Zidovudine (AZT): Medication Information and Guidelines

Zidovudine, also known as AZT (azidothymidine), is an antiretroviral medication used in the management of HIV/AIDS. It belongs to the class of medications known as nucleoside reverse transcriptase inhibitors (NRTIs), which inhibit the activity of the HIV reverse transcriptase enzyme, thereby preventing viral replication and reducing viral load.

Recommended Dose and Dosage Regimen

The recommended dose of zidovudine varies depending on factors such as the patient’s age, weight, renal function, and previous antiretroviral therapy. For adults and adolescents weighing 30 kg (66 lbs) or more, the typical dose is 300 mg orally twice daily or 200 mg orally three times daily. For pediatric patients weighing less than 30 kg, the dose is adjusted based on body weight and administered every 4 to 6 hours.

Frequency of Administration

Zidovudine is usually administered orally in divided doses to maintain therapeutic plasma concentrations throughout the day. The frequency of administration may vary depending on the specific dosing regimen prescribed by the healthcare provider. It is important to adhere to the prescribed dosing schedule to maximize the efficacy of zidovudine therapy and minimize the risk of viral resistance.

Route of Administration

Zidovudine is available for oral administration as capsules, tablets, or syrup. The medication is typically taken with or without food, as directed by the healthcare provider. Zidovudine may also be administered intravenously in certain clinical settings, such as for the prevention of mother-to-child transmission of HIV or the treatment of HIV-infected infants unable to swallow oral formulations.

Mechanism of Action (MOA)

The mechanism of action of zidovudine involves its phosphorylation by cellular kinases to form zidovudine triphosphate, which competes with endogenous deoxythymidine triphosphate for incorporation into viral DNA by the HIV reverse transcriptase enzyme. Once incorporated, zidovudine terminates the elongation of viral DNA chains, thereby inhibiting viral replication and reducing the production of new HIV particles.

Pharmacokinetics (PK)

Zidovudine is rapidly absorbed from the gastrointestinal tract after oral administration, with peak plasma concentrations achieved within 0.5 to 1.5 hours. The medication is widely distributed throughout the body, including into cerebrospinal fluid and seminal fluid. Zidovudine undergoes hepatic metabolism via glucuronidation to form inactive metabolites, which are primarily eliminated in the urine.

Pharmacodynamics (PD)

The pharmacodynamic effects of zidovudine are mediated by its inhibition of the HIV reverse transcriptase enzyme, which is essential for viral replication. By interfering with the synthesis of viral DNA, zidovudine suppresses HIV replication, reduces viral load, and slows the progression of HIV/AIDS. Zidovudine is often used in combination with other antiretroviral medications to achieve maximal viral suppression and immune reconstitution.

Primary Indications

Zidovudine is indicated for the treatment of HIV infection in combination with other antiretroviral agents. It is used for both initial therapy in antiretroviral-naive patients and as part of combination regimens in patients with virologic failure or drug resistance. Zidovudine may also be used for the prevention of mother-to-child transmission of HIV during pregnancy, labor, and delivery, as well as for post-exposure prophylaxis in certain occupational or non-occupational settings.

Contraindications

Contraindications to zidovudine use include hypersensitivity to zidovudine or any component of the formulation, as well as severe hepatic impairment. Zidovudine should be used with caution in patients with pre-existing hematologic disorders, such as anemia or neutropenia, as it may exacerbate these conditions. Regular monitoring of hematologic parameters is recommended during zidovudine therapy to detect and manage potential adverse effects.

Purpose of Taking Medication

The primary purpose of taking zidovudine is to suppress HIV replication, reduce viral load, and delay disease progression in patients with HIV/AIDS. Zidovudine therapy aims to achieve durable virologic suppression, immune reconstitution, and improvement in clinical outcomes, including reductions in HIV-related morbidity and mortality. Zidovudine is an essential component of combination antiretroviral therapy regimens recommended for the treatment of HIV infection.

Usage Instructions

Zidovudine should be taken orally as directed by the healthcare provider, usually in divided doses spaced evenly throughout the day. The medication should be swallowed whole with a glass of water and may be taken with or without food. It is important to adhere to the prescribed dosing schedule and regimen to maintain therapeutic plasma concentrations and maximize treatment efficacy.

Precautions and Care

Patients taking zidovudine should be monitored regularly for clinical response, virologic suppression, and adverse effects, including hematologic toxicity and lactic acidosis. Healthcare providers should assess renal function, liver function, and hematologic parameters before initiating zidovudine therapy and periodically thereafter. Dose adjustments or discontinuation may be necessary in patients experiencing severe or persistent adverse effects.

Dietary Considerations

There are no specific dietary restrictions associated with zidovudine use. However, patients should maintain a balanced diet and adequate hydration to support overall health and mitigate potential adverse effects such as gastrointestinal upset or hepatotoxicity. Patients with HIV/AIDS may benefit from nutritional counseling and supplementation to address specific dietary deficiencies and maintain optimal immune function.

Possible Side Effects

Common side effects of zidovudine may include nausea, vomiting, headache, fatigue, insomnia, myalgia, and gastrointestinal upset. These side effects are usually mild to moderate in severity and transient, resolving with continued use or dose adjustments. Less common but more serious side effects may include hematologic toxicity (e.g., anemia, neutropenia), lactic acidosis, hepatotoxicity, and mitochondrial toxicity. Patients should be advised to report any unusual or persistent symptoms to their healthcare provider.

Storage and Disposal

Zidovudine should be stored at room temperature away from moisture, heat, and light, in its original packaging to maintain stability and efficacy. Unused or expired medication should be disposed of properly according to local regulations or guidelines for pharmaceutical waste disposal. Patients should not share zidovudine with others or use it for longer than recommended without consulting their healthcare provider.

Important Note: Always consult with a healthcare professional for personalized medical advice and guidance regarding the use of given drug, especially regarding dosing, administration, and potential side effects. Your healthcare provider can provide tailored recommendations based on your individual medical history, current medications, and specific treatment needs. Never self-adjust your given drug regimen or discontinue treatment without first consulting your healthcare provider. If you have any questions or concerns about given drug or its use, talk to your doctor or pharmacist for further information and assistance.