Novel combinations of rate-controlling polymers for the release of leuprolide acetate in the colon.

Our objective was to investigate the controlled release and transport of leuprolide acetate polypeptide in the colon using novel combinations of rate-controlling polymers. Polymer swelling, disintegration, drug release, and transport characteristics were measured using different polymers, carbopol, chitosan and polyox, alone and in combination. Studies demonstrated Carbopol-containing combination formulations had maximum swelling and the slowest disintegration properties. A decrease in dissolution rate was observed from all combination formulations when compared with their individual counterparts. Carbopol combinations showed the slowest overall release. Drug transport studies using the everted sac technique demonstrated good correlation to the swelling, disintegration, and dissolution studies. Thus, novel polymer combinations can be used to deliver polypeptide drug to the colon effectively compared with individual polymers.