Zidovudine

Brand Names: Zidovudine

Drug Class: Human Immunodeficiency Virus Nucleoside Analog Reverse Transcriptase Inhibitor

Overview

11 DESCRIPTION Zidovudine (formerly called azidothymidine [AZT]), a pyrimidine nucleoside analogue active against HIV-1. The chemical name of zidovudine is 3'- azido-3'-deoxythymidine; it has the following structural formula: Zidovudine USP is a white to beige, odorless, crystalline solid with a molecular weight of 267.24 and a solubility of 20.1 mg per mL in water at 25°C.

Mechanism of Action

12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Zidovudine is an antiretroviral agent [see Microbiology ( 12.4 )]. 12.3 Pharmacokinetics Absorption and Bioavailability In adults, following oral administration, zidovudine is rapidly absorbed and extensively distributed, with peak serum concentrations occurring within 0.5 to 1.5 hours. The AUC was equivalent when zidovudine was administered as zidovudine tablets or syrup compared with zidovudine capsules. The pharmacokinetic properties of zidovudine in fasting adult subjects are summarized in Table 7. Table 7. Zidovudine Pharmacokinetic Parameters in Adult Subjects Parameter Mean ± SD (except where noted) Oral bioavailability (%) 64 ± 10 (n = 5) Apparent volume of distribution (L/kg) 1.6 ± 0.

Indications

  • 1 INDICATIONS & USAGE Zidovudine tablets are a nucleoside analogue reverse transcriptase inhibitor indicated for: •Treatment of Human Immunodeficiency Virus (HIV-1) infection in combination with other antiretroviral agents. ( 1.1 ) • Prevention of maternal-fetal HIV-1 transmission. ( 1.2 ) 1.1 Treatment of HIV-1 Zidovudine tablets, a nucleoside reverse transcriptase inhibitor, are indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. 1.

Common Doses

  • 300 mg
  • 100 mg
  • 24 mg
  • 12 mg

Dosage

2 DOSAGE & ADMINISTRATION • Treatment of HIV-1 infection: Adults: Recommended oral dosage is 300 mg twice a day with other antiretroviral agents. ( 2.1 ) Pediatric patients (aged 4 weeks to less than 18 years): Dosage should be calculated based on body weight not to exceed adult dose. ( 2.2 ) • Prevention of maternal-fetal HIV-1 transmission: Specific dosage instructions for mother and infant. ( 2.3 ) • Patients with severe anemia and/or neutropenia: Dosage interruption may be necessary. ( 2.

Black Box Warning

BOXED WARNING 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 )].

Contraindications

  • 4 CONTRAINDICATIONS Zidovudine tablets are contraindicated in patients who have had a potentially life-threatening hypersensitivity reaction (e.g., anaphylaxis, Stevens-Johnson syndrome) to any of the components of the formulations. Hypersensitivity to zidovudine or any of the components (e.g., anaphylaxis, Stevens-Johnson syndrome). ( 4 )

Side Effects

  • 6 ADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the labeling: • Hematologic toxicity, including neutropenia and anemia [see Boxed Warning, Warnings and Precautions ( 5.1 )]. • Symptomatic myopathy [see Boxed Warning, Warnings and Precautions ( 5.3 )]. • Lactic acidosis and severe hepatomegaly with steatosis [see Boxed Warning, Warnings and Precautions ( 5.4 )]. • Hepatic decompensation in patients co-infected with HIV-1 and hepatitis C [see Warnings and Precautions ( 5.5 )].

Interactions

  • 7 DRUG INTERACTIONS • Avoid use with stavudine. ( 7.1 ) • Avoid use with doxorubicin. ( 7.2 ) • Bone marrow suppressive/cytotoxic agents: May increase the hematologic toxicity of zidovudine. ( 7.3 ) 7.1 Antiretroviral Agents Stavudine Concomitant use of zidovudine with stavudine should be avoided since an antagonistic relationship has been demonstrated in vitro. Nucleoside Analogues Affecting DNA Replication Some nucleoside analogues affecting DNA replication, such as ribavirin, antagonize the in vitro antiviral activity of zidovudine against HIV-1; concomitant use of such drugs should be...