Zidovudine

Indications

Zidovudine (also called AZT) is an antiretroviral medicine used, always together with other HIV medicines, to treat HIV infection in adults and children. It is also used to reduce the chance of HIV passing from a mother with HIV to her baby during pregnancy, birth and early life. It is often given as a combined tablet with Lamivudine.

How It Works

HIV needs an enzyme called reverse transcriptase to copy its genetic material and multiply. Zidovudine is a nucleoside reverse transcriptase inhibitor (NRTI): it blocks this enzyme, so the virus multiplies less. This lowers the amount of virus in the blood and helps the immune system recover. It does not cure HIV.

Dosage and Administration

Take exactly as prescribed by an HIV specialist. The dose depends on age, weight, kidney function, blood counts and the other medicines in the treatment plan. It can be taken with or without food. Take it at the same times every day and do not miss doses, because missed doses can let the virus become resistant.

Interactions

Stavudine should not be used with it, as they cancel each other out. Medicines that also lower blood counts, such as Ganciclovir, Valganciclovir, Co-trimoxazole in high doses, Pyrimethamine, Interferon and some cancer medicines, increase the risk of anaemia and low white cells. Ribavirin may worsen anaemia. Probenecid, Fluconazole and Valproic Acid can raise its level, while Rifampicin can lower it. Tell your doctor about every medicine and herbal product you use.

Contraindications

Do not use if you are allergic to Zidovudine, or if you have a very low haemoglobin or very low neutrophil (white cell) count. Newborns with certain liver or blood problems may need special care.

Side Effects

Common side effects include nausea, headache, tiredness, muscle aches, loss of appetite and trouble sleeping, often improving after a few weeks. It can cause anaemia (low red blood cells) and low white blood cells, so regular blood tests are needed. Long-term use may cause muscle weakness, changes in body fat, and darkening of the nails or skin.

Get urgent medical help if you have severe tiredness, shortness of breath or very pale skin, fever or signs of infection, fast deep breathing with stomach pain and nausea (possible lactic acidosis), yellowing of the skin or eyes, severe muscle weakness, or signs of an allergic reaction.

Pregnancy and Lactation

Zidovudine is used in pregnancy, under specialist care, to help protect the baby from HIV. Whether and how to breastfeed depends on local HIV guidance and the mother's treatment; discuss this with your doctor.

Precautions and Warnings

Regular blood counts and liver tests are needed. Tell your doctor about liver disease, hepatitis B or C, kidney disease or low blood counts. As the immune system recovers, old infections may flare up (immune reconstitution). Use condoms to protect partners, as the medicine does not stop HIV being passed on completely.

Overdose

Overdose may cause nausea, vomiting, headache, drowsiness and blood count problems. Contact a doctor or the nearest hospital immediately.

Therapeutic Class

Antiretroviral, nucleoside reverse transcriptase inhibitor (NRTI).

Storage

Store below 30°C in a dry place, away from light and out of the reach of children.