Drug Detail


Last Updated April 26, 2013

Trade Names


Drug Classification

HIV protease inhibitor antiretroviral


50 mg/g oral powder

Indications and Pharmacology

Indication: treatment of HIV infection in combination with other antiretrovirals.

Mechanism of action*: inhibits cleavage of viral gag-pol polyproteins precursors into functional proteins by binding to the HIV protease enzyme.

Pharmacokinetics*: metabolized in the liver by CYP 2C19 and 3A4 (metabolized to active M8 metabolite). Inhibits CYP 450 3A4 enzyme. Half-life: 3.5-5.0 hours.


Adult Dose: 750 mg three times daily or 1250 mg twice daily.

Use in Renal or Hepatic Insufficiency*:

  • No dose adjustment for renal dysfunction.
  • No dosage adjustment for mild hepatic dysfunction. Do not use in moderate to severe hepatic dysfunction.

Use in Pregnancy and Breastfeeding*: Category B. Excreted into breast milk.

Use in Children:

  • Children > 2 years: 20-30 mg/kg 3 times daily.


See Drug–Drug Interactions.

Drug–Drug Interactions

Contraindicated: amiodarone, quinidine, lovastatin, simvastatin, rifampicin, rifapentine, cisapride, pimozide, midazolam, triazolam, dihydroergotamine, ergonovine, ergotamine, methylergonovine, St John’s wort, alfuzosin, salmeterol, sildenafil for pulmonary arterial hypertension.

Increased concentrations of concomitant medication: warfarin, carbamazepine, tricyclic antidepressants, bosentan, azithromycin, clarithromycin, trazodone, rifabutin (dose rifabutin 150 mg once daily or 300 mg 3 times per week; monitor for antimycobacterial activity and consider therapeutic drug monitoring), alprazolam, diazepam, fluticasone, atorvastatin, rosuvastatin, lovastatin, simvastatin, sildenafil, tadalafil, vardenafil, colchicine, cyclosporine, tacrolimus, sirolimus.

Decreased concentrations of concomitant medication: methadone, warfarin, phenytoin, ethinyl estradiol, norethindrone.

Considerations for Special Populations

See above for paediatric dosing.

Adverse Effects

Diarrhoea, hyperlipidemia, hyperglycaemia, fat maldistribution, potential for increased bleeding in patients with haemophilia, increased liver enzymes.

*Information from US prescribing information.