Hydroxycarbamide

Name: Hydroxycarbamide

Why is this medication prescribed?

Hydroxyurea (Hydrea) is used alone or with other medications or radiation therapy to treat a certain type of chronic myelogenous leukemia (CML; a type of cancer of the white blood cells) and certain types of head and neck cancer (including cancer of the mouth, cheek, tongue, throat, tonsils, and sinuses). Hydroxyurea (Droxia) is used to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia (an inherited blood disorder in which the red blood cells are abnormally shaped [shaped like a sickle] and cannot bring enough oxygen to all parts of the body). Hydroxyurea is in a class of medications called antimetabolites. Hydroxyurea treats cancer by slowing or stopping the growth of cancer cells in your body. Hydroxyurea treats sickle cell anemia by helping to prevent formation of sickle-shaped red blood cells.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What other information should I know?

Do not let anyone else take your medication. People who are not taking hydroxyurea should avoid touching hydroxyurea capsules or the bottle that contains the capsules.

Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Droxia®
  • Hydrea®

How to take hydroxycarbamide

  • Before you start the treatment, read any printed information you have been given by your doctor and the printed manufacturer's leaflet from inside the pack. These will give you more information about hydroxycarbamide and will provide you with a full list of the side-effects which you may experience from taking it.
  • Hydroxycarbamide will be given to you by a specialist doctor who is experienced in treating your condition. Your doctor will calculate what dose is right for you, and will tell you how much to take and how often to take it. You may be asked to take a dose each day, or every third day. Your dose will be printed on the label of the pack to remind you about what the doctor said to you, but if you have any concerns, contact your doctor or hospital clinic for advice.
  • If you are taking Hydrea® capsules and you have difficulties swallowing, you can stir the contents of the capsules into a glass of water and then drink it straightaway. If you do this, be careful not to get the contents of the capsule on your skin. You can take Hydrea® capsules either with or without food.
  • Siklos® tablets should preferably be taken in the morning before breakfast. If you have difficulty swallowing, you can allow the tablet to disintegrate in a little water before swallowing it. You can mask any bitter taste by adding a drop of honey or mixing in a small amount of food.

Getting the most from your treatment

  • You must try to keep your regular appointments with your doctor or hospital. This is so your doctor can check on your progress. You will need to have regular blood tests and check-ups during your treatment with hydroxycarbamide. The blood tests are important as a way of monitoring your treatment, and also to check that your kidneys and liver are working properly.
  • It is important that you do not get pregnant while you are taking hydroxycarbamide. Make sure you have discussed with your doctor which types of contraception are suitable for you and your partner. Many anti-cancer treatments are associated with reduced fertility (particularly in men), so you may also want to ask your doctor for family planning advice if you would like to have children.
  • While you are taking hydroxycarbamide and for six months after you have stopped the treatment, do not have any immunisations (vaccinations) without talking to your specialist doctor first. Hydroxycarbamide lowers your body's resistance and there is a risk that you will get an infection from some vaccines.
  • Rarely, people who take hydroxycarbamide over a long period of time can develop skin cancer. You can reduce the risk of this by protecting your skin from the sun by wearing suitable clothing and using a sunscreen with a high sun protection factor (SPF) of at least 15.

Pregnancy & Lactation

Pregnancy Category: D

Lactation: excreted in breast milk, do not nurse

Pregnancy Categories

A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA:Information not available.

Pharmacology

Mechanism of Action

The precise mechanism by which hydroxyurea produces its cytotoxic and cytoreductive effects is not known. However, various studies support the hypothesis that hydroxyurea causes an immediate inhibition of DNA synthesis by acting as a ribonucleotide reductase inhibitor, without interfering with the synthesis of ribonucleic acid or of protein.

The mechanisms by which hydroxyurea produces its beneficial effects in patients with sickle cell anemia (SCA) are uncertain. Known pharmacologic effects of hydroxyurea that may contribute to its beneficial effects include increasing hemoglobin F levels in red blood cells (RBCs), decreasing neutrophils, increasing the water content of RBCs, increasing deformability of sickled cells, and altering the adhesion of RBCs to endothelium.

Absorption

Duration: up to 24 hr

Peak Plasma Time: 1-4 hr

Distribution

Vd: 0.5 L/kg

Protein binding: 75-80%

Metabolism

Metabolized (60%) by liver and GI tract

Metabolites: CO2, urea

Elimination

Half-Life: 2-4 hr

Excretion: Urine (40% of administered dose in sickle cell anemia patients)

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