The pharmacokinetical study of plant alkaloid tetrandrine with a simple HPLC method in rabbits

A simple HPLC method was developed to quantify rabbit plasma tetrandrine (Tet) with propranolol (Pro) as internal standard. Based on the established method Tet and Pro were eluted at 7.1 and 12.0 min, respectively. It was shown that the concentration-time data of Tet fit the classical two-compartment model, no matter the drug was administered intravenously or orally to rabbits. The values of AUC(0 → ∞), clearance (Cl(0 → ∞)), volume of distribution (Vd), and elimination half-life (t(1/2β)) of Tet were 59861.149 ± 26962.196 μg/L⁎min, 0.503 ± 0.173 L/min/kg, 179 ± 76.185 L/kg, and 283.808 ± 162.937 min for intravenous injection of 5mg/kg, or 18986.217 ± 7462.308 μg/L⁎min, 0.805 ± 0.267 L/min/kg, 110.284 ± 94.176 L/kg, and 732.919 ± 847.32 min for gavage administration of 10mg/kg , respectively. The results indicate that Tet displays a limited absorption in intestinal tract, even though it has a favorable pharmacokinetic profile after oral or intravenous administration.