Table 1.

FDA Drug Label Dosage and Administration of Mercaptopurine (2020)

DeficiencyDosage and administration
Homozygous deficiency in either TPMT or NUDT15Individuals with homozygous deficiency of either enzyme typically require 10% or less of the standard mercaptopurine oral suspension dosage. Reduce initial dosage in individuals who are known to have homozygous TPMT or NUDT15 deficiency.
Heterozygous deficiency in TPMT and/or NUDT15Reduce the mercaptopurine oral suspension dosage based on tolerability. Most individuals with heterozygous TPMT or NUDT15 deficiency tolerate recommended mercaptopurine doses, but some require dose reduction based on toxicities. Individuals who are heterozygous for both TPMT and NUDT15 may require more substantial dosage reductions.

This FDA table is adapted from (1). TPMT, thiopurine S-methyltransferase; NUDT15, nudix hydrolase 15

From: Mercaptopurine Therapy and TPMT and NUDT15 Genotype

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