The recommended mercaptopurine dosage will be customized for each person, depending on his or her weight, how well the medicine is tolerated, and a number of other factors. This prescription drug comes as a tablet that is taken once daily, usually in the evening and on an empty stomach. The tablets can also be made into a liquid for those who have problems swallowing the tablets.
The dose of mercaptopurine (Purinethol®) your healthcare provider recommends will vary, depending on a number of factors, such as:
- Your weight
- How you respond to and tolerate the medication
- Other medical conditions you may have
- Other medications you are taking.
As is always the case, do not adjust your dosage unless your healthcare provider specifically tells you to do so.
Doses of mercaptopurine are highly individualized, and can vary significantly from person to person. The usual recommended amount for maintenance treatment of acute lymphatic leukemia is 1.5 to 2.5 mg per kg body weight (0.68 to 1.14 mg per lb), rounded to the nearest 25 mg, taken once a day. Your healthcare provider will do frequent tests, such as blood cell counts or a bone marrow examination, and adjust your dosage based on the results of these tests.
Mercaptopurine treatment can sometimes cause high levels of uric acid, which may be treated with a medication known as allopurinol (Zyloprim®). People who are taking allopurinol will be treated with lower-than-normal mercaptopurine doses. Lower amounts may also be used in people with kidney or liver disease.
People who have a certain inherited (genetic) condition known as thiopurine-S-methyltransferase (TPMT) deficiency are at a higher risk for mercaptopurine side effects. These people will need to be treated with lower doses.