[Determination of plasma concentration of N-methylcantharidimide by HPLC and its pharmacokinetics after intravenous administration in dogs].

OBJECTIVES: To establish a HPLC method for determination of N-methylcantharidimide in dogs' plasma and to study the pharmacokinetics of N-methylcantharidimide in dogs'. METHOD: The plasma samples were extracted by methanol. The acetonitrile and the purified water composed mobile phase. The flow rate was 0. 7 mL x min(-1), ultraviolet detection wavelength was at 212 nm. RESULT: The calibration curve was linear over the range from 0.01-10.0 mg x L(-1) with a correlation coefficiency of 0.996 3. The lower limit of quantitation was 0.01 mg x L(-1). The mean recovery was 92.3%. the relative standard deviation (RSD) of intra-day and inter-day were all less than 10%. After intravenous administration of N-methylcantharidimide with 3 dosages of 10, 15, 20 mg x kg(-1) to dogs, the corresponding distribution half-livers (t1/2alpha) were 1.8, 2.1, 1.7 min, and the elimination half-lives (t1/2beta) were 144,139, 146 min, respectively. CONCLUSION: This method is convenient, accurate and reliable. It can be used for determination of N-methylcantharidimide in dogs' plasma and pharmacokinetic studies.