Abstract
A rapid method for determination of cimetidine and rantidine in 100 ul human or rat plasma by isocratic reverse phase HPLC is described. Ranitidine is used as an internal standard for cimetidine assay and vice versa. The procedure consists of one step extraction of alkalinized plasma containing internal standard with 4% v/v isopropranolol in ethyl acetate by vortex for 1 min. The organic phase is transferred and evaporated under a stream of nitrogen. The residue was redissolved with methonal and subsequently eluted on u-Bondapack C
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column at 225 nm. The mobile phase consisted of 8% v/v acetonitrile in 5.0 mM potassium phosphate buffer at pH 5.1. The sample was completed eluted in 9 min. with a detection limit of 0.05 ug/ml for cimetidine and 0.1 ug/ml for ranitidine.