pharmacopeia
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/api/v1/drug/mercaptopurine

Mechanism of action

Sourced from openFDA

Mercaptopurine is a purine analog that undergoes intracellular transport and activation to form metabolites including thioguanine nucleotides (TGNs). Incorporation of TGNs into DNA or RNA results in cell-cycle arrest and cell death.

Nucleic Acid Synthesis

Indications

Sourced from openFDA
  • Mercaptopurine is a nucleoside metabolic inhibitor indicated for the treatment of patients with acute lymphoblastic leukemia (ALL) as part of a combination chemotherapy maintenance regimen. ( 1.1 ) 1.1 Acute Lymphoblastic Leukemia Mercaptopurine is indicated for the treatment of patients with acute lymphoblastic leukemia (ALL) as part of a combination chemotherapy maintenance regimen.ICD-10: C95.90

Contraindications

Sourced from openFDA
  • None.contraindicated

Dosage & administration

Sourced from openFDA

• The recommended starting dosage of mercaptopurine oral suspension is 1.5 mg/kg to 2.5 mg/kg (50 mg/m 2 to 75 mg/m 2 ) orally once daily as part of a combination chemotherapy maintenance regimen. Adjust dose to maintain desirable absolute neutrophil count and for excessive myelosuppression. ( 2.1 ) • Renal Impairment : Use the lowest recommended starting dose or increase the dosing interval. ( 2.3 , 8.6 ) • Hepatic Impairment : Use the lowest recommended starting dose. ( 2.3 , 8.7 ) 2.1 Recommended Dosage The recommended starting dose of mercaptopurine oral suspension is 1.5 mg/kg to 2.5 mg/kg (50 mg/m 2 to 75 mg/m 2 ) orally once daily as part of combination chemotherapy maintenance regimen. Take mercaptopurine oral suspension either consistently with or without food. After initiating mercaptopurine, monitor complete blood counts (CBC) and adjust the dose to maintain absolute neutrophil count (ANC) at a desirable level and for excessive myelosuppression. Evaluate the bone marrow in patients with prolonged myelosuppression or repeated episodes of myelosuppression to assess leukemia status and marrow cellularity. Evaluate thiopurine S-methyltransferase (TPMT) and nucleotide diphosphatase (NUDT15) status in patients with severe myelosuppression or repeated episodes of myelosuppression [see Dosage and Administration ( 2.2 )] . If a patient misses a dose, instruct the patient to continue with the next scheduled dose.

Warnings & precautions

Sourced from openFDA

• Myelosuppression : Monitor complete blood count (CBC) and adjust the dose of mercaptopurine for excessive myelosuppression. Consider testing in patients with severe myelosuppression or repeated episodes of myelosuppression for thiopurine S-methyltransferase (TPMT) or nucleotide diphosphatase (NUDT15) deficiency. Patients with homozygous-TPMT or homozygous-NUDT15 deficiency may require a dose reduction. ( 2.2 , 5.1 ) • Hepatotoxicity : Monitor transaminases, alkaline phosphatase and bilirubin. Withhold mercaptopurine at onset of hepatotoxicity. ( 5.2 ) • Immunosuppression : Response to all vaccines may be diminished and there is a risk of infection with live virus vaccines. Consult immunization guidelines for immunocompromised pediatrics. ( 5.3 ) • Treatment Related Malignancies : Aggressive and fatal cases of hepatosplenic T-cell lymphoma have occurred. ( 5.4 ) • Macrophage Activation Syndrome : Monitor for and treat promptly; discontinue mercaptopurine. ( 5.5 ) • Embryo-Fetal Toxicity : Can cause fetal harm. Advise patients of reproductive potential of the potential risk to a fetus and to use effective contraception. ( 5.6 , 8.1 , 8.3 ) • Phenylketonuria : Patients should be informed that mercaptopurine oral suspension contains phenylalanine, a component of aspartame. Each mL of the 20 mg/mL oral suspension contains 0.015 mg of phenylalanine. ( 5.7 ) 5.1 Myelosuppression The most consistent, dose-related adverse reaction of mercaptopurine is myelosuppression, manifested by anemia, leukopenia, thrombocytopenia, or any combination of these.

Adverse reactions

Sourced from openFDA

The following clinically significant adverse reactions are described elsewhere in the labeling: • Myelosuppression [see Warnings and Precautions ( 5.1 )] • Hepatotoxicity [see Warnings and Precautions ( 5.2 )] • Immunosuppression [see Warnings and Precautions ( 5.3 )] • Treatment Related Malignancies [see Warnings and Precautions ( 5.4 )] • Macrophage Activation Syndrome [see Warnings and Precautions ( 5.5 )] The most common adverse reaction (>20%) is myelosuppression, including anemia, neutropenia, lymphopenia and thrombocytopenia. Adverse reactions occurring in 5% to 20% of patients include anorexia, nausea, vomiting, diarrhea, malaise and rash. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Hikma Pharmaceuticals USA Inc. at 1-800-962-8364 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Based on multicenter cooperative group ALL trials, the most common adverse reaction occurring in > 20% of patients was myelosuppression, including anemia, neutropenia, lymphopenia and thrombocytopenia. Adverse reactions occurring in 5% to 20% of patients included anorexia, nausea, vomiting, diarrhea, malaise, and rash.

Use in specific populations

Sourced from openFDA

• Lactation : Advise not to breastfeed. ( 8.2 ) • Infertility : Can impair fertility. ( 8.3 ) 8.1 Pregnancy Risk Summary Mercaptopurine can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology ( 12.1 )] . Pregnant women who receive mercaptopurine have an increased incidence of miscarriage and stillbirth (see Data ) . Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population(s) is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Human Data Women receiving mercaptopurine in the first trimester of pregnancy have an increased incidence of miscarriage; the risk of malformation in offspring surviving first trimester exposure is not known. In a series of 28 women receiving mercaptopurine after the first trimester of pregnancy, 3 mothers died prior to delivery, 1 delivered a stillborn child, and 1 aborted; there were no cases of macroscopically abnormal fetuses. Animal Data Mercaptopurine was embryo-lethal and teratogenic in several animal species (rat, mouse, rabbit, and hamster) at doses less than the recommended human dose.

Pharmacokinetics

Sourced from openFDA
Metabolism
Following a single oral dose of mercaptopurine 50 mg under fasted conditions to adult healthy subjects, the median (min – max) AUC 0-INF was 137 h∙ng/mL (77 – 268 h∙ng/mL) and C max was 93 ng/mL (40 – 204 ng/mL). Absorption Mercaptopurine is absorbed after oral administration with a median (min – max) T max of 0.75 (0.33 – 2.5) hours.

Overdosage

Sourced from openFDA

Signs and symptoms of mercaptopurine overdosage may be immediate (anorexia, nausea, vomiting, and diarrhea) or delayed (myelosuppression, liver dysfunction, and gastroenteritis). Dialysis cannot be expected to clear mercaptopurine. Hemodialysis is thought to be of marginal use due to the rapid intracellular incorporation of mercaptopurine into active metabolites with long persistence. Withhold mercaptopurine immediately if severe or life-threatening adverse reactions occur during treatment. If a patient is seen immediately following an accidental overdosage, it may be useful to induce emesis.

Approval history

Sourced from openFDA
  • Sep 11, 1953NDANDA009053Stason Pharms
  • Feb 13, 2004ANDAANDA040528Hikma
  • Apr 28, 2014NDANDA205919Nova Labs Ltd
  • Feb 26, 2025ANDAANDA216418Hikma

FAERS reports

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Reference statistics only. FAERS reports are voluntarily submitted and are not incidence rates, safety signals, or causal evidence. Counts reflect reporting volume — how often a reaction was reported, not how often it occurs. For decision-grade use, consult openFDA and the FAERS Public Dashboard directly.
17,055 total reports matchedLatest report Share = reports listing the reaction ÷ total matched reports. Rows can sum to >100% because a single report often lists multiple reactions.
  1. 1Febrile Neutropenia1,87711%
  2. 2Pyrexia1,1836.9%
  3. 3Off Label Use1,1196.6%
  4. 4Drug Ineffective1,0956.4%
  5. 5Nausea7834.6%
  6. 6Vomiting7424.4%
  7. 7Diarrhoea6884.0%
  8. 8Abdominal Pain6834.0%
  9. 9Headache5963.5%
  10. 10Neutropenia5923.5%
  11. 11Fatigue5493.2%
  12. 12Pneumonia5153.0%
  13. 13Crohn^s Disease5103.0%
  14. 14Sepsis4902.9%
  15. 15Anaemia4672.7%

Literature

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Recent PubMed references pinned to Mercaptopurine as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

Clinical trials

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The 10 most recently updated of 437 ClinicalTrials.gov registrations naming Mercaptopurine as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

Pharmacogenomics

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CPIC-curated drug–gene pairs for Mercaptopurine. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

Frequently asked questions

How does Mercaptopurine work?
Mercaptopurine is a purine analog that undergoes intracellular transport and activation to form metabolites including thioguanine nucleotides (TGNs). Incorporation of TGNs into DNA or RNA results in cell-cycle arrest and cell death.
What is Mercaptopurine used for?
According to FDA labeling, Mercaptopurine carries indications including: Mercaptopurine is a nucleoside metabolic inhibitor indicated for the treatment of patients with acute lymphoblastic leukemia (ALL) as part of a combination chemotherapy maintenance regimen. ( 1.1 ) 1.1 Acute Lymphoblastic Leukemia Mercaptopurine is indicated for the treatment of patients with acute lymphoblastic leukemia (ALL) as part of a combination chemotherapy maintenance regimen.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
What class of drug is Mercaptopurine?
Mercaptopurine is classified as Purine analogues, Nucleic Acid Synthesis Inhibitors, Decreased DNA Integrity, Decreased RNA Integrity, Increased Cellular Death.
What are the brand names for Mercaptopurine?
Mercaptopurine is marketed under brand names including Purixan.
What are the contraindications for Mercaptopurine?
Mercaptopurine labeling lists contraindications including: None.. Always consult the full prescribing information and a clinician.
Note. Data for mercaptopurine is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.

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