Olsalazine and 6-mercaptopurine-related bone marrow suppression: a possible drug-drug interaction.

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Lewis LD, Benin A, Szumlanski CL, Otterness DM, Lennard L, Weinshilboum RM, Nierenberg DW

Olsalazine and 6-mercaptopurine-related bone marrow suppression: a possible drug-drug interaction.

Clin Pharmacol Ther. 1997 Oct;62(4):464-75.

PubMed ID

9357398 [ View in PubMed

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Abstract

A patient with refractory Crohn's disease had two separate episodes of bone marrow suppression while receiving 50 to 75 mg 6-mercaptopurine a day and 1000 to 1750 mg olsalazine a day. This adverse reaction necessitated dose reduction of 6-mercaptopurine on the first occasion and withdrawal of 6-mercaptopurine and olsalazine on the second occasion. The patient's red blood cell thiopurine methyltransferase (TPMT) activity was 1.2 U per milliliter red blood cells (low normal range) and her TPMT genotype was wild-type sequence for all known alleles of TPMT that result in low TPMT enzyme activity. In vitro enzyme kinetic studies confirmed the hypothesis that olsalazine and olsalazine-O-sulfate are potent noncompetitive inhibitors of recombinant human TPMT. We suggest that the patient's relatively low baseline level of TPMT activity was inhibited by olsalazine and olsalazine-O-sulfate, leading to decreased clearance of 6-mercaptopurine and its accumulation. This ultimately increased intracellular 6-thiopurine nucleotide levels to toxic concentrations, which caused bone marrow suppression.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Olsalazine	Thiopurine S-methyltransferase	Protein	Humans	Yes	Inhibitor	Details