Polyurethane excipient

A medical device comprising:

• a. a polyurethane comprising the residues of:
• i. an aliphatic diisocyanate,
• ii. an aliphatic diol comprising a poly(ethylene oxide) moiety,
• iii. an aliphatic diol comprising a polycarbonate moiety, and
• iv. a chain extender;
• and
• b. a bioactive agent,
• wherein the polyurethane has a melting temperature offset (Tm Offset) of from 95° C. to 140° C. and has a weight average molecular weight of from 100,000 to 500,000 g/mol.

A method of forming a polyurethane suitable for use in a medical device, comprising the steps of:

• a. reactively extruding a composition comprising:
• i. a pre-polymer formed from a pre-polymer composition comprising:
• 1. an aliphatic diisocyanate,
• 2. an aliphatic diol comprising a poly(ethylene oxide) moiety, and
• 3. an aliphatic diol comprising a polycarbonate moiety, and
• ii. a chain extender;
• thereby forming a polyurethane, wherein the composition is substantially devoid of catalyst,
• b. post-curing the polyurethane at a temperature of from 55° C. to 90° C., and wherein, after post-curing, the polyurethane has a melting temperature offset (Tm Offset) of from 95° C. to 140° C. and has a weight average molecular weight of from 100,000 to 500,000 g/mol.