Determination of amfepramone hydrochloride, fenproporex, and diazepam in so-called "natural" capsules used in the treatment of obesity

A simple and rapid method was developed for the determination of amfepramon e hydrochloride, fenprorex, and diazepam in capsules using high performance liquid chromatography (HPLC) with UV detection. This procedure provided co nditions for the separation of the active ingredient from the complex matri ces of the dosage forms by extraction in methanol. Isocratic reversed phase chromatography was performed using acetonitrile, methanol, and aqueous 0,1 % ammonium carbonate (50:10:40) as a mobile phase, LiChrospher 100 RP 18 co lumn (125 x 5 mm id, 5 mu m), a column temperature of 25 +/- 1 degrees C an d detection at 230 nm. The calibration curves were linear over a wide concentration range (20-2000 mu g.mL(-1) to amfepramone hydrochloride, 8-800 mu g.mL(-1) to fenproporex , and 4-200 mu g.mL(-1) to diazepam) and good analytical recovery (87.1 to 107.8%) was obtained. The method is accurate and precise, as well as having advantages such as simplicity and short duration of analysis. Twenty sampl es of pharmaceutical preparations labelled as "natural" products were analy sed. Anorectics and diazepam, were detected in 40% of the samples.