Pharmacokinetics on tramadol/acetaminophen combination tablets in Chinese healthy volunteers

Objective To study the pharmacokinetic of tramadol and acetaminophen in healthy volunteers. Methods Totally 20 healthy adult male volunteers participated in the study were randomly assigned to 2 treatment groups and were given respectively the dose of one and two pills by oral administration. Serum was separated and the concentrations of tramadol and acetaminophen in human serum were determined by HPLC using fluorescence and UV detector. The values of concentration were directly detected, and AUC was calculated by linear trapezoid method. Results The main pharmacokinetic parameters of tramadol and acetaminophen of 2 dosages groups were as follow: Tramadol: AUC(subscript u-24h)(ng•h mL^(-1) ) were 2724.89±1 016.54 and 1361.61 ± 441.79; AUC(subscript 0-∞) (ng•h•mL^(-1)) were 305.49 ± 1190.66 and 1555.04 ± 582.51 t(subscript max) (h) were 1.8±0.75 and 1.9 ±0.57; t(subscript 1/2),(h) were 7.34±1.39 and 7.63 ± 2.02; Kel(h^(-1)) were 0.098±0.019 and 0.197 ± 0. 027; Cl(subscript t)(mL•min^(-1) ) were 31.84 ± 13.65 and 30.03±9.20; MRT(h) were 7.62±1.07 and 7.77 ±0.75. Acetaminophen: AUC (subscript 0-24h)(μg•h mL^(-1)) were 40.28 ± 10.36 and 18.37±3.84; AUC(subscript 0-∞)(μg. h• mL^(-1)) were 41.63 ± 10.96 and 18.81± 4.06; t(subscript max) (h) were 0.9 ± 0.46 and 0.9 ± 0.39; t(subscript 1/2) (h) were 5.39 ± 1.16 and 4.96 ± 1.03; Kel (h^(-1)) were 0.13 ± 0.03 and 0.15 ±0.03; Clr (mL•min^(-1)) were 17.17 ± 4.57 and 18.42 ± 3.89; MRT(h) were 4.86 ±0.48 and 4.50 ± 0.53. Conclusions No significant difference in pharmacokinetic parameters, such as t(subscript max), t(subscript 1/2) Ke, V Cl. MRT, AUC(subscript u-t)/dose, AUC(subscript u-t)/dose, AUC(subscript 0-∞) and C(subscript max) dose are shown between these two dose groups and a linear pharmacokinetic is featured.