How it is administered

Mercaptopurine is taken by mouth (orally). It is available as tablets (usually 50 mg) and as an oral suspension (liquid form, 20 mg/mL). The oral suspension should be shaken well before use, and dosing syringes are provided for accurate measurement. It is important to take mercaptopurine either consistently with or without food, as food can affect how much of the medicine your body absorbs.

How it works

Mercaptopurine is a type of chemotherapy medicine called a nucleoside metabolic inhibitor. It works by interfering with the growth of cancer cells, especially those that multiply quickly, like the abnormal lymphocytes in acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma.

Inside the body, mercaptopurine is converted into active compounds called thioguanine nucleotides (TGNs). These compounds get incorporated into the DNA and RNA of cells, which disrupts their normal function and leads to cell-cycle arrest and cell death. Mercaptopurine also blocks the production of new purines, which are building blocks needed for making DNA and RNA. By stopping these processes, mercaptopurine helps to control the growth of cancer cells.

Because it targets rapidly dividing cells, mercaptopurine can also affect healthy cells that divide quickly, such as those in the bone marrow, which is why monitoring is important during treatment.

Who Should take it

Mercaptopurine is used as part of a combination chemotherapy maintenance regimen for patients with acute lymphoblastic leukemia (ALL), which includes lymphoblastic lymphoma as a related disease. It is suitable for both adults and children and is an important part of long-term therapy to keep the disease in remission after initial treatment.

Your doctor may recommend mercaptopurine if you are in the maintenance phase of treatment for ALL or lymphoblastic lymphoma. It is often used together with other chemotherapy drugs to maximize its effectiveness. The dose and duration are tailored to each patient, depending on factors such as age, weight, kidney and liver function, and how well the body tolerates the medicine.

Who should not take it

There are no absolute contraindications listed for mercaptopurine, but certain patients should use it with caution or may need dose adjustments.

People with a genetic deficiency in the enzymes TPMT or NUDT15 may be at higher risk for severe side effects and may require much lower doses. Patients with significant liver or kidney impairment should start with the lowest recommended dose. Mercaptopurine should not be used during pregnancy unless absolutely necessary, as it can harm an unborn baby. Women who are breastfeeding should not use mercaptopurine, and both men and women of childbearing potential should use effective contraception during treatment and for a period after stopping the medication. Always inform your doctor of all your medical conditions before starting mercaptopurine.

Commonly used with

Mercaptopurine is most commonly used in combination with other chemotherapy drugs as part of a maintenance regimen for ALL and lymphoblastic lymphoma. Common partners include methotrexate, vincristine, corticosteroids (like prednisone or dexamethasone), and sometimes other agents depending on the specific protocol.

It may also be used with medications to help prevent or manage side effects, such as antibiotics for infection prevention or medications to control nausea.

Commonly tested with

Mercaptopurine is often studied and used in combination with methotrexate, as this combination is a standard part of maintenance therapy for ALL and related blood cancers. Clinical trials and treatment protocols frequently test various combinations and dosing schedules of these drugs to find the most effective and safest regimens for patients.

It is also tested with other chemotherapy agents and supportive care medications as part of multi-drug protocols for blood cancers.