OBJECTIVETo investigate influence of electroacupuncture at "Zusanli" (ST 36) on pharmacokinetics after oral administration of Paracetamol in rats and explore the effect and mechanism of acupuncture combined with medicinal drugs.

METHODSForty-eight SD rats, in half respectively male and female, were randomly divided into 6 groups: Paracetamol groups of low, moderate, and high doses (oral dose of Paracetamol 300, 600 or 1200 mg/kg, respectively), and electroacupuncture plus Paracetamol groups of low, moderate, and high doses (electroacupuncture at "Zusanli" (ST 36) acupoint for 20 min after oral dose of Paracetamol 300, 600 or 1 200 mg/kg, respectively). Serum specimens of rats in each group were obtained at different time points to determine the concentrations of Paracetamol by RP-HPLC after oral administration of Paracetamol at different dosage, and the pharmacokinetic parameters were calculated by software 3P87, so as to observe the influence of electroacupuncture on absorption and metabolism of Paracetamol.

RESULTSExcept in electroacupuncture plus Paracetamol groups of high doses group showing a non-linear dynamics model, the pharmacokinetics parameters of Paracetamol in the other fives groups were all fitted to first order grade absorption of two-compartment open model. Compared with the Paracetamol groups of low and moderate doses, the time to peak concentration (T(max)) was advanced (P < 0.01), the peak values of plasma concentration (C(max)) were significantly higher (P < 0.01), and the absorption half-life (T1/2ka) speeded up apparently (P < 0.01), but the elimination half-life (T1/2ke) remained basically unchanged (P > 0.05), and the area under the curve (AUC) increased significantly (P < 0.01), and plasma clearance (Cl(s)) was lower (P < 0.01) in the electroacupuncture plus Paracetamol groups of low and moderate doses. Compared with the Paracetamol group of high doses, the AUC also increased significantly (P < 0.01) and the mean residence time (MRT) postponed relatively (P < 0.05) in the electroacupuncture plus Paracetamol group of high doses.

CONCLUSIONIt indicates that clinical consideration must be given to the drug dosage and the possible influence of electroacupuncture on the metabolism of some drugs in order to avoid and reduce adverse reactions.