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.

Objective To develop a sensitive and specific method for the determination of candesartan in human serum and to study the pharmacokinetics characteristics of candesartan cilexetil tablets in Chinese healthy volunteers using this method. Methods The samples were extracted from serum with diethyl ether. Chromatography was performed on an YMC ODS column (250 mm×4.6 mm i.d., 5 μm) with a mobile phase consisting of 10 mmol/L potassium dihydrogen phosphate (adjusted to pH 3.0 with phosphoric acid) and acetonitrile (60∶40, V/V) at a flow rate of 1.0 mL/min. Quantification was performed by fluorescence detection at an excitation wavelength of 270 nm and an emission wavelength of 390 nm. A single oral dose of 8mg candesartan cilexetil tablet was given to 20 healthy volunteers. The candesartan concentrations in serum were determined by the above-mentioned method. The main pharmacokinetic parameters were detected and calculated. Results The linear range of candesartan concentration was 1.01 to 202 μg/L in serum with a correlation coefficient (r) of 0.999 7. The relative standard deviations (RSDs) of intra-day and inter-day assays were 5.22%-9.14% and 3.58%-10.39%, respectively. Conclusions This method proved to be sensitive and reproducible for pharmacokinetic studies of candesartan cilexetil in healthy volunteers after a single oral administration (8 mg).