Pharmacokinetics and dose proportionality of three Tramadol Contramid OAD tablet strengths.

A three-way crossover study in 27 human volunteers was conducted to characterize the pharmacokinetics and to assess the dose proportionality of 100 mg, 200 mg and 300 mg strengths of a novel once-a-day tramadol controlled-release tablet (Tramadol Contramid OAD) following single-dose administration. Serial blood samples were collected at predefined timepoints over a 48 h period and racemic tramadol and O-desmethyltramadol concentrations in plasma were determined using a validated LC-MS/MS method. Pharmacokinetic parameters were derived using noncompartmental methods. Following dose normalization and logarithmic transformation of concentration-dependent parameters, the results were compared using analysis of variance (ANOVA). The residual variability thereby obtained was used to construct 90% classical confidence intervals. The two one-sided tests procedure was used for all pairwise comparisons. Dose proportionality was concluded since the 90% CI for the ratio of geometric means was included in the acceptance range of 0.80-1.25 for all comparisons.

Pharmacokinetics of naftidrofuryl in patients with renal impairment.

Naftidrofuryl (CAS 31329-57-4) is used, mainly in elderly patients, in the treatment of various vascular disorders. The aim of this study was to evaluate and compare the pharmacokinetics of naftidrofuryl after single oral administration of a 200 mg naftidrofuryl tablet (Praxilene) in caucasian male and female subjects with renal impairment versus healthy volunteers. This prospective and open study was conducted in three parallel groups: Group A = healthy subjects with a Cl(CR) > 80 ml/min, Group B = uraemic patients with a 20 < or = Cl(CR) < 40 ml/min, Group C = uraemic patients with a Cl(CR) < 20 ml/min. Blood samples were taken over a period of 32 h after dosing. The mean values (+/-SD) of the pharmacokinetic parameters of naftidrofuryl for group A were as follows: tmax: 1.3 h (median), Cmax: 174 +/- 46 ng/ml, t(1/2 beta): 4.4 +/- 1.1 h, AUC(0-infinity): 1541 +/- 384 ng x h/ml; for group B: tmax: 2.5 h (median), Cmax: 239 +/- 94 ng/ml, t(1/2 beta): 5.0 +/- 1.2 h, AUC(0-infinity): 2361 +/- 751 ng x h/ml; for group C: tmax: 3.0 h (median), Cmax: 236 +/- 104 ng/ml, t(1/2 beta): 5.0 +/- 2.1 h, AUC(0-infinity): 2488 +/- 2003 ng x h/ml. The statistical analysis was performed on the pharmacokinetic parameters with one-way ANOVA in order to compare each group. No significant difference between each group was observed. In conclusion, renal insufficiency did not appear to influence the pharmacokinetic profile of oral naftidrofuryl.