Derivative spectrophotometric determination of antiprotozoal drugs in two-component tablet preparation.

First (D1-) and second (D2-) derivative spectrophotometric methods for the determination of diloxanide furoate and metronidazole in two-component preparation are presented. The methods are based on the direct measurements of diloxanide furoate in 0.1N hydrochloric acid solution at 262 nm and 248 nm for D1- and D2- curves, respectively without the interference of the coexisting component. Metronidazole, on the other hand is determined before and after its acid extraction from chloroformic solution and the subsequent D1- measurement at 288 nm and D2- measurement at 296 nm. The methods have been applied for the determination of both components in laboratory made mixtures and in tablet with a coefficient of variation less than 2%.