Abstract: AIM: An LC-MS/MS method was set up for the comparative evaluation of pharmacokinetics of CA4P and CA4 in SD rats. METHODS: 12 fasted SD rats were single intravenous administration of 50 mg/kg CA4P or 36 mg/kg CA4 (same molar amount). Plasma samples were collected at different time points and concentrations of CA4P and CA4 were analyzed by LC-MS/MS.The pharmacokinetic parameters were calculated and CA4P-CA4 transformation were simulated by pharmacokinetic model.RESULTS: After i.v. administration of 50 mg/kg CA4P or 36 mg/kg CA4, the AUC_0-∞ of CA4P or CA4 were (27126±4142), (7751±801) and (5037±1433) ng·h·mL^-1, respectively, the t_1/2 were (0.85±0.35), (1.27±0.33) and (0.95±0.65) h, respectively. No gender differences were found in rats.CONCLUSION: The exposure of CA4 was increased significantly by soluble CA4 phosphate in SD rats. CA4P was rapidly transformed into CA4 after a single i.v. administration of CA4P in rats, according to the pharmacokinetic model of CA4P-CA4 transformation set up by us.

Key words: CA4P, CA4, LC-MS/MS, SD rat, Pharmacokinetics