Darunavir with cobicistat

How it works

Darunavir inhibits HIV-1 protease to prevent maturation of infectious virions, while cobicistat has no antiviral activity but inhibits CYP3A to boost and sustain darunavir exposure.

Prescribing in practice

• Cobicistat is a potent CYP3A inhibitor, so this combination has extensive contraindications and interactions and every co-prescription must be checked against an HIV drug-interaction resource.
• Darunavir contains a sulfonamide moiety and should be used with caution in patients with known sulfonamide allergy, with monitoring for severe skin reactions.
• Cobicistat inhibits renal tubular creatinine secretion, causing a non-pathological rise in serum creatinine, but a genuine fall in measured renal function should still be investigated.

Monitoring

Monitor HIV viral load and CD4 count for treatment response, together with renal and hepatic function and lipids.

Counselling the patient

• Take it once daily with food and do not miss doses, as missed doses risk resistance.
• Always check with your HIV team or pharmacist before starting any new medicine, including over-the-counter products.
• Report any significant rash promptly.

Evidence & guidelines

Darunavir boosted with cobicistat is an established protease-inhibitor option in national and international HIV treatment guidelines.