Norvir (Ritonavir)

Norvir is a protease inhibitor used in the management of HIV‑1 infection within combination antiretroviral regimens.

• HIV‑1 infection: reduces viral replication when combined with other antiretroviral agents, helping to achieve and maintain viral suppression.
• HIV‑1 infection (adults): contributes to immune recovery by lowering plasma HIV RNA levels.
• HIV‑1 infection (adolescents): part of recommended therapy to control disease progression.

• Ritonavir inhibits the HIV‑1 protease enzyme, preventing the cleavage of viral polyprotein precursors into functional proteins. This blockade results in the production of immature, non‑infectious viral particles, thereby reducing viral load and limiting disease progression when used with other antiretrovirals.

Ritonavir may cause a range of adverse reactions, some of which are common and others that are serious or rare.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Diarrhea: increased frequency of loose stools.
• Fatigue: feeling of tiredness or lack of energy.
• Headache: mild to moderate head pain.
• Rash: skin irritation or redness.
• Taste disturbance: altered sense of taste.

Serious or Rare Side Effects

• Hepatotoxicity: liver enzyme elevations or hepatitis.
• Severe allergic reactions: anaphylaxis, angioedema.
• QT prolongation: cardiac rhythm disturbances.
• Pancreatitis: inflammation of the pancreas.
• Severe hyperglycemia: marked increase in blood glucose.
• Lipodystrophy: abnormal fat distribution.

When prescribing Norvir, clinicians should consider several safety measures to minimize risk.

• Liver monitoring: assess hepatic function before and during therapy.
• Drug interaction review: evaluate concomitant medications for CYP3A4 effects.
• Cardiovascular assessment: monitor QT interval in patients with cardiac risk.
• Adherence counseling: emphasize importance of consistent dosing.
• Store at below 25°C: keep in the original pack, protect from moisture.

Ritonavir is a potent CYP3A4 inhibitor and can alter the exposure of many co‑administered drugs.

Major Interactions (Avoid)

• Simvastatin: risk of severe myopathy.
• Certain antiarrhythmics (e.g., amiodarone): may cause cardiac toxicity.
• Certain sedatives (e.g., midazolam): can lead to profound sedation.
• Certain anticoagulants (e.g., warfarin): may increase bleeding risk.
• Other protease inhibitors: can cause excessive plasma concentrations.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: reduced efficacy, consider alternative contraception.
• Antidiabetic agents (e.g., metformin): monitor blood glucose levels.
• Antiepileptics (e.g., carbamazepine): may require dose adjustment.
• Antihistamines (e.g., cetirizine): watch for increased sedation.
• Macrolide antibiotics (e.g., erythromycin): monitor for hepatotoxicity.