Drug information of mercaptopurine


Drug group:

An antimetabolite antineoplastic agent with immunosuppressant properties. It interferes with nucleic acid synthesis by inhibiting purine metabolism and is used, usually in combination with other drugs, in the treatment of or in remission maintenance programs for leukemia .

Mechanism of effect

Analog of naturally occurring purines hypoxanthine and guanine Purine antagonist, antineoplastic


Mercaptopurine is one of a large series of purine analogues which interfere with nucleic acid biosynthesis and has been found active against human leukemias. It is an analogue of the purine bases adenine and hypoxanthine.
It is not known exactly which of any one or more of the biochemical effects of mercaptopurine and its metabolites are directly or predominantly responsible for cell death.


- Bioavailability: 5-37%
- Peak Plasma Time: 2 hr
- Onset: 2 hr
- Duration: variable
Distribution - Protein Bound: 19%
- Vd: 0.56-0.9 L/kg
- GI mucosa, liver
- Metabolites: 6-thiouric acid
- Half-Life: 21 minutes (children), 47 min (adult)
- Clearance: 11 mL/min/kg
- Excretion: urine


Acute Lymphatic Leukemia
Induction: 2.5 mg/kg PO qDay; usually 100-200 mg PO qDay in average adult (other agents preferred)
May increase by 5 mg/kg/day after 4 weeks
Maintenance: 1.5-2.5 mg/kg PO qDay
Reduce dose by 75% if concomitant allopurinol administration
Reduce dose in renal impairment
Crohn Disease (Off-label)
1-1.5 mg/kg PO qHS

Drug contraindications

hypersensitivity to this drug


• The drug should not be used unless a diagnosis of acute lymphatic leukemia has been adequately established , and the patient’s physician is knowledgeable in assessing response to chemotherapy .
• If you have a thiopurine methyltransferase deficiency, talk with your doctor.
• This medicine may add to the chance of getting some types of cancer. Talk with the doctor.
• A rare type of cancer called hepatosplenic T-cell lymphoma (HSTCL) has happened with this medicine. These cases have been deadly. Most of the time, these cases happened in teenagers or young adults.
Most of these patients were using this medicine (mercaptopurine tablets) to treat certain types of bowel problems like Crohn disease and ulcerative colitis. This medicine is not approved for use to treat bowel problems like these. Tell the doctor if you have ever had any type of cancer. Talk with the doctor.
• A very bad and sometimes life-threatening problem called Macrophage Activation Syndrome (MAS) may rarely happen in people with autoimmune diseases. Talk with the doctor.
• Low blood sugar has happened in people taking this medicine, especially children. Signs may be dizziness, headache, feeling sleepy, feeling weak, shaking, a fast heartbeat, confusion, hunger, or sweating. Call your doctor right away if you have any of these signs.

Points of recommendation

• Take on empty stomach to reduce risk of N/V
• Take this medicine at the same time of day.
• Drink lots of noncaffeine liquids unless told to drink less liquid by your doctor.
• If you have upset stomach, throwing up, loose stools (diarrhea), or are not hungry, talk with your doctor. There may be ways to lower these side effects.
• You may have more chance of getting an infection. Wash hands often. Stay away from people with infections, colds, or flu.
• You may bleed more easily. Be careful and avoid injury. Use a soft toothbrush and an electric razor.
• If you are taking warfarin, talk with your doctor. You may need to have your blood work checked more closely while you are taking it with this medicine.
• Talk with your doctor before getting any vaccines. Use with this medicine ( mercaptopurine tablets ) may either raise the chance of an infection or make the vaccine not work as well.
• You may get sunburned more easily. Avoid sun, sunlamps, and tanning beds. Use sunscreen and wear clothing and eyewear that protects you from the sun.
• Use birth control that you can trust to prevent pregnancy while taking this medicine ( mercaptopurine tablets ).

Pregnancy level


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