Clobazam (Frisium) was hydrolyzed according to three methods commonly used in the determination of 1.4-benzo-diazepines; the reaction products were analyzed by gas chromatography/mass spectrometry and thin-layer chromatography. Five degradation products were obtained for which structure proposals are discussed. After oral intake two of these substances were also detected in human urine. It should be recognized that some of the above mentioned substances may be on-column degradation products of artifacts occurring during hydrolyzation and/or sample clean-up.

After oral ingestion of 400 mg Mefexamidehydrochloride for Mefexamide (I) and its main degradation product Desmethyl-Mefexamide (II) the following pharmakokinetic parameters have been determined: 1. Elimination of I and II follows 1st order kinetics. 2. Biological half-life t 1/2 for I is 4-6, for II 4.5-6.5 H. 3. Elimination rate constant for I and II is between 0.10 to 0.20 h-1. 4. 5-10% of the administered drug are excreted unchanged, 10-16% as Desmethyl-Mefexamide within 72 h after ingestion. 5. The described thinlayer chromatographic and gas chromatographic/mass spectrometric methods allow detection of I and II for at least 72 h after application. 6. II is excreted free and conjugated in nearly equal amounts.