cobicistat: clinical use

Prescribing considerations

• Initiation and regimen changes should be supervised by a clinician experienced in HIV management.
• Use only to enhance atazanavir or darunavir as specified in the selected licence; do not combine with another booster or cobicistat-containing product.
• Screen comprehensively for interactions, including corticosteroids, anticoagulants, antiplatelets, anticonvulsants, statins and herbal products.
• Pregnancy requires prompt specialist review because boosting becomes inadequate.
• Cobicistat can increase serum creatinine by inhibiting tubular creatinine secretion; interpret creatinine-based renal estimates in context.

Contraindications and cautions

• Hypersensitivity to cobicistat or an excipient
• Strong CYP3A inducers including rifampicin, carbamazepine, phenytoin, phenobarbital and St John’s wort
• CYP3A substrates where increased exposure may cause serious harm, including simvastatin, lovastatin, amiodarone, quinidine, alfuzosin, lurasidone, pimozide, oral midazolam and triazolam
• Dabigatran etexilate
• Not recommended in severe hepatic impairment; evidence in dialysis is unavailable

Monitoring

• HIV viral load and clinical effectiveness of the complete antiretroviral regimen
• Renal function and serum creatinine changes
• Liver tests and bilirubin where clinically appropriate, especially with atazanavir
• Toxicity or loss of effect from interacting medicines
• Medication changes made by any prescriber, including inhaled, injected or topical therapies

Clinical pharmacology

Cobicistat is a selective, mechanism-based CYP3A inhibitor and a weak CYP2D6 inhibitor. It also inhibits P-gp, BCRP, MATE1, OATP1B1 and OATP1B3. It enhances protease-inhibitor exposure but has no intrinsic antiviral activity.

Formulation and product differences

• The selected standalone product is an orange, round film-coated tablet.
• The tablet contains sunset yellow FCF and should not be chewed, crushed or split.
• Cobicistat is also present in fixed-combination HIV products, which are not interchangeable with standalone cobicistat without full regimen review.

Tablet

Route: Oral

Strengths: 150 mg