Zidovudine

Zidovudine is a prescription medication used to treat HIV leading to AIDS. It is also given during pregnancy to prevent the passing of the virus from an HIV-infected mother to the child.

• Zidovudine is available under the following different brand names: Retrovir, ZDV (formerly AZT)

Adult and pediatric dosage

Capsule

• 100mg

Tablet

• 300mg

Syrup

• 50mg/5mL

Injectable solution

• 10mg/mL

HIV Infection Treatment

Adult dosage

• 300 mg orally every 12 hours OR 200 mg orally every 8 hours (600 mg/day)
• IV: 1 mg/kg/dose every 4 hours (6 times daily)

Pediatric dosage

Oral

• Gestational age above 35 weeks
  • Birth to 4 weeks: 4 mg/kg orally twice daily
  • Above 4 weeks: 12 mg/kg orally twice daily
• Gestational age above 30 to below 35 weeks
  • Birth to 2 weeks: 2 mg/kg orally twice daily
  • 2 weeks: 3 mg/kg orally twice daily
  • Above 6-8 weeks: 12 mg/kg orally twice daily
• Gestational age above 30 weeks
  • Birth to 4 weeks: 2 mg/kg orally twice daily
  • 4 to 8 weeks: 3 mg/kg orally twice daily
  • Above 8-10 weeks: 12 mg/kg orally twice daily
• Infants born at or near term (Gestational age above 35 weeks)
  • Weight between 4 to 8  kg: 12 mg/kg orally twice daily
  • Weight between 9 to 29 kg: 9 mg/kg orally twice daily
  • Weight above 30 kg: 300 mg orally twice daily

Adolescents

• 300 mg orally twice daily

Body surface area-based dosing

• 180-240 mg/m² orally twice daily

IV

• Gestational age above 35 weeks
  • Birth to 4 weeks: 3 mg/kg IV twice daily
  • Above 4 weeks: 9 mg/kg IV twice daily
• Gestational age between 30 to 34 weeks
  • Birth to 2 weeks: 1.5 mg/kg IV twice daily
  • 2-6 weeks: 2.3 mg/kg IV twice daily
  • Above 6-8 weeks: 9 mg/kg IV twice daily
• Gestational age below 30 weeks
  • Birth to 4 weeks: 1.5 mg/kg IV twice daily
  • 4-8 weeks: 2.3 mg/kg IV twice daily
  • Above 8-10 weeks: 9 mg/kg IV twice daily

Infants above 3 months

• 120 mg/m²/dose IV every 6 hours; not to exceed 160 mg/dose

Adolescents above 30 kg

• 1-2 mg/kg IV every 4 hours

Prevention of Perinatal HIV Transmission

Adult dosage

IV administration (preferred)

• During labor and delivery: 2 mg/kg loading dose followed by continuous IV infusion of 1 mg/kg/hr until umbilical cord clamped  
• Scheduled cesarean delivery: Begin IV zidovudine 3 hours before surgery
• Unscheduled cesarean delivery resulting from maternal or fetal complications: Consider administering loading dose then proceed to delivery

Oral administration (if IV is not an option)

• 600 mg loading dose followed by 400 mg orally every 3 hr

Pediatric dosage

• 2 mg/kg orally every 6 hours or 1.5 mg/kg IV every 6 hours for 4-6 weeks as determined by risk

Neonatal ARV

• 2-drug ARV prophylaxis with zidovudine for 6 weeks and 3 doses of nevirapine (prophylactic dosage given within 48 hr of birth, 48 hr after the first dose, and 96 hr after the second dose) OR
• Empiric HIV therapy using either zidovudine, lamivudine, and nevirapine (treatment dosage) OR zidovudine, lamivudine, and raltegravir from birth to age 6 weeks

Newborn with HIV

• Oral dosage as determined by gestational (GA in weeks) and birth age
  • Gestational age below 30 weeks
    • Birth to 4 weeks: 2 mg/kg orally twice daily
    • Above 4 weeks: 3 mg/kg orally twice daily
  • Gestational age between 30 to 34 weeks
    • Birth to 2 weeks: 2 mg/kg orally twice daily
    • Above 2 weeks: 3 mg/kg orally twice daily
  • Gestational age above 35 weeks
    • 4 mg/kg/dose PO BID  
• Infants below 6 weeks (GA above 35 weeks)
  • The mother received standard antiretroviral therapy during pregnancy, viral suppression was sustained, maternal adherence was not a concern: a 4-week course recommended
  • Intravenous weight-based dosing: 2 mg/kg/dose every 12 hours

IV dosage as determined by gestational (GA in weeks) and birth age

• Gestational age below 30 weeks
  • Birth to 4 weeks: 1.5 mg/kg IV twice daily
  • Above 4 weeks: 2.3 mg/kg IV twice daily
• Gestational age between 30 to 34 weeks
  • Birth to 2 weeks: 1.5 mg/kg IV twice daily
  • Above 2 weeks: 2.3 mg/kg IV twice daily
• Gestational age above 35 weeks
  • 3 mg/kg/dose IV twice daily
• Infants born prematurely (GA below 35 weeks)
  • Use neonate dosing; standard infant dosing may be excessive in infants who were born prematurely
• Infants below 6 weeks (GA above 35 weeks)
  • The mother received standard antiretroviral therapy during pregnancy, viral suppression was sustained, maternal adherence was not a concern: a 4-week course recommended
  • IV weight-based dosing: 2 mg/kg/dose every 12 hours

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

Common side effects of Zidovudine include:

• headache,
• nausea,
• vomiting,
• constipation,
• trouble sleeping (insomnia),
• loss of appetite,
• joint pain, and
• changes in the shape or location of body fat (especially in your arms, legs, face, neck, breasts, and trunk).

Serious side effects of Zidovudine include:

• unexplained weight loss,
• persistent muscle aches or weakness,
• joint pain,
• numbness or tingling of the hands/feet/arms/legs,
• severe tiredness,
• vision changes,
• severe or persistent headaches,
• signs of infection (such as fever, chills, trouble breathing, cough, non-healing skin sores),
• signs of an overactive thyroid (such as irritability, nervousness, heat intolerance, fast/pounding/irregular heartbeat, bulging eyes, an unusual growth in the neck/thyroid known as a goiter), or
• signs of a certain nerve problem known as Guillain-Barre Syndrome (such as difficulty breathing/swallowing/moving your eyes, drooping face, paralysis, slurred speech).

Rare side effects of Zidovudine include:

• none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Zidovudine has severe interactions with the following drug:
  • elvitegravir/cobicistat/emtricitabine/tenofovir DF
• Zidovudine has serious interactions with the following drugs:
  • cabotegravir
  • cidofovir
  • clozapine
  • deferiprone
  • ganciclovir
  • pretomanid
  • ribavirin
  • ropeginterferon alfa 2b
  • stavudine
  • valganciclovir
• Zidovudine has moderate interactions with at least 54 other drugs.
• Zidovudine has minor interactions with at least 18 other drugs:

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

Contraindications

• Hypersensitivity

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Zidovudine?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Zidovudine?”

Cautions

• Risk of severe anemia and bone marrow depression; use with caution in patients with bone marrow compromise; hemoglobin reduction may occur 2-4 weeks and neutropenia may occur 6-8 weeks after initiating therapy; monitor blood counts; dose interruption may be required in patients who develop anemia or neutropenia
• Female sex and obesity may be risk factors for the development of lactic acidosis and severe hepatomegaly with steatosis in patients treated with antiretroviral nucleoside analogs
• Monitor CBC with differentials (patients with poor bone marrow reserve require more frequent monitoring); perform CD4 count every 3-6 months; liver function tests recommended every 6-12 months
• (All NRTIs): Risk of potentially fatal lactic acidosis and severe hepatomegaly with steatosis when used alone or in combination with other antiretrovirals; suspend treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or hepatotoxicity (elevation of transaminase with or without hepatomegaly and steatosis may occur)
• Risk of immune reconstitution syndrome if used in combination with other antiretroviral drugs; further evaluation and treatment may be required; autoimmune disorders (such as Graves’ disease, polymyositis, and Guillain-Barré syndrome) reported to occur in the setting of immune reconstitution; time to onset is more variable, and can occur many months after initiation of treatment
• Lipoatrophy, causing loss of subcutaneous fat, especially in the face and buttocks may occur; incidence and severity associated with cumulative exposure; maybe only partially reversible improvement may take months or years after switching to a regimen that does not contain zidovudine; monitor for signs of lipoatrophy and consider switching to the non-zidovudine-containing regimen if lipoatrophy occurs
• Myopathy associated with prolonged use exhibit pathological changes similar to that produced by HIV-1 disease

Pregnancy and Lactation

• Available data from the APR show no difference in the overall risk of birth defects for lamivudine or zidovudine compared with the background rate for birth defects of 2.7% in the Metropolitan Atlanta Congenital Defects Program (MACDP) reference population; APR uses the MACDP as the U.S. reference population for birth defects in the general population; MACDP evaluates women and infants from a limited geographic area and does not include outcomes for births that occurred at less than 20 weeks gestation; rate of miscarriage is not reported in the APR
• Hyperlactatemia, which may be due to mitochondrial dysfunction, was reported in infants with in utero exposure to zidovudine-containing products; events were transient and asymptomatic in most cases; developmental delay, seizures, and other neurological diseases were also reported; a causal relationship between these events and exposure to zidovudine-containing products in utero or peripartum not established
• The drug has been shown to cross the placenta and concentrations in neonatal plasma at birth were essentially equal to those in maternal plasma at delivery; mild, transient elevations in serum lactate levels were reported, which may be due to mitochondrial dysfunction, in neonates and infants exposed in utero or peripartum to zidovudine-containing products; clinical relevance of transient elevations in serum lactate is unknown
• Lactation
  • The Centers for Disease Control and Prevention recommend that HIV-1-infected mothers in the United States not breastfeed infants to avoid risking postnatal transmission of HIV-1 infection; lamivudine is present in human milk; there is no information on the effects of lamivudine or zidovudine on breastfed infant or effects of drugs on milk production; because of potential for (1) HIV-1 transmission (in HIV-negative infants), (2)developing viral resistance (in HIV-positive infants), and (3) serious adverse reactions in a breastfed infant, instruct mothers not to breastfeed if they are receiving therapy