Mercaptopurine (Systemic)

Brand Names : Purinethol, 6-MP

Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For mercaptopurine, the following should be considered:

Allergies - Tell your doctor if you have ever had any unusual or allergic reaction to mercaptopurine.

Pregnancy - Tell your doctor if you are pregnant or if you intend to have children. There is a chance that this medicine may cause birth defects if either the male or female is taking it at the time of conception or if it is taken during pregnancy. However, studies have not been done in humans. Mercaptopurine has been shown to cause damage to the fetus in rats and increases the risk of miscarriage or premature births in humans. In addition, many cancer medicines may cause sterility which could be permanent. Although this has not been reported with this medicine, the possibility should be kept in mind.

Be sure that you have discussed this with your doctor before taking this medicine. It is best to use some kind of birth control while you are taking mercaptopurine. Tell your doctor right away if you think you have become pregnant while taking mercaptopurine.

Breast-feeding - Tell your doctor if you are breast-feeding or if you intend to breast-feed during treatment with this medicine. Because mercaptopurine may cause serious side effects, breast-feeding is generally not recommended while you are taking it.

Children - Although there is no specific information comparing use of mercaptopurine in children with use in other age groups, it is not expected to cause different side effects or problems in children than it does in adults.

Older adults - Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of mercaptopurine in the elderly with use in other age groups.

Other medicines - Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking mercaptopurine, it is especially important that your health care professional know if you are taking any of the following:

• Acetaminophen (e.g., Tylenol) (with long-term, high-dose use) or
• Amiodarone (e.g., Cordarone) or
• Anabolic steroids (nandrolone [e.g., Anabolin], oxandrolone [e.g., Anavar], oxymetholone [e.g., Anadrol], stanozolol [e.g., Winstrol]) or
• Androgens (male hormones) or
• Anti-infectives by mouth or by injection (medicine for infection) or
• Antithyroid agents (medicine for overactive thyroid) or
• Carbamazepine (e.g., Tegretol) or
• Chloroquine (e.g., Aralen) or
• Dantrolene (e.g., Dantrium) or
• Disulfiram (e.g., Antabuse) or
• Divalproex (e.g., Depakote) or
• Estrogens (female hormones) or
• Etretinate (e.g., Tegison) or
• Gold salts (medicine for arthritis) or
• Hydroxychloroquine (e.g., Plaquenil) or
• Methyldopa (e.g., Aldomet) or
• Naltrexone (e.g., Trexan) (with long-term, high-dose use) or
• Oral contraceptives (birth control pills) containing estrogen or
• Phenothiazines (acetophenazine [e.g., Tindal], chlorpromazine [e.g., Thorazine], fluphenazine [e.g., Prolixin], mesoridazine [e.g., Serentil], perphenazine [e.g., Trilafon], prochlorperazine [e.g., Compazine], promazine [e.g., Sparine], promethazine [e.g., Phenergan], thioridazine [e.g., Mellaril], trifluoperazine [e.g., Stelazine], triflupromazine [e.g., Vesprin], trimeprazine [e.g., Temaril]) or
• Phenytoin (e.g., Dilantin) or
• Plicamycin (e.g., Mithracin) or
• Valproic acid (e.g., Depakene) - Risk of unwanted effects on the liver may be increased

• Azathioprine (e.g., Imuran) or
• Corticosteroids (cortisone-like medicine) or
• Cyclosporine (e.g., Sandimmune) or
• Muromonab-CD3 (monoclonal antibody) (e.g., Orthoclone OKT3) - There may be an increased risk of infection and development of cancer because mercaptopurine reduces the body's immunity

• Allopurinol (e.g., Zyloprim) - Effects of mercaptopurine may be increased because allopurinol blocks its removal from the body

• Amphotericin B by injection (e.g., Fungizone) or
• Antithyroid agents (medicine for overactive thyroid) or
• Azathioprine (e.g., Imuran) or
• Chloramphenicol (e.g., Chloromycetin) or
• Colchicine or
• Flucytosine (e.g., Ancobon) or
• Ganciclovir (e.g., Cytovene) or
• Interferon (e.g., Intron A, Roferon-A) or
• Plicamycin (e.g., Mithracin) or
• Zidovudine (e.g., AZT, Retrovir) or
• If you have ever been treated with radiation or cancer medicines - Mercaptopurine may increase the effects of these medicines or radiation therapy on the blood

• Probenecid (e.g., Benemid) or
• Sulfinpyrazone (e.g., Anturane) - Mercaptopurine may raise the concentration of uric acid in the blood. Since these medicines are used to lower uric acid levels, they may not be as effective in patients taking mercaptopurine

Other medical problems - The presence of other medical problems may affect the use of mercaptopurine. Make sure you tell your doctor if you have any other medical problems, especially:

• Chickenpox (including recent exposure) or
• Herpes zoster (shingles) - Risk of severe disease affecting other parts of the body

• Gout (history of) or
• Kidney stones (history of) - Mercaptopurine may increase levels of uric acid in the body, which can cause gout or kidney stones

• Infection - Mercaptopurine may decrease your body's ability to fight infection

• Kidney disease or
• Liver disease - Effects of mercaptopurine may be increased because of slower removal from the body