Coadministration is contraindicated. Co-administration with medicinal products that are strong cytochrome P450 (CYP) 3A enzyme inducers is contraindicated as significant decreases in doravirine plasma concentrations are expected to occur, which may decrease the effectiveness of Delstrigo. These medicinal products include rifampicin. Coadministration of single dose rifampicin (600 mg) and doravirine (100 mg single dose) decreased doravirine AUC and C24 by 9% and 10%, but increased Cmax by 40%. Coadministration of multiple doses of rifampicin (600 mg once daily) and doravirine (100 mg single dose) decreased doravirine AUC, Cmax and C24 by 88%, 57% and 97%, respectively.

Co-administration is contraindicated with rifampicin. Co-administration of doravirine (100 mg single dose) with rifampicin (600 mg once daily) was studied in 10 subjects. Doravirine AUC, Cmax and C24 decreased by 88%, 57% and 97% respectively. At least a 4-week cessation period is recommended prior to initiation of Delstrigo.

Co-administration of doravirine (100 mg, single dose) and rifampicin (600 mg, single dose or once daily) was studied in 10 healthy subjects. Doravirine AUC and C24 were unchanged when administered with a single dose of rifampicin; doravirine Cmax increased by 40%. From this, the authors conclude that interaction through P-gp inhibition by rifampicin is unlikely to be an issue. Conversely, when a single dose of doravirine was administered alongside once daily rifampicin, doravirine AUC, Cmax and C24 reduced by 88%, 57% and 97%, respectively. This reduction in doravirine exposure is likely to be due to CYP3A induction by rifampicin. The authors do not recommend co-administration of doravirine and rifampicin, as doravirine C24 concentrations fall below levels required for an antiviral effect.