Etravirine and Fosaprepitant interaction
Etravirine and Fosaprepitant: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Fosaprepitant (FOCINVEZ) label · effective 2026-03-30
CYP3A4 Interactions: Fosaprepitant is a weak inhibitor of CYP3A4, and aprepitant, the active moiety, is a substrate, inhibitor, and inducer of CYP3A4; see Full Prescribing Information for recommendations regarding contraindications, risk of adverse reactions, and dosage adjustment of FOCINVEZ and concomitant drugs.
Use of FOCINVEZ with strong CYP3A4 inducers (e.g., rifampin) may result in a reduction in aprepitant plasma concentrations and decreased efficacy of FOCINVEZ.
Single dose fosaprepitant does not induce CYP3A4.
Co-administration of FOCINVEZ with drugs that are inhibitors or inducers of CYP3A4 may result in increased or decreased plasma concentrations of aprepitant, respectively, as shown in Table 8.
…concomitant use of FOCINVEZ Examples Moderate inhibitor: diltiazem Strong inhibitors: ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromycin, ritonavir, nelfinavir Strong CYP3A4 Inducers Clinical Impact Substantially decreased exposure of aprepitant in patients chronically taking a strong CYP3A4 inducer may decrease the efficacy of FOCINVEZ [see Clinical…
From the Etravirine label · effective 2025-04-02
CCR5 antagonists maraviroc ↔ etravirine ↓ maraviroc When Etravirine is co-administered with maraviroc in the absence of a potent CYP3A inhibitor (e.g., ritonavir boosted protease inhibitor), the recommended dose of maraviroc is 600 mg twice daily.
Antifungals : itraconazole ketoconazole posaconazole ↑ etravirine ↓ itraconazole ↓ ketoconazole ↔ posaconazole Posaconazole, a potent inhibitor of CYP3A4, may increase plasma concentrations of etravirine.
Therefore, co-administration of Etravirine with drugs that induce or inhibit CYP3A, CYP2C9, and CYP2C19 may alter the therapeutic effect or adverse reaction profile of Etravirine (see Table 4 ) [see Clinical Pharmacology (12.3) ].
…maraviroc/darunavir/ ritonavir The reference for etravirine exposure is the pharmacokinetic parameters of etravirine in the presence of darunavir/ritonavir. ↔ etravirine ↑ maraviroc When Etravirine is co-administered with maraviroc in the presence of a potent CYP3A inhibitor (e.g., ritonavir boosted protease inhibitor), the recommended dose of maraviroc is 150 mg twice daily.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.