Determination of multicomponent dissolution profiles of pharmaceutical products by in situ fiber-optic UV measurements

The feasibility of using a fiber-optic UV/visible spectrograph for in situ dissolution testing of a pharmaceutical product containing two active ingredients, sulfamethoxazole and trimethoprim, was demonstrated. Detailed dissolution profiles clearly showed that trimethoprim dissolved rapidly, while sulfamethoxazole dissolved slowly. Multivariate calibration of the fiberoptic spectrograph was accomplished using full-range spectra from 250 to 320 nm and principal component regress (PCR). Calibration mixtures were prepared from standard reference materials according to a three-level, central composite factorial design. It was not necessary to include excipients in the calibration mixtures. The accuracy of the new in situ UV/visible method was compared to a standard HPLC method and was limited to about +/-3% due to the high spectral similarity of the two active ingredients. The detailed dissolution profiles afforded by this new method may be an invaluable aid in the development of multicomponent, time-released drug products.