Thioguanine Tabloid

Name: Thioguanine Tabloid

Introduction

Antineoplastic agent; antimetabolite, synthetic purine antagonist.103 b

Interactions for Thioguanine Tabloid

Specific Drugs

Drug

Interaction

Comments

Allopurinol

Pharmacokinetic interactions not expected103

Dosage adjustments not required103

Aminosalicylates (e.g., olsalazine, mesalamine, sulfasalazine)

Potential pharmacokinetic interaction; increased risk of thioguanine myelotoxicity103 (see Hematologic Effects under Cautions)

Use concomitantly with caution103

Myelosuppressive agents

Possible additive myelosuppressive effects103

Reduced thioguanine dosage may be necessary with concomitant therapy103

Thioguanine Tabloid Pharmacokinetics

Absorption

Bioavailability

Absorption from GI tract is variable and incomplete; approximately 30% of an oral dose may be absorbed.103

Distribution

Extent

Incorporated into the DNA and RNA of bone marrow cells.103

Does not reach therapeutic concentrations in the CSF.103

Thioguanine crosses the placenta; not known whether distributed into milk.103

Elimination

Metabolism

Rapidly and extensively metabolized in the liver and other tissues, principally to the less toxic and less active methylated derivative 2-amino-6-methylthiopurine.103

Elimination Route

Excreted principally in urine as metabolites.103 b

Half-life

Biphasic; terminal half-life averages 11 hours.b

Stability

Storage

Oral

Tablets

15–25°C.103

Actions

  • Converted intracellularly to ribonucleotides that result in a sequential blockade of the synthesis and utilization of purine and guanine nucleotides.103 b

  • Thioguanine ribonucleotides incorporate into DNA and RNA; cytotoxic effects may be related primarily to substitution of ribonucleotides into DNA.103 b

  • Usually complete cross-resistance between thioguanine and mercaptopurine.103 b

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