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.