Darunavir

How it works

It selectively inhibits the HIV-1 protease enzyme, preventing cleavage of viral polyproteins and thereby blocking production of mature, infectious virions.

Prescribing in practice

• Darunavir must always be co-administered with a pharmacokinetic booster (ritonavir or cobicistat) to achieve effective plasma concentrations.
• It contains a sulfonamide moiety, so use with caution in patients with known sulfonamide allergy and monitor for severe skin reactions.
• Numerous clinically significant drug interactions occur via CYP3A4, so review concomitant medicines carefully before prescribing.

Monitoring

Monitor HIV viral load and CD4 count to assess response, together with liver function and metabolic parameters during treatment.

Counselling the patient

• Take exactly as prescribed alongside the recommended booster and with food to maintain effective drug levels.
• Report any rash, which should be assessed promptly as serious skin reactions can occur.
• Do not start any new medicines, including over-the-counter products, without checking for interactions.

Evidence & guidelines

Boosted darunavir-based regimens are recommended in UK and international HIV treatment guidelines, supported by large randomised antiretroviral trials.