Cobicistat

How it works

It is a potent inhibitor of cytochrome P450 3A, slowing metabolism of co-administered boosted drugs and thereby raising and sustaining their plasma concentrations.

Prescribing in practice

• Its strong CYP3A inhibition causes extensive, potentially serious drug interactions, so all co-medication (including statins, inhaled and intranasal corticosteroids, sedatives and ergot derivatives) must be screened before and during use.
• It inhibits tubular creatinine secretion, producing a non-progressive rise in serum creatinine without a true fall in glomerular filtration.
• It must be given with the specific agent it boosts and is not interchangeable with ritonavir on a like-for-like basis.

Monitoring

Monitor renal function (interpreting creatinine changes in context) and review for drug interactions at every prescribing point.

Counselling the patient

• Always tell pharmacists and other prescribers you take a boosting agent before starting any new medicine, including over-the-counter products.
• Take it together with food and with the antiretroviral it accompanies.
• Do not stop or change doses without specialist advice.

Evidence & guidelines

Use reflects established HIV treatment guidelines and product information for boosted antiretroviral regimens.