Coadministration of methadone (60-100 mg once daily, individualised dose) and rilpivirine decreased the AUC, Cmin and Cmax of R-methadone by 16%, 22% and 14%; AUC, Cmin and Cmax of S-methadone decreased by 16%, 21% and 13%. Based on historic controls, there was no change in rilpivirine AUC, Cmin or Cmax. No dose adjustment is required. Clinical monitoring is recommended as methadone maintenance therapy may need to be adjusted in some patients.
Odefsey Summary of Product Characteristics, Gilead Sciences Ltd, January 2019.

Coadministration is expected to decrease concentrations of R- and S-methadone and to have no effect on rilpivirine concentrations. No effect on methadone concentrations is expected when used with tenofovir. No dosage adjustments are required when initiating coadministration of methadone with Odefsey. However, clinical monitoring is recommended, as methadone maintenance therapy may need to be adjusted in some patients. Coadministration of methadone (60-100 mg once daily, individualized dose) and rilpivirine (25 mg once daily) to 12 subjects had no effect on rilpivirine Cmax, AUC and Cmin. Data from 13 subjects showed Cmax, AUC and Cmin of R-methadone decreased by 14%, 16% and 22%, respectively, whilst those of S-methadone decreased by 13%, 16% and 21%, respectively.
Odefsey US Prescribing Information, Gilead Sciences Inc, October 2018.