Mylostat

Indications

Hydroxyurea (also called hydroxycarbamide) is used for certain blood cancers and blood disorders, such as chronic myeloid leukaemia, polycythaemia vera and essential thrombocythaemia (conditions with too many blood cells), and sometimes for some solid tumours alongside radiotherapy. It is also used to reduce painful crises and the need for blood transfusions in sickle cell disease. It is a specialist medicine.

How It Works

Hydroxyurea blocks an enzyme called ribonucleotide reductase, which cells need to make DNA. This slows the growth of rapidly dividing cells, such as cancer cells and overactive bone marrow cells. In sickle cell disease, it increases the amount of foetal haemoglobin (HbF), which makes red blood cells less likely to become sickle-shaped and block blood vessels.

Dosage and Administration

Hydroxyurea is taken exactly as prescribed by a specialist. The dose is based on body weight and the condition being treated, and it is adjusted according to regular blood tests. Capsules are usually taken once a day, at the same time each day, with water; swallow them whole and do not open them. People handling capsules (including carers) should wear disposable gloves or wash their hands before and after touching them.

Interactions

Live vaccines (such as oral polio, yellow fever, MMR or BCG) should be avoided during treatment. Using it with other medicines that suppress the bone marrow or with radiotherapy increases the risk of low blood counts. In people with HIV, combining it with Didanosine and Stavudine can cause serious pancreas and liver problems and nerve damage. It may affect uric acid levels, so gout medicine doses may need adjusting.

Contraindications

Do not use hydroxyurea if you are allergic to it, have severe bone marrow suppression (very low white cells, platelets or red cells), or are breastfeeding. It should not be used in pregnancy unless the specialist decides it is essential.

Side Effects

Common side effects include low blood counts (raising the risk of infection, bleeding and anaemia), nausea, loss of appetite, mouth sores, diarrhoea or constipation, skin darkening or dryness, nail changes and hair thinning. Long-term use can cause painful leg ulcers and increases the risk of skin cancer. Lung inflammation, liver and kidney changes and reduced fertility can also occur.

Get urgent medical help if you have fever, chills or other signs of infection, unusual bleeding or bruising, severe tiredness or breathlessness, painful ulcers on the legs, a new cough or shortness of breath, yellow skin or eyes, or signs of a serious allergic reaction.

Pregnancy and Lactation

Hydroxyurea can harm an unborn baby. Women and men should use effective contraception during treatment and for some months after stopping, as advised by the specialist (usually at least 6 months for women and 1 year for men). Men may wish to discuss sperm storage before starting. It passes into breast milk, and breastfeeding must be avoided during treatment.

Precautions and Warnings

Regular blood tests are essential. Avoid contact with people who have infections where possible. Protect your skin from the sun and check your skin regularly. Drink plenty of fluids. Use with care in kidney or liver disease and in people who have had radiotherapy. Do not give capsules to anyone else.

Overdose

Overdose can cause severe mouth sores, painful red swelling of the hands and feet, skin changes and dangerous falls in blood counts. Contact your specialist or go to hospital immediately.

Therapeutic Class

Antineoplastic agent, antimetabolite (ribonucleotide reductase inhibitor).

Storage

Store below 30°C in a dry place, away from light and out of the reach of children. Keep capsules in the original container and return unused capsules to a pharmacy; do not throw them in household waste.