Table 1.

FDA Drug Label Dosage and Administration of Thioguanine (2020)

EnzymeDosage and administration
TPMT
  • Individuals with homozygous deficiency of either thiopurine S-methyl transferase (TPMT) or nucleotide diphosphatase (NUDT15) enzyme typically require 10% or less of the standard thioguanine dosage.
  • Reduce initial dosage in individuals who are known to have homozygous* TPMT or NUDT15 deficiency.
  • Most individuals with heterozygous TPMT or NUDT15 deficiency tolerate recommended thioguanine doses, but some require dose reduction based on toxicities.
  • Individuals who are heterozygous for both TPMT and NUDT15 deficiency may require more substantial dosage reductions.
  • Reduce the dosage based on tolerability.
NUDT15
*

This also applies to compound heterozygous TPMT or NUDT15 deficiency, as multiple no function alleles exist. See Tables 4 and 5.

This FDA table is adapted (1).

From: Thioguanine Therapy and TPMT and NUDT15 Genotype

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