Hydroxyurea

Hydroxyurea or hydroxycarbamide (the latter being the recommended International Non-Proprietary Name), (brand names include Hydrea®) is an antineoplastic drug used in hematological malignancies. It is also used as an antiretroviral agent (eg. against HIV). Its mechanism of action is believed to be based on its inhibition of the enzyme ribonucleotide reductase.

Uses

  • Polycythemia vera
  • Chronic myelogenous leukaemia
  • Essential thrombocytosis
  • Sickle-cell disease (breaks down cells that are prone to sickle, as well as increasing foetal haemoglobin content)
  • AIDS as an adjunct to ddI in combination antiretroviral therapies
  • Biochemical research as an agent that causes ribonucleotide depletion and results in DNA double strand breaks near replication forks (see DNA repair)

    • Dose

    500 milligrams once or twice a day, or more if pancytopaenia does not develop.

    Side effects

    Reported side-effects are: drowsiness, nausea, vomiting and diarrhoea, constipation, mucositis, anorexia, stomatitis, bone marrow toxicity (which may take 7-21 days to recover after the drug has been discontinued), alopecia (hair loss), skin changes, abnormal liver enzymes, creatinine and blood urea nitrogen.

    Due to its effect on the bone marrow, regular monitoring of the full blood count is vital, as well as early response to possible infections. In addition, renal function, uric acid and electrolytes, as well as liver enzymes, are commonly checked.

    Use in Pregnancy

    Category D - investigational or post-marketing data show risk to the foetus. However, potential benefits may outweigh the potential risk. Generally this rating is reserved for drugs with no safer alternatives.

    Contraindications

    Contraindications are: severe anaemia, bone marrow depression or neutropaenia.

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