Bioavailability of moclobemide from two formulation tablets in healthy humans.

A ,,sine qua non" requirement for a generic formulation to be admitted for a medical use is to provide bioavailability studies in healthy subjects. Therefore, those studies were performed for 150 mg moclobemide tablets (Jelfa, Poland) versus 150 mg Aurorix (Hoffmann la Roche) reference tablets. An open-label, two-phase crossover study was conducted with 10 healthy subjects. Pharmacokinetic parameters (AUC, ke, t1/2, Cmax, tmax, tlag, V/f, Cl/f) obtained at the same time for moclobemide were supposed to be confronted with the literature data available for healthy volunteers. The plasma moclobemide levels as a function of time were calculated according to either an open one-compartment body model with lag time of absorption or non-compartmental method for calculation of bioavailability using Phoenix WinNonlin 8.0 software. For those reasons a suitable HPLC method was worked out. Carbamazepine was proposed as an internal standard and ammonia as well as Na2HPO4 as alkalizing agents for the mobile phase and the liquid-liquid extraction of moclobemide from human blood plasma, respectively. Basic pharmacokinetic parameters of moclobemide obtained in the paper are essentially equal to the literature data for the healthy subjects. However, bioavailability parameters (AUC0→t, AUC0→∞, Cmax, tmax) were greater for moclobemide tablets (Jelfa) if compared to Aurorix tablets (Roche) by more than 20 %. Furthermore, the extent of bioavailability (110.6 %) for the generic moclobemide tablets if compared to Aurorix tablets is not significantly different. It seems to us that the number of subjects should be increased from 10 to 24 to help to clarify that inconsequence.

Impact of common ABCB1 polymorphism on pharmacokinetics and pharmacodynamics of clopidogrel and its metabolites.

WHAT IS KNOWN AND OBJECTIVE: The reasons of clopidogrel (CLP) resistance are still unclear. The response to CLP may be influenced by both genetic and non-genetic factors. Among genetic factors, common polymorphisms in the gene coding glycoprotein-P (P-gp, MDR1 and ABCB1) are considered as potential determinants of the efficacy of CLP treatment. The aim of this study was to evaluate the influence of ABCB1 3435C>T genetic polymorphism on the pharmacokinetics and pharmacodynamics of CLP and its metabolites: diastereoisomers of thiol metabolite (the inactive H3 and the active H4) and inactive carboxylic derivative. METHODS: The study group included 42 patients undergoing elective coronary angiography and percutaneous coronary intervention. The plasma concentrations of CLP and its metabolites were measured by a validated HPLC-MS/MS method. Whole-blood aggregation was determined with Multiplate analyzer. For evaluation of ABCB1 3435C>T polymorphism, PCR-RFLP method was applied. RESULTS AND DISCUSSION: It was found that Exposition to the unchanged CLP, measured by AUC0-t of the drug, was significantly lower (P = 0·012) in TT homozygotes comparing to that observed in CC and CT genotypes, although no correlation was found between platelet aggregation and ABCB1 genetic polymorphism. WHAT IS NEW AND CONCLUSION: Our findings show that the presence of 3435C>T allele has an impact on CLP pharmacokinetics but not on the drug pharmacodynamics. Therefore, the 3435C>T genotype may not be the primary determinant influencing the pharmacokinetics of the active H4 metabolite and antiplatelet effect of the drug.