Severe acute Crohn’s disease | Maintenance of remission of
Crohn’s disease | Ulcerative colitis
▶BY MOUTH
▶Adult: 1–1.5 mg/kg daily, some patients may respond
to lower doses
Acute leukaemias | Chronic myeloid leukaemia
▶BY MOUTH USING TABLETS
▶Adult: Initially 2.5 mg/kg daily, adjusted according to
response, alternatively initially 50–75 mg/m2 daily,
adjusted according to response
▶BY MOUTH USING ORAL SUSPENSION
▶Adult: Initially 25–75 mg/m2 daily, adjusted according
to response
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DUE TO INTERACTIONS
▶Manufacturer advises reduce dose to one-quarter of
the usual dose with concurrent use of allopurinol.
DOSE EQUIVALENCE AND CONVERSION
▶Mercaptopurine tablets and Xaluprine ® oral
suspension are not bioequivalent, haematological
monitoring is advised when switching formulations.
l UNLICENSED USE Not licensed for use in severe ulcerative
colitis and Crohn’s disease.
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Absent thiopurine
methyltransferase activity
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Reduced thiopurine methyltransferase activity
CAUTIONS, FURTHER INFORMATION
▶Thiopurine methyltransferase The enzyme thiopurine
methyltransferase (TPMT) metabolises thiopurine drugs
(azathioprine, mercaptopurine, tioguanine); the risk of
myelosuppression is increased in patients with reduced
activity of the enzyme, particularly for the few individuals
in whom TPMT activity is undetectable. Patients with
absent TPMT activity should not receive thiopurine drugs;
those with reduced TPMT activity may be treated under
specialist supervision.
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Consider measuring
thiopurine methyltransferase (TPMT) activity before
starting mercaptopurine therapy.
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Flavours of
oral liquid formulations may include raspberry.
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