Prezcobix is an antiretroviral medicine used as part of combination treatment for HIV-1 infection. It combines two medicines in one tablet:

• Darunavir: a protease inhibitor that blocks an enzyme HIV needs to produce new, infectious virus particles
• Cobicistat: a pharmacokinetic booster that inhibits the liver enzyme responsible for breaking down darunavir, keeping darunavir levels high enough for once-daily dosing
  

Prezcobix simplifies treatment compared to taking darunavir and a separate booster (ritonavir) as two tablets.

Take one tablet once daily with food. Food is important because it improves absorption and reduces stomach upset.

Take at the same time each day. Prezcobix must always be used in combination with other antiretroviral medicines. Do not take it as the sole HIV treatment.

Do not stop without speaking to your HIV doctor.

If you remember within 12 hours of your usual dose time, take it with food immediately. If more than 12 hours have passed, skip that dose and take the next one as usual. Never take two doses at once.

Contact your HIV specialist or a poison control centre immediately.

• Store below 30°C
• Keep in the original packaging
• Keep out of reach of children

Common side effects:

• Diarrhoea
• Nausea
• Headache
• Rash: darunavir contains a sulfonamide component and can cause rash, particularly in people with sulfonamide allergy

Less common but important:

• Liver enzyme elevations: liver function is checked during treatment. Report signs of jaundice
• Kidney changes: cobicistat raises creatinine, similar to other cobicistat-containing regimens. This is usually not true kidney damage but must be monitored
• Raised cholesterol and blood sugar (protease inhibitor class effects)
  

Blood tests for kidney, liver, lipids, and viral load are checked regularly.

Cobicistat is a strong CYP3A4 inhibitor with the same broad interaction profile as ritonavir. Important interactions include:

• Statins: cobicistat significantly affects how some statins are processed, which can increase the risk of muscle side effects. Your doctor will review which statins are safe to use
• Rifampicin: dramatically reduces darunavir levels. Tell your doctor if you take rifampicin before starting Prezcobix
• Antiepileptics (carbamazepine, phenytoin): can reduce darunavir levels. Tell your doctor about any anticonvulsant medicines you take
• Sildenafil (for pulmonary arterial hypertension): there is an important interaction that requires specialist management. Tell your specialist you are on Prezcobix
• St John's Wort: significantly reduces darunavir levels; avoid

Always have a pharmacist review all medicines before starting or changing anything while on Prezcobix.

What is the difference between Prezcobix and Evotaz?

Both are single tablets combining a protease inhibitor with cobicistat. Prezcobix contains darunavir 800 mg with cobicistat, while Evotaz contains atazanavir 300 mg with cobicistat. They target the same HIV enzyme but are different protease inhibitors with slightly different side effect profiles and resistance patterns. Your HIV doctor will choose based on your history, resistance profile, and other medicines you take.

Do I have a sulfa allergy risk with Prezcobix?

Darunavir contains a sulfonamide moiety. If you have a known sulfonamide antibiotic allergy (e.g., to trimethoprim-sulfamethoxazole), there is a potential for cross-reaction, though this is uncommon. Tell your HIV doctor about any sulfa drug allergies before starting.

Ace provides accurate and independent information medically reviewed on prescription medications. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.