Intravenous Prophylaxis of maternal-fetal HIV transmission during labour and delivery
Adult: 2 mg/kg by infusion over 1 hr, given at the start of labour, then 1 mg/kg/hr by continuous infusion until umbilical cord is clamped. For caesarean section, start infusion 4 hr before the operation.
Intravenous HIV infection
Adult: 1 mg/kg or 2 mg/kg 4 hrly, by infusion over 1 hr. Child: 80-160 mg/m2 6 hrly by infusion.
Intravenous Prophylaxis of HIV infection in neonates
Child: 1.5 mg/kg 6 hrly by infusion over 30 min, starting w/in 12 hr after birth and continuing for 6 wk.
Oral Prophylaxis of HIV infection in neonates
Child: 2 mg/kg 6 hrly, starting w/in 12 hr after birth and continuing for 6 wk.
Oral HIV infection
Adult: 250 mg or 300 mg bid, in combination w/ other antiretroviral agents. Child: As soln: 4 to <9 kg: 12 mg/kg bid; 9 to <30 kg: 9 mg/kg bid; ≥30 kg: 250 mg or 300 mg bid. As cap/tab: 8-13 kg: 100 mg bid; 14-21 kg: 100 mg in the morning, 200 mg in the evening; 22-30 kg: 200 mg bid; ≥30 kg: 250 mg or 300 mg bid. Alternatively (based on BSA), 480 mg/m2 daily in 2-3 divided doses. Doses are given in combination w/ other antiretroviral agents.
Oral Prophylaxis of maternal-fetal HIV transmission
Adult: 100 mg 5 times daily, starting on the 14th wk of gestation until the start of labour.
Renal Impairment
Oral:
ESRD maintained on haemodialysis or peritoneal dialysis: 100 mg 6-8 hrly.
CrCl (mL/min)
Dosage
<10-15
100 mg 6-8 hrly.
Intravenous:
ESRD maintained on haemodialysis or peritoneal dialysis: 1 mg/kg 6-8 hrly.
CrCl (mL/min)
Dosage
<10-15
1 mg/kg 6-8 hrly.
Hepatic Impairment
Dose reduction may be needed.
Administration
May be taken with or without food.
Reconstitution
W/draw the required dose from the vial and dilute in dextrose 5% soln to provide a final concentration of 2 mg/mL or 4 mg/mL.
Incompatibility
Blood products and protein soln.
Contraindications
Hypersensitivity; abnormally low neutrophil counts (<0.75 x 109/L) or Hb levels (<7.5 g/dL or 4.65 mmol/L); newborn infants w/ hyperbilirubinaemia requiring treatment other than phototherapy, or w/ increased transaminase levels >5 times the ULN. Lactation. Concomitant use w/ interferon alfa (w/ or w/o ribavirin) in HIV and hepatitis B or C virus co-infected patients.
Special Precautions
Severe renal and hepatic impairment. Childn. Pregnancy.
Monitor viral load, CD4 count; CBC w/ differential, LFT, lipid, glucose. Observe for appearance of opportunistic infection.
Overdosage
Symptoms: Vomiting, CNS effects (e.g. fatigue, dizziness, drowsiness, lethargy, confusion), haematologic effects (e.g. anaemia, decreased Hb). Bone marrow hypoplasia, mild ataxia, tonic-clonic seizure and increased serum concentration of AST and ALT may also occur. Management: Supportive and symptomatic treatment. Induce emesis and admin activated charcoal to prevent further absorption of unrecovered drug.
Drug Interactions
Decreased plasma concentration w/ rifampicin resulting in partial or total loss of efficacy of zidovudine. Increased risk of anaemia w/ ribavirin in patients co-infected w/ HCV. Antagonistic effect w/ stavudine or doxorubicn. Increased plasma level w/ probenecid, atovaquone, valproic acid, fluconazole, or methadone. May alter phenytoin blood levels. Increased adverse effect w/ potentially nephrotoxic or myelosuppressive drugs (e.g. systemic pentamidine, dapsone, pyrimethamine, co-trimoxazole, amphotericin, flucytosine, ganciclovir, interferon, vincristine, vinblastine, doxorubicin). Reduced absorption w/ clarithromycin. Potentially Fatal: Risk of hepatic decompensation when used concomitantly w/ interferon alfa (w/ or w/o ribavirin) in HIV and HBV/HCV co-infected patients.
Food Interaction
Absorption is delayed when given w/ food.
Action
Description: Zidovudine is converted intracellularly to zidovudine triphosphate, which inhibits replication of retroviruses, including HIV, by interfering w/ viral RNA-directed DNA polymerase (reverse transcriptase). Pharmacokinetics: Absorption: Rapidly absorbed from the GI tract. Delayed absorption w/ food. Bioavailability: Approx 60-70%. Time to peak plasma concentration: Approx 1 hr. Distribution: Crosses the blood-brain barrier and placenta, enters breast milk and detected in semen. Volume of distribution: 1-2.2 L/kg. Plasma protein binding: 34-38%. Metabolism: Metabolised intracellularly to the active triphosphate form and undergoes hepatic metabolism, mainly to the inactive glucuronide. Excretion: Via urine, as unchanged drug and metabolite. Plasma half-life: Approx 1 hr.
Chemical Structure
Zidovudine Source: National Center for Biotechnology Information. PubChem Database. Zidovudine, CID=35370, https://pubchem.ncbi.nlm.nih.gov/compound/Zidovudine (accessed on Jan. 22, 2020)
Storage
Store between 15-25°C. Protect from light, heat and moisture. Diluted IV soln: Store at 25°C (stable for 8 hr) or at between 2-8°C (stable for 24 hr).
J05AF01 - zidovudine ; Belongs to the class of nucleoside and nucleotide reverse transcriptase inhibitors. Used in the systemic treatment of viral infections.
References
Anon. Zidovudine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 21/09/2015.Buckingham R (ed). Zidovudine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 21/09/2015.McEvoy GK, Snow EK, Miller J et al (eds). Zidovudine. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 21/09/2015.Zidovudine Syrup (Cipla ltd.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 21/09/2015.Zidovudine Tablet, Film-Coated (Aurobindo Pharma Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 21/09/2015.
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