Abstract: Aim To compare the pharmacokinetic parameters of the domestic astemizole suspension with those of the imported product in Chinese healthy volunteers. Methods Astemizole and demethylastemizole concentration was measured by radioimmunoassay in a clinical trial of crossover design. Results The main pharmacokinetic parameters of the domestic product calculated by practical pharmacokinetics program 87 were Vd =6.88 ±1.36 L; αT_1/2 =4.24 ±4.06 h; βT_1/2 =170.31 ±73.80 h; CL =0.067±0.023 ng/ml; T_peak =1.00 ±0.53 h; C_max =1.25 ±0.17 ng/ml; AUC =162.97±48.57 ng/ml·h^-1, while the parameters of the i mport ed product were Vd =6.40 ±3.07 L; αT_1/2 =1.31 ±0.91 h; βT_1/2 =156.02 ±120.74 h; CL =0.079±0.045 ng /ml; T_peak =1.00 ±0.53 h; C_max =1.08 ±0.19 ng/ml; A UC =173.46 ±114.66 ng/ml·h^-1. The relative bioavailability of the domestic suspension was 90.5%. Conclusion No significant pharmacokinetic difference has been found between the domestic and the imported as temizole suspensions.

Key words: astemizole, suspension, radioimmunoassay, pharmacokinetics