Pharmacokinetics and bioequivalence of paeonol capsules and tablets by the HPLC method

Objective: To establish the HPLC method for determination of paeonol in human plasma and to evaluate the pharmacokinetic parameters and the bioequivalence of its capsules and tablets in healthy Chinese volunteers.Methods: A liquor of plasma was collected at scheduled time points before and after a single dose of 160mg paeonol was orally given to 20 healthy volunteers in a two-way cross-over design test.The plasma samples were extracted with 300μl acetonitrile.The paeonol concentration in plasma was determined by HPLC method using a XB-C18(250mm×4.6mm,5μm) column as a stationary phase,and THF-methanol-water-phosphonic acid(6∶60∶34∶0.1,V∶V)as a mobile phase.The pharmacokinetic parameters were determined and the bioequivalence of paeonol capsules and tablets was evaluated with DAS 2.0.Results: The limit of detection for paeonol was 10ng/ml,and a linearity obtained in the range of 10～500ng/ml was excellent(r=0.9998).The relative standard deviations of intra-day and inter-day determination were less than 13.72%.The main pharmacokinetic parameters of paeonol after a single oral dose of 160 mg paeonol capsules and tablets were as follows: t1/2(h)1.03±0.35 and 1.09±0.62,Tmax(h)1.02±0.13 and 1.03±0.15,Cmax(ng/ml)116.39±45.57 and 111.16±41.24,AUC0～3(ng·h/ml) 173.91±45.41 and 1.26±42.63,AUC0-∞(ng·h/ml) 217.13±56.55 and 220.27±67.24,respectively.The relative bioavailability of paeonol capsules was(101.56±9.31)%.Conclusion: The established HPLC method is highly sensitive and accurate,and can be successfully used in the determination of plasma paeonol and is its pharmacokinetics studies.The pharmacokinetic parameter of paeonol shows no significant differences between capsules and tablets.The two preparations are bioequivalent.