Zidovudine Dosage

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for HIV Infection

Oral: 300 mg orally every 12 hours or 200 mg orally every 8 hours

IV: 1 mg/kg IV (infused over 1 hour) every 4 hours around the clock, for a total daily dose of 5 to 6 mg/kg

Duration: Therapy should be continued for as long as the patient tolerates, or until the patient is switched to another antiretroviral agent.

Usual Adult Dose for Reduction of Perinatal Transmission of HIV

Maternal dosing: 100 mg orally 5 times a day until start of labor; however, most authorities would also consider the standard oral dosages of 300 mg every 12 hours or 200 mg every 8 hours

During labor and delivery: 2 mg/kg IV (infused over 1 hour) followed by a continuous IV infusion of 1 mg/kg/hour until clamping of the umbilical cord

Therapy should begin at 14 to 34 weeks gestation. Neonates should also be treated for 6 weeks. Despite the use of this regimen, transmission to infants may still occur in some cases.

Usual Adult Dose for Nonoccupational Exposure

(Not approved by FDA)

Centers for Disease Control and Prevention (CDC) recommendations: 300 mg orally every 12 hours or 200 mg orally every 8 hours, in combination with (efavirenz or lopinavir-ritonavir) plus (lamivudine or emtricitabine)

Duration: 28 days

Prophylaxis should be initiated as soon as possible, within 72 hours of exposure.

Usual Adult Dose for Occupational Exposure

(Not approved by FDA)

CDC recommendations:
Preferred basic regimen for HIV postexposure prophylaxis: 300 mg orally every 12 hours or 200 mg orally every 8 hours, in combination with lamivudine or emtricitabine

Duration: Generally 28 days; however, the exact duration of therapy may differ based on the institution's protocol.

Prophylaxis should be initiated immediately, preferably within hours after exposure.

Usual Pediatric Dose for HIV Infection

4 weeks to less than 18 years:
Oral:
Based on body weight:
4 to less than 9 kg: 12 mg/kg orally twice a day or 8 mg/kg orally 3 times a day
9 to less than 30 kg: 9 mg/kg orally twice a day or 6 mg/kg orally 3 times a day
30 kg or more: 300 mg orally twice a day or 200 mg orally 3 times a day

Based on body surface area: 240 mg/m2 (maximum: 300 mg/dose) orally twice a day or 160 mg/m2 (maximum: 200 mg/dose) orally 3 times a day

The dosage calculated by body weight may not be the same as the dosage calculated by body surface area in some cases.

Panel on Antiretroviral Therapy and Medical Management of HIV-Infected Children recommendations:
Premature neonates (less than 35 weeks gestation):
Oral: 2 mg/kg orally every 12 hours
IV: 1.5 mg/kg IV (infused over 30 minutes) every 12 hours

Dosage frequency should increase to every 8 hours at 4 weeks of age in neonates less than 30 weeks gestation at birth and at 2 weeks of age in neonates 30 to less than 35 weeks gestation at birth.

Full-term neonates and infants less than 6 weeks:
Oral: 2 mg/kg orally every 6 hours
IV: 1.5 mg/kg IV (infused over 30 minutes) every 6 hours

6 weeks to less than 18 years:
Oral:
Based on body weight:
4 to less than 9 kg: 12 mg/kg orally twice a day
9 to less than 30 kg: 9 mg/kg orally twice a day
30 kg or more: 300 mg orally twice a day

Based on body surface area: 180 to 240 mg/m2 orally every 12 hours or 160 mg/m2 orally every 8 hours

Usual Pediatric Dose for Reduction of Perinatal Transmission of HIV

Neonates:
Oral: 2 mg/kg orally every 6 hours
IV: 1.5 mg/kg IV (infused over 30 minutes) every 6 hours

Neonatal dosing should begin within 12 hours after birth and continue through 6 weeks of age. IV zidovudine may be administered to neonates unable to receive oral dosing.

Panel on Antiretroviral Therapy and Medical Management of HIV-Infected Children recommendations:
Neonates (less than 35 weeks gestation at birth):
Oral: 2 mg/kg orally every 12 hours
IV: 1.5 mg/kg IV (infused over 30 minutes) every 12 hours

Dosage frequency should increase to every 8 hours at 4 weeks of age in neonates less than 30 weeks gestation at birth and at 2 weeks of age in neonates 30 to less than 35 weeks gestation at birth.

Full-term neonates and infants less than 6 weeks (born at 35 weeks gestation or greater):
Oral: 4 mg/kg orally twice a day
IV: 1.5 mg/kg IV (infused over 30 minutes) every 6 hours

Zidovudine should be started as soon after birth as possible, preferably within 6 to 12 hours of delivery, and should continue through 6 weeks of age. IV zidovudine may be administered to neonates unable to tolerate oral agents.

In addition to 6 weeks of zidovudine therapy, 3 doses of nevirapine may be given in the first week of life to infants born to HIV-infected women who have not received antepartum antiretroviral therapy. The neonatal regimen (oral zidovudine plus nevirapine) should be started as soon as possible after birth.

Renal Dose Adjustments

CrCl less than 15 mL/min:
Oral: 100 mg orally every 6 to 8 hours
IV: 1 mg/kg IV (infused over 1 hour) every 6 to 8 hours

Liver Dose Adjustments

Mild to moderate impaired hepatic function or liver cirrhosis:
Oral: Data not available

IV: Data not available; since zidovudine is primarily eliminated by hepatic metabolism, a reduction in the daily dose may be necessary in these patients

Dose Adjustments

Doses should be titrated on an individual basis according to patient tolerance and clinical condition. Lower doses or a brief interruption of therapy should be considered for those who develop severe adverse reaction.

Significant anemia (hemoglobin less than 7.5 g/dL or reduction greater than 25% of baseline) and/or significant neutropenia (granulocyte count less than 750 cells/mm3 or reduction greater than 50% from baseline) may require a dose interruption until evidence of marrow recovery is observed. In patients who develop significant anemia, dose interruption may not eliminate the need for transfusion. If the marrow recovers following dose interruption, resumption in dose may be appropriate using adjunctive therapy such as epoetin alfa at recommended doses, depending on hematologic indices such as serum erythropoietin level and patient tolerance.

Precautions

For the purposes of drug toxicity monitoring and dosage adjustment, a complete blood count as well as renal and hepatic function tests should be performed at baseline and every 3 months thereafter over the entire duration of therapy.

Zidovudine may cause bone marrow toxicity, most commonly neutropenia and anemia, particularly in patients with advanced symptomatic HIV disease. Hematologic toxicities appear to be associated with bone marrow reserve prior to therapy and to dose and duration of treatment. Zidovudine should be used with extreme caution in patients with bone marrow suppression indicated by a granulocyte count below 1000 cells/mm3 or hemoglobin less than 9.5 g/dL. Routine blood counts are recommended, and generally should occur more frequently in patients with advanced disease. If bone marrow toxicity occurs, a dose adjustment, dosage interruption, or discontinuation of zidovudine therapy and/or blood transfusions may be necessary.

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination with other antiretroviral agents. Risk factors may include female gender, obesity, and prolonged nucleoside exposure. Caution is recommended in patients with risk factors for liver disease; however, cases have also been reported in patients with no known risk factors. Treatment with zidovudine should be suspended in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity.

Exacerbation of anemia has been observed with concomitant use of zidovudine and ribavirin. Coadministration of zidovudine and ribavirin is not recommended. Coadministration of zidovudine with interferon alfa with or without ribavirin in HIV/HCV coinfected patients may precipitate hepatic decompensation, fatal in some cases. Patients receiving interferon alfa with or without ribavirin and zidovudine should be closely monitored for treatment-associated toxicities including neutropenia, anemia, and hepatic decompensation. Discontinuation of zidovudine should be considered as medically appropriate. Dose reduction or discontinuation of interferon alpha, ribavirin, or both should be considered if any of these toxicities occur.

Immune reconstitution syndrome has occurred during combination antiretroviral therapy. Patients responding to therapy may develop an inflammatory response to indolent or residual opportunistic infections and require evaluation and treatment.

Patients with allergies to nuts or soy should be aware that zidovudine oral capsules contain soya lecithin.

Patients with diabetes should be aware that the oral syrup contains sucrose.

Related drugs not for coadministration with zidovudine include abacavir/lamivudine/zidovudine and lamivudine-zidovudine, in which zidovudine is one of the active components.

The potential for HIV cross-resistance among nucleoside reverse transcriptase inhibitors exists but has not been fully explored. The effect of zidovudine therapy on the activity of subsequently administered nucleoside reverse transcriptase inhibitors has not been fully explored. Selection of antiretroviral agents for a patient's medication regimen should be done carefully and with the assistance of expert consultation.

Pediatric dosages are calculated based on body weight or body surface area. Special vigilance is recommended during calculation of dose, transcription of medication order, dispensing information, and dosing instructions to reduce the risk of medication errors.

Dialysis

Hemodialysis or peritoneal dialysis:
Oral: 100 mg orally every 6 to 8 hours
IV: 1 mg/kg IV (infused over 1 hour) every 6 to 8 hours

Other Comments

Patients should receive IV zidovudine only until oral therapy can be administered.

Zidovudine may be taken without regard to meals.

If a patient is unable to reliably swallow a zidovudine tablet or capsule, then the oral syrup should be used.

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