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Updated: Jul 14, 2026

Quantitative Structure-Activity Relationship, Activity Prediction, and Molecular Dynamics of Non-nucleotide Reverse Transcriptase Inhibitors
Published on: May 9, 2025
Ritonavir 100 mg does not cause QTc prolongation in healthy subjects: a possible role as CYP3A inhibitor in thorough
N Sarapa1, D J Nickens, S R Raber
1Clinical Pharmacology, Pfizer Global R&D, San Diego, California, USA. nenadsarapa@yahoo.com
Abstract:
To assess the QTc prolongation by ritonavir (RTV) 100 mg and explore its potential use as CYP3A inhibitor in thorough QTc (TQT) studies. Randomized, crossover study of single-dose RTV 100 mg, placebo, and moxifloxacin (MFLX) 400 mg in 65 healthy subjects with serial triplicate electrocardiograms obtained for 12 h post-dose. Largest mean placebo-adjusted QTcF increase from baseline (90% confidence interval (CI)) for RTV 100 mg was noninferior to placebo (0.16 ms (-1.38, 1.69)). Study sensitivity was validated by detecting the largest mean placebo-adjusted QTcF increase from baseline (90% CI) for MFLX of 8.31 ms (6.44, 10.18). A single dose of RTV 100 mg does not cause QTc prolongation in healthy subjects. Based on the potent CYP3A4 inhibition, lack of QTc effect and better safety profile, RTV 100 mg could replace ketoconazole as the CYP3A4 inhibitor in TQT studies.
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