European Bioanalysis Forum: recommendation on dealing with hemolyzed and hyperlipidemic matrices.

Recent guidelines on bioanalytical method validation have recommended to investigate matrix effects in special matrices such as hemolytic and hyperlipidemic plasma. However, these guidelines were not clear on how to implement these recommendations. The European Bioanalysis Forum has discussed this topic in depth and has asked for feedback from member companies. Those discussions have resulted in more specific guidance on how to define hemolytic and hyperlipidemic plasma, how to validate bioanalytical methods for these matrices and how to deal with hemolytic and hyperlipidemic study samples. These recommendations are presented in this manuscript.

Repeat analysis and incurred sample reanalysis: recommendation for best practices and harmonization from the global bioanalysis consortium harmonization team.

The A7 harmonization team (A7 HT), a part of the Global Bioanalysis Consortium (GBC), focused on reviewing best practices for repeat analysis and incurred sample reanalysis (ISR) as applied during regulated bioanalysis. With international representation from Europe, Latin America, North America, and the Asia Pacific region, the team first collated common practices and guidance recommendations and assessed their suitability from both a scientific and logistical perspective. Subsequently, team members developed best practice recommendations and refined them through discussions and presentations with industry experts at scientific meetings. This review summarizes the team findings and best practice recommendations. The few topics where no consensus could be reached are also discussed. The A7 HT recommendations, together with those from the other GBC teams, provide the basis for future international harmonization of regulated bioanalytical practices.

Pharmacokinetic interaction between telaprevir and methadone.

Hepatitis C virus (HCV) antibody is present in most patients enrolled in methadone maintenance programs. Therefore, interactions between the HCV protease inhibitor telaprevir and methadone were investigated. The pharmacokinetics of R- and S-methadone were measured after administration of methadone alone and after 7 days of telaprevir (750 mg every 8 h [q8h]) coadministration in HCV-negative subjects on stable, individualized methadone therapy. Unbound R-methadone was measured in predose plasma samples before and during telaprevir coadministration. Safety and symptoms of opioid withdrawal were evaluated throughout the study. In total, 18 subjects were enrolled; 2 discontinued prior to receiving telaprevir. The minimum plasma concentration in the dosing interval (C(min)), the maximum plasma concentration (Cmax), and the area under the plasma concentration-time curve from h 0 (time of administration) to 24 h postdose (AUC(0-24)) for R-methadone were reduced by 31%, 29%, and 29%, respectively, in the presence of telaprevir. The AUC0-24 ratio of S-methadone/R-methadone was not altered. The median unbound percentage of R-methadone increased by 26% in the presence of telaprevir. The R-methadone median (absolute) unbound C(min) values in the absence (10.63 ng/ml) and presence (10.45 ng/ml) of telaprevir were similar. There were no symptoms of opioid withdrawal and no discontinuations due to adverse events. In summary, exposure to total R-methadone was reduced by approximately 30% in the presence of telaprevir, while the exposure to unbound R-methadone was unchanged. No symptoms of opioid withdrawal were observed. These results suggest that dose adjustment of methadone is not required when initiating telaprevir treatment. (This study has been registered at ClinicalTrials.gov under registration no. NCT00933283.).