OBJECTIVEA high performance liquid chromatography (HPLC) method was developed to determine the concentration of nitidine chloride in plasma and successfully applied to study pharmacokinetics after i.v. administration in rabbits.

METHODTwelve rabbits, randomized into 2 groups , were given i.v. at the dose of 4, 6 mg x kg(-1) respectively. Chloramphenicol was used as an internal standard. Nitidine chloride was extracted from plasma with ion pair reagent, and was determined by HPLC.

RESULTThe calibration curves of nitidine chloride was linear in the range of 0.03-2.04 mg x L(-1). Its recoveries were more than 95%, intra-day and inter-day precisions were lower than 6%. The concentration-time curve of nitidine chloride in rabbits after i.v. of 4 and 6 mg x kg(-1) were shown to fit a two-compartment model, the main pharmacokinetic parameters showed no significant difference between the low and high dosage, and the AUC values are directly relative to doses. T1/2alpha were (5.46 +/- 0.89), (4.76 +/- 0.33) min respectively, T1/2beta were (263.33 +/- 16.4), (274.71 +/- 16.52) min respectively, AUC were (46.56 +/- 1.80), (69.19 +/- 2.30) microg x min(-1) x mL(-1) respectively.

CONCLUSIONIt is first time to establish the HPLC method to determine the concentration of nitidine chloride in rabbits plasma. The method is sensitive, accurate and reproducible. It is first time to study the pharmacokinetic characters of nitidine chloride in rabbits after i.v. administration, the elimination of nitidine chloride is linear pharmacokinetics.