Retrovir

Ret·ro·vir (rtr-vîr)

A trademark for the drug zidovudine.

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Retrovir,

trademark for an antiretroviral drug (zidovudine).

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Retrovir [ret´ro-vir]

trademark for preparations of zidovudine, an antiretroviral active against the human immunodeficiency virus.

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Retrovir,

n.pr brand name for zidovudine, a dideoxynucleoside used in the treatment of HIV-positive patients.

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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.

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Retrovir®

Zidovudine, see there