Systematic (IUPAC) name
Clinical data
Trade names Purinethol
AHFS/ monograph
MedlinePlus a682653
Pregnancy cat.  ?,(Increased Risk of Abortion)
Legal status  ?
Routes Oral
Pharmacokinetic data
Bioavailability 5 to 37%
Metabolism xanthine oxidase
Half-life 60 to 120 min., longer for its active metabolites
Excretion Renal
CAS number 50-44-2 YesY
ATC code L01BB02
PubChem CID 667490
DrugBank APRD01096
ChemSpider 580869 YesY
KEGG D04931 YesY
Chemical data
Formula C5H4N4S 
Mol. mass 152.177 g/mol
SMILES eMolecules & PubChem
 N(what is this?)  (verify)

Mercaptopurine (also called 6-mercaptopurine, 6-MP or its brand name Purinethol) is an immunosuppressive drug.

It is a thiopurine.[1]



It is used to treat leukemia, pediatric non-Hodgkin's lymphoma,[citation needed] polycythemia vera,[citation needed] psoriatic arthritis,[citation needed] and inflammatory bowel disease (such as Crohn's disease and ulcerative colitis).[2]

It has demonstrated some in vitro effectiveness against Mycobacterium paratuberculosis.[3]

Mechanisms of action

6-MP ribonucleotide inhibits purine nucleotide synthesis and metabolism. This alters the synthesis and function of RNA and DNA. Mercaptopurine interferes with nucleotide interconversion and glycoprotein synthesis.

Adverse reactions

Some of the adverse reactions of taking mercaptopurine might include diarrhea, nausea, vomiting, loss of appetite, fatigue, stomach/abdominal pain, weakness, skin rash, darkening of the skin, or hair loss. Serious adverse reactions include mouth sores, fever, sore throat, easy bruising or bleeding, pinpoint red spots on the skin, yellowing of eyes or skin, dark urine, and painful or difficult urination. Unlikely but serious side-effects include: black or tarry stools (melena), bloody stools, and bloody urine.

Symptoms of allergic reaction to mercaptopurine include rash, itching, swelling, dizziness, trouble breathing, and pancreatitis.

Mercaptopurine causes myelosuppression, suppressing the production of white blood cells and red blood cells. It may be toxic to bone marrow. Weekly blood counts are recommended for patients on mercaptopurine. The patient should stop taking the medication at least temporarily if there is an unexplained, abnormally large drop in white blood cell count, or any other blood count.

Patients exhibiting myelosuppression or bone marrow toxicity should be tested for thiopurine methyltransferase (TPMT) enzyme deficiency. Patients with TPMT deficiency are much more likely to develop dangerous myelosuppression. In such patients, it may be possible to continue using mercaptopurine, but at a lower dose.

Drug interactions

Allopurinol inhibits xanthine oxidase, the enzyme that breaks down mercaptopurine. Those taking allopurinol (often used to prevent gout) are at risk for mercaptopurine toxicity. The dose should be reduced or allopurinol should be discontinued.


Mercaptopurine can lower the body's ability to fight off infection. Those taking mercaptopurine should get permission from a doctor in order to receive immunizations and vaccinations. It is also recommended that, while on the drug, one should avoid those having recently received oral polio vaccine.

This drug is traditionally not recommended during pregnancy, but this issue has been debated, and current evidence indicates that pregnant women on the drug show no increase in fetal abnormalities. However, women receiving mercaptopurine during the first trimester of pregnancy have an increased incidence of miscarriage.[4] Davis et al. 1999 found that mercaptopurine, compared to methotrexate, was ineffective as a single-agent abortifacient; every woman in the mercaptopurine arm of the study had fetal cardiac activity at follow-up (two weeks later) and was given a suction abortion.[5]

Mercaptopurine causes changes to chromosomes in animals and humans, though a study in 1990[6] found that, "while the carcinogenic potential of 6-MP cannot be precluded, it can be only very weak or marginal." Another study in 1999[7] noted an increased risk of developing leukemia when taking large doses of 6-MP together with other cytotoxic drugs.

See also


  1. ^ Sahasranaman S, Howard D, Roy S (August 2008). "Clinical pharmacology and pharmacogenetics of thiopurines". Eur. J. Clin. Pharmacol. 64 (8): 753–67. doi:10.1007/s00228-008-0478-6. ISBN 0022800804786. PMID 18506437. 
  2. ^ Nielsen OH, Vainer B, Rask-Madsen J (November 2001). "Review article: the treatment of inflammatory bowel disease with 6-mercaptopurine or azathioprine". Aliment. Pharmacol. Ther. 15 (11): 1699–708. doi:10.1046/j.1365-2036.2001.01102.x. PMID 11683683. 
  3. ^ Shin SJ, Collins MT (February 2008). "Thiopurine drugs azathioprine and 6-mercaptopurine inhibit Mycobacterium paratuberculosis growth in vitro". Antimicrob. Agents Chemother. 52 (2): 418–26. doi:10.1128/AAC.00678-07. PMC 2224720. PMID 18070971. 
  4. ^ Nørgård, B.; L. Pedersen, K. Fonager, S. Rasmussen, H. Sørensen (March 2003). "Azathioprine, mercaptopurine and birth outcome: a population-based cohort study". Alimentary pharmacology and therapeutics 17 (6): 827–834. doi:10.1046/j.1365-2036.2003.01537.x. PMID 12641505. 
  5. ^ Davis, Anne R.; Leslie Miller, Hisham Tamimi, and Allen Gown (June 1999). "Methotrexate Compared With Mercaptopurine for Early Induced Abortion". Obstetrics & Gynecology 93 (6): 904–9. doi:10.1016/S0029-7844(98)00569-9. PMID 10362152. 
  6. ^ Maekawa, A.; T. Nagaoka, H. Onodera, Y. Matsushima, A. Todate, M. Shibutani, H. Ogasawara, Y. Kodama and Y. Hayashi (May 1990). "Two-year carcinogenicity study of 6-mercaptopurine in F344 rats". Journal of Cancer Research and Clinical Oncology 116 (3): 245–250. doi:10.1007/BF01612898. PMID 2370249. 
  7. ^ Bo J, Schrøder H, Kristinsson J, Madsen B, Szumlanski C, Weinshilboum R, Andersen JB, Schmiegelow K (September 1999). "Possible carcinogenic effect of 6-mercaptopurine on bone marrow stem cells: relation to thiopurine metabolism". Cancer 86 (6): 1080–6. doi:10.1002/(SICI)1097-0142(19990915)86:6<1080::AID-CNCR26>3.0.CO;2-5. PMID 10491537. 

External links

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Look at other dictionaries:

  • Mercaptopurine — Général Nom IUPAC Mercaptopurine No CAS …   Wikipédia en Français

  • mercaptopurine — ● mercaptopurine nom féminin Médicament alkylant agissant sur la biosynthèse des nucléotides, utilisé dans le traitement de certaines leucémies …   Encyclopédie Universelle

  • mercaptopurine — mer·cap·to·pu·rine (.)mər .kap tə pyu̇(ə)r .ēn n an antimetabolite C5H4N4S that interferes esp. with the metabolism of purine bases and the biosynthesis of nucleic acids and that is sometimes useful in the treatment of acute leukemia * * * n. a… …   Medical dictionary

  • Mercaptopurine — Strukturformel Allgemeines Freiname Mercaptopurin Andere Namen 7H Purin 6 thi …   Deutsch Wikipedia

  • mercaptopurine — noun Etymology: mercaptan + o + purine Date: circa 1952 an antimetabolite C5H4N4S that interferes especially with the metabolism of purine bases and the biosynthesis of nucleic acids and that is sometimes used in the treatment of acute leukemia …   New Collegiate Dictionary

  • mercaptopurine — /meuhr kap toh pyoor een/, n. Pharm. a yellow, crystalline, water insoluble powder, C5H4N4S, used in the treatment of leukemia. [1950 55; MERCAPTO + PURINE] * * * …   Universalium

  • mercaptopurine — noun A particular oral drug used in the treatment of cancer …   Wiktionary

  • mercaptopurine — n. chemical substance which is used to treat leukemia (Pharmacology) …   English contemporary dictionary

  • mercaptopurine — mer·cap·to·purine …   English syllables

  • mercaptopurine — n. a drug that prevents the growth of cancer cells and is administered by mouth, chiefly in the treatment of some types of leukaemia (see antimetabolite). It commonly reduces the numbers of white blood cells; mouth ulcers and digestive upsets may …   The new mediacal dictionary