pharmacopeia
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/api/v1/drug/thioguanine

Mechanism of action

Sourced from openFDA

Mechanism-of-action class: Nucleic Acid Synthesis Inhibitors.

Nucleic Acid Synthesis

Indications

Sourced from openFDA
  • a) Acute Nonlymphocytic Leukemias TABLOID brand Thioguanine is indicated for remission induction and remission consolidation treatment of acute nonlymphocytic leukemias. However, it is not recommended for use during maintenance therapy or similar long-term continuous treatments due to the high risk of liver toxicity (see WARNINGS and ADVERSE REACTIONS).

Contraindications

Sourced from openFDA
  • Thioguanine should not be used in patients whose disease has demonstrated prior resistance to this drug. In animals and humans, there is usually complete cross-resistance between PURINETHOL (mercaptopurine) and TABLOID brand Thioguanine.contraindicated

Dosage & administration

Sourced from openFDA

TABLOID brand Thioguanine is administered orally. The dosage which will be tolerated and effective varies according to the stage and type of neoplastic process being treated. Because the usual therapies for adult and pediatric acute nonlymphocytic leukemias involve the use of thioguanine with other agents in combination, physicians responsible for administering these therapies should be experienced in the use of cancer chemotherapy and in the chosen protocol. Patients with homozygous deficiency of either TPMT or NUDT15 enzyme typically require 10% or less of the standard thioguanine dosage. Reduce initial dosage in patients who are known to have homozygous TPMT or NUDT15 deficiency. Most of the patients with heterozygous TPMT or NUDT15 deficiency tolerate recommended thioguanine doses, but some require dose reduction based on toxicities. Patients who are heterozygous for both TPMT and NUDT15 may require more substantial dosage reduction. Reduce the dosage based on tolerability. Ninety-six (59%) of 163 pediatric patients with previously untreated acute nonlymphocytic leukemia obtained complete remission with a multiple-drug protocol including thioguanine, prednisone, cytarabine, cyclophosphamide, and vincristine. Remission was maintained with daily thioguanine, 4-day pulses of cytarabine and cyclophosphamide, and a single dose of vincristine every 28 days. The median duration of remission was 11.5 months.

Warnings & precautions

Sourced from openFDA

SINCE DRUGS USED IN CANCER CHEMOTHERAPY ARE POTENTIALLY HAZARDOUS, IT IS RECOMMENDED THAT ONLY PHYSICIANS EXPERIENCED WITH THE RISKS OF THIOGUANINE AND KNOWLEDGEABLE IN THE NATURAL HISTORY OF ACUTE NONLYMPHOCYTIC LEUKEMIAS ADMINISTER THIS DRUG. THIOGUANINE IS NOT RECOMMENDED FOR MAINTENANCE THERAPY OR SIMILAR LONG-TERM CONTINUOUS TREATMENTS DUE TO THE HIGH RISK OF LIVER TOXICITY ASSOCIATED WITH VASCULAR ENDOTHELIAL DAMAGE (see DOSAGE AND ADMINISTRATION and ADVERSE REACTIONS). This liver toxicity has been observed in a high proportion of children receiving thioguanine as part of maintenance therapy for acute lymphoblastic leukemia and in other conditions associated with continuous use of thioguanine. This liver toxicity is particularly prevalent in males. Liver toxicity usually presents as the clinical syndrome of hepatic veno-occlusive disease (hyperbilirubinemia, tender hepatomegaly, weight gain due to fluid retention, and ascites) or with signs of portal hypertension (splenomegaly, thrombocytopenia, and oesophageal varices). Histopathological features associated with this toxicity include hepatoportal sclerosis, nodular regenerative hyperplasia, peliosis hepatitis, and periportal fibrosis. Thioguanine therapy should be discontinued in patients with evidence of liver toxicity as reversal of signs and symptoms of liver toxicity have been reported upon withdrawal. Patients must be carefully monitored (see PRECAUTIONS, Laboratory Tests).

Adverse reactions

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To report SUSPECTED ADVERSE REACTIONS, contact Waylis Therapeutics LLC Toll-Free at 1-888-514-4727 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . The most frequent adverse reaction to thioguanine is myelosuppression. The induction of complete remission of acute myelogenous leukemia usually requires combination chemotherapy in dosages which produce marrow hypoplasia. Since consolidation and maintenance of remission are also effected by multiple-drug regimens whose component agents cause myelosuppression, pancytopenia is observed in nearly all patients. Dosages and schedules must be adjusted to prevent life-threatening cytopenias whenever these adverse reactions are observed. Hyperuricemia frequently occurs in patients receiving thioguanine as a consequence of rapid cell lysis accompanying the antineoplastic effect. Adverse effects can be minimized by increased hydration, urine alkalinization, and the prophylactic administration of a xanthine oxidase inhibitor such as ZYLOPRIM ® (allopurinol). Unlike PURINETHOL (mercaptopurine) and IMURAN ® (azathioprine), thioguanine may be continued in the usual dosage when allopurinol is used conjointly to inhibit uric acid formation. Less frequent adverse reactions include nausea, vomiting, anorexia, and stomatitis. Intestinal necrosis and perforation have been reported in patients who received multiple-drug chemotherapy including thioguanine.

Use in specific populations

Sourced from openFDA

Pregnancy Drugs such as thioguanine are potential mutagens and teratogens. Thioguanine may cause fetal harm when administered to a pregnant woman. Thioguanine has been shown to be teratogenic in rats when given in doses 5 times the human dose. When given to the rat on the 4th and 5th days of gestation, 13% of surviving placentas did not contain fetuses, and 19% of offspring were malformed or stunted. The malformations noted included generalized edema, cranial defects, and general skeletal hypoplasia, hydrocephalus, ventral hernia, situs inversus, and incomplete development of the limbs. There are no adequate and well-controlled studies in pregnant women. If this drug is used during pregnancy, or if the patient becomes pregnant while taking the drug, the patient should be apprised of the potential hazard to the fetus. Women of childbearing potential should be advised to avoid becoming pregnant.

Overdosage

Sourced from openFDA

Signs and symptoms of overdosage may be immediate, such as nausea, vomiting, malaise, hypotension, and diaphoresis; or delayed, such as myelosuppression and azotemia. It is not known whether thioguanine is dialyzable. Hemodialysis is thought to be of marginal use due to the rapid intracellular incorporation of thioguanine into active metabolites with long persistence. The oral LD 50 of thioguanine was determined to be 823 mg/kg ± 50.73 mg/kg and 740 mg/kg ± 45.24 mg/kg for male and female rats, respectively. Symptoms of overdosage may occur after a single dose of as little as 2.0 to 3.0 mg/kg thioguanine. As much as 35 mg/kg has been given in a single oral dose with reversible myelosuppression observed. There is no known pharmacologic antagonist of thioguanine. The drug should be discontinued immediately if unintended toxicity occurs during treatment. Severe hematologic toxicity may require supportive therapy with platelet transfusions for bleeding, and granulocyte transfusions and antibiotics if sepsis is documented. If a patient is seen immediately following an accidental overdosage of the drug, it may be useful to induce emesis.

Approval history

Sourced from openFDA
  • Jan 18, 1966NDANDA012429Waylis Therap

FAERS reports

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Reference statistics only. FAERS reports are voluntarily submitted and are not incidence rates, safety signals, or causal evidence. Counts reflect reporting volume — how often a reaction was reported, not how often it occurs. For decision-grade use, consult openFDA and the FAERS Public Dashboard directly.
2,083 total reports matchedLatest report Share = reports listing the reaction ÷ total matched reports. Rows can sum to >100% because a single report often lists multiple reactions.
  1. 1Febrile Neutropenia48223%
  2. 2Haematotoxicity1386.6%
  3. 3Neutropenia1346.4%
  4. 4Pyrexia1326.3%
  5. 5Off Label Use1155.5%
  6. 6Thrombocytopenia994.8%
  7. 7Sepsis984.7%
  8. 8Vomiting874.2%
  9. 9Pancytopenia864.1%
  10. 10Febrile Bone Marrow Aplasia703.4%
  11. 11Platelet Count Decreased673.2%
  12. 12Venoocclusive Liver Disease673.2%
  13. 13Death612.9%
  14. 14Nausea582.8%
  15. 15Mucosal Inflammation572.7%

Literature

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Recent PubMed references pinned to Thioguanine as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

Clinical trials

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The 10 most recently updated of 103 ClinicalTrials.gov registrations naming Thioguanine as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

Pharmacogenomics

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CPIC-curated drug–gene pairs for Thioguanine. Levels describe the strength of curated evidence and guideline status — never a recommendation to test or to adjust therapy.

Frequently asked questions

How does Thioguanine work?
Mechanism-of-action class: Nucleic Acid Synthesis Inhibitors.
What is Thioguanine used for?
According to FDA labeling, Thioguanine carries indications including: a) Acute Nonlymphocytic Leukemias TABLOID brand Thioguanine is indicated for remission induction and remission consolidation treatment of acute nonlymphocytic leukemias. However, it is not recommended for use during maintenance therapy or similar long-term continuous treatments due to the high risk of liver toxicity (see WARNINGS and ADVERSE REACTIONS).. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
What class of drug is Thioguanine?
Thioguanine is classified as Purine analogues, Nucleic Acid Synthesis Inhibitors, Decreased DNA Integrity, Decreased RNA Integrity.
What are the brand names for Thioguanine?
Thioguanine is marketed under brand names including Tabloid.
What are the contraindications for Thioguanine?
Thioguanine labeling lists contraindications including: Thioguanine should not be used in patients whose disease has demonstrated prior resistance to this drug. In animals and humans, there is usually complete cross-resistance between PURINETHOL (mercaptopurine) and TABLOID brand Thioguanine.. Always consult the full prescribing information and a clinician.
Note. Data for thioguanine is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.

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