Related Experiment Video
Updated: Feb 7, 2026

How to Study Placebo Responses in Motion Sickness with a Rotation Chair Paradigm in Healthy Participants
Published on: December 14, 2014
No Pharmacokinetic Interactions Between Elbasvir or Grazoprevir and Methadone in Participants Receiving Maintenance
Hwa-Ping Feng1, Zifang Guo1, Luzelena Caro1
1Merck & Co., Inc., Kenilworth, New Jersey, USA.
Abstract:
We conducted two phase I trials to evaluate the pharmacokinetic interactions between elbasvir (EBR), grazoprevir (GZR), and methadone (MK-8742-P010 and MK-5172-P030) in non-hepatitis C virus (HCV)-infected participants on methadone maintenance therapy. Coadministration of EBR or GZR with methadone had no clinically meaningful effect on EBR, GZR, or methadone pharmacokinetics. The geometric mean ratios (GMRs) for R- and S-methadone AUC0-24 were 1.03 (90% confidence interval (CI), 0.92-1.15) and 1.09 (90% CI, 0.94-1.26) in the presence/absence of EBR; and 1.09 (90% CI, 1.02-1.17) and 1.23 (90% CI, 1.12-1.35) in the presence/absence of GZR. The GMRs for EBR and GZR AUC0-24 in participants receiving methadone relative to a healthy historical cohort not receiving methadone were 1.20 (90% CI, 0.94-1.53) and 1.03 (90% CI, 0.76-1.41), respectively. These results indicate that no dose adjustment is required for individuals with HCV infection receiving stable methadone therapy and the EBR/GZR fixed-dose regimen.
Related Concept Videos
Direct-Acting Cholinergic Agonists: Pharmacokinetics
Indirect-Acting Cholinergic Agonists: Pharmacokinetics
Reversible agents containing quaternary amines, such as neostigmine and edrophonium, are not easily absorbed orally because they...
Drug-Receptor Interaction: Agonist
Agonists can bind to receptors in different ways. Some agonists bind directly to the receptor's active site, mimicking the endogenous...
Opioid Analgesics: Synthetic and Semisynthetic Opioids
Pharmacokinetics: Drug–Drug Interactions
Pharmacokinetics: Drug–Food and Drug–Viral Interactions

