, the compositions comprising the particles of the invention can incorporate an agent in the particles, carry an agent with the particles and/or co-deliver an agent or any combination thereof. Examples of agents include, but are not limited to, therapeutic agents, prophylactic agents, diagnostic agents and prognostic agents. Suitable agents also include bioactive agents. Some examples of suitable bioactive agents include but are not limited to drugs (e.g., hydrophobic drugs, hydrophilic drugs), pharmaceutical formulations, vitamins, pharmaceutical adjuvants, proteins, peptides, polypeptides, hormones, amino acids, nucleic acids, vaccine formulations, inactivated viruses, lung surfactants and any combinations thereof. Other examples include synthetic compounds, inorganic compounds and organic compounds, proteins and peptides, polysaccharides and other sugars, lipids, and DNA and RNA nucleic acid sequences having therapeutic, prophylactic, diagnostic and/or prognostic activities. Nucleic acid sequences include genes, antisense molecules which bind to complementary DNA to inhibit transcription, and ribozymes. The drugs include hydrophobic and hydrophilic drugs.

Agents, including agents incorporated into, adhered onto, in chemical association with, and/or blended and co-delivered with the particles of the invention can have a variety of biological activities. Such agents include, but are not limited to, vasoactive agents, neuroactive agents, hormones, anticoagulants, immunomodulating agents, cytotoxic agents, prophylactic agents, antibiotics, antiviral agents, antisense agents, antigens, and antibodies, such as, for example, monoclonal antibodies, e.g., palivizumab (Medimmune, Gaithersberg, Md.). In some instances, the proteins may be antibodies or antigens which otherwise would have to be administered by injection to elicit an appropriate response. Compounds with a wide range of molecular weight can be encapsulated, for example, between 100 and 500,000 Daltons. Proteins are defined herein as consisting of 100 amino acid residues or more; peptides are less than 100 amino acid residues. Unless otherwise stated, the term protein refers to both proteins and peptides. Examples include insulin and other hormones. Polysaccharides, such as heparin, can also be administered.

The particles, especially the highly dispersible particles described herein, may include a bioactive agent suitable for systemic treatment. Alternatively, the particles can include a bioactive agent for local delivery within the lung, such as, for example, agents for the treatment of asthma, emphysema, or cystic fibrosis, or for systemic treatment. For example, genes for the treatment of diseases such as cystic fibrosis can be administered, as can beta agonists for asthma. Other specific bioactive agents include, but are not limited to, growth hormone (e.g., mammalian growth hormone, in particular human growth hormone), interleukins, insulin, calcitonin, luteinizing hormone releasing hormone ("LHRH") or gonadotropin-releasing hormone ("LHRH") and analogs thereof (e.g. leoprolide), granulocyte colony-stimulating factor ("G-CSF"), parathyroid hormone-related peptide, somatostatin, testosterone, progesterone, estradiol, nicotine, fentanyl, norethisterone, clonidine, scopolamine, salicylate, cromolyn sodium, salmeterol, formeterol, ipratropium bromide, albuterol (including albuterol sulfate), fluticasone, valium, alprazolam and levodopa (L-Dopa). Other suitable therapeutic and/or prophylatic agents include, but are not limited to those listed in U.S. Pat. No. 5,875,776, and U.S. application Ser. No. 09/665,252 filed Sep. 19, 2000 the entire teachings of which are incorporated herein by reference. Those therapeutic agents which are charged, such as most of the proteins, including insulin, can be administered as a complex between the charged agent and a molecule of opposite charge. Preferably, the molecule of opposite charge is a charged lipid or an oppositely-charged protein. The particles can incorporate substances such as lipids which allow for the sustained release of small and large molecules. Addition of these complexes or substances is applicable to particles of any size and shape, and is especially useful for altering the rate of release of therapeutic agents from inhaled particles.

Any of a variety of diagnostic and/or prognostic agents can be incorporated within the highly dispersible particles, which can locally or systemically deliver the incorporated agents, following administration to a patient. Alternatively, diagnostic and/or prognostic agents can be carried with, adhered onto, chemically-associated with, and/or co-delivered with the highly dispersible particles of the invention. Particles incorporating diagnostic agents can be detected using standard techniques available in the art and commercially available equipment.

In one embodiment, a composition comprising the particles of the invention further comprises a diagnostic and/or prognostic agent. The diagnostic and/or prognostic agent can comprise a label, including, but not limited to, a radioisotope, an epitope label, an affinity label, a spin label, an enzyme label, a fluorescent group and a chemiluminescent group. In one embodiment, the label is a radioisotope, for example, .sup.99mTc. It is understood that additional labels are well known in the art and are encompassed by the present invention.

Any biocompatible or pharmacologically acceptable gas, for example, can be incorporated into the particles or trapped in the pores of the particles using technology known to those skilled in the art. The term gas refers to any compound which is a gas or is capable of forming a gas at the temperature at which imaging is being performed. In one embodiment, retention of gas in the particles is improved by forming a gas-impermeable barrier around the particles. Such barriers are well known to those of skill in the art.

Other imaging agents which may be utilized include commercially available agents used in positron emission tomography (PET), computer-assisted tomography (CAT), single photon emission computerized tomography, x-ray, fluoroscopy, and magnetic resonance imaging (MRI).

Examples of suitable materials for use as contrast agents in MRI include gadolinium chelates, such as diethylene triamine pentacetic acid (DTPA) and gadopentotate dimeglumine, as well as iron, magnesium, manganese, copper and chromium.

Examples of materials useful for CAT and x-rays include iodine-based materials for intravenous administration, such as ionic monomers typified by diatrizoate and iothalamate, non-ionic monomers such as iopamidol, isohexol, and ioversol, non-ionic dimers, such as iotrol and iodixanol, and ionic dimers, for example, ioxagalte.

Agents also include targeting molecules which can be attached to the particles via reactive functional groups on the particles. Targeting molecules permit binding interaction of the particle with specific receptor sites, such as those within the lungs. The particles can be targeted by attachment of ligands which specifically or non-specifically bind to particular targets. Exemplary targeting molecules include antibodies (e.g., polyclonal sera, monoclonal, chimeric, humanized, human) and fragments thereof (e.g., Fab, Fab', F(ab').sub.2, Fv), including antibody variable regions, lectins, and hormones or other organic molecules capable of specific binding, for example, to receptors on the surfaces of the target cells.

Agents, and in particular bioactive agents, can also include surfactants, such as surfactants which are endogenous to the lung. Both naturally-occurring and synthetic lung surfactants are encompassed in the scope of the invention.

The methods of the invention also relate to administering to the respiratory tract of a subject, particles and/or compositions comprising the particles of the invention, which can be enclosed in a receptacle. As described herein, in certain embodiments, the invention is drawn to methods of delivering the particles of the invention, while in other embodiments, the invention is drawn to methods of delivering respirable compositions comprising the particles of the invention. As used herein, the term "receptacle" includes but is not limited to, for example, a capsule, blister, film covered container well, chamber and other suitable means of storing particles, a powder or a respirable composition in an inhalation device known to those skilled in the art.

In a preferred embodiment, the receptacle is used in a dry powder inhaler. Examples of dry powder inhalers that can be employed in the methods of the invention include but are not limited to, the inhalers disclosed is U.S. Pat. Nos. 4,995,385 and 4,069,819, the Spinhaler.RTM. (Fisons, Loughborough, U.K.), Rotahaler.RTM. (Glaxo-Wellcome, Research Triangle Technology Park, N.C.), FlowCaps.RTM. (Hovione, Loures, Portugal), Inhalator.RTM. (Boehringer-Ingelheim, Germany), and the Aerolizer.RTM. (Novartis, Switzerland), the Diskhaler (Glaxo-Wellcome, RTP, NC) and others known to those skilled in the art. In one embodiment, the inhaler employed is described in U.S. Patent Application Ser. No. 09/835,302, entitled Inhalation Device and Method, by David A. Edwards, et al., filed on Apr. 16, 2001. The entire contents of this application are incorporated by reference herein.

In one embodiment, the volume of the receptacle is at least about 0.37 cm.sup.3.

In another embodiment, the volume of the receptacle is at least about 0.48 cm.sup.3. In yet another embodiment, are receptacles having a volume of at least about 0.67 cm.sup.3 or 0.95 cm.sup.3. The invention is also drawn to receptacles which are capsules, for example, capsules designated with a particular capsule size, such as 2, 1, 0, 00 or 000. Suitable capsules can be obtained, for example, from Shionogi (Rockville, Md.). Blisters can be obtained, for example, from Hueck Foils, (Wall, N.J.). Other receptacles and other volumes thereof suitable for use in the instant invention are known to those skilled in the art.

The receptacle encloses or stores particles and/or respirable compositions comprising particles. In one embodiment, the particles and/or respirable compositions comprising particles are in the form of a powder. The receptacle is filled with particles and/or compositions comprising particles, as known in the art. For example, vacuum filling or tamping technologies may be used. Generally, filling the receptacle with powder can be carried out by methods known in the art. In one embodiment of the invention, the particles, powder or respirable composition which is enclosed or stored in a receptacle has a mass of at least about 5 milligrams. Preferably, the mass of the particles or respirable compositions stored or enclosed in the receptacle is at least about 10 milligrams.

In one embodiment of the invention, the receptacle encloses a mass of particles, especially a mass of highly dispersible particles as described herein. The mass of particles comprises a nominal dose of an agent. As used herein, the phrase "nominal dose" means the total mass of an agent which is present in the mass of particles in the receptacle and represents the maximum amount of agent available for administration in a single breath.

Particles and/or respirable compositions comprising particles are stored or enclosed in the receptacles and are administered to the respiratory tract of a subject. As used herein, the terms "administration" or "administering" of particles and/or respirable compositions refer to introducing particles to the respiratory tract of a subject.

As described herein, in one embodiment, the invention is drawn to a respirable composition comprising carrier particles and an agent. In another embodiment, the invention is drawn to a method of delivering a respirable composition comprising carrier particles and an agent. As used herein, the term "carrier particle" refers to particles which may or may not comprise an agent, and aid in delivery of an agent to a subject's respiratory system, for example, by increasing the stability, dispersibility, aerosolization, consistency and/or bulking characteristics of an agent. It is clear that in certain embodiments, the particles of the invention are carrier particles which are capable of being delivered to the respiratory tract of a subject.

In one embodiment, the invention is drawn to a respirable composition which is formed from the blending or mixing of carrier particles (without an agent) with a composition comprising an agent. This respirable composition can then be administered to the respiratory tract of a subject. In another embodiment, the respirable composition is delivered to a subject's respiratory system, for example, through the use of a dry powder inhaler device. In one embodiment, the respirable composition comprises a composition which includes an agent which is in the form of micronized particles (e.g., submicron particles).

In embodiments where the particles of the invention are carrier particles which are co-administered with an agent, the carrier particles preferably enhance delivery of the agent to a subject's respiratory system (e.g., upper airways, lower airways, deep lungs). In one embodiment, the particles of the invention are carrier particles which are co-administered with an agent and enhance uniform delivery of the agent to a particular region of a subject's respiratory system (for example, the upper airways, central airways, or preferably the deep lungs). Co-administration of the carrier particles of the invention with an agent may also help reduce phagocytosis of the agent by macrophages (for example, alveolar macrophages) and/or increase the dispersibility and aerosolization of the agent (for example, by decreasing particle aggregation or agglomeration).

As described herein, the particles and respirable compositions comprising the particles of the invention may optionally include a surfactant, such as a surfactant which is endogenous to the lung. The particles and respirable compositions comprising the particles of the invention described herein are also preferably biodegradable and biocompatible, and optionally are capable of affecting the biodegradability and/or the rate of delivery of a co-administered agent.

As described herein, the particles, including the carrier particles contained in the respirable compositions described herein, are preferably "aerodynamically light". As described below, "aerodynamically light", as used herein, refers to particles having a tap density of less than 0.4 g/cm.sup.3. In one embodiment, the carrier particles have a tap density of near to or less than about 0.1 g/cm.sup.3. Further descriptions of tap density and methods of measuring tap density are described in greater detail below.

In one embodiment, the particles, including the carrier particles contained in the respirable compositions described herein, preferably have a mass median geometric diameter (MMGD) greater than about 5 .mu.m. In other embodiments, the particles have a MMGD greater than about 5 .mu.m and ranging to about 30 .mu.m or a MMGD ranging from about 10 .mu.m to about 30 .mu.m. Further descriptions of MMGD and methods for calculating the MMGD of the particles are described in greater detail below.

It is understood that the particles and/or respirable compositions comprising the particles of the invention which can be administered to the respiratory tract of a subject can also optionally include pharmaceutically-acceptable carriers, as are well known in the art. The term "pharmaceutically-acceptable carrier" as used herein, refers to a carrier which can be administered to a patient's respiratory system without any significant adverse toxicological effects. Appropriate pharmaceutically-acceptable carriers, include those typically used for inhalation therapy (e.g., lactose) and include pharmaceutically-acceptable carriers in the form of a liquid (e.g., saline) or a powder (e.g., a particulate powder). In one embodiment, the pharmaceutically-acceptable carrier comprises particles which have a mean diameter ranging from about 50 .mu.m to about 200 .mu.m, and in particular lactose particles in this range. It is understood that those of skill in the art can readily determine appropriate pharmaceutically-acceptable carriers for use in administering, accompanying and or co-delivering the particles of the invention.

In one embodiment of the invention, the particles and/or respirable compositions comprising particles, are administered in a single, breath-activated step. As used herein, the phrases "breath-activated" and "breath-actuated" are used interchangeably. As used herein, "a single, breath-activated step" means that particles are dispersed and inhaled in one step. For example, in single, breath-activated inhalation devices, the energy of the subject's inhalation both disperses particles and draws them into the oral or nasopharyngeal cavity. Suitable inhalers which are single, breath-actuated inhalers that can be employed in the methods of the invention include but are not limited to simple, dry powder inhalers disclosed in U.S. Pat. Nos. 4,995,385 and 4,069,819, the Spinhaler.RTM. (Fisons, Loughborough, U.K.), Rotahaler.RTM. (Glaxo-Wellcome, Research Triangle Technology Park, N.C.), FlowCaps.RTM. (Hovione, Loures, Portugal), Inhalator.RTM. (Boehringer-Ingelheim, Germany), and the Aerolizer.RTM. (Novartis, Switzerland), the Diskhaler (Glaxo-Wellcome, RTP, NC) and others, such as known to those skilled in the art. In one embodiment, the inhaler employed is described in U.S. Patent Application SER. No. 09/985,302, entitled Inhalation Device and Method, by David A. Edwards, et al., filed on Apr. 16, 2001. The entire contents of this application are incorporated by reference herein.

"Single breath" administration can include single, breath-activated administration, but also administration during which the particles, respirable compositions or powders are first dispersed, followed by the inhalation or inspiration of the dispersed particles, respirable compositions or powders. In the latter mode of administration, additional energy than the energy supplied by the subject's inhalation disperses the particles. An example of a single breath inhaler which employs energy other than the energy generated by the patient's inhalation is the device described in U.S. Pat. No. 5,997,848 issued to Patton et al. on Dec. 7, 1999, the entire teachings of which are incorporated herein by reference.

In a preferred embodiment, the receptacle enclosing the particles, respirable compositions comprising particles or powder is emptied in a single, breath-activated step. In another preferred embodiment, the receptacle enclosing the particles is emptied in a single inhalation. As used herein, the term "emptied" means that at least 50% of the particle mass enclosed in the receptacle is emitted from the inhaler during administration of the particles to a subject's respiratory system.

In a preferred embodiment of the invention, the particles administered are highly dispersible. As used herein, the phrase "highly dispersible" particles or powders refers to particles or powders which can be dispersed by a RODOS dry powder disperser (or equivalent technique) such that at about 1 Bar, particles of the dry powder emit from the RODOS orifice with geometric diameters, as measured by a HELOS or other laser diffraction system, that are less than about 1.5 times the geometric particle size as measured at 4 Bar. Highly dispersible powders have a low tendency to agglomerate, aggregate or clump together and/or, if agglomerated, aggregated or clumped together, are easily dispersed or de-agglomerated as they emit from an inhaler and are breathed in by the subject. Typically, the highly dispersible particles suitable in the methods of the invention display very low aggregation compared to standard micronized powders which have similar aerodynamic diameters and which are suitable for delivery to the pulmonary system. Properties that enhance dispersibility include, for example, particle charge, surface roughness, surface chemistry and relatively large geometric diameters. In one embodiment, because the attractive forces between particles of a powder varies (for constant powder mass) inversely with the square of the geometric diameter and the shear force seen by a particle increases with the square of the geometric diameter, the ease of dispersibility of a powder is on the order of the inverse of the geometric diameter raised to the fourth power. The increased particle size diminishes interparticle adhesion forces. (Visser, J., Powder Technology, 58:1-10 (1989)). Thus, large particle size, all other things equivalent, increases efficiency of aerosolization to the lungs for particles of low envelope mass density. Increased surface irregularities, and roughness also can enhance particle dispersibility. Surface roughness can be expressed, for example by rugosity.

The particles preferably are biodegradable and biocompatible, and optionally are capable of biodegrading at a controlled rate for delivery of a therapeutic, prophylactic, diagnostic agent or prognostic agent. In addition to an agent, preferably a bioactive agent, the particles can further include a variety of materials. Both inorganic and organic materials can be used. For example, ceramics may be used. Fatty acids may also be used to form aerodynamically light particles. Other suitable materials include, but are not limited to, amino acids, gelatin, polyethylene glycol, trehalose, lactose, and dextran. Preferred particle compositions are further described below. In one embodiment, the particles of the invention are non-polymeric. In another embodiment, respirable compositions include carrier particles which are non-polymeric.

In one embodiment of the invention, particles administered to a subject's respiratory tract have a tap density of less than about 0.4 g/cm.sup.3. Particles having a tap density of less than about 0.4 g/cm.sup.3 are referred to herein as "aerodynamically light". In a preferred embodiment, the particles have a tap density of near to or less than about 0.1 g/cm.sup.3. Tap density is a measure of the envelope mass density characterizing a particle. The envelope mass density of a particle of a statistically isotropic shape is defined as the mass of the particle divided by the minimum sphere envelope volume within which it can be enclosed. Features which can contribute to low tap density include irregular surface texture and hollow or porous structure.

Tap density can be measured by using instruments known to those skilled in the art such as the Dual Platform Microprocessor Controlled Tap Density Tester (Vankel, N.C.). Tap density is a standard measure of the envelope mass density. Tap density can be determined using the method of USP Bulk Density and Tapped Density, United States Pharmacopia convention, Rockville, Md., 10.sup.th Supplement, 4950-4951, 1999. In another embodiment, the particles have a mass median geometric diameter (MMGD) greater than about 5 .mu.m and preferably near to or greater than about 10 .mu.m. In one embodiment, the particles have a MMGD greater than about 5 .mu.m and ranging to about 30 .mu.m. In another embodiment, the particles have a MMGD ranging from about 10 .mu.m to about 30 .mu.m.

In one embodiment, compositions comprising the particles of the instant invention have a dynamic bulk density of 0.1 g/cm.sup.3 or greater and a tap density of less than about 0.4 g/cm.sup.3. In a preferred embodiment, the particles have a dynamic bulk density of greater than 0.1 g/cm.sup.3 and a tap density of near to or less than about 0.1 g/cm.sup.3.

The MMGD of the particles can be measured using an electrical zone sensing instrument such as Coulter Multisizer IIe (Coulter Electronics, Luton, Beds, England) or a laser diffraction instrument (for example Helos, Sympatec, Inc., Princeton, N.J.). The diameter of particles in a sample will range depending upon factors such as particle composition and methods of synthesis. The distribution of size of particles in a sample can be selected to permit optimal deposition within targeted sites within the respiratory tract.

The aerodynamically light particles suitable for use in the instant invention may be fabricated or separated, for example by filtration or centrifugation, to provide a particle sample with a preselected size distribution. For example, greater than 30%, 50%, 70%, or 80% of the particles in a sample can have a diameter within a selected range of at least 5 .mu.m. The selected range within which a certain percentage of the particles must fall may be for example, between about 5 and 30 .mu.m, or optionally between 5 and 15 .mu.m. In one embodiment, at least a portion of the particles have a diameter between about 9 and 11 .mu.m. Optionally, the particle sample also can be fabricated wherein at least 90%, or optionally 95% or 99% of the particles, have a diameter within the selected range. The presence of the higher proportion of the aerodynamically light, larger diameter (at least about 5 .mu.m) particles in the particle sample enhances the delivery of therapeutic prophylactic, diagnostic or prognostic agents which are incorporated into, carried with, adhered to the surface, adsorbed to the surface and/or co-delivered with, the particles to the deep lung.

In one embodiment, in the particle sample, the interquartile range may be 2 .mu.m, with a mean diameter for example, between about 7.5 and 13.5 .mu.m. Thus, for example, between at least 30% and 40% of the particles may have diameters within the selected range. Preferably, the said percentages of particles have diameters within a 1 .mu.m range, for example, between 6.0 and 7.0 .mu.m, 10.0 and 11.0 .mu.m or 13.0 and 14.0 .mu.m.

In a further embodiment, the particles have an aerodynamic diameter ranging from about 1 .mu.m to about 5 .mu.m. The aerodynamic diameter, d.sub.aer, can be calculated from the equation: d.sub.aer=d.sub.g .rho..sub.tap where d.sub.g is the geometric diameter, for example the MMGD and .rho. is the powder density. Experimentally, aerodynamic diameter can be determined by employing a gravitational settling method, whereby the time for an ensemble of particles to settle a certain distance is used to directly infer the aerodynamic diameter of the particles. An indirect method for measuring the mass median aerodynamic diameter (MMAD) is the multi-stage liquid impinger (MSLI).

In one embodiment, the particles of the invention have a dynamic bulk density greater than 0.1 g/cm.sup.3.

In one embodiment of the invention, at least 50% of the mass of the particles stored in a receptacle are delivered to a subject's respiratory tract in a single, breath-activated step. Preferably, at least 55% of the mass of particles is delivered.

In another embodiment of the invention, at least 5 milligrams and preferably at least 7 milligrams or at least 10 milligrams of agent, preferably a bioactive agent, is delivered by administering, in a single breath, to a subject's respiratory tract particles enclosed in the receptacle. Amounts of at least 15, preferably of at least 20 and more preferably of at least 25, 30, 35, 40 and 50 milligrams can be delivered. In a preferred embodiment, amounts of at least 35 milligrams are delivered. In another preferred embodiment, amounts of at least 50 milligrams are delivered.

Particles administered to the respiratory tract of the subject are delivered to the pulmonary system. Particles suitable for use in the methods of the invention can travel through the upper airways (oropharynx and larynx), the lower airways which include the trachea followed by bifurcations into the bronchi and bronchioli and through the terminal bronchioli which in turn divide into respiratory bronchioli leading then to the ultimate respiratory zone, the alveoli or the deep lung. In one embodiment of the invention, most of the mass of particles deposit in the deep lung. In another embodiment of the invention, delivery is primarily to the central airways. In another embodiment, delivery is to the upper airways.

The particles suitable for use in the instant invention may be fabricated with the appropriate material, surface roughness, diameter and tap density for localized delivery to selected regions of the respiratory tract such as the deep lung, central or upper airways. For example, higher density or larger particles may be used for upper airway delivery, or a mixture of different-sized particles in a sample, provided with the same or a different agent may be administered to target different regions of the lung in one administration. Particles with degradation and release times ranging from seconds to months can be designed and fabricated, based on factors such as the particle material.

Delivery to the pulmonary system of particles in a single, breath-actuated step is enhanced by employing particles which are dispersed at relatively low energies, such as, for example, at energies typically supplied by a subject's inhalation. Such energies are referred to herein as "low". As used herein, "low energy administration" refers to administration wherein the energy applied to disperse and inhale the particles is in the range typically supplied by a subject during inhaling.

In one embodiment of the invention, highly dispersible particles which are administered to a subject comprise a bioactive agent and a biocompatible, and preferably biodegradable polymer, copolymer, or blend. The polymers may be tailored to optimize different characteristics of the particles including: i) interactions between the agent to be delivered and the polymer to provide stabilization of the agent and retention of activity upon delivery; ii) rate of polymer degradation and, thereby, rate of drug release profiles; iii) surface characteristics and targeting capabilities via chemical modification; and iv) particle porosity.

Surface eroding polymers such as polyanhydrides may be used to form particles. For example, polyanhydrides such as poly[(p-carboxyphenoxy)-hexane anhydride] (PCPH) may be used. Biodegradable polyanhydrides are described in U.S. Pat. No. 4,857,311. Bulk eroding polymers such as those based on polyesters including poly(hydroxy acids) also can be used. For example, polyglycolic acid (PGA), polylactic acid (PLA), or copolymers thereof may be used to form the particles. The polyester may also have a charged or functionalizable group, such as an amino acid. In a preferred embodiment, particles with controlled release properties can be formed of poly(D,L-lactic acid) and/or poly(D,L-lactic-co-glycolic acid) ("PLGA") which incorporate a surfactant such as dipalmitoyl phosphatidylcholine (DPPC).

Other polymers include polyamides, polycarbonates, polyalkylenes such as polyethylene, polypropylene, poly(ethylene glycol), poly(ethylene oxide), poly(ethylene terephthalate), poly vinyl compounds such as polyvinyl alcohols, polyvinyl ethers, and polyvinyl esters, polymers of acrylic and methacrylic acids, celluloses and other polysaccharides, and peptides or proteins, or copolymers or blends thereof. Polymers may be selected with or modified to have the appropriate stability and degradation rates in vivo for different controlled drug delivery applications.

Highly dispersible particles can be formed from functionalized polyester graft copolymers, as described in Hrkach et al., Macromolecules, 28:4736-4739 (1995); and Hrkach et al., "Poly(L-Lactic acid-co-amino acid) Graft Copolymers: A Class of Functional Biodegradable Biomaterials," Hydrogels and Biodegradable Polymers for Bioapplications, ACS Symposium Series No. 627, Raphael M. Ottenbrite et al., Eds., American Chemical Society, Chapter 8, pp. 93-101, 1996.

In a preferred embodiment of the invention, highly dispersible particles including a bioactive agent and a phospholipid are administered. Examples of suitable phospholipids include, among others, those listed in U.S. patent application Ser. No. 09/665,252 filed on Sep. 19, 2000 described above. Other suitable phospholipids include phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols, phosphatidylserines, phosphatidylinositols and combinations thereof. Specific examples of phospholipids include but are not limited to phosphatidylcholines dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylethanolamine (DPPE), distearoyl phosphatidylcholine (DSPC), dipalmitoyl phosphatidyl glycerol (DPPG) or any combination thereof. Other phospholipids are known to those skilled in the art. In a preferred embodiment, the phospholipids are endogenous to the lung.

The phospholipid, can be present in the particles in an amount ranging from about 0 to about 90 weight %. More commonly it can be present in the particles in an amount ranging from about 10 to about 60 weight %.

In another embodiment of the invention, the phospholipids or combinations thereof are selected to impart controlled release properties to the highly dispersible particles. The phase transition temperature of a specific phospholipid can be below, around or above the physiological body temperature of a patient. Preferred phase transition temperatures range from 30.degree. C. to 50.degree. C., (e.g., within .+-.10.degree. C. of the normal body temperature of patient). By selecting phospholipids or combinations of phospholipids according to their phase transition temperature, the particles can be tailored to have controlled release properties. For example, by administering particles which include a phospholipid or combination of phospholipids which have a phase transition temperature higher than the patient's body temperature, the release of dopamine precursor, agonist or any combination of precursors and/or agonists can be slowed down. On the other hand, rapid release can be obtained by including in the particles phospholipids having lower transition temperatures. Particles having controlled release properties and methods of modulating release of a biologically active agent are described in U.S. Provisional Patent Application No. 60/150,742 entitled Modulation of Release From Dry Powder Formulations by Controlling Matrix Transition, filed on Aug. 25, 1999, the contents of which are incorporated herein in their entirety.

In another embodiment of the invention the particles can include a surfactant. As used herein, the term "surfactant" refers to any agent which preferentially absorbs to an interface between two immiscible phases, such as the interface between water and an organic polymer solution, a water/air interface or organic solvent/air interface. Surfactants generally possess a hydrophilic moiety and a lipophilic moiety, such that, upon absorbing to microparticles, they tend to present moieties to the external environment that do not attract similarly-coated particles, thus reducing particle agglomeration.

In addition to lung surfactants, such as, for example, phospholipids discussed above, suitable surfactants include but are not limited to hexadecanol; fatty alcohols such as polyethylene glycol (PEG); polyoxyethylene-9-lauryl ether; a surface active fatty acid, such as palmitic acid or oleic acid; glycocholate; surfactin; a poloxomer; a sorbitan fatty acid ester such as sorbitan trioleate (Span 85); and tyloxapol.

The surfactant can be present in the particles in an amount ranging from about 0 to about 90 weight %. Preferably, it can be present in the particles in an amount ranging from about 10 to about 60 weight %.

Methods of preparing and administering particles which are aerodynamically light and include surfactants, and, in particular phospholipids, are disclosed in U.S. Pat. No 5,855,913, issued on Jan. 5, 1999 to Hanes et al. and in U.S. Pat. No. 5,985,309, issued on Nov. 16, 1999 to Edwards et al. The teachings of both are incorporated herein by reference in their entirety. Methods of administering particles to patients in acute distress are disclosed. The highly dispersible particles being administered in the instant invention are capable of being delivered to the lung and absorbed into the system when other conventional means of delivering drugs fail.

In yet another embodiment, highly dispersible particles only including a bioactive agent and surfactant are administered. Highly dispersible particles may be formed of the surfactant and include a therapeutic prophylactic, or diagnostic agent, to improve aerosolization efficiency due to reduced particle surface interactions, and to potentially reduce loss of the agent due to phagocytosis by alveolar macrophages.

In another embodiment of the invention, highly dispersible particles including an amino acid are administered. Hydrophobic amino acids are preferred. Suitable amino acids include naturally occurring and non-naturally occurring hydrophobic amino acids. Some naturally occurring hydrophobic amino acids, including but not limited to, non-naturally occurring amino acids include, for example, beta-amino acids. Both D, L and racemic configurations of hydrophobic amino acids can be employed. Suitable hydrophobic amino acids can also include amino acid analogs. As used herein, an amino acid analog includes the D or L configuration of an amino acid having the following formula: --NH--CHR--CO--, wherein R is an aliphatic group, a substituted aliphatic group, a benzyl group, a substituted benzyl group, an aromatic group or a substituted aromatic group and wherein R does not correspond to the side chain of a naturally-occurring amino acid. As used herein, aliphatic groups include straight chained, branched or cyclic C1-C8 hydrocarbons which are completely saturated, which contain one or two heteroatoms such as nitrogen, oxygen or sulfur and/or which contain one or more units of desaturation. Aromatic groups include carbocyclic aromatic groups such as phenyl and naphthyl and heterocyclic aromatic groups such as imidazolyl, indolyl, thienyl, furanyl, pyridyl, pyranyl, oxazolyl, benzothienyl, benzofuranyl, quinolinyl, isoquinolinyl and acridintyl.

Suitable substituents on an aliphatic, aromatic or benzyl group include --OH, halogen (--Br, --Cl, --I and --F), --O(aliphatic, substituted aliphatic, benzyl, substituted benzyl, aryl or substituted aryl group), --CN, --NO.sub.2, --COOH, --NH.sub.2, --NH(aliphatic group, substituted aliphatic, benzyl, substituted benzyl, aryl or substituted aryl group), --N(aliphatic group, substituted aliphatic, benzyl, substituted benzyl, aryl or substituted aryl group).sub.2, --COO(aliphatic group, substituted aliphatic, benzyl, substituted benzyl, aryl or substituted aryl group), --CONH.sub.2, --CONH(aliphatic, substituted aliphatic group, benzyl, substituted benzyl, aryl or substituted aryl group), --SH, --S(aliphatic, substituted aliphatic, benzyl, substituted benzyl, aromatic or substituted aromatic group) and --NH--C(.dbd.NH)--NH.sub.2. A substituted benzylic or aromatic group can also have an aliphatic or substituted aliphatic group as a substituent. A substituted aliphatic group can also have a benzyl, substituted benzyl, aryl or substituted aryl group as a substituent. A substituted aliphatic, substituted aromatic or substituted benzyl group can have one or more substituents. Modifying an amino acid substituent can increase, for example, the lypophilicity or hydrophobicity of natural amino acids which are hydrophilic.

A number of the suitable amino acids, amino acids analogs and salts thereof can be obtained commercially. Others can be synthesized by methods known in the art. Synthetic techniques are described, for example, in Green and Wuts, "Protecting Groups in Organic Synthesis", John Wiley and Sons, Chapters 5 and 7, 1991.

Hydrophobicity is generally defined with respect to the partition of an amino acid between a nonpolar solvent and water. Hydrophobic amino acids are those acids which show a preference for the nonpolar solvent. Relative hydrophobicity of amino acids can be expressed on a hydrophobicity scale on which glycine has the value 0.5. On such a scale, amino acids which have a preference for water have values below 0.5 and those that have a preference for nonpolar solvents have a value above 0.5. As used herein, the term hydrophobic amino acid refers to an amino acid that, on the hydrophobicity scale, has a value greater or equal to 0.5, in other words, has a tendency to partition in the nonpolar acid which is at least equal to that of glycine.

Examples of amino acids which can be employed include, but are not limited to: glycine, proline, alanine, cysteine, methionine, valine, leucine, tyrosine, isoleucine, phenylalanine, tryptophan. Preferred hydrophobic amino acids include leucine, isoleucine, alanine, valine, phenylalanine and glycine. Combinations of hydrophobic amino acids can also be employed. Furthermore, combinations of hydrophobic and hydrophilic (preferentially partitioning in water) amino acids, where the overall combination is hydrophobic, can also be employed.

The amino acid can be present in the particles of the invention in an amount of at least 10 weight %. Preferably, the amino acid can be present in the particles in an amount ranging from about 20 to about 80 weight %. The salt of a hydrophobic amino acid can be present in the particles of the invention in an amount of at least 10 weight percent. Preferably, the amino acid salt is present in the particles in an amount ranging from about 20 to about 80 weight %. In preferred embodiments the particles have a tap density of less than about 0.4 g/cm.sup.3.

Methods of forming and delivering particles which include an amino acid are described in U.S. patent application Ser. No. 09/382,959, filed on Aug. 25, 1999, entitled Use of Simple Amino Acids to Form Porous Particles During Spray Drying, the teachings of which are incorporated herein by reference in their entirety.

The particles of the invention can also include excipients such as one or more of the following; a sugar, such as lactose, a protein, such as albumin, cholesterol and/or a surfactant.

If the agent to be delivered is negatively charged (such as insulin), protamine or other positively charged molecules can be added to provide a lipophilic complex which results in the sustained release of the negatively charged agent. Negatively charged molecules can be used to render insoluble positively charged agents.

Highly dispersible particles suitable for use in the methods of the invention may be prepared using single and double emulsion solvent evaporation, spray drying, solvent extraction, solvent evaporation, phase separation, simple and complex coacervation, interfacial polymerization, supercritical carbon dioxide (CO.sub.2) and other methods well known to those of ordinary skill in the art. Particles may be made using methods for making microspheres or microcapsules known in the art, provided that the conditions are optimized for forming particles with the desired aerodynamic properties (e.g., aerodynamic diameter) or additional steps are performed to select particles with the density and diameter sufficient to provide the particles with an aerodynamic diameter between one and five microns, preferably between one and three microns.

With some polymeric systems, polymeric particles prepared using a single or double emulsion technique vary in size depending on the size of the droplets. If droplets in water-in-oil emulsions are not of a suitably small size to form particles with the desired size range, smaller droplets can be prepared, for example, by sonication or homogenization of the emulsion, or by the addition of surfactants.

If the particles prepared by any of the above methods have a size range outside of the desired range, particles can be sized, for example, using a sieve, and further separated according to density using techniques known to those of skill in the art.

The particles are preferably prepared by spray drying.

The following equipment and reagents are referred to herein and for convenience will be listed once with the pertinent information. Unless otherwise indicated, all equipment was used as directed in the manufacturer's instructions. Also, unless otherwise indicated, other similar equipment can be used as well know to those skilled in the art.

Unless otherwise indicated, all equipment and reagents were used as directed in the manufacturer's instructions. Further, unless otherwise indicated, that suitable substitution for said equipment and reagents would be available and well know to those skilled in the art. (1) RODOS dry powder disperser (Sympatec Inc., Princeton, N.J.) (2) HELOS laser diffractometer (Sympatec Inc., N.J.) (3) Single-stage Andersen impactor (Andersen Inst., Sunyra, Ga.) (4) AeroDisperser (TSI, Inc., Amherst, Mass.) (5) Aerosizer (TSI Inc., Amherst, Mass.) (6) blister pack machine, Fantasy Blister Machine (Schaefer Tech, Inc., Indianapolis, Ind.) (7) collapsed Andersen cascade impactor (consisting of stage 0 as defined by manufacturer) and the filter stage (Anderson Inst., Sunyra, Ga.) (8) a spirometer (Spirometrics, USA, Auburn, Me.) (9) a multistage liquid impinger (MSLI) (Erweka, USA, Milford, Conn.) (10) fluorescent spectroscope (Hitachi Instruments, San Jose, Calif.) (11) gamma camera (generic) Reagents albuterol sulfate particles (Profarmco Inc., Italy) human growth hormone (Eli Lilly, Indianapolis, Ind.) size #2 methyl cellulose capsules (Shionogi, Japan) blister packs (Heuck Foils, Well, N.J.) DPPC (Avanti, Alabaster, Ala.)

As discussed in more detail in the Example section below, the methods of the instant invention require powders which exhibit good aerosolization properties from a simple inhaler device. In order to determine if a powder has the appropriate aerosolization properties, the powder is tested for deaggregation and emission properties. Although those skilled in the art will recognize equivalent means to measure these properties, an example of an in vitro test which demonstrates delivery of a mass of powder onto an impactor is performed. The powder to be tested is introduced into a powder dispensing apparatus, for example a RODOS dry powder disperser at varying shear forces. This is accomplished by manipulating the regulator pressure of the air stream used to break up the particles. The geometric size is measured to determine whether a powder has successfully deaggregated under the conditions. In addition to the deaggregation properties, it is possible to evaluate the ability of a powder to emit from a simple, breath-activated inhaler. Examples of inhalers suitable for the practice of the instant invention are the Spinhaler.RTM. (Fisons, Loughborough, U.K.), Rotahaler.RTM. (Glaxo-Wellcome, Research Triangle Park (RTP), N.C.), FlowCaps.RTM. (Hovione, Loures, Portugal), Inhalator.RTM. (Boehringer-Ingelheim, Germany), and the Aerolizer.RTM. (Novartis, Switzerland). It will be appreciated that other inhalers such as the Diskhaler (Glaxo-Wellcome, RTP, N.C.) may also be used. Especially suitable inhalers are the simple, dry powder inhalers (U.S. Pat. Nos. 4,995,385 and 4,069,819). A specific non-limiting example describing an experiment to determine the deaggregation and emission properties of three different powders is described in further detail herein. Briefly, three different dry powders believed to have different deaggregation properties were characterized. The first powder was micronized albuterol sulfate particles. The second and third powders were prepared by dissolving a combination of excipients and a bioactive agent in an ethanol/water solvent system and spray drying to create dry powders. The geometric diameter, tap density and aerodynamic diameter of the three powders were determined.

The Applicants introduced the powders into and dispersed the powder through an orifice in the RODOS dry powder disperser at varying shear forces by manipulating the regulator pressure of the air stream used to break up the particles. The Applicants obtained the geometric size distribution from the HELOS laser diffractometer as the powder exited and recorded the median value. The data was summarized and plotted as the mass median geometric diameter (MMGD) against pressure.

Applicants postulated and through experimentation disclosed herein found that at high pressure, for example 3 or 4 bars, all three powders exited the disperser as primary (deaggregated) particles. This supports the finding that relatively high energy successfully deaggregates all three powders. However at pressures below 2 bars, which more closely corresponds with physiological breath rate, the micronized powder (Powder 1 Table 1 (see Original Patent)) exited the orifice in an aggregated state, evidenced by a mean particle size leaving the orifice that was greater than the powder's primary particle size. This is not the case for the spray-dried powders (Powders 2 and 3 Table 1), which emitted from the orifice at approximately their primary particles size. These powders are highly dispersible powders.

To further evaluate the ability of the three powders to emit from a simple, breath-activated inhaler, Applicants placed 5 mg of each powder in a size #2 methyl cellulose capsule and inserted the capsule into a breath-activated inhaler. It will be appreciated by those skilled in the art that the receptacle into which the powders are placed will depend on the type of inhaler selected. The results are discussed in the Examples below. Generally, applicants found that given the relatively low energy supplied by the inhaler to break up the powder, the micronized albuterol sulfate powder was emitted from the inhaler as an aggregate with a geometric diameter greater than 30 microns, even though the primary particle size, as measured by RODOS, was on the order of 2 microns. On the other hand, the highly dispersible particles of spray-dried albuterol sulfate or hGH were emitted at particle sizes that were very comparable to their primary particle size. The same results were obtained from measurements of the aerodynamic diameter, with spray-dried particles emitting with very similar aerodynamic diameters as compared to the primary particles. Using the methods of the instant invention, one skilled in the art can achieve high-efficiency delivery from a simple breath-activated device by loading it with powder that is highly dispersible.

A further feature of the instant invention is the ability to emit large percentages of a nominal dose at low energy not only from a single-dose, breath-actuated inhaler but also from a range of breath-actuated Dry Powder Inhalers (DPIs).

To illustrate that a highly dispersible powder can efficiently emit and penetrate into the lungs from a range of breath-activated DPIs, Applicants prepared a spray-dried powder comprised of sodium citrate, DPPC, calcium chloride buffer, and a rhodamine fluorescent label. This is explained thoroughly in Example 2. The powder possessed a median aerodynamic diameter of 2.1 .mu.m (measured by the AeroDisperser and Aerosizer) and a geometric diameter of 11.0 .mu.m (measured using the RODOS/HELOS combination described above). Applicants found that the powders tested displayed excellent deaggregation properties.

In particular, Applicants placed 5 mg of the powders to be tested in the capsules using a semi-automated capsule filling device in the following inhalers: a breath-activated inhaler under development by the applicant, the Spinhaler.RTM. (Fisons, Loughborough, U.K.), Rotahaler.RTM. (Glaxo-Wellcome, RTP, NC), FlowCaps.RTM. (Hovione, Loures, Portugal), Inhalator.RTM. (Boehringer-Ingelheim, Germany) and the Aerolizer.RTM. (Novartis, Switzerland). We also tested the Diskhaler (Glaxo-Wellcome, RTP, NC), for which 3 mg of the powder was machine-filled into the blister packs. Applicants connected each inhaler to a collapsed Andersen cascade impactor (consisting of stage 0 and the filter stage,) and extracted air at 60 L/minute for 2 seconds after actuating the device. The fine particle fraction less than stage 0, having a 4.0 .mu.m cut-off, was determined using fluorescent spectroscopy.

Applicants found that in each case, approximately 50% or more of the emitted dose displayed a mean aerodynamic diameter (Da) less than 4 .mu.m in size, indicating that the powder efficiently entered the lungs of a human subject at a physiological breath rate, despite the simplicity of these breath-activated devices.

In order to test the highly dispersible powders in vivo, Applicants performed human deposition studies, as described in Example 3, to determine whether a highly dispersible powder emitted from a simple breath-actuated inhaler could produce highly efficient delivery to the lungs (>50% of the nominal dose). This is especially important because many devices rely on inhalation by the patient to provide the power to break up the dry material into a free-flowing powder. Such devices prove ineffective for those lacking the capacity to strongly inhale, such as young patients, old patients, infirm patients or patients with asthma or other breathing difficulties. An advantage of the method of the instant invention is that highly efficient delivery can be achieved independent of the flow rate. Thus, using the methods of the invention, even a weak inhalation is sufficient to deliver the desired dose. This is surprising in light of the expected capabilities of standard DPIs. As can be seen in FIG. 7 (see Original Patent), using the methods described herein, superior delivery can be achieved at flow rates ranging from about 25 L/min to about 75 L/min, as compared to standard DPIs. The methods of the instant invention can be optimized at flow rates of at least about 20 L/min to about 90 L/min.

Powder possessing the following characteristics: Dg=6.7 .mu.m; p=0.06 g/cc; and Da=1.6 .mu.m was labeled with .sup.99mTc nanoparticles. Equivalence between the mass and gamma radiation particle size distributions was obtained and is discussed in detail in Example 3 below. Approximately 5 mg of powder was loaded into size 2 capsules. The capsules were placed into a breath-activated inhaler and actuated. Ten healthy subjects inhaled through the inhaler at an approximately inspiratory flow rate of 60 L/min. as measured by a spirometer. The deposition image was obtained using a gamma camera. The percentage of lung deposition (relative to the nominal dose) obtained from the ten subjects is shown in FIG. 5 (see Original Patent). The average lung deposition, relative to the nominal dose, was 59.0%. Those skilled in the art will recognize that such deposition levels confirm that a highly dispersible drug powder can be inhaled into the lungs with high efficiency using a single breath-actuated inhaler.

Further, Applicants have discovered that the same preparations of a highly dispersible powder that had excellent aerosolization from a single inhaler can be used to deliver a surprisingly high dose in a single inhalation. The highly dispersible powder can be loaded into a large pre-metered dose (50 mg) or a smaller pre-metered dose (6 mg). The particle characteristics of the powder were as follows: Dg=10.6 .mu.m; p=0.11 g/cc; Da=3.5 .mu.m. One skilled in the art would appreciate the possible ranges of characteristics of particles suitable for use in the instant invention, as disclosed previously herein.

The aerodynamic particle size distributions were characterized using a multistage liquid impinger (MSLI) operated at 60 L/min. Size 2 capsules were used for the 6 mg dose and size 000 capsules were used for the 50 mg dose. Applicants compared the two particle size distributions obtained for the 6 and 50 mg doses. The fine particle fraction <6.8 .mu.m (relative to the total dose (FPF.sub.TD<6.8 .mu.m)) for the 6 and 50 mg doses was 74.4% and 75.0%, respectively. Thus Applicants have demonstrated that a large dose of drug can be delivered to the lungs as efficiently as a small drug dose by combining the properties of a highly dispersible powder.
 

Claim 1 of 33 Claims

1. A method of delivering an agent to the pulmonary system, in a single, breath-activated step, comprising administering particles comprising an agent from a receptacle having a mass consisting of said particles to a subject's respiratory tract, wherein: i) about 50% or more of the mass of particles stored in the receptacle is delivered to the pulmonary system of the subject; and ii) about 5 milligrams or more of the agent is delivered to the pulmonary system of the subject; wherein the particles have a tap density of about 0.1 g/cm.sup.3 or less.
 

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