Mercaptopurine Accord: Uses, Dosage & Side Effects
A purine antimetabolite and immunosuppressant used primarily in the maintenance treatment of acute lymphoblastic leukemia (ALL) and for inflammatory bowel disease
Mercaptopurine Accord contains the active substance mercaptopurine (also known as 6-mercaptopurine or 6-MP), a purine antimetabolite that belongs to the thiopurine class of drugs. It is a cornerstone of maintenance chemotherapy in acute lymphoblastic leukemia (ALL), used worldwide in virtually all treatment protocols for both children and adults. Mercaptopurine works by interfering with DNA synthesis in rapidly dividing cells, thereby suppressing the growth of leukemic cells and modulating the immune system. It is also used off-label as an immunosuppressant for inflammatory bowel disease (IBD), autoimmune hepatitis, and other immune-mediated conditions. Mercaptopurine is listed on the WHO Model List of Essential Medicines and requires careful dose adjustment based on individual genetic factors, particularly TPMT and NUDT15 enzyme activity.
Quick Facts: Mercaptopurine Accord
Key Takeaways
- Mercaptopurine is a WHO Essential Medicine used as a critical component of ALL maintenance chemotherapy, significantly improving long-term survival rates in children and adults with leukemia.
- TPMT and NUDT15 genotyping is strongly recommended before starting treatment, as genetic variations in these enzymes dramatically affect drug metabolism and the risk of severe bone marrow suppression.
- Concurrent use with allopurinol requires a 75% dose reduction of mercaptopurine to prevent life-threatening myelotoxicity due to inhibition of xanthine oxidase.
- Regular blood count monitoring (weekly during dose titration, then at least monthly) is essential to detect myelosuppression early and adjust doses accordingly.
- Mercaptopurine should be taken on an empty stomach at a consistent time each day, preferably in the evening, to maximize absorption and therapeutic effect.
What Is Mercaptopurine Accord and What Is It Used For?
Mercaptopurine, commonly referred to as 6-mercaptopurine or 6-MP, is a purine analogue that was first synthesized in the 1950s by Gertrude Elion and George Hitchings, work that later earned them the Nobel Prize in Physiology or Medicine in 1988. It remains one of the most important drugs in pediatric oncology and is an indispensable component of maintenance therapy for acute lymphoblastic leukemia (ALL), the most common childhood cancer.
The drug works by mimicking the natural purines (adenine and guanine) that cells need to build DNA. Once inside the cell, mercaptopurine is converted into active metabolites called thioguanine nucleotides (TGNs), which become incorporated into the DNA of rapidly dividing cells. This incorporation causes DNA strand breaks, preventing the cells from dividing normally and ultimately leading to cell death. Additionally, one of its metabolites, methylated thioinosine monophosphate (MeTIMP), inhibits de novo purine synthesis, further starving cells of the building blocks they need to replicate.
In the treatment of ALL, mercaptopurine is typically used during the maintenance phase, which follows the initial intensive chemotherapy. This maintenance phase usually lasts for 2 to 3 years and is crucial for preventing relapse. Mercaptopurine is taken daily as a tablet, usually in combination with weekly methotrexate, and this regimen has been shown in numerous randomized controlled trials to significantly reduce the risk of leukemia recurrence and improve long-term disease-free survival.
Beyond its role in oncology, mercaptopurine has established off-label uses as an immunosuppressant. Its ability to suppress the proliferation of activated lymphocytes makes it effective in the management of inflammatory bowel disease (both Crohn's disease and ulcerative colitis), autoimmune hepatitis, and various other immune-mediated conditions. In these contexts, it is used as a steroid-sparing agent, allowing patients to reduce or discontinue corticosteroids while maintaining disease remission.
Mercaptopurine is on the WHO Model List of Essential Medicines, underscoring its critical importance in global healthcare. Mercaptopurine Accord is a generic formulation that provides the same active ingredient and therapeutic effects as the original branded products, making this vital medication more widely accessible.
Mechanism of Action
After oral administration, mercaptopurine is absorbed from the gastrointestinal tract and enters cells where it undergoes complex metabolic activation. The enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) converts mercaptopurine to thioinosine monophosphate (TIMP), which is then further metabolized along two major pathways. One pathway produces the active thioguanine nucleotides (TGNs), which are incorporated into DNA and RNA, causing cytotoxicity. The other pathway, catalyzed by thiopurine methyltransferase (TPMT), produces methylated metabolites including MeTIMP, which inhibits purine synthesis. A third pathway involving xanthine oxidase (XO) produces inactive metabolites (thiouric acid) and represents the major route of drug inactivation.
The balance between these pathways is critically influenced by individual genetic variation, particularly polymorphisms in the TPMT and NUDT15 genes. Patients with reduced activity of these enzymes accumulate higher levels of active cytotoxic metabolites, placing them at significantly increased risk of severe myelosuppression. This pharmacogenomic variability is one of the most well-characterized examples in clinical medicine and forms the basis for pre-treatment genetic testing recommendations.
What Should You Know Before Taking Mercaptopurine Accord?
Mercaptopurine is a potent medication that requires careful medical oversight before, during, and after treatment. Several important factors must be evaluated before starting therapy to ensure safety and optimize outcomes. Your prescribing physician, typically a hematologist, oncologist, or gastroenterologist, will conduct a thorough assessment before initiating treatment.
Contraindications
Mercaptopurine must not be used in certain situations. You should not take this medication if you have a known hypersensitivity (allergy) to mercaptopurine or any of the excipients in the tablet formulation. Live vaccines, including but not limited to yellow fever vaccine, measles-mumps-rubella (MMR), varicella, BCG, and oral polio vaccine, must not be administered during treatment with mercaptopurine, as the immunosuppressive effects of the drug can lead to severe, potentially fatal infections from live vaccine organisms.
Concurrent use with febuxostat (a xanthine oxidase inhibitor used for gout) is contraindicated because, like allopurinol, it dramatically increases mercaptopurine exposure and the risk of severe toxicity. If you are currently taking febuxostat, your doctor will need to consider alternative treatments for either condition.
Warnings and Precautions
Bone marrow suppression (myelosuppression) is the most important toxicity of mercaptopurine. It can manifest as leucopenia (low white blood cells), thrombocytopenia (low platelets), anemia, or pancytopenia (reduction of all blood cell types). This toxicity is dose-dependent and is more likely to occur in patients with TPMT or NUDT15 deficiency, when combined with other myelosuppressive drugs, or when allopurinol is co-administered without appropriate dose reduction. Regular monitoring of complete blood counts is mandatory throughout treatment.
Hepatotoxicity is another significant concern with mercaptopurine therapy. Liver damage can range from asymptomatic elevations of liver enzymes to more serious conditions including cholestatic jaundice, hepatic necrosis, and veno-occlusive disease (sinusoidal obstruction syndrome). Liver function tests should be monitored regularly, and the drug should be discontinued if jaundice develops. The risk of hepatotoxicity may be increased when mercaptopurine is used at doses exceeding 2.5 mg/kg/day or in combination with other hepatotoxic agents.
There is a recognized increased risk of secondary malignancies, particularly hepatosplenic T-cell lymphoma, with thiopurine use, especially when combined with anti-TNF agents in patients with inflammatory bowel disease. Patients and their physicians should be aware of this risk and remain vigilant for signs and symptoms of lymphoma. Additionally, the risk of non-melanoma skin cancer is increased, and patients should be advised to use sun protection measures and undergo regular dermatological examinations.
Mercaptopurine causes immunosuppression, making patients more susceptible to bacterial, viral, fungal, and parasitic infections. Patients should be advised to avoid contact with individuals who have chickenpox or shingles if they have not previously had these infections or been vaccinated. Any signs of infection should be reported to the treating physician promptly.
Pregnancy and Breastfeeding
Animal studies have demonstrated teratogenic effects of mercaptopurine, and human case reports have documented both normal births and birth defects in offspring exposed during pregnancy. The decision to use mercaptopurine during pregnancy must be made on a case-by-case basis, carefully weighing the risks to the fetus against the potential consequences of untreated disease in the mother. In situations where leukemia treatment is essential, the oncology team will discuss the risks and benefits in detail.
There is limited evidence regarding the concentration of mercaptopurine and its metabolites in breast milk. Given the potential for serious adverse effects in the nursing infant, breastfeeding is generally not recommended during mercaptopurine treatment. If breastfeeding is being considered, the decision should be made in consultation with the treating physician, taking into account the importance of the drug to the mother.
Male patients should be aware that mercaptopurine may affect sperm quality and quantity. Men who wish to father children should discuss fertility preservation options (such as sperm banking) with their doctor before starting treatment. Both male and female patients should use reliable contraception during treatment and for at least 3 months after discontinuation.
How Does Mercaptopurine Accord Interact with Other Drugs?
Mercaptopurine is metabolized by several enzyme systems, making it susceptible to numerous drug interactions that can either increase toxicity or reduce efficacy. Understanding these interactions is essential for safe prescribing and for patients to communicate all their medications to their healthcare providers. Some interactions are so severe that they can be life-threatening if not properly managed.
Major Interactions
| Drug/Class | Interaction | Clinical Effect | Management |
|---|---|---|---|
| Allopurinol | Inhibits xanthine oxidase, reducing mercaptopurine metabolism | 4-5 fold increase in mercaptopurine levels; severe myelosuppression | Reduce mercaptopurine dose to 25% of standard; frequent blood counts |
| Febuxostat | Xanthine oxidase inhibitor | Marked increase in mercaptopurine levels; severe toxicity | Contraindicated; use alternative urate-lowering therapy |
| Aminosalicylates (mesalazine, olsalazine, sulfasalazine) | Inhibit TPMT enzyme in vitro | Potential increase in myelotoxicity | Use with caution; monitor blood counts more frequently |
| Warfarin | Mercaptopurine may reduce anticoagulant effect | Reduced INR; increased thrombotic risk | Monitor INR closely; adjust warfarin dose as needed |
| Methotrexate | Inhibits first-pass metabolism of mercaptopurine; synergistic myelosuppression | Increased mercaptopurine bioavailability and combined bone marrow toxicity | Used therapeutically in ALL protocols; doses are adjusted accordingly |
| Azathioprine | Azathioprine is a prodrug of mercaptopurine | Combined use leads to additive/excessive thiopurine exposure | Do not use concurrently; duplicative therapy |
| Live vaccines | Immunosuppression from mercaptopurine | Risk of disseminated infection from live vaccine organisms | Contraindicated during treatment; use inactivated vaccines where possible |
| Other myelosuppressive drugs | Additive bone marrow suppression | Increased risk of pancytopenia | Monitor blood counts frequently; adjust doses as needed |
Minor Interactions
Ribavirin, used in the treatment of hepatitis C, may inhibit the enzyme inosine monophosphate dehydrogenase (IMPDH), which is involved in the metabolic pathway of mercaptopurine. This can potentially reduce the formation of active thioguanine nucleotides, decreasing the efficacy of mercaptopurine. If concurrent use is necessary, closer therapeutic drug monitoring and clinical assessment are recommended.
Food can affect the absorption of mercaptopurine, particularly milk and dairy products which may reduce bioavailability. It is generally recommended to take mercaptopurine on an empty stomach (at least 1 hour before or 2 hours after food) to ensure consistent absorption. Taking the medication at the same time each day, preferably in the evening before bed, helps maintain steady drug levels.
Patients should be advised to inform all their healthcare providers, including dentists and emergency physicians, that they are taking mercaptopurine. They should also avoid starting any new medications, including over-the-counter products and herbal supplements, without first consulting their prescribing physician, as unexpected interactions may occur.
What Is the Correct Dosage of Mercaptopurine Accord?
Mercaptopurine dosing is highly individualized and depends on the specific indication, treatment protocol, patient body weight or body surface area, genetic enzyme status, concurrent medications, and the patient's response as assessed by regular blood counts. The following are general guidelines; your doctor will determine the exact dose for your specific situation.
Adults
Acute Lymphoblastic Leukemia (ALL) - Maintenance
The standard oral dose for maintenance therapy is 1.5 to 2.5 mg/kg body weight per day (approximately 50-75 mg/m²/day), usually taken as a single daily dose. Most adult protocols use a starting dose around 60-75 mg/m²/day, with adjustments based on white blood cell counts and the target neutrophil range specified by the treatment protocol. The maintenance phase typically lasts 2 to 3 years from diagnosis.
Inflammatory Bowel Disease (Off-label)
When used for Crohn's disease or ulcerative colitis, the typical target dose is 1.0 to 1.5 mg/kg/day. Treatment is usually started at a lower dose and gradually increased over several weeks while monitoring blood counts and liver function. Therapeutic effect in IBD may take 3 to 6 months to become apparent, so this medication should not be used for acute flares but rather for long-term maintenance of remission.
Children
Acute Lymphoblastic Leukemia (ALL) - Maintenance
Pediatric dosing follows the same weight-based or body-surface-area-based approach as adults: 1.5 to 2.5 mg/kg/day or approximately 50-75 mg/m²/day. The treating pediatric oncologist will specify the exact dose according to the particular treatment protocol being used (e.g., UKALL, COG, BFM, or NOPHO protocols). Dose adjustments are made frequently based on regular blood count monitoring, aiming to keep the white blood cell count and absolute neutrophil count within a specified target range.
Dose Adjustments for TPMT/NUDT15 Status
| Genotype Status | Enzyme Activity | Recommended Starting Dose |
|---|---|---|
| Normal/Normal (homozygous wild-type) | Normal (high) activity | Full standard dose |
| Heterozygous (one variant allele) | Intermediate activity | Start at 30-70% of standard dose; titrate based on tolerance |
| Homozygous variant (two variant alleles) | Low or absent activity | Start at approximately 10% of standard dose; consider 3 times weekly dosing |
Elderly
No specific dose adjustments are recommended solely based on age. However, elderly patients may have reduced renal and hepatic function, and they are more likely to be taking other medications that could interact with mercaptopurine. A more cautious approach to dosing, with careful monitoring of blood counts and organ function, is generally advisable in older adults. Starting at the lower end of the dose range and titrating upward based on tolerance is a prudent approach.
Renal and Hepatic Impairment
In patients with significant renal impairment, dose reduction should be considered, as the clearance of mercaptopurine metabolites may be reduced. Similarly, patients with pre-existing liver disease should be started on lower doses with close monitoring of liver function tests. If significant hepatotoxicity develops during treatment (rising bilirubin, transaminases, or clinical jaundice), mercaptopurine should be temporarily withheld and restarted at a lower dose only after liver function has recovered, if clinically appropriate.
Missed Dose
If you miss a dose, take it as soon as you remember on the same day. If it is nearly time for your next dose, skip the missed dose and continue with your usual schedule. Do not take a double dose to make up for a missed one. If you regularly forget doses, consider setting a daily alarm or using a pill organizer. Consistent daily dosing is important for maintaining therapeutic drug levels, particularly in leukemia maintenance therapy where gaps in treatment may increase the risk of relapse.
Overdose
Symptoms of overdose may be delayed and initially not apparent. The primary concern is severe myelosuppression (bone marrow failure) leading to dangerously low blood counts, which typically manifests 1-2 weeks after the overdose. Early symptoms may include nausea, vomiting, and diarrhea, followed later by infections (due to low white blood cells), bleeding or easy bruising (due to low platelets), and severe fatigue (due to anemia). Gastrointestinal toxicity, including mucositis and liver damage, may also occur.
Management of overdose involves gastric decontamination if the patient presents early (within 1-2 hours of ingestion), followed by intensive supportive care including regular full blood count monitoring for at least 4 weeks. Blood and platelet transfusions, granulocyte colony-stimulating factor (G-CSF), and broad-spectrum antibiotics may be required. The patient should be managed in a specialist unit with experience in handling chemotherapy-related toxicity.
What Are the Side Effects of Mercaptopurine Accord?
Like all chemotherapy and immunosuppressive agents, mercaptopurine can cause side effects. The frequency and severity of side effects vary considerably between individuals, largely due to genetic differences in drug metabolism. Not everyone will experience all or any of these side effects, and your medical team will monitor you closely to detect and manage any problems early. Always report new or worsening symptoms to your healthcare provider promptly.
Very Common (affects more than 1 in 10 patients)
- Myelosuppression (bone marrow suppression) – leucopenia, neutropenia, thrombocytopenia, anemia
- Nausea and loss of appetite
- Increased susceptibility to infections
Common (affects 1 in 10 to 1 in 100 patients)
- Liver enzyme elevations (raised transaminases, alkaline phosphatase)
- Stomatitis (mouth ulcers)
- Diarrhea
- Vomiting
- Rash
- Hyperbilirubinemia (elevated bilirubin)
- Joint pain (arthralgia)
Uncommon (affects 1 in 100 to 1 in 1,000 patients)
- Cholestatic jaundice (yellowing of skin/eyes due to bile duct problems)
- Pancreatitis (inflammation of the pancreas) – presents as severe abdominal pain
- Alopecia (hair thinning or loss)
- Fever (drug-related)
- Oral ulceration
Rare (affects fewer than 1 in 1,000 patients)
- Hepatic necrosis (severe liver damage)
- Veno-occlusive disease / sinusoidal obstruction syndrome (VOD/SOS)
- Intestinal ulceration
- Hepatosplenic T-cell lymphoma (particularly with concurrent anti-TNF therapy)
- Non-melanoma skin cancer (squamous cell and basal cell carcinoma)
- Acute myeloid leukemia / myelodysplastic syndrome (secondary malignancy)
- Severe allergic reactions (including anaphylaxis)
- Oligospermia (reduced sperm count)
- Photosensitivity
Not Known (frequency cannot be estimated)
- Macrophage activation syndrome (MAS)
- Progressive multifocal leukoencephalopathy (PML) in immunosuppressed patients
When to Seek Immediate Medical Attention
Contact your doctor or go to the nearest emergency department immediately if you experience any of the following while taking mercaptopurine:
- Signs of infection: unexplained fever (temperature above 38°C / 100.4°F), chills, sore throat, cough, or painful urination – these may indicate that your white blood cell count is dangerously low
- Unusual bleeding or bruising: bleeding gums, nosebleeds, blood in urine or stool, or unexplained bruising – these may indicate low platelet counts
- Yellowing of the skin or whites of the eyes (jaundice): this may indicate liver damage
- Severe abdominal pain: especially if radiating to the back, which may indicate pancreatitis
- Severe fatigue, pale skin, shortness of breath: these may indicate significant anemia
- Allergic reaction signs: skin rash, swelling of face or throat, difficulty breathing
The risk of myelosuppression is highest during the first few weeks of treatment and after any dose increase. Your medical team will schedule regular blood tests to monitor your blood counts, particularly during these higher-risk periods. It is essential that you attend all scheduled blood tests and medical appointments, even if you are feeling well, as significant blood count changes can occur without symptoms initially.
How Should You Store Mercaptopurine Accord?
Proper storage of mercaptopurine is important to ensure the medication remains effective and safe throughout its shelf life. As a cytotoxic medication, special care should be taken in its handling and disposal.
Store the tablets at room temperature, generally below 25°C (77°F). Keep them in the original blister pack or container to protect from light and moisture. Do not store mercaptopurine in the bathroom or other humid environments, as moisture can degrade the medication. Keep the container tightly closed when not in use.
Because mercaptopurine is a cytotoxic (chemotherapy) drug, it should be handled with care. Tablets should not be crushed or split unless specifically instructed by your pharmacist or doctor, as this can release powder that may be harmful if inhaled or if it contacts the skin. If handling broken tablets is necessary, use gloves and wash hands thoroughly afterward. Pregnant women and those planning pregnancy should avoid handling the tablets altogether.
Do not use this medication after the expiry date printed on the packaging. Unused or expired mercaptopurine should not be disposed of via household waste or flushed down the toilet. Return unused medication to your pharmacy for safe disposal according to local regulations for cytotoxic waste. This is important both for environmental protection and to prevent accidental exposure.
As with all medications, keep mercaptopurine out of the reach and sight of children. Given the serious nature of this medication, accidental ingestion by a child could have severe consequences and would require immediate emergency medical attention.
What Does Mercaptopurine Accord Contain?
Understanding the composition of your medication is important, particularly if you have known allergies or intolerances to any pharmaceutical ingredients. Below is a detailed breakdown of the components in Mercaptopurine Accord tablets.
Active Ingredient
Each tablet contains 50 mg of mercaptopurine (as mercaptopurine monohydrate). Mercaptopurine monohydrate is the form used in the manufacturing process, and the 50 mg refers to the amount of active mercaptopurine base. The chemical name is 6-mercaptopurine monohydrate (also known as 3,7-dihydropurine-6-thione monohydrate), with the molecular formula C₅H₄N₄S·H₂O and a molecular weight of 170.19 g/mol.
Inactive Ingredients (Excipients)
The tablet also contains the following inactive ingredients, which are used to aid in the manufacturing process, maintain tablet stability, and facilitate disintegration and absorption:
- Lactose monohydrate – a common tablet filler (diluent). Patients with lactose intolerance should note this ingredient, although the amount is small
- Maize starch (corn starch) – used as a binder and disintegrant to help the tablet break apart in the stomach
- Maize starch, pregelatinized – a modified form of corn starch used as a binder
- Stearic acid – a lubricant used in tablet manufacturing
- Magnesium stearate – a lubricant that prevents the tablet from sticking to the manufacturing equipment
Appearance
Mercaptopurine Accord 50 mg tablets are typically white to off-white, round, flat-faced tablets that may be scored (have a line across one face) to facilitate dose splitting if required. The exact appearance may vary slightly between batches but should always match the description in the patient information leaflet provided with your medication. If the tablets look different from usual, consult your pharmacist before taking them.
Frequently Asked Questions About Mercaptopurine Accord
Mercaptopurine Accord is primarily used in the maintenance treatment of acute lymphoblastic leukemia (ALL), the most common childhood cancer. It is taken daily as a tablet, typically for 2-3 years, alongside weekly methotrexate as part of a maintenance chemotherapy regimen. It is also used off-label as an immunosuppressant for inflammatory bowel disease (Crohn's disease and ulcerative colitis), autoimmune hepatitis, and certain other immune-mediated conditions where its ability to suppress the immune system helps control disease activity.
Thiopurine S-methyltransferase (TPMT) is one of the key enzymes that metabolizes mercaptopurine. Approximately 10% of the population has reduced TPMT activity (heterozygous) and about 0.3% have very low or absent activity (homozygous variant). Patients with reduced TPMT activity accumulate higher levels of the active cytotoxic metabolites (thioguanine nucleotides), placing them at dramatically increased risk of severe, potentially fatal bone marrow suppression. TPMT genotyping or phenotyping before starting treatment allows the doctor to prescribe an appropriate starting dose, significantly reducing the risk of this serious toxicity. Similar testing is also recommended for the NUDT15 enzyme, particularly in patients of East Asian or Hispanic descent.
Mercaptopurine should not be taken at its standard dose alongside allopurinol. Allopurinol inhibits xanthine oxidase, one of the main enzymes that breaks down mercaptopurine. This dramatically increases mercaptopurine blood levels (up to 4-5 times higher) and can lead to life-threatening bone marrow suppression. If allopurinol is medically necessary, the mercaptopurine dose must be reduced to approximately 25% (one-quarter) of the usual dose, with very close and frequent monitoring of complete blood counts. Febuxostat, another xanthine oxidase inhibitor, is contraindicated entirely with mercaptopurine.
Regular blood monitoring is essential during mercaptopurine treatment. A complete blood count (CBC/FBC) should be checked at least weekly during the initial weeks of treatment and during dose adjustments, then at least every 1-2 months once a stable dose is established. Liver function tests (LFTs), including transaminases and bilirubin, should be monitored every 1-3 months. In leukemia treatment, thioguanine nucleotide (TGN) levels may also be measured to assess whether the drug is being metabolized appropriately and to optimize dosing. Your doctor may increase the frequency of monitoring if you have TPMT or NUDT15 deficiency, if interacting medications are introduced, or if blood counts show significant changes.
Mercaptopurine is classified as teratogenic (capable of causing birth defects) based on animal studies and limited human data. It should generally be avoided during pregnancy, particularly during the first trimester when organ development occurs. However, in life-threatening situations such as active leukemia, the risks of not treating the cancer may outweigh the risks to the fetus, and the decision is made on a case-by-case basis by the oncology team. Both women and men should use effective contraception during treatment and for at least 3 months after stopping the medication. Breastfeeding is not recommended during mercaptopurine therapy. Men who wish to have children in the future should discuss sperm banking before starting treatment.
If you miss a dose, take it as soon as you remember on the same day. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Never take a double dose to compensate. Consistent daily dosing is particularly important in leukemia maintenance therapy, where gaps in treatment can increase the risk of relapse. If you frequently miss doses, talk to your doctor about strategies to improve adherence, such as setting a daily alarm, using a pill box, or incorporating the dose into a fixed daily routine.
References & Medical Sources
- European Medicines Agency (EMA). Mercaptopurine Summary of Product Characteristics (SmPC). Last updated 2025.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd List, 2023. Geneva: WHO; 2023.
- National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Acute Lymphoblastic Leukemia. Version 2.2025.
- British National Formulary (BNF). Mercaptopurine Monograph. BMJ Group and Pharmaceutical Press; 2025.
- U.S. Food and Drug Administration (FDA). Purinethol (mercaptopurine) Prescribing Information. Revised 2024.
- Relling MV, Schwab M, Whirl-Carrillo M, et al. Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for Thiopurine Dosing Based on TPMT and NUDT15 Genotypes: 2018 Update. Clin Pharmacol Ther. 2019;105(5):1095-1105.
- Schmiegelow K, Nielsen SN, Frandsen TL, Nersting J. Mercaptopurine/Methotrexate maintenance therapy of childhood acute lymphoblastic leukemia: clinical facts and fiction. J Pediatr Hematol Oncol. 2014;36(7):503-517.
- Lamb CA, Kennedy NA, Raine T, et al. British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults. Gut. 2019;68(Suppl 3):s1-s106.
- Lennard L. The clinical pharmacology of 6-mercaptopurine. Eur J Clin Pharmacol. 1992;43(4):329-339.
- GRADE Working Group. Grading quality of evidence and strength of recommendations. BMJ. 2004;328(7454):1490.
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