Retrovir (zidovudine) is a nucleoside reverse transcriptase inhibitor (NRTI) indicated for the treatment of human immunodeficiency virus (HIV) infection. As one of the foundational antiretroviral agents developed, it remains a critical component in combination therapy regimens aimed at suppressing viral replication, improving immunological function, and reducing HIV-related morbidity and mortality. Its established efficacy and well-characterized safety profile make it a cornerstone option in both treatment-naïve and experienced patients, supported by decades of clinical use and ongoing research.

Features

• Active pharmaceutical ingredient: Zidovudine 300 mg
• Formulation: Film-coated tablets for oral administration
• Pharmacological class: Nucleoside reverse transcriptase inhibitor (NRTI)
• Mechanism: Inhibits reverse transcriptase, blocking HIV RNA-dependent DNA polymerase
• Bioavailability: Approximately 60-70% following oral administration
• Half-life: 1.1 hours (intracellular half-life of active metabolite: 3-4 hours)
• Metabolism: Hepatic glucuronidation via UGT2B7
• Excretion: Primarily renal (50-80% as metabolites)

Benefits

• Effectively suppresses HIV viral replication when used in combination therapy
• Demonstrates proven reduction in disease progression and mortality in HIV-infected individuals
• Provides well-established pharmacokinetic profile with predictable dosing parameters
• Shows efficacy in preventing maternal-fetal HIV transmission when administered during pregnancy
• Offers flexible dosing options compatible with various combination regimens
• Maintains activity against HIV-1 and HIV-2 viral strains

Common use

Retrovir is indicated for the treatment of HIV infection in adults and children, always in combination with other antiretroviral agents. It is typically prescribed as part of a three-drug regimen, often paired with lamivudine and a third agent from another antiretroviral class. The medication is also used for prevention of maternal-fetal HIV transmission when administered to pregnant individuals with HIV infection and their newborns. Clinical decisions regarding its use consider viral load, CD4 cell count, treatment history, and potential drug interactions.

Dosage and direction

Adults: 300 mg twice daily or 200 mg three times daily
Pediatric patients: 160 mg/m² body surface area three times daily (maximum 200 mg per dose)
Prevention of maternal-fetal transmission:

• Maternal dosing: 100 mg five times daily or 300 mg twice daily beginning at 14-34 weeks gestation and continuing through delivery
• Neonatal dosing: 2 mg/kg orally every 6 hours beginning 8-12 hours after birth and continuing for 6 weeks

Administration should occur with or without food, though consistent timing relative to meals is recommended. Tablets should be swallowed whole with water. Dosage adjustments are required in patients with impaired renal function (creatinine clearance <50 mL/min) or significant hepatic impairment.

Precautions

• Regular monitoring of hematological parameters is essential due to potential bone marrow suppression
• Hepatic function should be assessed periodically, particularly in patients with pre-existing liver disease
• Lactic acidosis and severe hepatomegaly with steatosis have been reported with nucleoside analogues
• Fat redistribution and metabolic abnormalities may occur with antiretroviral therapy
• Immune reconstitution syndrome may manifest during initial treatment phase
• Patients should be advised regarding potential neurological side effects including insomnia and headache

Contraindications

• Hypersensitivity to zidovudine or any component of the formulation
• Life-threatening allergic reactions to any nucleoside analogue
• Concomitant use with stavudine due to antagonistic antiviral effects
• Combination with ribavirin in HIV/HCV co-infected patients due to increased risk of mitochondrial toxicity
• Severe hepatic impairment without appropriate dosage adjustment
• Pre-existing significant bone marrow suppression (hemoglobin <7.5 g/dL or neutrophil count <0.75 × 10⁹/L)

Possible side effects

Common (≥10%):

• Headache (35-45%)
• Nausea (30-40%)
• Insomnia and other sleep disturbances (20-25%)
• Fatigue (15-20%)
• Gastrointestinal discomfort (10-15%)

Less common (1-10%):

• Anemia and neutropenia
• Myopathy with prolonged use
• Nail pigmentation changes
• Hepatic transaminase elevations
• Hyperbilirubinemia

Rare (<1%):

• Lactic acidosis
• Severe hepatomegaly with steatosis
• Lipoatrophy
• Pancreatitis
• Seizures

Drug interaction

• Ganciclovir/valganciclovir: Increased risk of hematological toxicity
• Ribavirin: Antagonistic effect and increased mitochondrial toxicity
• Other bone marrow suppressive agents: Additive myelosuppression
• Probenecid: May increase zidovudine levels by inhibiting glucuronidation
• Clarithromycin: Reduced zidovudine concentrations
• Methadone: May increase zidovudine levels by 30-40%
• Phenytoin: Altered levels of both medications requiring monitoring

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next scheduled dose. In that case, the missed dose should be skipped and the regular dosing schedule resumed. Patients should not double the dose to make up for a missed administration. Consistent adherence is critical for maintaining viral suppression and preventing resistance development.

Overdose

Symptoms of overdose may include fatigue, headache, nausea, vomiting, and hematological abnormalities. Hemodialysis and peritoneal dialysis have limited effectiveness in removing zidovudine. Management is supportive and symptomatic, including monitoring of hematological parameters and providing appropriate medical intervention for specific manifestations. There is no specific antidote for zidovudine overdose.

Storage

Store at controlled room temperature (20-25°C/68-77°F) with excursions permitted between 15-30°C (59-86°F). Protect from light and moisture. Keep in the original container with the lid tightly closed. Do not store in bathroom cabinets or other humid locations. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Treatment decisions should be made in consultation with a qualified healthcare professional familiar with the patient’s complete medical history. Dosage and administration may vary based on individual patient factors. The prescribing physician should be consulted for specific recommendations and monitoring requirements.

Reviews

“Retrovir has demonstrated consistent efficacy in our HIV treatment cohort over two decades of use. While newer agents offer advantages in certain populations, zidovudine remains a valuable option, particularly in resource-limited settings and for prevention of vertical transmission.” - Infectious Disease Specialist, University Teaching Hospital

“Long-term follow-up of patients on zidovudine-containing regimens shows durable viral suppression when combined with appropriate partner agents. The hematological monitoring requirements are manageable with proper patient education and follow-up.” - HIV Clinical Pharmacist, Regional Treatment Center

“Despite the development of newer antiretrovirals, zidovudine maintains its place in therapy due to its well-characterized safety profile and extensive clinical experience. The twice-daily formulation has improved adherence compared to the historical TID dosing.” - Clinical Researcher, HIV Therapeutics Program