Title:  Formulation for electrically assisted delivery of lidocaine and epinephrine

United States Patent:  6,295,469

Assignee:  Alza Corporation (Mountain View, CA)

Filed:  November 14, 1997

The invention relates to formulations for the electrically assisted transdermal delivery of lidocaine and epinephrine. The present invention further provides methods and devices for the electrically assisted delivery of local anesthetics, preferably lidocaine.

DISCLOSURE OF THE INVENTION

The present invention relates to the electrically assisted transport of lidocaine and epinephrine. Specifically, the invention provides compositions for the electrically assisted delivery of lidocaine and epinephrine. Preferably, the compositions comprise about 1-10% lidocaine and about 0.01-0.2% epinephrine. In a preferred embodiment, both lidocaine and epinephrine are positively charged. Preferably, the compositions comprise lidocaine HCl and epinephrine bitartrate.

The compositions preferably further comprise one or more anti-oxidants, metal chelators or other agents, which deter microbial growth and enhance the stability of the epinephrine. Preferably, the antioxidant is sodium metabisulfite. Preferably, the metal chelator is edetate bisodium dihydrate.

The present invention further provides an electrotransport delivery device for delivering one or more agents, preferably a local anesthetic, and preferably lidocaine, by electrotransport through a body surface such as skin. The device comprises a pair of electrode assemblies, at least one of the assemblies comprising the agent to be delivered, and a source of electrical power adapted to be electrically connected to the pair of electrode assemblies. The device comprises a circuit means connecting the pair of electrode assemblies and the source of electrical power, the circuit means comprising an activation circuit and a current generating circuit. The activation circuit, which comprises a body surface resistance detection circuit and a current pulsing circuit, is electrically connected to the power source. The activation circuit is responsive to the completion of a circuit between the electrode assemblies, wherein upon completion of the circuit, the resistance detection circuit detects the resistance between the electrode assemblies (i.e., the electrical resistance of the body surface). Where the resistance is equal to or greater than a pre-determined threshold value, a pulsed voltage is delivered across the electrode assemblies which is effective to reduce the resistance of the body surface to a value less than the threshold value. Where the resistance is less than the threshold value, whether initially or as a result of being lowered by delivery of pulsed voltage, the activation circuit activates the current generating circuit. The generating circuit is electrically connected to the activation circuit for generating current for delivering the agents and is selectively activatable by the activating circuit. The activation circuit draws substantially no power consumption when the circuit between the electrodes assemblies is open, while the current generating circuit draws substantially no power consumption when not activated.

Claim 1 of 18 Claims

What is claimed is:

1. An electrotransport delivery device for delivering an agent by electrotransport through a body surface, said device comprising:

a pair of electrode assemblies, at least one of the assemblies comprising the agent to be delivered;

a source of electrical power having a cell voltage and adapted to be electrically connected to said pair of electrode assemblies;

a controller which regulates electrical power between the power source and the electrode assemblies, said controller comprising an electrotransport current generating circuit which provides an output current to said pair of electrode assemblies and an activation circuit capable of detecting resistance between said electrode assemblies and said activating circuit capable of controlling the output current of the current generating circuit;

said current generating circuit capable of generating pulsed and non-pulsed output current and capable of providing said output current at a voltage both at or below the cell voltage and at a voltage greater than the cell voltage; and

said activating circuit adapted to cause the current generating circuit to provide one or more pulses of output current at a voltage level greater than the cell voltage and said activating circuit adapted to detect resistance between said electrode assemblies any time during or after said pulses of output current, and when said detected resistance falls below a predetermined threshold value, said activating circuit causes the current generating circuit to generate a non-pulsed output current.

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