THE IN-VITRO RELEASE OF SOME ANTIMUSCARINIC DRUGS FROM MONOOLEIN WATER LYOTROPIC LIQUID-CRYSTALLINE GELS/

Purpose, To investigate the potential use of a monoolein/water lyotrop ic liquid crystalline gel for the vaginal delivery of the antimuscarin ic drags, propantheline bromide and oxybutynin hydrochloride to treat urinary incontinence, using Myverol 18-99 as a commercially available grade of monoolein. Methods, The influence of propantheline bromide an d oxybutynin hydrochloride on the phase structure of Myverol 18-99/wat er gels was investigated using polarising microscopy. The in-vitro rel ease of the antimuscarinic drugs from Myverol 18-99/water gels was det ermined and the release pattern interpreted with the aid of results fr om swelling studies and partition coefficient determinations. Results, Myverol 18-99 forms gels with lyotropic liquid crystalline structures in the presence of water. The addition of propantheline bromide and o xybutynin hydrochloride promoted the formation of gels with a lamellar phase structure. The gels absorbed water at a rate inversely proporti onal to their initial water content until they reached an equilibrium water content of similar to 40% w/w whilst maintaining their physical integrity. The release of the antimuscarinic drugs was sustained over a period of similar to 18 hours and followed square root of time kinet ics indicating that the rate of release was diffusion controlled. Conc lusions. The in-vitro release behaviour of Myverol 18-99/water gels su ggested that they are suitable carriers to deliver propantheline bromi de or oxybutynin hydrochloride. The results of swelling studies indica ted that a confined area, such as the vaginal cavity, would be a suita ble site of administration.