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Zidovudine
- indication:For the treatment of human immunovirus (HIV) infections.
- pharmacologypharmacology:
- mechanism: Zidovudine, a structural analog of thymidine, inhibits the activity of HIV-1 reverse transcriptase (RT) both by competing with the natural substrate dGTP and by its incorporation into viral DNA.
- toxicity: Symptoms of overdose include fatigue, headache, nausea, and vomiting. LD<sub>50</sub> is 3084 mg/kg (orally in mice).
- absorprion: Rapid and nearly complete absorption from the gastrointestinal tract following oral administration; however, because of first-pass metabolism, systemic bioavailability of zidovudine capsules and solution is approximately 65% (range, 52 to 75%). Bioavailability in neonates up to 14 days of age is approximately 89%, and it decreases to approximately 61% and 65% in neonates over 14 days of age and children 3 months to 12 years, respectively. Administration with a high-fat meal may decrease the rate and extent of absorption.
- halflife: 0.5-3 hours
- roouteelimination: As in adult patients, the major route of elimination was by metabolism to GZDV. After intravenous dosing, about 29% of the dose was excreted in the urine unchanged and about 45% of the dose was excreted as GZDV
- volumedistribution:
- clearance: * 0.65 +/- 0.29 L/hr/kg [HIV-infected, Birth to 14 Days of Age] * 1.14 +/- 0.24 L/hr/kg [HIV-infected, 14 Days to 3 Months of Age] * 1.85 +/- 0.47 L/hr/kg [HIV-infected, 3 Months to 12 Years of Age]