Fostemsavir

How it works

Temsavir, the active moiety, binds the HIV-1 gp120 envelope glycoprotein and prevents its conformational change, blocking viral attachment to and entry into host CD4 cells.

Prescribing in practice

• It must be used as part of an optimised combination antiretroviral regimen and not as monotherapy, to avoid the rapid emergence of resistance.
• QT-interval prolongation can occur, so use caution with other QT-prolonging drugs and in patients at risk of arrhythmia.
• Numerous drug interactions exist, including with strong enzyme inducers; review concomitant therapy against the SPC and current prescribing references.

Monitoring

Monitor HIV viral load and CD4 count to confirm virological response, alongside clinical review for immune reconstitution inflammatory syndrome and relevant drug interactions.

Counselling the patient

• Take every dose as prescribed and do not stop without specialist advice, as missed doses risk resistance.
• Tell your team about all other medicines, including over-the-counter and herbal products.
• This medicine controls but does not cure HIV; continue measures to prevent transmission.

Evidence & guidelines

Fostemsavir was studied in heavily treatment-experienced adults with multidrug-resistant HIV-1 in the BRIGHTE trial and is positioned for this population in HIV treatment guidance.