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Zidovudine

Medically reviewed on August 12, 2018

Pronunciation

(zye DOE vyoo deen)

Index Terms

  • Azidothymidine
  • AZT (error-prone abbreviation)
  • Compound S
  • ZDV

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Capsule, Oral:

Retrovir: 100 mg [contains soybean lecithin]

Generic: 100 mg

Solution, Intravenous [preservative free]:

Retrovir: 10 mg/mL (20 mL)

Syrup, Oral:

Retrovir: 50 mg/5 mL (240 mL) [contains sodium benzoate; strawberry flavor]

Generic: 50 mg/5 mL (240 mL)

Tablet, Oral:

Generic: 300 mg

Brand Names: U.S.

  • Retrovir

Pharmacologic Category

  • Antiretroviral, Reverse Transcriptase Inhibitor, Nucleoside (Anti-HIV)

Pharmacology

Zidovudine is a thymidine analog which interferes with the HIV viral RNA-dependent DNA polymerase resulting in inhibition of viral replication; nucleoside reverse transcriptase inhibitor

Absorption

Oral: Well absorbed

Distribution

Significant penetration into the CSF

Vd: 1 to 2.2 L/kg

CSF/plasma ratio:

Infants 3 months to Children 12 years (n=38): Median: 0.68; Range: 0.03 to 3.25

Adults (n=39): Median: 0.6; Range: 0.04 to 2.62

Metabolism

Hepatic via glucuronidation to inactive metabolites, including GZDV; extensive first-pass effect

Excretion

Oral: Urine (72% to 74% as metabolites, 14% to 18% as unchanged drug)

IV: Urine (45% to 60% as metabolites, 18% to 29% as unchanged drug)

Time to Peak

Serum: 30 to 90 minutes

Half-Life Elimination

Terminal:

Premature neonate: 6.3 hours

Full-term neonates: 3.1 hours

Infants 14 days to 3 months: 1.9 hours

Infants 3 months to Children 12 years: 1.5 hours

Adults: 0.5 to 3 hours (mean 1.1 hours)

Protein Binding

25% to 38%

Special Populations: Renal Function Impairment

Cl is decreased, resulting in an increased half-life and AUC of zidovudine and major metabolite GZDV.

Special Populations: Hepatic Function Impairment

Clearance is decreased and plasma concentrations are increased.

Use: Labeled Indications

HIV-1 infection, treatment: Treatment of HIV-1 infection in combination with other antiretroviral agents

Perinatal HIV-1 transmission, prevention: Prevention of mother to fetus HIV-1 transmission

Off Label Uses

HIV-1 nonoccupational postexposure prophylaxis (nPEP)

Based on the Centers for Disease Control and Prevention (CDC), US Department of Health and Human Services updated guidelines for antiretroviral postexposure prophylaxis after sexual, injection drug use, or other nonoccupational exposure to HIV, zidovudine is an effective and recommended treatment option (in conjunction with other antiretrovirals) as postexposure prophylaxis of HIV-1 infection following nonoccupational exposure (nPEP) in individuals exposed to blood, genital secretions, or other potentially infectious body fluids that may contain HIV when that exposure represents a substantial risk for HIV transmission.

Contraindications

Potentially life-threatening hypersensitivity to zidovudine or any component of the formulation

Canadian labeling: Additional contraindications (not in US labeling): Neutrophil count <750/mm3 or hemoglobin <7.5 g/dL (4.65 mmol/L)

Dosing: Adult

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

Prevention of perinatal HIV transmission: Zidovudine should be administered by continuous IV infusion near delivery regardless of antepartum regimen or mode of delivery in women with HIV RNA >1,000 copies/mL or unknown HIV RNA status; use may be considered in women with HIV RNA between 50 and 999 copies/mL. If oral zidovudine was part of the antepartum regimen, discontinue during intrapartum IV infusion. Other antiretroviral agents should be continued orally. Zidovudine IV is not required in women receiving combination antiretroviral therapy who have HIV RNA <50 copies/mL near delivery and there are no concerns related to adherence with the regimen (HHS [perinatal] 2017).

IV (preferred route): During labor and delivery: Loading dose: 2 mg/kg followed by a continuous IV infusion of 1 mg/kg/hour until delivery. For scheduled cesarean delivery, begin IV zidovudine 3 hours before surgery. In cases of unscheduled cesarean delivery due to maternal and fetal indications, consider administering the loading dose then proceeding to delivery. Note: Dosage based on total body weight.

Oral (if IV not possible): Loading dose: 600 mg, then 400 mg every 3 hours (oral is not the preferred route of administration in the United States) (HHS [perinatal] 2017)

HIV-1 infection, treatment: Note: Use in combination with other antiretroviral agents.

Oral: 300 mg twice daily

IV: 1 mg/kg/dose administered every 4 hours around-the-clock (6 doses daily)

HIV-1 nonoccupational postexposure prophylaxis (nPEP) (off-label use) (HHS [nPEP] 2016): Oral:

CrCl ≥60 mL/minute: Zidovudine is not a component of the recommended antiretroviral regimen for these patients.

CrCl <60 and ≥15 mL/minute: 300 mg twice daily in combination with other antiretroviral agents. Initiate therapy within 72 hours of exposure and continue for 28 days

CrCl <15 mL/minute: Adjust dose based on renal function. Give in combination with other antiretroviral agents. Initiate therapy within 72 hours of exposure and continue for 28 days

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

HIV-1 infection, treatment: Use in combination with other antiretroviral agents.

Oral:

Neonates:

GA <30 weeks: 2 mg/kg/dose every 12 hours; at 4 weeks of age, increase dose to 3 mg/kg/dose every 12 hours; at >8 to 10 weeks of age, increase to 12 mg/kg/dose every 12 hours

GA ≥30 weeks and <35 weeks: 2 mg/kg/dose every 12 hours; at PNA 15 days, increase dose to 3 mg/kg/dose every 12 hours; at >6 to 8 weeks of age, increase to 12 mg/kg/dose every 12 hours

GA ≥35 weeks:

Birth to PNA ≤4 weeks of age:

Weight-directed: 4 mg/kg/dose every 12 hours for 4 weeks then increase dose (see PNA >4 weeks dosing or infant dosing as appropriate)

Fixed weight-band dosing: Continue for 4 weeks then increase dose (see PNA >4 weeks dosing or infant dosing as appropriate)

2 to <3 kg: 10 mg every 12 hours

3 to <4 kg: 15 mg every 12 hours

4 to <5 kg: 20 mg every 12 hours

PNA >4 weeks of age: 12 mg/kg/dose every 12 hours

Infants born prematurely (PMA <35 weeks) weighing <4 kg: Refer to Neonates; standard infant doses may be excessive in infants who were born prematurely

Infants (born at or near term with PMA ≥35 weeks) weighing ≥4 kg, Children, and Adolescents: Note: The 3-times-daily dosing is FDA approved but rarely used in practice; twice-daily dosing is recommended in the current pediatric HIV guidelines (HHS [pediatric] 2017).

Weight-directed dosing:

4 to <9 kg: 12 mg/kg/dose twice daily or 8 mg/kg/dose 3 times daily

9 to <30 kg: 9 mg/kg/dose twice daily or 6 mg/kg/dose 3 times daily

≥30 kg: 300 mg twice daily or 200 mg 3 times daily

BSA-directed dosing: 240 mg/m2/dose every 12 hours, range: 180 to 240 mg/m2/dose every 12 hours (maximum dose: 300 mg/dose) or 160 mg/m2/dose every 8 hours (maximum dose: 200 mg/dose)

IV: Note: Use IV route only until oral therapy can be administered:

Neonates: Note: The IV dose is 75% of the oral dose administered at the same interval

GA <30 weeks: 1.5 mg/kg/dose every 12 hours; at 4 weeks of age, increase dose to 2.3 mg/kg/dose every 12 hours; at >8 to 10 weeks of age, increase to 9 mg/kg/dose every 12 hours

GA ≥30 weeks and <35 weeks: 1.5 mg/kg/dose every 12 hours; at PNA 15 days, increase dose to 2.3 mg/kg/dose every 12 hours; at >6 to 8 weeks of age, increase to 9 mg/kg/dose every 12 hours

GA ≥35 weeks: 3 mg/kg/dose every 12 hours; at >4 weeks of age, increase to 9 mg/kg/dose every 12 hours

Infants ≥3 months, Children, and Adolescents weighing <30 kg: 120 mg/m2/dose every 6 hours; maximum dose: 160 mg/dose (Retrovir prescribing information [Canada] 2014)

Adolescents ≥30 kg: 1 to 2 mg/kg every 4 hours around the clock (Retrovir prescribing information [Canada] 2014)

HIV-1 perinatal transmission, prevention (HHS [perinatal] 2017): Zidovudine dosing should begin as soon as possible after birth (within 6 to 12 hours after delivery). In neonates at low risk of perinatal HIV transmission (mother received standard combination antiretroviral therapy during pregnancy, viral suppression was sustained, and maternal adherence is not a concern), treatment should continue for 4 weeks. For patients at high risk of HIV acquisition, a 2- or 3-drug regimen may be needed, and therapy should continue for 6 weeks. If neonate or infant is diagnosed as HIV positive, discontinue prevention (prophylaxis) dosing and begin a treatment regimen.

Neonates:

Oral:

GA <30 weeks: 2 mg/kg/dose every 12 hours; at 4 weeks of age, increase dose to 3 mg/kg/dose every 12 hours

GA ≥30 weeks and <35 weeks: 2 mg/kg/dose every 12 hours; at PNA 15 days, increase dose to 3 mg/kg/dose every 12 hours

GA ≥35 weeks:

Weight-directed dosing: 4 mg/kg/dose every 12 hours

Fixed weight-band dosing:

2 to <3 kg: 10 mg every 12 hours

3 to <4 kg: 15 mg every 12 hours

4 to <5 kg: 20 mg every 12 hours

IV: Note: Use IV route only until oral therapy can be administered:

GA <30 weeks: 1.5 mg/kg/dose every 12 hours; at 4 weeks of age, increase dose to 2.3 mg/kg/dose every 12 hours

GA ≥30 weeks and <35 weeks: 1.5 mg/kg/dose every 12 hours; at PNA 15 days, increase dose to 2.3 mg/kg/dose every 12 hours

GA ≥35 weeks: 3 mg/kg/dose every 12 hours

Infants born prematurely (GA <35 weeks): Refer to Neonates; standard infant doses may be excessive in infants who were born prematurely

Infants <6 weeks (GA ≥35 weeks) (HHS [perinatal] 2017):

Oral: Usual duration is 4 to 6 weeks. The shorter 4-week course is recommended if the mother received standard combination antiretroviral therapy during pregnancy, viral suppression was sustained, and maternal adherence is not a concern.

Weight-directed dosing: 4 mg/kg/dose every 12 hours

Fixed weight-band dosing regimen:

2 to <3 kg: 10 mg every 12 hours

3 to <4 kg: 15 mg every 12 hours

4 to <5 kg: 20 mg every 12 hours

IV: 3 mg/kg/dose every 12 hours. Note: Use IV route only until oral therapy can be administered.

HIV-1 nonoccupational postexposure prophylaxis (nPEP) (off-label use) (HHS [nPEP] 2016): Oral: Note: Initiate therapy within 72 hours of exposure and continue for 28 days; use in combination with other antiretroviral agents.

Infants (PCA ≥35 weeks and PNA ≥4 weeks of age) and Children:

4 to <9 kg: 12 mg/kg/dose twice daily

9 to <30 kg: 9 mg/kg/dose twice daily

≥30 kg: 300 mg twice daily

Adolescents: Refer to adult dosing.

Dosing: Renal Impairment

CrCl ≥15 mL/minute: No dosage adjustment necessary.

CrCl <15 mL/minute:

Oral:

Manufacturer’s labeling: 100 mg every 6 to 8 hours

Alternate dosing: 100 mg 3 times daily or 300 mg once daily (HHS [adult] 2017)

IV: 1 mg/kg every 6 to 8 hours

ESRD on intermittent hemodialysis (IHD) (administer dose after dialysis on dialysis days):

Oral:

Manufacturer’s labeling: 100 mg every 6 to 8 hours

Alternate dosing: 100 mg 3 times daily or 300 mg once daily (HHS [adult] 2017)

IV: 1 mg/kg every 6 to 8 hours

Peritoneal dialysis (PD):

Oral: 100 mg every 6 to 8 hours

IV: 1 mg/kg every 6 to 8 hours

Continuous renal replacement therapy (CRRT): No adjustment needed (Aronoff 2007)

Dosing: Hepatic Impairment

There are no specific dosage adjustments provided in the manufacturer's labeling (has not been studied). However, adjustment may be necessary due to extensive hepatic metabolism.

Dosing: Adjustment for Toxicity

Consider dose interruption for significant anemia (hemoglobin <7.5 g/dL or >25% reduction from baseline) and/or neutropenia (granulocyte count <750 cells/mm3 or >50% reduction from baseline) until evidence of recovery. Resumption in dose in combination with adjunctive measures (eg, epoetin alfa) may be appropriate, depending on erythropoietin level and patient tolerance.

Reconstitution

Solution for injection should be removed from the vial and diluted with D5W to a concentration ≤4 mg/mL.

Administration

Oral: Administer without regard to meals.

IV: Avoid rapid infusion or bolus injection. Do not administer IM

Infuse over 1 hour; infuse over 30 minutes in neonates; in pregnant women, infuse loading dose over 1 hour followed by continuous infusion.

Storage

IV: Store undiluted vials at 15°C to 25°C (59°F to 77°F). Protect from light. When diluted in D5W, solution is physically and chemically stable for 24 hours at room temperature and 48 hours if refrigerated at 2°C to 8°C (36°F to 46°F). Attempt to administer diluted solution within 8 hours if stored at room temperature or 24 hours if refrigerated at 2°C to 8°C (36°F to 46°F) to minimize potential for microbial-contaminated solutions (vials are single-use and do not contain preservative).

Tablets, capsules, syrup: Store at 15°C to 25°C (59°F to 77°F). Protect capsules from moisture.

Drug Interactions

Acemetacin: May enhance the adverse/toxic effect of Zidovudine. Specifically, the risk for hematologic toxicity may be increased. Monitor therapy

Acyclovir-Valacyclovir: May enhance the CNS depressant effect of Zidovudine. Monitor therapy

Amodiaquine: Zidovudine may enhance the neutropenic effect of Amodiaquine. Avoid combination

BCG (Intravesical): Myelosuppressive Agents may diminish the therapeutic effect of BCG (Intravesical). Avoid combination

Chloramphenicol (Ophthalmic): May enhance the adverse/toxic effect of Myelosuppressive Agents. Monitor therapy

Clarithromycin: May enhance the myelosuppressive effect of Zidovudine. Clarithromycin may decrease the serum concentration of Zidovudine. Management: Monitor response to zidovudine closely when used with clarithromycin, and consider staggering zidovudine and clarithromycin doses when possible in order to minimize the potential for interaction. Consider therapy modification

CloZAPine: Myelosuppressive Agents may enhance the adverse/toxic effect of CloZAPine. Specifically, the risk for neutropenia may be increased. Monitor therapy

Deferiprone: Myelosuppressive Agents may enhance the neutropenic effect of Deferiprone. Avoid combination

Dexketoprofen: May enhance the adverse/toxic effect of Zidovudine. Monitor therapy

Dipyrone: May enhance the adverse/toxic effect of Myelosuppressive Agents. Specifically, the risk for agranulocytosis and pancytopenia may be increased Avoid combination

DOXOrubicin (Conventional): May enhance the adverse/toxic effect of Zidovudine. DOXOrubicin (Conventional) may diminish the therapeutic effect of Zidovudine. Consider therapy modification

DOXOrubicin (Liposomal): May enhance the adverse/toxic effect of Zidovudine. DOXOrubicin (Liposomal) may diminish the therapeutic effect of Zidovudine. Consider therapy modification

Fluconazole: May decrease the metabolism of Zidovudine. Monitor therapy

Ganciclovir-Valganciclovir: May enhance the adverse/toxic effect of Zidovudine. Specifically, hematologic toxicity may be enhanced. Monitor therapy

Interferons: May enhance the adverse/toxic effect of Zidovudine. Interferons may decrease the metabolism of Zidovudine. Monitor therapy

Methadone: May increase the serum concentration of Zidovudine. Monitor therapy

Orlistat: May decrease the serum concentration of Antiretroviral Agents. Monitor therapy

Probenecid: May decrease the metabolism of Zidovudine. Monitor therapy

Promazine: May enhance the myelosuppressive effect of Myelosuppressive Agents. Monitor therapy

Protease Inhibitors: May decrease the serum concentration of Zidovudine. Monitor therapy

Raltegravir: May enhance the myopathic (rhabdomyolysis) effect of Zidovudine. Monitor therapy

Ribavirin (Oral Inhalation): Zidovudine may enhance the adverse/toxic effect of Ribavirin (Oral Inhalation). Specifically, the risk/severity of anemia may be increased. Management: Due to significantly increased risk of anemia, consider even closer monitoring for anemia than routinely recommended. Alternative therapies should be considered when clinically possible, particularly for patients with other risk factors. Consider therapy modification

Ribavirin (Systemic): Zidovudine may enhance the adverse/toxic effect of Ribavirin (Systemic). Specifically, the risk/severity of anemia may be increased. Management: Due to significantly increased risk of anemia, consider even closer monitoring for anemia than routinely recommended for ribavirin. Alternative therapies should be considered when clinically possible, particularly for patients with other risk factors. Consider therapy modification

Rifamycin Derivatives: May decrease the serum concentration of Zidovudine. Exceptions: Rifabutin. Monitor therapy

Stavudine: Zidovudine may diminish the therapeutic effect of Stavudine. Avoid combination

Tenoxicam: May enhance the adverse/toxic effect of Zidovudine. Monitor therapy

Teriflunomide: May increase the serum concentration of OAT3 Substrates. Monitor therapy

Tolvaptan: May increase the serum concentration of OAT3 Substrates. Consider therapy modification

Valproate Products: May increase the serum concentration of Zidovudine. Monitor therapy

Adverse Reactions

Percentages noted with adults unless otherwise stated.

>10%:

Central nervous system: Headache (63%), malaise (53%)

Dermatologic: Skin rash (children: 12%)

Gastrointestinal: Nausea (adults: 51%; children: 8%), anorexia (20%), vomiting (adults: 17%; children: 8%)

Hematologic & oncologic: Macrocytosis (children: >50%), anemia (neonates: 22%; children: 4%; adults: 1%; onset: 2 to 4 weeks)

Hepatic: Hepatomegaly (children: 11%)

Respiratory: Cough (children: 15%)

Miscellaneous: Fever (children: 25%)

1% to 10%:

Cardiovascular: Cardiac failure (children: <6%), ECG abnormality (children: <6%), edema (children: <6%), left ventricular dilation (children: <6%)

Central nervous system: Irritability (children: <6%), nervousness (children: <6%), chills (≥5%), fatigue (≥5%), insomnia (≥5%), neuropathy (≥5%)

Endocrine & metabolic: Weight loss (children: <6%)

Gastrointestinal: Diarrhea (children: 8%), constipation (6%), abdominal cramps (≥5%), abdominal pain (≥5%), dyspepsia (≥5%)

Genitourinary: Hematuria (children: <6%)

Hematologic & oncologic: Neutropenia (children: 8%), granulocytopenia (2%; onset 6 to 8 weeks), thrombocytopenia (children: 1%)

Hepatic: Increased serum transaminases (1% to 3%)

Neuromuscular & skeletal: Weakness (9%), arthralgia (≥5%), musculoskeletal pain (≥5%), myalgia (≥5%)

Otic: Auricular edema (≤7%), ear redness (≤7%), ear residue, debris or precipitate (≤7%), otalgia (≤7%)

<1%, postmarketing and/or case reports: Amblyopia, anaphylaxis, angioedema, anxiety, aplastic anemia, back pain, cardiomyopathy, chest pain, confusion, decreased mental acuity, depression, diabetes mellitus, diaphoresis, dizziness, drowsiness, dyschromia (blue pigmentation of nails and skin), dysgeusia, dyslipidemia, dysphagia, dyspnea, flatulence, flu-like symptoms, gynecomastia, hearing loss, hemolytic anemia, hepatitis, hepatomegaly with steatosis, hyperbilirubinemia, hypersensitivity reaction, immune reconstitution syndrome, increased creatine phosphokinase, increased lactate dehydrogenase, insulin resistance, jaundice, lactic acidosis, leukopenia, lymphadenopathy, macular edema, mania, muscle spasm, myopathy, myositis, oral mucosa hyperpigmentation, oral mucosa ulcer, pancreatitis, pancytopenia (with marrow hypoplasia), paresthesia, photophobia, pruritus, pure red cell aplasia, redistribution of body fat, rhabdomyolysis, rhinitis, seizure, sinusitis, Stevens-Johnson syndrome, syncope, toxic epidermal necrolysis, tremor, urinary frequency, urinary hesitancy, urticaria, vasculitis, vertigo

ALERT: U.S. Boxed Warning

Hematologic toxicity:

Zidovudine has been associated with hematologic toxicity, including neutropenia and severe anemia, particularly in patients with advanced HIV-1 disease.

Myopathy:

Prolonged use of zidovudine has been associated with symptomatic myopathy.

Lactic acidosis/severe hepatomegaly:

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination, including with zidovudine and other antiretrovirals. Suspend treatment if clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity occur.

Warnings/Precautions

Concerns related to adverse effects:

• Hematologic toxicity: [US Boxed Warning]: Hematologic toxicity, including neutropenia and severe anemia have been reported with use, especially with advanced HIV-1 disease. Toxicity may be related to duration of use and prior bone marrow reserve. Hemoglobin reduction may occur in as early as 2 to 4 weeks; neutropenia usually occurs after 6 to 8 weeks. Pancytopenia has been reported (usually reversible). Use with caution in patients with bone marrow compromise (granulocytes <1,000 cells/mm3 or hemoglobin <9.5 mg/dL). Monitor blood counts; dose interruption may be required in patients who develop anemia or neutropenia.

• Immune reconstitution syndrome: Patients may develop immune reconstitution syndrome resulting in the occurrence of an inflammatory response to an indolent or residual opportunistic infection during initial HIV treatment or activation of autoimmune disorders (eg, Graves disease, polymyositis, Guillain-Barré syndrome) later in therapy; further evaluation and treatment may be required.

• Lactic acidosis/hepatomegaly: [US Boxed Warning]: Lactic acidosis and severe hepatomegaly with steatosis have been reported with nucleoside analogues, including fatal cases. Risk may be increased with obesity or in females. Suspend treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or hepatotoxicity (transaminase elevation may/may not accompany hepatomegaly and steatosis).

• Lipoatrophy: May cause loss of subcutaneous fat, especially in the face, limbs, and buttocks. Lipoatrophy incidence and severity are related to cumulative exposure and may be only partially reversible; improvement may take months to years after switching to a regimen that does not contain zidovudine. Monitor patients for signs of lipoatrophy and consider switching to a non-zidovudine-containing regimen if lipoatrophy occurs.

• Myopathy: [US Boxed Warning]: Prolonged use has been associated with symptomatic myopathy and myositis. Pathological changes observed are similar to that produced by HIV-1 disease.

Disease-related concerns:

• Hepatic impairment: Hematologic toxicity may be increased due to increased serum concentrations in patients with hepatic impairment.

• Renal impairment: Use with caution in patients with CrCl <15 mL/minute; dosage adjustment recommended.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Special populations:

• Newborns: Zidovudine newborn prophylaxis may affect diagnostic virologic assays in HIV-exposed infants. If a virologic assay result is negative while the infant is receiving combination antiretroviral prophylaxis, repeat virologic testing should be considered 2 to 4 weeks after cessation of antiretroviral prophylaxis (HHS [pediatric] 2016).

Dosage form specific issues:

• Benzyl alcohol and derivatives: Some dosage forms may contain sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC, 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol derivative with caution in neonates. See manufacturer's labeling.

Dosage form specific issues:

• Injection: Latex is used in vial stopper. May cause allergic reactions in latex-sensitive individuals.

Monitoring Parameters

CBC with differential (more frequent monitoring required in patients with poor bone marrow reserve); LFTs; serum creatinine; HIV viral load and CD4 count.

Pregnancy Considerations

Zidovudine has a high level of transfer across the human placenta; the placenta also metabolizes zidovudine to the active metabolite. No increased risk of overall birth defects has been observed following first trimester exposure according to data collected by the antiretroviral pregnancy registry. Maternal antiretroviral therapy (ART) may increase the risk of preterm delivery, although available information is conflicting possibly due to variability of maternal factors (disease severity; gestational age at initiation of therapy); however, maternal antiretroviral medication should not be withheld due to concerns of preterm birth. Information related to stillbirth, low birth weight, and small for gestational age infants is limited. Long-term follow-up is recommended for all infants exposed to antiretroviral medications; children who develop significant organ system abnormalities of unknown etiology (particularly of the CNS or heart) should be evaluated for potential mitochondrial dysfunction. Cases of lactic acidosis and hepatic steatosis related to mitochondrial toxicity have been reported with use of nucleoside reverse transcriptase inhibitors (NRTIs). These adverse events are similar to other rare but life-threatening syndromes that occur during pregnancy (eg, HELLP syndrome). In general, NRTIs are well tolerated and the benefits of use generally outweigh potential risk.

The Health and Human Services (HHS) Perinatal HIV Guidelines consider zidovudine a component in alternative regimens for initial therapy in antiretroviral-naïve pregnant females. Zidovudine should be administered IV near delivery regardless of antepartum regimen or mode of delivery in females with HIV RNA >1,000 copies/mL or unknown HIV RNA status (even in cases of documented zidovudine resistance) and may be considered in females with HIV RNA between 50 to 999 copies/mL, unless there is a history of hypersensitivity. The pharmacokinetics of zidovudine are not significantly altered in pregnancy and dosing adjustment is not needed.

In general, ART is recommended for all pregnant females with HIV to keep the viral load below the limit of detection and reduce the risk of perinatal transmission. When HIV is diagnosed during pregnancy in a female who has never received antiretroviral therapy, ART should begin as soon as possible after diagnosis. Females who become pregnant on a stable ART regimen may continue that regimen if viral suppression is effective, appropriate drug exposure can be achieved, contraindications for use in pregnancy are not present, and the regimen is well tolerated. Monitoring during pregnancy is more frequent than in nonpregnant adults; ART should be continued postpartum for all females living with HIV.

Health care providers are encouraged to enroll pregnant females exposed to antiretroviral medications as early in pregnancy as possible in the Antiretroviral Pregnancy Registry (1-800-258-4263 or http://www.APRegistry.com). Health care providers caring for HIV-infected females and their infants may contact the National Perinatal HIV Hotline (888-448-8765) for clinical consultation (HHS [perinatal] 2017).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience constipation, headache, lack of appetite, vomiting, or nausea. Have patient report immediately to prescriber signs of infection, signs of liver problems (dark urine, fatigue, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or jaundice), signs of lactic acidosis (fast breathing, tachycardia, abnormal heartbeat, vomiting, fatigue, shortness of breath, severe loss of strength and energy, severe dizziness, feeling cold, or muscle pain or cramps), signs of pancreatitis (severe abdominal pain, severe back pain, severe nausea, or vomiting), severe loss of strength and energy, muscle pain, muscle weakness, bruising, bleeding, change in body fat, or signs of Stevens-Johnson syndrome/toxic epidermal necrolysis (red, swollen, blistered, or peeling skin [with or without fever]; red or irritated eyes; or sores in mouth, throat, nose, or eyes) (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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