Patent ID: 8653085

Claim:
A microparticulate system for drug delivery comprising a composition comprising: microparticles of a pharmaceutically acceptable anion of a heterocyclic compound and a biologically active agent, wherein said microparticles release a biologically active agent; and a cation; wherein said anion is 3,6-di(citraconate-4-aminobutyl)-2,5-diketopiperazine, 3,6-di(oxalate-4-aminobutyl)-2,5-diketopiperazine, 3,6-di(malonate-4-aminobutyl)-2,5-diketopiperazine, 3,6-di(succinate-4-aminobutyl)-2,5-diketopiperazine, 3,6-di(maleate-4-aminobutyl)-2,5-diketopiperazine, 3,6-di(fumarate-4-aminobutyl)-2,5-diketopiperazine or 3,6-di(glutarate-4-aminobutyl)-2,5-diketopiperazine.