Methadone levels reduced moderately by rilpivirine
1 June 2010. Related: Conference reports, PK and drug interactions, PK Workshop 11th 2010.
The effect of TMC278 (25 mg once daily) on the pharmacokinetics and pharmacodynamics of methadone was studied in 13 HIV negative volunteers stable on methadone maintenance therapy (60-150 mg/day). TMC278 decreased the AUC, Cmax and Cmin of active R-methadone by 16%, 14% and 22%, respectively. Decreases were also seen in the AUC (16%), Cmax (13%) and Cmin (21%) of inactive S-methadone. Exposure of TMC278 in the presence of methadone was within the expected range. No signs of opiate withdrawal were observed.
Although no a-priori dose adjustment of methadone is required, clinical monitoring for withdrawal symptoms is recommended as some patients may require dose adjustment.
Ref: Crauwels HM et al. Pharmacokinetic interaction study between TMC278, a next-generation NNRTI and methadone. 11th PK Workshop, 2010. Abstract 33.