United States Patent:  6,022,554

Assignee:  American Home Products Corporation (Madison, NJ)

Filed:  December 15, 1997

This invention relates to coating formulations for coating sustained-release drug implants. The coating formulations are capable of formulations are capable of forming a porous film coat over a biologically active agent to provide a release of the active agent at a constant rate over a prolonged period of time. The pore forming agent is used in the formulation of the invention in the amount effective to regulate the release of a biologically active compound at a desired rate. Preferably, the effective amount of the pore forming agent provides long term delivery of the active agent. The invention also provides an improved implant for the sustained administration of a biologically active compound suitable for subcutaneous implantation. The invention also relates to methods for making and using the formulation and the implant of the invention.

SUMMARY OF THE INVENTION

This invention encompasses novel coating formulations for coating sustained-release drug implants. The coating formulations are capable of forming a porous film over a biologically active agent to provide a release of the active agent at a constant rate over a prolonged period of time. The formulation of the invention comprises a water soluble pore forming agent, such as polyethylene glycol, mixed with a water insoluble polymer. The pore forming agent is used in the formulation of the invention in the amount effective to regulate the release of a biologically active compound at a desired rate. The pore forming agent leaches out through the film in situ, and thus creates a perforated film around the implants which regulates the release rate of actives through micro-channels. Preferably, the effective amount of the pore forming agent provides long term delivery of the active agent.

In another aspect, the invention provides an improved implant for the sustained administration of a biologically active compound, suitable for subcutaneous implantation, which comprises an effective amount of a biologically active agent and a sufficient amount of the porous film coating. The porous film coating comprises a water soluble pore forming agent, such as polyethylene glycol, and water insoluble polymers and is prepared by coating the biologically active compound with the formulation of the invention. The porous film comprises the pore forming agent in the amount effective to increase the useful life of the implant.

In a further aspect, the invention provides for a method for making the formulation and the implant of the invention.

In yet another aspect, the invention provides for a method of treating a mammal by implanting the improved implant of the invention.

Claim 1 of 21 Claims

1. A long term sustained-release implant comprising:

(i) an effective amount of a biologically active agent; and

(ii) a film coat comprising a mixture of a water insoluble polymer and a polyethylene glycol as a water soluble pore forming agent, said polyethylene glycol being in an amount effective to regulate the release of said biologically active compound, wherein the duration of sustained release of the implant in a mammal is greater than 100 days.

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