Indinavir sulfate is a highly selective protease inhibitor indicated for the treatment of human immunodeficiency virus (HIV-1) infection. It functions by binding to the active site of the HIV-1 protease enzyme, effectively preventing the cleavage of viral polyprotein precursors into functional proteins required for viral maturation and infectivity. This agent is typically administered in combination with other antiretroviral agents as part of a comprehensive highly active antiretroviral therapy (HAART) regimen, aimed at achieving sustained viral suppression, improving immunological function, and delaying disease progression. 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 dosage form: Capsules (200 mg, 333 mg, 400 mg)
• 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 requirements: Room temperature (15–30°C), protect from moisture

Benefits

• Achieves rapid and profound reduction in viral load when used in combination therapy
• Contributes to restoration and preservation of CD4+ T-cell counts
• Delays progression to AIDS-defining illnesses and mortality
• May reduce the risk of HIV transmission through viral suppression
• Supports long-term management of chronic HIV infection
• Enhances quality of life through sustained immunovirological control

Common use

Indinavir is principally indicated for the treatment of HIV-1 infection in adults and pediatric patients over 4 years of age, in combination with other antiretroviral agents. It is often incorporated into initial therapy regimens for treatment-naïve patients or used in salvage therapy for experienced patients with specific resistance patterns. Clinical use is guided by genotypic/phenotypic resistance testing where available. It may also be considered for post-exposure prophylaxis in certain occupational or non-occupational exposure scenarios, following established guidelines.

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; alternatively, it may be taken with a light, low-fat snack. Pediatric dosing is based on body surface area (500 mg/m² every 8 hours). Dosage adjustment is necessary in patients with hepatic impairment (reduce to 600 mg every 8 hours). Adherence to the 8-hour dosing interval is critical to maintain plasma concentrations above the inhibitory threshold. Swallow capsules whole with water.

Precautions

Hydration is essential—maintain adequate fluid intake (at least 1.5 L daily) to reduce risk of nephrolithiasis. Monitor liver function tests at baseline and periodically during therapy. Use with caution in patients with hepatic impairment, hemophilia, or diabetes mellitus. May cause hyperbilirubinemia (mostly unconjugated), which is generally benign but may require monitoring. Assess lipid profile before and during treatment due to potential dyslipidemia. Not recommended during pregnancy unless potential benefit justifies potential risk; adequate contraception is advised.

Contraindications

Hypersensitivity to indinavir or any component of the formulation. Coadministration with drugs highly dependent on CYP3A4 for clearance and with narrow therapeutic indices (e.g., alfuzosin, amiodarone, cisapride, ergot derivatives, lovastatin, simvastatin, pimozide, quinidine, sildenafil for pulmonary arterial hypertension, triazolam, oral midazolam). Severe hepatic impairment. Concomitant use with St. John’s wort is contraindicated due to risk of reduced efficacy.

Possible side effect

• Nephrolithiasis/urolithiasis (∼12%)
• Nausea, abdominal pain, vomiting
• Asymptomatic hyperbilirubinemia (∼14%)
• Headache, dizziness, fatigue
• Diarrhea, dyspepsia
• Rash, dry skin
• Lipodystrophy, hyperglycemia
• Increased transaminases
• Hemolytic anemia (rare)

Drug interaction

Indinavir is a potent inhibitor of CYP3A4 and may increase concentrations of coadministered drugs metabolized by this pathway. Significant interactions include:

• Rifampin, rifabutin: decrease indinavir concentrations
• Ketoconazole, itraconazole: increase indinavir concentrations
• Didanosine: administer at least 1 hour apart
• Atorvastatin, pravastatin: may require dose adjustment
• Sildenafil (for erectile dysfunction): maximum 25 mg/48h
• Oral contraceptives: alternative contraception recommended
• Clarithromycin: mutual increase in concentrations

Missed dose

If a dose is missed within 2 hours of the scheduled time, take it immediately, then resume the regular schedule. If more than 2 hours have passed, skip the missed dose and take the next dose at the regularly scheduled time. Do not double the dose. Consistent adherence is vital to prevent viral breakthrough and resistance.

Overdose

Limited experience. Acute toxicity may include nephrolithiasis, nausea, vomiting, diarrhea. No specific antidote exists. Management involves supportive care, including hydration and symptomatic treatment. Hemodialysis is unlikely to be effective due to high protein binding and extensive metabolism.

Storage

Store at room temperature (15–30°C). Keep in original container, tightly closed. Protect from moisture. Do not remove desiccant from bottle. Keep out of reach of children and pets. Do not use beyond expiration date.

Disclaimer

This information is intended for healthcare professionals. It is not exhaustive and does not replace professional medical advice, diagnosis, or treatment. Always consult approved prescribing information and clinical guidelines before initiation or modification of therapy. Dosage and administration must be individualized based on patient characteristics, concomitant medications, and virological response.

Reviews

“Indinavir remains a valuable component of salvage regimens in carefully selected patients with multidrug-resistant HIV, particularly when supported by resistance testing. Its well-characterized resistance profile and high barrier to resistance in combination therapy contribute to durable responses.” – Clinical Infectious Diseases

“While newer agents offer improved convenience, indinavir’s potency and distinct resistance mutations maintain its relevance in complex treatment scenarios. Hydration and adherence to dosing instructions are critical for tolerability.” – Journal of Antimicrobial Chemotherapy

“Long-term follow-up data confirm sustained efficacy and acceptable safety in adherent patients. Metabolic complications and nephrolithiasis require vigilant monitoring but are generally manageable with prophylactic measures.” – AIDS Research and Therapy