Indinavir: Potent Protease Inhibition for Effective HIV Management
Indinavir
| Product dosage: 400 mg | |||
|---|---|---|---|
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| 60 | $3.12
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Synonyms | |||
Indinavir is a protease inhibitor antiretroviral medication indicated for the treatment of human immunodeficiency virus (HIV-1) infection. It functions by selectively binding to the active site of the HIV-1 protease enzyme, thereby inhibiting the cleavage of viral polyprotein precursors into functional proteins required for viral replication. This agent is typically administered in combination with other antiretroviral agents as part of a highly active antiretroviral therapy (HAART) regimen to reduce viral load, increase CD4 cell counts, and delay the progression to acquired immunodeficiency syndrome (AIDS). Proper adherence to dosing schedules and dietary recommendations is critical to maintaining therapeutic drug levels and minimizing the risk of resistance development.
Features
- Active pharmaceutical ingredient: Indinavir sulfate
- Standard formulation: 200 mg, 400 mg capsules
- Mechanism: Selective inhibition of HIV-1 protease
- Bioavailability: Approximately 65% under fasting conditions
- Half-life: 1.5–2 hours in adults
- Metabolism: Hepatic, primarily via CYP3A4
- Excretion: Renal (<20%) and fecal
- Storage: Room temperature (15–30°C) in tightly closed container
Benefits
- Significantly reduces HIV viral load in treatment-naïve and experienced patients
- Increases CD4+ T-cell counts, improving immune function
- Delays disease progression and reduces HIV-related morbidity and mortality
- Effective as part of combination therapy against resistant strains
- Well-established pharmacokinetic and safety profile in clinical use
- Contributes to sustained virological suppression when adherence is maintained
Common use
Indinavir is principally used in the management of HIV-1 infection in adults and pediatric patients over 4 years of age. It is prescribed as a component of combination antiretroviral therapy, typically alongside nucleoside reverse transcriptase inhibitors (NRTIs) such as zidovudine or lamivudine. Its use is guided by genotypic or phenotypic resistance testing where available. Off-label applications have been explored in post-exposure prophylaxis regimens, though other agents are generally preferred due to indinavir’s pharmacokinetic variability and side effect profile.
Dosage and direction
The recommended adult dosage is 800 mg orally every 8 hours. Administration must occur either 1 hour before or 2 hours after a meal to ensure optimal absorption; co-administration with a low-fat, light snack is acceptable. For patients with mild to moderate hepatic impairment (Child-Pugh classes A and B) due to cirrhosis, a dose reduction to 600 mg every 8 hours is advised. Pediatric dosing is based on body surface area or weight, with 500 mg/m² every 8 hours being a typical regimen. Dosage adjustments may be necessary when co-administered with drugs that induce or inhibit CYP3A4.
Precautions
Hydration is critical during therapy; patients should consume at least 1.5 liters of fluids daily to reduce the risk of nephrolithiasis. Liver function should be monitored periodically, as transaminase elevations may occur. Patients with hemophilia may experience increased bleeding frequency. Hyperglycemia, new-onset diabetes mellitus, and exacerbation of pre-existing diabetes have been reported. Redistribution/accumulation of body fat may occur. Use with caution in patients with a history of renal impairment or nephrolithiasis.
Contraindications
Indinavir is contraindicated in patients with known hypersensitivity to indinavir or any component of the formulation. Concomitant use with drugs highly dependent on CYP3A4 for clearance and with narrow therapeutic indices—such as alfuzosin, amiodarone, ergot derivatives, lovastatin, simvastatin, pimozide, sildenafil (for pulmonary arterial hypertension), and triazolam—is contraindicated due to the risk of serious or life-threatening reactions. It is also contraindicated with drugs that strongly induce CYP3A4, such as rifampin, St. John’s wort, and lovastatin.
Possible side effect
Common adverse reactions include nephrolithiasis (≥12%), nausea (12%), abdominal pain (9%), vomiting (8%), and headache (6%). Less frequently, asymptomatic hyperbilirubinemia (10%), diarrhea, insomnia, dizziness, rash, and taste perversion may occur. Laboratory abnormalities may include elevated ALT/AST, hypertriglyceridemia, and hyperglycemia. Rare but serious effects include acute hemolytic anemia, hepatitis, and Stevens-Johnson syndrome.
Drug interaction
Indinavir is a potent inhibitor of CYP3A4 and a substrate of the same enzyme. Significant interactions occur with:
- CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): increase indinavir exposure
- CYP3A4 inducers (e.g., rifampin, carbamazepine): decrease indinavir exposure
- Didanosine: administer at least 1 hour apart due to buffered formulation
- Atorvastatin, pravastatin: may require dose adjustment
- Oral contraceptives: alternative non-hormonal methods recommended
- Sildenafil (for erectile dysfunction): dose reduction advised
Missed dose
If a dose is missed within 2 hours of the scheduled time, it should be taken as soon as possible. If more than 2 hours have passed, skip the missed dose and resume the usual dosing schedule. Do not double the dose. Consistent adherence is vital to maintain effective concentrations and prevent resistance.
Overdose
There is limited experience with acute overdose. Reported events include nephrolithiasis and gastrointestinal disturbances. Management should include supportive measures and maintenance of hydration. Hemodialysis is unlikely to be effective due to high protein binding and extensive metabolism.
Storage
Store at controlled room temperature, 15–30°C (59–86°F). Keep container tightly closed and protect from moisture. Do not remove desiccant from bottle. Keep out of reach of children and pets.
Disclaimer
This information is intended for healthcare professionals and should not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for personalized recommendations. Dosage and indications may vary based on individual patient factors, regional guidelines, and updated clinical evidence.
Reviews
Clinical trials and post-marketing surveillance have demonstrated indinavir’s efficacy in reducing viral load and increasing CD4 counts, particularly when used in combination regimens. However, its use has declined in favor of better-tolerated protease inhibitors with more favorable dosing schedules and fewer dietary restrictions. Expert consensus acknowledges its historical importance and continued utility in specific resistance scenarios or resource-limited settings. Long-term adherence remains challenging due to the strict dosing schedule and side effect profile.