High-performance liquid chromatographic determination of diazepam in plasma of children with severe malaria

A sensitive, selective and reproducible reversed-phase HPLC method with ult raviolet detection was developed for the quantification of diazepam in smal l plasma samples from children with severe malaria. The method involves pla sma deproteinization with acetonitrile, followed by liquid-liquid extractio n with ethyl acetate-n-hexane. Diazepam. was eluted at ambient temperatures from a reversed-phase C-18 column with an acidic (pH 3.5) aqueous mobile p hase (10 MM KH2PO4-acetonitrile, 69:31, v/v), Calibration curves in spiked plasma were linear from 10 to 200 ng (r(2)greater than or equal to0.99). Th e limit of detection was 5.0 ng/ml, and relative recoveries at 25 and 180 n g were > 87%. Intra- and inter-assay relative standard deviations were < 15 %. There was no interference from drugs commonly administered to children w ith severe malaria (phenobarbitone, phenytoin, chloroquine, quinine, sulfad oxine, pyrimethamine, halofantrine, cycloguanil, chlorcycloguanil, acetamin ophen and salicylate). This method has been used for monitoring plasma diaz epam concentrations in children with seizures associated with severe malari a. (C) 2001 Elsevier Science B.V. All rights reserved.