Bioavailability and pharmacokinetic studies in the development of an oral formulation of stobadine dipalmitate

The pyridoindole stobadine is a novel drug with antioxidant and cardioprotective properties. The objective of this study was to compare the bioavailability and the main pharmacokinetic parameters of two different stobadine dosage forms, STBtest and STBref, after single oral dosing in the form of gelatine capsules to 6 dogs. The dose ranged from 2.9 to 4.7 mg/kg and a randomized two-period crossover design was applied. To quantify the drug in plasma, a GC/MS method was developed with a quantification limit of 1 ng/ml. The time profiles of stobadine plasma concentrations were fitted by pharmacokinetic models. The extent of relative bioavailability ranged between 0.71 and 1.56. Practically no difference was found between the bioavailability rate of the two capsules, expressed as Cmax/AUC, with values ranging from 0.0022-0.0047 min-1 for STBtest and 0.0022-0.0045 min-1 for STBref. In conclusion, the technological difference of the capsules investigated did not yield deviations in either their extent or rate of absorption. Therefore the two stobadine formulations were concluded to be bioequivalent.