Importance

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Abstract

A composition of microparticles for delivery to the pulmonary system provides sustained release of a pharmaceutical agent. The microparticles comprise a lipid structural matrix comprising a multilamellar structure of lipid bilayers having lipid chains ordered in an L.sub..beta.L phase. The lipid matrix at least partially encapsulates the pharmaceutical agent at a bilayer interface formed between head groups of adjacent lipid layers. The microparticles are prepared by heating a precursor formulation comprising a solvent, matrix-forming excipient and pharmaceutical agent to a temperature above the liquid-crystalline transition temperature T.sub.c of the matrix-forming excipient and below the melting or denaturation point of the pharmaceutical agent. The solvent is then removed to form microparticles with partially encapsulated pharmaceutical agent.

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First Claim