Indinavir is a protease inhibitor antiretroviral medication indicated for the treatment of human immunodeficiency virus (HIV-1) infection. It functions by selectively inhibiting the viral protease enzyme, preventing the cleavage of viral polyproteins and resulting in the production of immature, non-infectious viral particles. This agent is typically prescribed as part of a combination antiretroviral therapy (cART) regimen to suppress viral replication, 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 optimizing clinical outcomes.

Features

• Active pharmaceutical ingredient: Indinavir sulfate
• Standard formulation: 200 mg, 400 mg capsules
• Mechanism: Selective inhibition of HIV-1 protease
• High oral bioavailability when administered under fasting conditions or with a low-fat meal
• Metabolism primarily hepatic via cytochrome P450 3A4 (CYP3A4)
• Elimination half-life: approximately 1.8 hours in adults

Benefits

• Significantly reduces HIV-1 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 to prevent viral resistance
• Well-established safety and efficacy profile in clinical use since 1996
• Contributes to long-term 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 always administered as a component of a multidrug antiretroviral regimen, which typically includes two nucleoside reverse transcriptase inhibitors (NRTIs). Its use is guided by genotypic or phenotypic resistance testing when available, particularly in treatment-experienced individuals where protease inhibitor resistance may be a concern. Off-label use has been explored in post-exposure prophylaxis (PEP) protocols, though other agents are generally preferred in contemporary guidelines due to indinavir’s side effect profile and dosing requirements.

Dosage and direction

The recommended adult dosage is 800 mg (two 400 mg capsules) orally every 8 hours. Administration must occur either 1 hour before or 2 hours after a meal, or with a light, low-fat snack to ensure adequate absorption. Dosage adjustment is necessary in patients with hepatic impairment due to reduced metabolism—600 mg every 8 hours is recommended for moderate hepatic insufficiency. Pediatric dosing is based on body surface area: 500 mg/m² every 8 hours, not to exceed the adult dose. Patients must maintain adequate hydration (at least 1.5 L daily) to reduce the risk of nephrolithiasis. Dosage may require modification when co-administered with drugs that affect CYP3A4 activity.

Precautions

Hydration status must be carefully monitored, as indinavir is associated with nephrolithiasis in approximately 10% of patients. Liver function tests should be performed at baseline and periodically during therapy, as transaminase elevations and hyperbilirubinemia may occur. Patients with hemophilia may experience increased bleeding frequency. Hyperglycemia and new-onset diabetes mellitus have been reported with protease inhibitors; glucose monitoring is advised. Fat redistribution (lipodystrophy) and lipid abnormalities (hypertriglyceridemia, hypercholesterolemia) may develop with long-term use. 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 administration with drugs highly dependent on CYP3A4 for clearance and with narrow therapeutic indices is contraindicated, including alfuzosin, amiodarone, cisapride, ergot derivatives, lovastatin, simvastatin, pimozide, sildenafil (for pulmonary arterial hypertension), triazolam, and oral midazolam. Serious and/or life-threatening reactions such as cardiac arrhythmias, prolonged sedation, or respiratory depression may occur. Use is also contraindicated with St. John’s wort due to reduced indinavir concentrations and potential loss of virologic response.

Possible side effect

Common adverse reactions include nephrolithiasis (9-12%), nausea (12%), abdominal pain (9%), headache (6%), asthenia (4%), and vomiting (4%). Asymptomatic hyperbilirubinemia (10-15%) and elevated liver transaminases (5-10%) are frequently observed laboratory abnormalities. Less common effects include diarrhea, insomnia, dizziness, rash, dry skin, and taste perversion. Rare but serious side effects include acute hemolytic anemia, diabetes mellitus exacerbation, and severe skin reactions including Stevens-Johnson syndrome. Nephrolithiasis may present with flank pain, hematuria, and renal colic, requiring temporary interruption of therapy and hydration.

Drug interaction

Indinavir is a potent inhibitor of CYP3A4 and may increase concentrations of co-administered drugs metabolized by this pathway. Significant interactions occur with: rifampin (reduces indinavir AUC by 90%), ketoconazole (increases indinavir AUC by 70%), delavirdine (increases indinavir AUC by 40%), and efavirenz (reduces indinavir AUC by 30%). Dose adjustment is required with these agents. Caution is advised with phosphodiesterase inhibitors (increased sildenafil concentrations), calcium channel blockers, and immunosuppressants. Antacids and didanosine should be administered at least 1 hour apart from indinavir. Herbal supplements like garlic capsules may reduce indinavir concentrations.

Missed dose

If a dose is missed within 2 hours of the scheduled time, the patient should take it immediately. If more than 2 hours have passed, the missed dose should be skipped and the regular dosing schedule resumed. Patients should not double the next dose to make up for a missed dose, as this may increase the risk of adverse effects. Consistent adherence to the 8-hour dosing schedule is critical to maintain therapeutic drug levels and prevent viral breakthrough. Healthcare providers should educate patients on strategies to improve adherence, including the use of pill organizers and alarm reminders.

Overdose

Limited data exist on acute indinavir overdose. Single doses up to 2.4 g have been administered without severe adverse effects. Expected manifestations would include exacerbation of known adverse reactions, particularly nephrolithiasis, nausea, vomiting, and diarrhea. Management should include supportive care with maintenance of hydration and electrolyte balance. Hemodialysis is unlikely to be effective due to high protein binding and extensive metabolism. Activated charcoal may be administered if presented within 1-2 hours of ingestion. Symptomatic treatment for specific manifestations should be instituted as required.

Storage

Store capsules at controlled room temperature (20-25°C or 68-77°F) in the original container with the cap tightly closed. Protect from moisture and light. Keep out of reach of children and pets. Do not use beyond the expiration date printed on the packaging. Avoid storing in bathrooms or other areas with high humidity. Excursions between 15-30°C (59-86°F) are permitted. Do not freeze. Properly discard any unused medication through medication take-back programs or according to local regulations.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Treatment decisions should be made by qualified healthcare professionals based on individual patient characteristics. The prescribing physician should be consulted for specific dosage recommendations and management of adverse effects. This summary is not exhaustive and may not include all available information regarding uses, directions, warnings, precautions, interactions, adverse effects, or risks associated with indinavir therapy. Always refer to the full prescribing information and current clinical guidelines for complete product details.

Reviews

Clinical trials demonstrated that indinavir-containing regimens achieved viral suppression below detectable limits (<500 copies/mL) in 60-80% of treatment-naïve patients at 24 weeks. Long-term follow-up studies show durable virological response in adherent patients, with CD4 count increases averaging 100-150 cells/μL per year. Real-world evidence confirms its efficacy but notes challenges with adherence due to the strict dosing schedule and side effect profile. Many clinicians now reserve indinavir for specific cases where resistance patterns or individual patient factors make it the optimal choice, particularly as newer protease inhibitors with improved dosing convenience have become available. Patient-reported outcomes indicate satisfaction with virological control but frequent concerns about gastrointestinal side effects and nephrolithiasis risk.