Methods and compositions for delivering macromolecules to or via the respiratory tract, such that the macromolecules exhibit improved local and/or systemic bioavailability are provided. Such methods utilize lipid-based microstructures formed in combination with at least one bioactive macromolecule, which have a superior ability to rapidly release the bioactive macromolecule(s) thereby resulting in improved local and/or systemic bioavailability of the bioactive macromolecule(s). Such improved bioavailability is believed to be due, in part, to reduction of scavenging by bronchoalveolar macrophages and/or mucociliary clearance. Compositions with improved bioavailability are provided comprising a plurality of lipid-based microstructures formed in combination with at least one bioactive macromolecule, wherein the bioavailability of the bioactive macromolecule is improved by modifying the rate of release of the bioactive macromolecule from the microstructure thereby reducing scavenging by bronchoalveolar macrophages and/or mucociliary clearance.

SUMMARY OF THE INVENTION

The present invention generally relates to novel methods and compositions for delivering macromolecules to or via the respiratory tract, such that the macromolecules exhibit improved local and/or systemic bioavailability.

To this end, one aspect of the present invention relates to lipid-based microstructures formed in combination with at least one bioactive macromolecule, which have a superior ability to rapidly release the bioactive macromolecule(s) thereby resulting in improved local and/or systemic bioavailability of the bioactive macromolecule(s). Such improved bioavailability is believed to be due, in part, to reduction of scavenging by bronchoalveolar macrophages and/or mucociliary clearance.

More particularly, in one aspect of the invention, novel compositions with improved bioavailability are provided comprising a plurality of lipid-based microstructures formed in combination with at least one macromolecule, wherein the bioavailability of the macromolecule is improved by modifying the rate of release of the macromolecule from the microstructure thereby reducing scavenging by bronchoalveolar macrophages and/or mucociliary clearance.

In a preferred embodiment, the novel microstructure compositions are formulated to be compatible with drug delivery to or via the respiratory tract through, e.g., nasal or inhaled administration.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the present invention teaches the design of novel pharmaceutical formulations for delivery to or via the respiratory tract comprising a plurality of lipid-based microstructures that quickly release incorporated macromolecules, thereby reducing macrophage scavenging and mucociliary clearance to improve bioavailability of the macromolecules. Particularly, quick release of the incorporated macromolecules can at least partially avoid scavenging by Fc-gamma receptor-expressing bronchoalveolar macrophages. The novel compositions disclosed herein may be used to effectively deliver macromolecules to tissues of the respiratory tract, or systemically to the blood subsequent to respiratory administration.

The compositions of the present invention have an improved ability over conventional particle-based formulations to rapidly release the incorporated macromolecule payload, thereby reducing microstructure and/or bioactive macromolecule scavenging and clearance to result in improved bioavailability of the macromolecule. The improved bioavailability is associated with a near-complete release of the macromolecules within 30 minutes after administration to the airway or exposure to an aqueous environment. In a preferred embodiment, the disclosed compositions can be used to modulate the release rate of the incorporated macromolecules from the lipid-based microstructures.

In this regard, it was unexpectedly discovered that the local and/or systemic bioavailability of macromolecules is dependent on the release profile of the macromolecules upon administration, and that the release profile can be tightly controlled. More particularly, it was unexpectedly discovered according to the present invention that the rate of release of incorporated macromolecules from lipid-based microstructures can be achieved by (a) modifying the type and amount of the major lipid excipient and/or carbohydrate co-excipients, (b) the addition of co-excipients with surfactant-detergent properties, and/or (c) modulation of the ionic content of the final formulation.

A. Compositions

The compositions of the present invention are comprised of a plurality of lipid-based microstructures that comprise a major lipid excipient and at least one macromolecule. The lipid-based microstructures of the invention can further comprise minor co-excipients such as carbohydrates, polyvalent metal ions, detergent surfactants, and combinations thereof. The macromolecule can be any therapeutic or prophylactic macromolecule known in the art such as peptides, proteins, nucleotides, antibodies, immunoglobulins, etc.

1. Microstructure Components

The major lipid excipient may be present in the microstructure in an amount ranging from about 10% to about 89% by weight, preferably about 25% to about 75% by weight, and most preferably about 50% by weight, based on the total weight of the microstructure. The macromolecule may be included in a range of about 5% to about 89% by weight, preferably about 15% to about 65% by weight, and more preferably about 25% by weight, based on the total weight of the microstructure. Carbohydrate co-excipients may be present in the microstructure an amount 70% by weight or less, preferably between about 5% and about 50% by weight, and most preferably about 10% by weight, based on the total weight of the microstructure. Biocompatible polyvalent metal ion co-excipients may be present in the microstructure in a metal/lipid molar ratio of about 2 or less, preferably a molar ratio of about 1. Detergent surfactant co-excipients may be included in the microstructure in an amount of about 10% by weight or less, preferably about 0.5% to about 5% by weight, and more preferably about 1% by weight, based on the total weight of the microstructure.

Preferred major lipid excipients include phosphatides such as homo and heterochain phosphatidylcholines (PC's), phosphatidylserines (PS's), phosphatidylethanolamines (PE's), phosphatidyiglycerols (PG's), phosphatidylinositols (PI's), sphingomyelins, gangliosides, 3-trimethylammonium-propane phosphatides (TAP's) and dimethylammonium-propane phosphatides (DAP's), having hydrocarbon chain length ranging from 5 to 22 carbon atoms. Single (lysophosphatides) or double chain phosphatides are also contemplated. The phosphatides may be hydrogenated, unsaturated or partially hydrogenated. Preferred phosphatides are natural phosphatides and hydrogenated phosphatides derived from soy or egg, partially hydrogenated phosphatides derived from soy and egg, dipalmitoleioylphosphatidylcholine (DiC18PC), distearoylnhosphatidylcholine (DiC16PC), dipalmitoylphosphatidylcholine (DiC14PC), dicaproylphosphatidylcholine (DiC8PC), dioctanoylphosphatidylcholine (DiC6PC), distearoylphosphatidylserine (DiC16PS), dipalmitoylphosphatidylserine (DiC14PS), dicaproylphosphatidylserine (DiC8PS) and dioctanoylphosphatidylserine (DiC6PS). As used herein, short-chain phosphatides include those having a hydrocarbon chain length ranging from 5 to 10 carbon atoms. Particularly preferred phosphatides include distearoylphosphatidylcholine (DiC16PC), dipalmitoylphosphatidylcholine (DiC14PC), and dioctanoylphosphatidylcholine (DiC6PC).

Preferred carbohydrate co-excipients for use in the lipid-based microstructures disclosed herein include monosaccharides, disaccharides and polysaccharides. For example, monosaccharides such as dextrose (anhydrous and monohydrate), galactose, mannitol, D-mannose, sorbitol, sorbose and the like; disaccharides such as lactose, maltose, sucrose, trehalose, and the like; trisaccharides such as raffinose and the like; and other carbohydrates such as hetastarch, starches (hydroxyethylstarch), dextrins, cyclodextrins and maltodextrins, lactose, mannitol, mannose, inulin, mannan, sorbitol, sucrose, trehalose, raffinose, maltose, glucose, cellulose, pectins, saponins, chitosan, chitin, mucopolysaccharides, chondroitin sulfate etc. Other optional co-excipients can include proteins such as albumin (human, egg or bovine), oligopeptides, oligoleucine, oligoalanine, etc.; osmotic agents such as NaCl, KCl, magnesium chloride, calcium chloride, zinc chloride, etc.; and buffer systems such as PBS, acetate, citrate, tris, etc.

Preferred polyvalent metal ions include metal ions or salts from groups IIa, IIIa and metal ions from atomic numbers 21 30; 39 48, 57 80 and 89 106. The preferred polyvalent metal ions are calcium, magnesium, aluminum and zinc. Further, the polyvalent metal ions may be provided in salt form.

Contemplated detergent surfactants may include non-ionic surfactants such as POLOXAMER's (polyethylene-polypropylene glycol, which is a nonionic polyoxyethylene-polyoxypropylene block co-polymer), TWEEN's (polyoxyethylene sorbitan monolaurate), TRITON 's (2,4,6-Trinitrotoluene), PEG's (polyethylene gycols), and sugar esters. Most preferable detergent surfactants are POLOXAMER 188 (polyethylene-polypropylene glycol with an average molecular weight of 8400 g/mol), POLOXAMER 407 (polyethylene-polypropylene glycol with an average molecular weight of 12,500 g/mol), TWEEN 80 (polyoxyethylene sorbitan monooleate), PEG 1540 (polyethylene gycols with an average molecular weight of 1500 g/mol). cetyl alcohol, and TYLOXAPOL (phenol, 4-(1,1,3,3-tetramethyibutyl) polymer with formaldehyde and oxirane). Cationic-surfactants may include benzalkonium chloride. Anionic surfactants may be selected from the cholate and deoxycholate family, such as CHAPS (sulfobetaine-type zwitterionic detergent) (MERCK index 11 ed., monography pg. 2034), taurocholate, deoxytaurocholate, or phosphate fatty acid salts such as dicetyl phosphate. Other surface active compounds include albumin, leucine, oligopeptides, oligoleucine, oligoalanine and saponins (for a further listing see Cowers handbook of industrial surfactants 1993, pages 885 904, ISBN 0566074575 which is hereby incorporated by reference).

Any of a variety of therapeutic or prophylactic macromolecules can be incorporated within the lipid-based microstructures of the invention. The microstructures of the invention can thus be used to locally or systemically deliver a variety of therapeutic or prophylactic agents to an animal. Examples of contemplated macromolecules include proteins, peptides, immunogenic agents, polysaccharides, other sugars, lipids, and nucleic acid sequences having therapeutic or prophylactic activities. Immunogenic agents can include, but are not limited to, protein antigens or antigenic fragment, antibodies or single-chain binding molecules, and immunoglobulins or immunoglobulin-like molecules. Nucleic acid sequences can include genes, antisense molecules which bind to complementary DNA to inhibit transcription, and ribozymes.

The macromolecules to be incorporated can have a variety of biological activities, such as vasoactive agents, neuroactive agents, hormones, anticoagulants, immunomodulating agents, cytotoxic agents, prophylactic agents, antibiotics, antivirals, antisense, antigens, and antibodies. In some instances, the proteins may be immuno active agents such as antibodies, immunoglobulins, 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 utilized, for example, between 100 and 500,000 grams or more per mole.

In one aspect of the invention, the microstructures described herein may include a macromolecule for local delivery within the lung, such as macromolecules for the treatment of asthma, emphysema, or cystic fibrosis. Alternatively, the microstructures may include a macromolecule for systemic delivery. For example, contemplated bioactive macromolecules include, but are not limited to, insulin, calcitonin, leuprolide (or gonadotropin-releasing hormone ("LHRH")), granulocyte colony-stimulating factor ("G-CSF"), parathyroid hormone-related peptide, somatostatin, testosterone, progesterone, estradiol, norethisterone, clonidine, scopolomine, salicylate, cromolyn sodium, salmeterol, formeterol, albuterol, and valium.

Besides the aforementioned co-excipients, it may be desirable to add other excipients to the lipid-based microstructures of the present invention to improve particle rigidity, production yield, emitted dose and deposition, shelf-life and patient acceptance. Such optional excipients include, but are not limited to: coloring agents, taste masking agents, buffers, hygroscopic agents, antioxidants, and chemical stabilizers. Further, various excipients may be incorporated in, or added to, the lipid-based microstructure to provide structure and form to the microstructure compositions (i. e. microspheres such as latex particles). In this regard it will be appreciated that the rigidifying components can be removed using a post-production technique such as selective solvent extraction.

2. Microstructure Physical Parameters

It will be appreciated that the lipid-based microstructures disclosed herein can comprise any suitable structural matrix known in the art, such as particulates, microparticulates, perforated microstructures, and combinations thereof. In a particularly preferred embodiment of the invention, the microstructures comprise a structural matrix of spray dried, hollow and porous particulates, as disclosed in WO 99/16419, which is hereby incorporated by reference in its entirety. Such hollow and porous particulates comprise particles having a relatively thin porous wall defining a large internal void, although, other void containing or perforated structures are contemplated as well. The absolute shape (as opposed to the morphology) of the perforated microstructure is generally not critical and any overall configuration that provides the desired characteristics is contemplated as being within the scope of the invention. Accordingly, preferred embodiments can comprise approximately microspherical shapes. However, collapsed, deformed or fractured particulates are also compatible.

The lipid-based microstructures of the present invention preferably have a mean aerodynamic diameter less than about 10 .mu.m, more preferably ranging from about 0.5 .mu.m to about 5 .mu.m. "Aerodynamic diameter," as used herein, is a measure of the aerodynamic size of a dispersed microstructure. The aerodynamic diameter is used to describe an aerosolized microparticles in terms of its settling behavior, and is the diameter of a unit density sphere having the same settling velocity, generally in air, as the microstructure. The aerodynamic diameter encompasses microstructure shape, density, and physical size.

The lipid-based microstructures of the present invention preferably have a mean geometric diameter ranging from about 1 .mu.m to about 30 .mu.m, preferably from about 1 .mu.m to about 10 .mu.m. A particularly preferred embodiment is directed to microstructures having a mean geometric diameter of about 1 .mu.m to about 5 .mu.m. Because the compositions of the present invention are generally polydisperse (i.e., consist of a range of microstructure sizes), "mean geometric diameter" is used as a measure of mean microstructure size. Mean geometric diameters as reported herein are determined by laser diffraction, although any number of commonly employed techniques can be used.

The lipid-based microstructures of the present invention typically have bulk densities less than about 0.5 g/cm.sup.3, preferably less than about 0.3 g/cm.sup.3, more preferably less 0.1 g/cm.sup.3, and most preferably less than 0.05 g/cm.sup.3. By providing microstructures with low bulk density, the minimum powder mass that can be filled into a unit dose container is reduced, which eliminates the need for carrier particles. That is, the relatively low density of the microstructures of the present invention provides for the reproducible administration of relatively low dose macromolecules. Moreover, the elimination of carrier particles will potentially minimize throat deposition and any "gag" effect from the large carrier particles impacting the throat and upper airways upon administration.

3. Optional Composition Components

The compositions of the present invention can further comprise non-aqueous carriers or suspension media. For instance, the lipid-based microstructures of the present invention may optionally be dispersed in non-aqueous media to thereby be compatible with aerosolization or delivery by instillation in non-aqueous suspension media. By way of example, such non-aqueous suspension media can include hydrofluoroalkanes, fluorocarbons, perfluorocarbons, fluorocarbon/hydrocarbon diblocks, hydrocarbons, alcohols, ethers, and combinations thereof. However, it is understood that any non-aqueous suspension media known in the art may be used in conjunction with the present invention.

B. Administration

In a preferred aspect of the invention, the compositions disclosed herein can be formulated for delivery to or via the respiratory tract of a patient in need of treatment. Such formulations can be delivered to or via the respiratory tract for prophylactic or therapeutic purposes in any manner known in the art such as, but not limited to, dry-powder inhalation, instillation, metered dose inhalation, nebulization, aerosolization, or instillation as suspension in compatible vehicles. Other routes of administration are also contemplated, such as topical, transdermal, intradermal, intraperitoneal, intravenous, intramuscular, subcutaneous, vaginal, rectal, aural, oral, or ocular administration.

As discussed above, the compositions disclosed herein may be administered to the respiratory tract of a patient via aerosolization, such as with a dry powder inhaler (DPI). The use of such microstructures provides for superior dispersibility and improved lung deposition as disclosed in WO 99/16419, hereby incorporated in its entirety by reference. DPIs are well known in the art and could easily be employed for administration of the claimed microsturctures without undue experimentation.

The compositions disclosed herein may also be administered to the respiratory tract of a patient via aerosolization, such as with a metered dose inhaler (MDI). The use of such stabilized preparations provides for superior dose reproducibility and improved lung deposition as disclosed in WO 99/16422, hereby incorporated in its entirety by reference. MDIs are well known in the art and could easily be employed for administration of the claimed dispersions without undue experimentation.

Breath activated MDIs, as well as those comprising other types of improvements which have been, or will be, developed are also compatible with the stabilized dispersions and present invention and, as such, are contemplated as being within the scope thereof.

However, it should be emphasized that, in preferred embodiments, the compositions may be administered with an MDI using a number of different routes including, but not limited to, topical, nasal, pulmonary or oral. Those skilled in the art will appreciate that, such routes are well known and that the dosing and administration procedures may be easily derived for the stabilized dispersions of the present invention.

Along with the aforementioned embodiments, the compositions of the present invention may also be used in conjunction with nebulizers as disclosed in PCT WO 99/16420, the disclosure of which is hereby incorporated in its entirety by reference, in order to provide an aerosolized medicament that may be administered to the pulmonary air passages of a patient in need thereof. Nebulizers are well known in the art and could easily be employed for administration of the claimed dispersions without undue experimentation.

Breath activated nebulizers, as well as those comprising other types of improvements which have been, or will be, developed are also compatible with the stabilized dispersions and present invention and are contemplated as being with in the scope thereof.

Along with DPFs, MDIs and nebulizers, it will be appreciated that the compositions of the present invention may be used in conjunction with liquid dose instillation (LDI) or LDI techniques as disclosed in, for example, WO 99/16421 hereby incorporated by reference in its entirety. Liquid dose instillation involves the direct administration of a stabilized dispersion to the lung. In this regard, direct pulmonary administration of macromolecules is particularly effective in the treatment of disorders especially where poor vascular circulation of diseased portions of a lung reduces the effectiveness of intravenous drug delivery. With respect to LDI the stabilized dispersions are preferably used in conjunction with partial liquid ventilation or total liquid ventilation. Moreover, the present invention may further comprise introducing a therapeutically beneficial amount of a physiologically acceptable gas (such as nitric oxide or oxygen) into the pharmaceutical microdispersion prior to, during or following administration.

C. Methods Associated with Improved Bioavailability

In another aspect of the invention, methods for improving the local and/or systemic bioavailability of a macromolecule delivered to or via the respiratory tract are provided. Generally, the bioavailability of the macromolecule maybe improved by modifying the rate of release of the macromolecule from the lipid-based microstructure such that at least about 95% of the incorporated macromolecule is released within about 30 minutes after exposure to an aqueous environment to thereby reducing scavenging by bronchoalveolar macrophages and/or mucociliary clearance after administration to or via the respiratory tract.

Macromolecules have a natural tendency to interact or associate with the matrix of conventional microstructures, thus creating retentive structures with limited bioavailability. However, the present invention provides methods for improving the bioavailability of macromolecules that comprise incorporating the macromolecules in lipid-based microstructures such that at least about 95%, preferably 99% of the macromolecules incorporated therein are released from the lipid-based microstructures within about 30 minutes after administration to or via the respiratory tract or after exposure to an aqueous environment. In a particularly preferred embodiment, at least about 60%, preferably 80%, more preferably 90%, and most preferably 99% of the macromolecules incorporated therein are released from the lipid-based microstructures within about 15 minutes after administration to or via the respiratory tract or after exposure to an aqueous environment.

In yet another aspect of the invention, methods for administering a macromolecule with improved local and/or systemic bioavailability to or via the respiratory tract of a patient in need of treatment are provided. Such methods comprise administering a therapeutically or prophylactically effective amount of a composition comprising a plurality of the lipid-based microstructures, wherein the lipid-based microstructures are formulated so as to release about 95%, preferably 99% of the macromolecules incorporated therein within about 30 minutes after administration to the patient. Again, in a particularly preferred embodiment, at least about 60%, preferably 80%, more preferably 90%, and most preferably 99% of the macromolecule incorporated therein is released from the lipid-based microstructure within about 15 minutes after administration to the patient.

Any lipid-based microstructure described herein may be used in the disclosed methods associated with improved bioavailability. However, it has been unexpectedly discovered according to the present invention that the inclusion of at least one detergent surfactant in the lipid-based microstructure further enhances the local and/or systemic bioavailability of the incorporated macromolecule upon administration to or via the respiratory tract by reducing microstructure scavenging and/or clearance. As such, preferred lipid-based microstructures for improving local and/or systemic bioavailability of the macromolecule incorporated therein include those comprising at least one major lipid excipient, at least one minor carbohydrate excipient, and at least one minor detergent surfactant excipient.

It has also been unexpectedly discovered according to the present invention that the inclusion of a short-chain phosphatide as a major lipid excipient of the lipid-based microstructure results in even more enhanced systemic bioavailability of the incorporated macromolecule. A particularly preferred lipid-based macromolecule in this regard comprises a major lipid excipient selected from the group consisting of short-chain phosphatides having a hydrocarbon chain length of between 5 and 10 carbon atoms, a minor carbohydrate excipient, and optionally, at least one minor co-excipient selected from the group consisting of polyvalent metal ions, detergent surfactants, and combinations thereof.
 

Claim 1 of 39 Claims

1. A method for improving the local and/or systemic bioavailability of a macromolecule upon administration to or via the respiratory tract of a patient in need of treatment, the method comprising: incorporating said macromolecule into a lipid-based microstructure that comprises: (a) a major lipid excipient comprising a major amount of the lipid-based microstructure based on the total weight of the microstructure, the major lipid excipient comprising a lipid excipient or a mixture of lipid excipients; and (b) a minor co-excipient comprising a minor amount of the lipid-based microstructure based on the total weight of the microstructure, the minor amount being lesser than the major amount, and the minor co-excipient being selected from the group consisting of detergent surfactants, carbohydrates, and combinations thereof; wherein said lipid-based microstructure is formulated so as to release at least about 95% of said macromolecule incorporated therein within about 30 minutes after administration to or via the respiratory tract of said patient in need of treatment to thereby at least partially avoid scavenging by bronchoalveolar macrophages and/or a mucociliary clearance after said administration and improve said local and/or systemic bioavailability of said macromolecule.

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