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Zidovudine information from DrugsUpdate  

See Available Brands of Zidovudine in India

P - Caution when used during pregnancy
L - Contraindicated in Lactation
LI - Lab *

Zidovudine or azidothymidine is a nucleoside analog reverse transcriptase inhibitor (NRTI), a type of antiretroviral drug. It was the first approved treatment for HIV. It is also sold under the names Retrovir and Retrovis, and as an ingredient in Combivir and Trizivir. It is an analog of thymidine.

Pharmacodynamics

Pharmacokinetics

Zidovudine is a thymidine analogue. It is phosphorylated in the body to its active form zidovudine triphosphate which interferes in DNA synthesis of retroviruses by inhibiting DNA replication. Zidovudine inhibits the key enzyme reverse transcriptase. Human DNA polymerase is inhibited only at a conc 100 times more than that required to inhibit viral reverse transcriptase.

Absorption
Rapidly absorbed from the GI tract, delayed if taken with food (oral). Peak plasma concentrations: 1 hour. Bioavailability: 60-70%.

Distribution
Crosses the placenta and blood-brain barrier; enters breast milk and semen. Protein-binding: 34-38%

Metabolism
Intracellular; converted to the active antiviral triphosphate. Hepatic; converted to the inactive glucuronide.

Excretion

Urine (as unchanged drug and metabolites); 1 hour (elimination half-life).

Zidovudine Indications / Zidovudine Uses

Information Not Available

Zidovudine Adverse Reactions / Zidovudine Side Effects

Nausea, severe headache, myalgia, insomnia, vomiting, anorexia, diarrhoea, asthenia, dizziness, taste perversion, convulsions, myopathy, nail, skin and oral mucosa pigmentation, raised LFT, pancreatitis, fat redistribution.

Potentially Fatal: Lactic acidosis, severe hepatomegaly with steatosis, hepatotoxicity. Blood dyscrasias, e.g. serious anaemia (may require transfusion), neutropenia, leucopenia.

Precautions

Information Not Available

Special Precautions

Anaemia or myelosuppression, renal and hepatic impairment, elderly, pregnancy. Monitor patients with risk factors for liver disease. Blood tests should be carried out regularly, reduce dose if neutrophil or haemoglobin count is low. Monitor serum CK concentration every 3 months in patients who have received >6 months of treatment. Patients to contact doctor if they experience muscle weakness, shortness of breath, symptoms of hepatitis or pancreatitis.

Other Drug Interactions

Decreased zidovudine concentration with tipranavir. Increased risk of peripheral neuropathy with bortezomib. Increased haematological toxicity with IV pentamidine, lamivudine, dapsone, vancomycin flucytosine, amphotericin, ganciclovir, interferon alfa, cyclophosphamide and other bone marrow suppressive or cytotoxic agents Increased risk of zidovudine toxicity with atovaquone, chloramphenicol, fluconazole, valproate. Decreased absorption with clarithromycin, minimise interactions by admin at least 2 hours apart. Increased zidovudine concentration and increased potential for hypersensitivity reactions with probenecid. Increased zidovudine clearance and haematological toxicity with rifampicin. Increased bioavailability of zidovudine with nimodipine. Increased incidences of headache with benzodiazepines. Possible increase in zidovudine concentration with methadone.

Potentially Fatal: Avoid stavudine (due to inhibition of activation of stavudine), didanosine, ribavirin (antagonize effect of zidovudine), zalcitabine (inferior virological activity and a higher rate of side effects) with zidovudine. Increased risk of toxicity (e.g. hepatic decompensation, neutropenia) in patients with interferon alfa with or without ribavirin.

Other Interactions

Information Not Available

Dosage

Oral
HIV infection
Adult: 600 mg daily in divided doses, in combination with other antiretroviral agents.
Child: 6 weeks - 12 years: 160 mg/m2 every 8 hours. Max: 200 mg every 8 hours. May be used in combination with other anti-retrovirals.
Renal impairment: Haemodialysis or peritoneal dialysis: 100 mg every 6-8 hours.

CrCl (ml/min)    Dosage Recommendation
<10                  100 mg every 6-8 hours.
Hepatic impairment: Dose reduction may be needed.

Oral

Prophylaxis of maternal-foetal HIV transmission
Adult: 100 mg 5 times daily or 200 mg tid or 300 mg bid. Start treatment after 14th weeks of gestation until the start of labour.
Renal impairment: Haemodialysis or peritoneal dialysis: 100 mg every 6-8 hours.

CrCl (ml/min)    Dosage Recommendation
<10                  100 mg every 6-8 hours.
Hepatic impairment: Dose reduction may be needed.


Oral
Prophylaxis of HIV infection in neonates
Child: Neonates: 2 mg/kg every 6 hours for 1st 6 weeks of life, starting within 12 hours after birth.
Renal impairment: Dose adjustment may be needed.
Hepatic impairment: Dose adjustment may be needed.

Intravenous
HIV infection
Adult: 1-2 mg/kg every 4 hours, given as 2-4 mg/ml infusion over 1 hour.
Child: As continuous infusion: 20 mg/m2/hour. Alternatively, as intermittent infusion: 120 mg/m2 every 6 hours.
Renal impairment: Haemodialysis or peritoneal dialysis: 1 mg/kg every 6-8 hours.
CrCl (ml/min)    Dosage Recommendation
<10                  1 mg/kg every 6-8 hours.
Hepatic impairment: Dose reduction may be needed.

Intravenous
Prophylaxis of HIV infection in neonates
Child: Neonates: 1.5 mg/kg every 6 hours. Start treatment within 12 hours after birth and continue for 1st 6 weeks of life. Dose to be given via IV infusion over 30 minutes.

Renal impairment: Dose adjustment may be needed.
Hepatic impairment: Dose adjustment may be needed.

Intravenous
Prophylaxis of maternal-foetal HIV transmission during labour and delivery
Adult: Loading dose: 2 mg/kg, followed by continuous infusion of 1 mg/kg/hour until umbilical cord is clamped. If caesarean section is planned, start the IV infusion 4 hours before the operation.
Renal impairment: Dose reduction may be needed.
Hepatic impairment: Dose reduction may be needed.

Reconstitution
Required dose to be removed from vial and added to 5% dextrose injection solution to achieve a concentration <4 mg/ml.

Incompatibility
May not be compatible with meropenem and total parenteral nutrition.

Food(before/after)

May be taken with or without food.

List of Contraindications

Zidovudine and Pregnancy

Caution when used during pregnancy

Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Zidovudine and Lactation

Contraindicated in lactation

Zidovudine and Children

Zidovudine has been studied in HIV-1-infected pediatric patients ≥6 weeks of age who had HIV-1-related symptoms or who were asymptomatic with abnormal laboratory values indicating significant HIV-1-related immunosuppression. Zidovudine has also been studied in neonates perinatally exposed to HIV-1

Zidovudine and Geriatic

Dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Zidovudine and Other Contraindications

Dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Storage

Intravenous
Store at 15-25°C (59-77°F).

Oral
Store at 15-25°C (59-77°F).

Lab interference

Intravenous
Store at 15-25°C (59-77°F).

Oral
Store at 15-25°C (59-77°F).

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