Study of ocular pharmacokinetics of in situ gel system for S(-)-satropane evaluated by microdialysis

S(-)-Satropane is currently being developed to in situ forming ophthalmic gel, a new ophthalmic delivery system, for the treatment of glaucoma. To evaluate the pharmacokinetic profiles of S(-)-satropane, the microdialysis method was employed. The concentration of S(-)-satropane in dialysates was measured by using liquid chromatography/tandem mass spectrometry (LC-MS/MS). Unlike the common solution prepared in normal saline, in which the level of S(-)-satropane in aqueous humor increased rapidly after instillation and reached the maximal level (C(max) of 1.508+/-0.297 microg ml(-1)) within 1h, S(-)-satropane exhibited 3.2-fold greater C(max) and 2.2-fold greater AUC(0-3h) (p<0.05) in the in situ forming gel. The results showed that the in situ forming gel system could improve the ocular bioavailability of S(-)-satropane.