ritonavir: clinical use

Prescribing considerations

• Prescribing should be supervised by clinicians experienced in HIV treatment.
• Review the contraindications, warnings and interaction profile of both ritonavir and the co-administered protease inhibitor.
• Complete medication reconciliation must include non-prescription products, herbal remedies and recreational substances.
• Persistent vomiting, diarrhoea or malabsorption may compromise exposure and adherence; assess hydration and renal function where clinically indicated.
• Use cautiously in stable severe hepatic impairment because exposure to the accompanying protease inhibitor may increase.

Contraindications and cautions

• Hypersensitivity to ritonavir or a formulation excipient
• Decompensated liver disease
• Contraindicated interacting medicines, including St John’s wort, simvastatin, lovastatin, oral midazolam, triazolam, quetiapine, lurasidone and specified antiarrhythmics
• Any additional contraindication applying to the co-administered protease inhibitor

Monitoring

• HIV viral load, treatment adherence and clinical response within specialist care
• Liver function, blood lipids and glucose according to the regimen and clinical context
• Renal function if severe or persistent gastrointestinal symptoms occur, especially with pre-existing impairment
• Medicine-specific parameters when interactions cannot be avoided, such as thyroid function with levothyroxine or drug concentrations with calcineurin inhibitors
• ECG or additional hepatic monitoring where required by interacting medicines or underlying conduction disease

Clinical pharmacology

Ritonavir is a peptidomimetic HIV-1 and HIV-2 protease inhibitor. It is a potent CYP3A4 inhibitor, also inhibits CYP2D6 and P-glycoprotein, and can induce several other metabolic pathways. It is principally metabolised by the liver and eliminated through the hepatobiliary route; renal clearance is negligible.

Formulation and product differences

• Film-coated tablets must be swallowed whole with food.
• Powder for oral suspension can be mixed with specified soft food or liquid and supports administration through a feeding tube.
• Prepared powder mixtures must be consumed within 2 hours; the supplied measuring equipment is required when only part of a mixture is administered.
• The powder has a persistent bitter aftertaste, which may be reduced using the food options described in the product instructions.

Oral suspension

Route: Oral

Strengths: 100 mg

Tablet

Route: Oral

Strengths: 100 mg