Zidovudine.txt

CLINICAL USE

Nucleoside reverse transcriptase inhibitor: Treatment of HIV in combination with other antiretroviral drugs Prevention of maternal-foetal HIV transmission

DOSE IN NORMAL RENAL FUNCTION

Oral: 500–600 mg daily in 2–3 divided doses IV: 1–2 mg/kg every 4 hours

PHARMACOKINETICS

Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp : 267.2

%Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp : 34–38

%Excreted unchanged in urine &nbsp &nbsp : 8–25

Volume of distribution (L/kg) &nbsp &nbsp &nbsp : 1.6

half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp : 1.1/1. 4–3

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 &nbsp &nbsp : Give 100% of normal dose every 8 hours

10 to 20 &nbsp &nbsp : Give 100% of normal dose every 8 hours

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : Give 50% of normal dose every 8 hours1

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp: Not dialysed. Dose as in GFR <10 mL/min

HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp : Not dialysed. Dose as in GFR <10 mL/min Give post dialysis

HDF/high flux &nbsp : Unknown dialysability. Dose as in GFR <10 mL/min Give post dialysis

CAV/VVHD &nbsp &nbsp &nbsp: Not dialysed. Dose as in GFR 10 to 20 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Antibacterials: absorption reduced by clarithromycin; avoid concomitant use with rifampicin

Anti-epileptics: phenytoin levels may be raised or lowered; concentration possibly increased by valproate (increased risk of toxicity)

Antifungals: concentration increased by fluconazole

Antivirals: profound myelosuppression with ganciclovir – avoid if possible; extreme lethargy on administration of IV aciclovir; effects of stavudine inhibited – avoid concomitant use; concentration reduced by tipranavir

ADMINISTRATION

Reconstition

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Route

IV, oral

Rate of Administration

1 hour

Comments

Dilute with glucose 5% infusion to give a final concentration of 2 mg/mL or 4 mg/mL

OTHER INFORMATION

Dialysis has little effect on zidovudine, presumably because of rapid metabolism. The glucuronide metabolite (T½ =1 hour) has no antiviral activity and will be significantly removed by dialysis Patients with severe renal failure have 50% higher maximum plasma concentrations 90% of a dose is excreted renally, mostly as the glucuronide. There is substantial accumulation of this metabolite in renal failure Main risk in renal impairment is haematological toxicity

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