DETERMINATION OF ROCURONIUM AND ITS PUTATIVE METABOLITES IN BODY-FLUIDS AND TISSUE-HOMOGENATES

A sensitive and selective HPLC method was developed for the quantifica tion of the neuromuscular blocking agent rocuronium and its putative m etabolites (the 17-desacetyl derivative and the N-desallyl derivative of rocuronium) in plasma, urine, bile, tissue homogenates and stoma fl uid. Samples were prepared by extraction of the biological matrix with dichloromethane, after mixing with a KI-glycine buffer. After evapora tion of the organic solvent the samples were chromatographed on a reve rsed-phase HPLC column, using an aqueous buffer-dioxane (84:16, v/v) a s the mobile phase. The aqueous buffer consisting of 0.1 M sodium dihy drogen phosphate, 0.11 mM 9,10-dimethoxyanthracene-2-sulphonate (DAS), 0.11 mM 1-heptane-sulfonic acid, was adjusted to pH 3 with orthophosp horic acid. After separation, the eluent was extracted with dichloroet hane, and the organic phase was led to a fluorimetric detector, operat ing at 385 nm (excitation) and 452 nm (emission). The method was valid ated for the assay in plasma, urine, bile, tissue homogenates and stom a fluid, by determination of the repeatability, reproducibility, accur acy, lower limit of quantification, lower limit of detection, extracti on recovery, effect of sample volume, and stability in the biological matrix. The method was found to be sensitive (lower limit of quantific ation for rocuronium in plasma is 10 ng/ml) and accurate. The interfer ence of concomitant drugs with the assay of rocuronium and its putativ e metabolites has been studied extensively. In order to confirm the id entity of rocuronium and its putative metabolites, a TLC method was de veloped. The method has been applied successfully in several pharmacok inetic studies with rocuronium.