Ret·ro·vir (r t r -vîr) A trademark for the drug zidovudine. |
Retrovir,
Retrovir,
zidovudine
Apo-Zidovudine (CA), Retrovir
Pharmacologic class: Nucleoside reverse transcriptase inhibitor
Therapeutic class: Antiretroviral
Pregnancy risk category C
FDA Boxed Warning
• Drug has been linked to hematologic toxicity (including neutropenia and severe anemia), particularly in patients with advanced human immunodeficiency virus (HIV) infection. Prolonged use is associated with symptomatic myopathy.
• Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) have occurred with use of nucleoside analogs alone or in combination, including zidovudine and other antiretrovirals.
Action
After conversion to its active metabolite, inhibits activity of HIV reverse transcriptase and terminates viral DNA growth
Availability
Capsules: 300 mg
Injection: 10 mg/ml in 20-ml vial
Syrup: 50 mg/5 ml
Tablets: 100 mg
⊘Indications and dosages
➣ HIV infection
Adults and children older than age 12: 200 mg P.O. t.i.d. or 300 mg P.O. b.i.d. for a total daily dosage of 600 mg/day, or 1 mg/kg I.V. five to six times daily; usually given with other antiretrovirals
Children ages 6 weeks to 12 years: 160 mg/m2 P.O. q 8 hours (480 mg/m2/day, to a maximum of 200 mg q 8 hours), given with other antiretrovirals
➣ To prevent maternal-fetal HIV transmission
Pregnant women: 500 mg P.O. daily in divided doses (usually as five 100-mg doses) until labor begins; then 2 mg/kg I.V. over 1 hour followed by a continuous infusion of 1 mg/kg/hour until umbilical cord is clamped
Neonates: 2 mg/kg P.O. q 6 hours starting within 12 hours of delivery and continuing for 6 weeks
Dosage adjustment
• Hepatic or renal impairment
Off-label uses
• Occupational exposure to HIV
Contraindications
• Hypersensitivity to drug or its components
• Concomitant use of Combivir or Trizivir (zidovudine-containing products)
Precautions
Use cautiously in:
• renal or hepatic impairment, decreased bone marrow reserve, hemoglobin less than 9.5 g/dl, granulocyte count less than 1,000 cells/mm3
• pregnant or breastfeeding patients.
Administration
• For I.V. use, remove dose from vial and add to I.V. solution containing dextrose 5% in water, to yield a final concentration no higher than 4 mg/ml. Infuse over 1 hour.
• In adults, give by I.V. route only until patient can tolerate oral dose.
| Route | Onset | Peak | Duration |
| P.O. | Variable | 30-90 min | 4 hr |
| I.V. | Rapid | End of infusion | 4 hr |
Adverse reactions
CNS: headache, paresthesia, malaise, insomnia, dizziness, drowsiness, asthenia, seizures
GI: nausea, vomiting, constipation, abdominal pain, dyspepsia, anorexia, pancreatitis
Hematologic: severe anemia (necessitating transfusions), agranulocytopenia, severe bone marrow depression
Musculoskeletal: myalgia, back pain, myopathy
Respiratory: dyspnea
Skin: diaphoresis, rash, altered nail pigmentation
Other: abnormal taste, fever
Interactions
Drug-drug. Acetaminophen, aspirin, indomethacin: increased risk of zidovudine toxicity
Amphotericin B, dapsone, flucytosine, pentamidine: increased risk of nephrotoxicity and bone marrow depression
Cyclosporine: extreme drowsiness, lethargy
Cytotoxic drugs, myelosuppressants, nephrotoxic drugs (such as ganciclovir, interferon alfa): increased risk of hematologic toxicity
Fluconazole, methadone, probenecid, valproic acid: increased zidovudine blood level, greater risk of toxicity
Ribavirin: antagonism of zidovudine's antiviral activity
Drug-diagnostic tests. Granulocytes, hemoglobin, platelets: decreased levels
Drug-herbs. St. John's wort: decreased zidovudine efficacy
Patient monitoring
• Monitor neurologic status, especially for signs and symptoms of impending seizure.
☞ Periodically assess CBC and kidney and liver function tests. Be aware that drug can cause hepatotoxicity.
• Watch for signs and symptoms of pancreatitis.
Patient teaching
• Tell patient he may take with or without food.
• Instruct patient to take capsules with at least 4 oz of fluid and to stay upright after taking.
• Explain therapy to patient. Emphasize that drug doesn't cure HIV infection.
• Urge patient to take drug exactly as prescribed.
☞ Teach patient to recognize and immediately report signs and symptoms of serious side effects, such as seizures.
• Stress importance of follow-up laboratory testing.
• Advise female of childbearing age to use effective contraception.
• Inform pregnant patient that drug reduces risk of, but may not prevent, HIV transmission to neonate.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and herbs mentioned above.
Retrovir®
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