ABSTRACT
A high-performance liquid chromatographic method is reported for the determination of clonazepam and its metabolites 7-amino- and 7-acetamidoclonazepam. Extraction from buffered plasma is carried out at pH 9.5 with hexane-ethyl acetate (7:3) for clonazepam and with chloroform for the metabolites. Flunitrazepam, 7-aminodemethylflunitrazepam and 7-acetamidoflunitrazepam are used as the internal standards for clonazepam and its 7-amino and 7-acetamido metabolites, respectively. To prevent decomposition of 7-aminoclonazepam a high concentration of 7-aminomethylclonazepam is added to the plasma. Chromatography is carried out on a reversed-phase column with detection at 254 nm for clonazepam and 240 nm for the metabolites. Using the method it was possible to determine 5 ng/ml clonazepam, 7-aminoclonazepam and 7-acetamidoclonazepam in plasma with coefficients of variation of 9.5%, 5.9% and 8.9%, respectively. This method can be used to measure clonazepam in plasma from patients treated with other antiepileptics. It may also be utilized for in vitro studies on the metabolism of clonazepam in subcellular fractions from the liver.
Subject(s)
Benzodiazepinones/blood , Clonazepam/blood , Anticonvulsants/blood , Clonazepam/analogs & derivatives , Drug Stability , Humans , Spectrophotometry, Ultraviolet/methodsABSTRACT
The aim of this study was to see if the immediate EEG and clinical response to an intravenous dose of clonazepam was predictive for the effect of oral clonazepam maintenance therapy. Four children with petit mal epilepsy were given clonazepam intravenously during continuous EEG recording. Clonazepam plasma concentrations were determined repeatedly with a high performance liquid chromatographic method using a reversed phase system. The day after the intravenous dose the patients were given oral therapy with clonazepam. Repeated long-term EEG recordings were made and plasma concentrations of clonazepam were determined. There was no clinically satisfactory effect of clonazepam during oral maintenance treatment in three of the children who responded well to the intravenous dose of clonazepam. Thus, the immediate response to intravenous clonazepam was not a good predictor of the long-term effects in our patients.