Pharmacokinetics of oral XXXX : relevance of the distribution phase.

@entity1 @entity8034 @entity594
Pharmacokinetics of oral @entity594 was studied in 12 Mexican young healthy volunteers, six @entity1 and six @entity1 , who received a 10 mg capsule. Plasma levels were determined by a @entity594 specific HPLC assay. Experimental data were fitted and pharmacokinetic parameters were calculated using an open two compartment model. No statistically significant difference was detected between @entity1 and @entity1 , thus both sexes were considered as a single population. @entity594 plasma levels rose rapidly (ka = 8.46 +/- 1.96 h-1) reaching a maximum concentration of 145 +/- 23 ng/ml in 0.61 +/- 0.07 h. Plasma levels then decayed with a distribution phase (alpha = 1.98 +/- 0.40 h-1, @entity8034 = 0.46 +/- 0.06 h) and a terminal elimination phase (beta = 0.17 +/- 0.03 h-1, @entity8034 = 4.98 +/- 0.55 h). AUC was 384 +/- 41 ng h/ml. Values of AUC and @entity8034 were higher than those reported by other authors. Differences in the AUC could be due to ethnic origin, environmental factors or nutritional habits. Ten subjects presented plasma concentration-time curves in which the distribution phase was clearly distinguishable, having a ka/alpha relationship higher than 1.5. For the other two subjects, the distribution phase was not apparent and ka/alpha was lower than 1.5. The results show that an adequate characterization of the distribution phase is required if one pretends to use pharmacokinetic data for dosage regimen design.
