Liverpool HIV Interactions

Stribild is indicated for use as a complete regimen for the treatment of HIV 1 infection and must not be administered with other antiretroviral products. When switching patients who are CYP2B6 poor metabolisers from an efavirenz containing regimen to Stribild, there is a potential for lower elvitegravir exposure due to prolonged CYP3A induction by efavirenz. Monitoring of viral load is recommended for these patients during the first month after switching treatment to Stribild.
Stribild Summary of Product Characteristics, Gilead Sciences International Ltd, November 2021.

Stribild is a complete regimen for the treatment of HIV-1 infection; therefore, Stribild should not be administered with other antiretroviral medications for treatment of HIV-1 infection.

Stribild Prescribing Information, Gilead Sciences Inc, September 2021.

The impact of Atripla (EFV/FTC/TDF) on EVG/COBI/FTC/TDF PK was evaluated in 29 healthy volunteers. Subjects received EVG/COBI/FTC/TDF (150/150/200/300 once daily) for days 1-7 followed by washout. Subjects were then given EFV/FTC/TDF (600/200/300 mg once daily) for days 15-28 and switched to EVG/COBI/FTC/TDF (150/150/200/300 once daily) for days 29-62. When compared to pre-Atripla, EVG exposures were lower at both 1 week and 2 weeks post-Atripla (week 1 AUC, Cmax and Ctrough decreased by 37%, 18%, 67%, respectively; week 2 AUC, Cmax and Ctrough decreased by 29%, 11%, 55%, respectively). COBI AUC and Cmax within the lack of interaction boundary by 2 weeks post switch, but Ctrough was 35% lower. Mean EVG Ctrough was 3-fold and 5-fold greater than the protein-binding adjusted IC95 at weeks 1 and 2 post switch, respectively, and 7-8-fold above IC95 by 5 weeks post switch. EFV exposures were comparable to historical data. The lower EVG exposures following switch from EFV/FTC/TDF to EVG/COBI/FTC/TDF are due to CYP3A and UGT induction by EFV. EVG and/or EFV exposures were in a range associated with potent antiviral activity throughout the study Pharmacokinetics of EVG/COBI/FTC/TDF single tablet regimen following treatment with EFV/FTC/TDF (Atripla®) in healthy subjects. Ramanathan S et al. 13th International Workshop on clinical Pharmacology of HIV Therapy, Barcelona 2012, abstract O_21.