Human immunodeficiency virus or HIV primarily disrupts CD4+ T cells, thus compromising the host's immune system. The virus replicates via reverse transcriptase, and if not treated properly, it can progress to acquired immunodeficiency syndrome. It is imperative that providers screen and treat at-risk patient populations. If patients are left untreated, their CD4+ T cell count can drop to dangerous levels leaving the patient susceptible to deadly opportunistic infections and neoplasms. Zidovudine first received approval in the United States in 1987. It is part of a class of medications known as nucleoside reverse transcriptase inhibitors. This class of medications is a crucial aspect of highly active antiretroviral viral therapy (HAART). Zidovudine is indicated for the treatment of human immunodeficiency virus (HIV-1) in conjunction with other antiretroviral medications. Zidovudine is indicated for the prevention of vertical transmission of the human immunodeficiency virus (HIV-1) between mother and fetus. Zidovudine indications also include the treatment of adult T cell leukemia.[1][2][3][4][5][6]

Zidovudine is a pyrimidine nucleoside reverse transcriptase inhibitor (NRTI) that works primarily through a complex multistep mechanism of action. First, zidovudine is phosphorylated into zidovudine-triphosphate. The phosphorylation of zidovudine inhibits thymidine's ability to integrate into viral DNA through competitively inhibiting viral reverse transcriptase. Zidovudine then incorporates itself into viral DNA. Integration into viral DNA causes chain termination due to the lack of a 3' hydroxyl group. This achieving of chain termination is primarily through zidovudine's unreactive 3′-azido group.[1][2][7]

Antiretroviral therapy such as zidovudine should be administered promptly upon diagnosis of the human immunodeficiency virus (HIV-1). Clinicians ought to pay careful attention to dosing based on the patient's current clinical state as well as for which clinical indication it is being used. Zidovudine has a half-life between 1 to 1.5 hours in patients, a plasma clearance rate of 1.3 L/h/kg, and a renal clearance rate of 0.23 L/h/kg.

Treatment of HIV-1 Infection

1. Adults: Should receive 600 mg per day with split doses
2. Dosage for pediatric patients between 6 weeks and 18 years of age is based on body weight and should not be greater than the adult indicated dose. Patients weighing between 4 kg and 9kg will receive a maximum daily dose of 24 mg/kg/day. Patients weighing between 9 kg and 30 kg will receive a maximum daily dose of 18 mg/kg/day. Patients weighing over 30 kg will receive a maximum daily dose of 600 mg/day.

• Prevention of HIV-1 maternal-fetal transmission: 100 mg five times per day by mouth until the induction of labor. Zidovudine should be given intravenously over one hour at 2 mg/kg while the patient is undergoing labor and delivery. Upon completion of this infusion, patients should receive 1 mg/kg/hour until the clamping of the umbilical cord. The administration of neonatal dosing should be within the first 12 hours after birth. The neonate should receive 2 mg/kg of zidovudine by mouth every 6 hours until the neonate reaches six weeks of age.
• Special patient populations: Patients with severe anemia or neutropenia should stop treatment until bone marrow recovery is evident. Patients on hemodialysis should receive 100 mg of zidovudine every 6 to 8 hours.[1][4][7][8]

Adverse events are extremely common, with patients receiving zidovudine treatment. Up to 84% of patients report adverse effects. The most commonly reported side effects are nausea, vomiting, severe headaches, muscle aches, and insomnia. Hematologic adverse effects occur in up to 45% of patients. These include neutropenia, leukopenia, and anemia. In rare cases, patients may develop pancytopenia. There are reports of severe lactic acidosis and hepatomegaly with steatosis have been reported. Patients with known liver disease should receive careful monitoring.[1][9][10][11]

Zidovudine is contraindicated for any patients that have had severe life-threating hypersensitivity reactions to this medication, including anaphylaxis and Stevens-Johnson syndrome. Anaphylaxis may present with difficulty breathing, diffuse rash, and hypotension. Stevens-Johnson syndrome is a very painful blistering skin condition. Prompt discontinuation of zidovudine therapy is critical if any of these symptoms arise.[1]