Retrovir

What is it?

A nucleoside reverse transcriptase inhibitor available as capsules in 2 strengths, both containing zidovudine. White capsules, marked 100 and Y9C contain 100mg; blue/ white capsules, marked 250 and H2F contain 250mg. All capsules Also, marked Wellcome and with blue band. Also, RETROVIR SYRUP, a light yellow, sugar-free liquid containing 50mg of zidovudine per 5ml supplied with oral syringe. Also, RETROVIR INFUSION, a solution in vials containing 10mg of zidovudine per ml.

Medical Uses

Combined with other retroviral drugs to treat HIV infections; as sole therapy in HIV-positive, pregnant women more than 14 weeks into pregnancy and their new-born babies, to prevent mother-child transmission.

Dosage

Adults, capsules and syrup, 500 to 600mg each day in 2 to 3 divided doses. Infusion, 1 to 2mg per kg of body weight every 4 hours by slow pintravenous infusion over 1 hour; patients should be given oral preparations as soon as possible. Children, capsules and syrup, aged 3 months to 12 years, 360 to 480mg per square metre of body surface area in 3 to 4 divided doses each day with a maximum dose of 200mg every 6 hours. Infusion, 80 to 160mg per square metre of body surface area every 6 hours. In adults and children combined with other retrovirals. Prevention of mother-child transmission, capsules, syrup, infusion: mother, 100mg 5 times each day taken by mouth until labour starts then 2mg per kg of body weight by intravenous infusion over 1 hour during labour and delivery, continuing with 1mg per kg of body weight until baby is delivered and cord is clamped. Baby, 2mg per kg of body weight by mouth or 1.5mg per kg of body weight by intravenous infusion over half an hour, both every 6 hours and starting within 12 hours of birth, continuing for 6 weeks. If caesarian birth or false labour, consult manufacturer's literature.

Special Care

Elderly, pregnant women during first 14 weeks of pregnancy (treatment not usually given unless benefit to mother greatly outweighs risk to foetus), liver or kidney disorders. Dosages may require adjusting if bone marrow suppression or anaemia occurs. Blood tests must be carried out every week in those receiving infusion and every 2 weeks in those taking oral preparations during initial 3 months of treatment. These should continue to be carried out every month in patients with advanced HIV

Avoid Use

Breastfeeding, low white blood cell counts or haemoglobin levels, newborn babies with high levels of bilirubin in blood or raised transaminase levels.

Possible Drug and Food Interactions

Tribavirin, probenecid, some drugs affecting liver function, phenytoin, stavudine, chronic use of analgesics, especially paracetamol, other drugs suppressing bone marrow or nephrotoxic preparations. Patients should be carefully warned about taking other drugs.

Known Side Effects

Gastrointestinal upset, insomnia, blood changes (leucopenia, thrombocytopenia, anaemia, pancytopenia), muscle pains and muscle disease, rash, heart muscle disease, raised liver enzymes, enlargement of liver with steatosis, lactic acid acidosis, headache, pancreatitis, cough, shortness of breath, anxiety, depression, sensation of numbness/tingling/ pins and needles, pigmentation affecting skin and nails, fits.