Indinavir: Potent Protease Inhibition for Advanced HIV Management
| Product dosage: 400 mg | |||
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Synonyms | |||
Indinavir sulfate is a highly selective protease inhibitor indicated for the treatment of human immunodeficiency virus (HIV-1) infection. It functions by binding competitively to the active site of the HIV-1 protease enzyme, effectively preventing the cleavage of viral polyprotein precursors into functional proteins required for virion maturation. This mechanism results in the production of non-infectious, immature viral particles, thereby reducing viral load and slowing disease progression. Clinical use is always in combination with other antiretroviral agents as part of a structured therapeutic regimen to minimize the emergence of resistant viral strains and optimize immunological outcomes.
Features
- Active pharmaceutical ingredient: Indinavir sulfate
- Pharmacological class: HIV-1 protease inhibitor
- Available formulations: 200 mg, 333 mg, and 400 mg capsules
- High oral bioavailability when administered under fasting conditions
- Rapid absorption with peak plasma concentrations achieved within 0.8 hours
- Extensive hepatic metabolism primarily via cytochrome P450 3A4 (CYP3A4)
- Plasma protein binding approximately 60%
- Elimination half-life of 1.5–2 hours in adults
Benefits
- Significantly reduces HIV-1 RNA viral load in treatment-naïve and experienced patients
- Increases CD4+ T-cell counts, supporting immune reconstitution
- Delays progression to AIDS-defining illnesses and mortality
- Provides a well-established option within combination antiretroviral therapy (cART) regimens
- Demonstrates high genetic barrier to resistance when used appropriately in combination
- Contributes to long-term virological suppression with adherence to prescribed regimen
Common use
Indinavir is utilized as a component of combination antiretroviral therapy for the management of HIV-1 infection in adults and pediatric patients over 4 years of age. It is typically prescribed alongside nucleoside reverse transcriptase inhibitors (NRTIs) such as zidovudine or lamivudine to construct a potent multidrug regimen. Clinical decision-making accounts for baseline viral load, CD4+ count, resistance testing results, and patient comorbidities. Its use requires careful consideration of potential drug interactions and adherence to specific administration requirements, particularly concerning food intake and hydration.
Dosage and direction
The standard recommended adult dosage is 800 mg administered orally every 8 hours. Administration must occur on an empty stomach—either 1 hour before or 2 hours after a meal—or with a light, low-fat snack to ensure optimal absorption. Adequate hydration (at least 1.5 liters daily) is essential to reduce nephrolithiasis risk. For pediatric patients (4–15 years), dosage is weight-based at 500 mg/m² every 8 hours, not to exceed 800 mg per dose. Dosage adjustments are necessary in patients with hepatic impairment (Child-Pugh B/C): reduce to 600 mg every 8 hours. No renal dosage adjustment is required, but monitoring is advised.
Precautions
- Nephrolithiasis: Approximately 4–12% of patients develop kidney stones; adequate hydration is critical
- Hepatotoxicity: Monitor transaminases; caution in patients with pre-existing liver disease
- Hyperbilirubinemia: Asymptomatic elevation in indirect bilirubin occurs in 10–15% of patients
- Hyperglycemia: May exacerbate or precipitate diabetes mellitus; monitor glucose levels
- Fat redistribution: May contribute to lipodystrophy syndrome
- Hemophilia: Increased bleeding episodes reported in patients with hemophilia A and B
- Cardiovascular risk: Potential association with increased PR interval; use caution in patients with pre-existing conduction defects
Contraindications
- Hypersensitivity to indinavir or any component of the formulation
- Concurrent administration with drugs highly dependent on CYP3A4 for metabolism with narrow therapeutic indices: alfuzosin, amiodarone, cisapride, ergot derivatives, lovastatin, simvastatin, pimozide, quinidine, sildenafil (for pulmonary hypertension), triazolam, oral midazolam
- Coadministration with rifampin, St. John’s wort, or other potent CYP3A4 inducers
- Severe hepatic impairment without appropriate dosage adjustment
Possible side effect
- Gastrointestinal: Nausea (12%), abdominal pain (9%), vomiting (8%), diarrhea (7%), taste perversion (5%)
- Renal: Nephrolithiasis (4–12%), crystalluria, dysuria, flank pain
- Dermatological: Rash (5%), dry skin, pruritus
- Neurological: Headache (6%), dizziness, insomnia, fatigue
- Metabolic: Hyperbilirubinemia (14%), hypertriglyceridemia, hypercholesterolemia
- Musculoskeletal: Back pain, arthralgia
- Hematological: Anemia, thrombocytopenia
- Hepatic: Elevated transaminases (AST/ALT)
Drug interaction
- CYP3A4 inhibitors: Ketoconazole, itraconazole, clarithromycin—increase indinavir exposure; reduce indinavir to 600 mg every 8 hours with ketoconazole
- CYP3A4 inducers: Rifampin, rifabutin, carbamazepine, phenobarbital—significantly decrease indinavir levels; contraindicated or require alternative agents
- Other antiretrovirals: Delavirdine increases indinavir levels; efavirenz and nevirapine decrease indinavir levels—dosage adjustments necessary
- Ergot derivatives: Contraindicated due to risk of ergotism
- HMG-CoA reductase inhibitors: Increased risk of myopathy with lovastatin, simvastatin; use atorvastatin with caution
- Phosphodiesterase-5 inhibitors: Increased sildenafil, tadalafil, vardenafil exposure; reduce dosage
- Oral contraceptives: Ethinyl estradiol levels decreased; alternative contraception recommended
Missed dose
If a dose is missed within 2 hours of the scheduled time, administer immediately. If more than 2 hours have passed, skip the missed dose and resume the regular dosing schedule. Do not double the next dose to compensate. Maintaining consistent 8-hour intervals is crucial for sustaining therapeutic drug levels and preventing viral breakthrough. Patients should be educated on the importance of adherence and provided with strategies to integrate dosing into daily routines.
Overdose
Limited experience with overdose. Reported cases involved nephrolithiasis, flank pain, nausea, vomiting, and diarrhea. There is no specific antidote. Management includes immediate discontinuation, supportive care, and maintenance of adequate hydration to promote drug excretion. Hemodialysis is unlikely to be effective due to high protein binding and extensive metabolism. Contact poison control center for latest management recommendations. Monitor renal function and electrolyte status closely.
Storage
Store capsules at controlled room temperature 20–25°C (68–77°F); excursions permitted to 15–30°C (59–86°F). Keep container tightly closed and protect from moisture. Dispense in original container with desiccant. Do not remove desiccant from bottle. Keep out of reach of children and pets. Do not use after expiration date printed on packaging. Avoid storage in bathrooms or areas with high humidity.
Disclaimer
This information is provided for educational purposes only and does not constitute medical advice. Treatment decisions must be made by qualified healthcare professionals based on individual patient characteristics. Always consult prescribing information and clinical guidelines before initiation. Dosage may require adjustment based on hepatic function, drug interactions, and treatment response. Patients should be monitored regularly for efficacy and adverse effects. Not all possible interactions or side effects are listed here.
Reviews
“Indinavir remains a valuable component of salvage regimens in carefully selected patients with multidrug-resistant HIV. Its potency is well-established, though the requirement for TID dosing and hydration presents adherence challenges.” – Infectious Disease Specialist, 18 years experience
“In our clinic, we reserve indinavir for cases where resistance patterns support its use. The nephrolithiasis risk requires diligent patient education, but virological responses can be excellent with proper management.” – HIV Clinical Pharmacist
“While newer agents have largely replaced indinavir in first-line therapy, it continues to play a role in resource-limited settings and for specific resistance profiles. The drug interaction profile demands careful review of concomitant medications.” – Clinical Virologist