ZIDOVUDINE — zidovudine tablet
Camber Pharmaceuticals, Inc.
WARNING: RISK OF HEMATOLOGICAL TOXICITY, MYOPATHY, LACTIC ACIDOSIS AND SEVERE HEPATOMEGALY WITH STEATOSIS
Zidovudine tablets have been associated with hematologic toxicity including neutropenia and severe anemia, particularly in patients with advanced HIV-1 disease [see Warnings and Precautions (5.1)].
Prolonged use of zidovudine has been associated with symptomatic myopathy [see Warnings and Precautions (5.3)]. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogues alone or in combination, including zidovudine and other antiretrovirals. Suspend treatment if clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity occur [see Warnings and Precautions (5.4)].
Zidovudine tablets, a nucleoside reverse transcriptase inhibitor, are indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection.
Zidovudine tablets are indicated for the prevention of maternal-fetal HIV-1 transmission [see Dosage and Administration (2.3)]. The indication is based on a dosing regimen that included 3 components:
1. antepartum therapy of HIV-1-infected mothers
2. intrapartum therapy of HIV-1-infected mothers
3. post-partum therapy of HIV-1-exposed neonate
Points to consider prior to initiating zidovudine in pregnant women for the prevention of maternal-fetal HIV-1 transmission include:
• In most cases, zidovudine for prevention of maternal-fetal HIV-1 transmission should be given in combination with other antiretroviral drugs.
• Prevention of HIV-1 transmission in women who have received zidovudine for a prolonged period before pregnancy has not been evaluated.
• Because the fetus is most susceptible to the potential teratogenic effects of drugs during the first 10 weeks of gestation and the risks of therapy with zidovudine during that period are not fully known, women in the first trimester of pregnancy who do not require immediate initiation of antiretroviral therapy for their own health may consider delaying use; this indication is based on use after 14 weeks’ gestation.
Oral Dosing The recommended oral dose of zidovudine is 300 mg twice daily in combination with other antiretroviral agents.
Healthcare professionals should pay special attention to accurate calculation of the dose of zidovudine, transcription of the medication order, dispensing information, and dosing instructions to minimize risk for medication dosing errors.
Prescribers should calculate the appropriate dose of zidovudine for each child based on body weight (kg) and should not exceed the recommended adult dose.
Before prescribing zidovudine tablets, children should be assessed for the ability to swallow tablets. If a child is unable to reliably swallow a zidovudine tablet, the zidovudine syrup formulation should be prescribed.
The recommended oral dosage in pediatric patients aged 4 weeks to less than 18 years and weighing greater than or equal to 4 kg is provided in Table 1. Zidovudine Syrup should be used to provide accurate dosage when tablets are not appropriate.Table 1. Recommended Pediatric Oral Dosage of Zidovudine
|Body Weight (kg)||Total Daily Dose||Dosage Regimen and Dose|
|Twice Daily||Three Times Daily|
|4 to <9||24 mg/kg/day||12 mg/kg||8 mg/kg|
|≥9 to <30||18 mg/kg/day||9 mg/kg||6 mg/kg|
|≥30||600 mg/day||300 mg||200 mg|
Alternatively, dosing for zidovudine can be based on body surface area (BSA) for each child. The recommended oral dose of zidovudine is 480 mg per m2 per day in divided doses (240 mg per m2 twice daily or 160 mg per m2 three times daily). In some cases the dose calculated by mg per kg will not be the same as that calculated by BSA.
The recommended dosage regimen for administration to pregnant women (greater than 14 weeks of pregnancy) and their neonates is:
100 mg orally 5 times per day until the start of labor [see Clinical Studies (14.3)]. During labor and delivery, intravenous zidovudine should be administered at 2 mg per kg (total body weight) over 1 hour followed by a continuous intravenous infusion of 1 mg per kg per hour (total body weight) until clamping of the umbilical cord.
Start neonatal dosing within 12 hours after birth and continue through 6 weeks of age. Neonates unable to receive oral dosing may be administered zidovudine intravenously. See Table 2 for dosing recommendations.Table 2. Recommended Neonatal Dosages of Zidovudine
|Route||Total Daily Dose||Dose and Dosage Regimen|
|Oral||8 mg/kg/day||2 mg/kg every 6 hours|
|Intravenous||6 mg/kg/day||1.5 mg/kg infused over 30 minutes, every 6 hours|
Use an appropriate-sized syringe with 0.1-mL graduation to ensure accurate dosing of the syrup formulation in neonates.
Significant anemia (hemoglobin less than 7.5 g per dL or reduction greater than 25% of baseline) and/or significant neutropenia (granulocyte count less than 750 cells per mm3 or reduction greater than 50% from baseline) may require a dose interruption until evidence of marrow recovery is observed [see Warnings and Precautions (5.1)]. In patients who develop significant anemia, dose interruption does not necessarily eliminate the need for transfusion. If marrow recovery occurs following dose interruption, resumption in dose may be appropriate using adjunctive measures such as epoetin alfa at recommended doses, depending on hematologic indices such as serum erythropoietin level and patient tolerance.
In patients maintained on hemodialysis or peritoneal dialysis or with creatinine clearance (CrCl) by Cockcroft-Gault less than 15 mL per min, the recommended oral dosage is 100 mg every 6 to 8 hours [see Use in Specific Populations (8.6), Clinical Pharmacology (12.3)].
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