Patent ID: 7648960

Claim:
A method for delivering monomeric or dimeric insulin to a patient in need thereof, comprising administering to the patient a delivery formulation for the monomeric or dimeric insulin comprising an effective amount of insulin complexed with a diketopiperazine derivative, wherein the delivery formulation is prepared by complexing the insulin with microparticles of the diketopiperazine derivative by the steps of: a) providing pre-formed microparticles of the diketopiperazine derivative in a suspension comprising a solvent; b) adding insulin to said suspension; and c) removing solvent from said suspension; wherein the diketopiperazine derivative has the formula 2,5-diketo-3,6-di(4-X-aminobutyl)piperazine, wherein X is selected from the group consisting of fumaryl, succinyl, maleyl, and glutaryl, and wherein the microparticles release monomeric or dimeric insulin upon dissociation.