Thioguanine

Thioguanine is a prescription medicine used for the treatment of acute nonlymphocytic leukemia.

• Thioguanine is available under the following different brand names: 6TG, 6Thioguanine, Tabloid

Common side effects of Thioguanine include:

• upset stomach
• nausea
• vomiting
• diarrhea
• hair loss
• itching or skin rash, or
• darkened skin color.

Serious side effects of Thioguanine include:

• hives,
• difficulty breathing,
• swelling of the face, lips, tongue, or throat,
• stomach bloating,
• rapid weight gain,
• unusual tiredness,
• nausea,
• loss of appetite,
• upper stomach pain,
• dark urine,
• yellowing of the skin or eyes (jaundice),
• easy bruising,
• unusual bleeding,
• bloody or tarry stools,
• coughing up blood,
• vomit that looks like coffee grounds,
• fever,
• chills,
• tiredness,
• mouth sores,
• skin sores,
• pale skin,
• cold hands and feet,
• lightheadedness, and
• shortness of breath

Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;

Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheadedness, or passing out;

Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

Rare side effects of Thioguanine include:

none

Seek medical care or call 911 at once if you have the following serious side effects:

• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
• Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out. 

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

Adult and pediatric dosage

Tablet

• 40 mg

Acute Nonlymphocytic Leukemia

Adult and pediatric dosage

• 2 mg/kg/day orally 
• Cautiously increase to 3 mg/kg/day if no response after 4 weeks
• May be used in multi-drug therapy, including prednisone, cytarabine, cyclophosphamide, vincristine

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

• Thioguanine has severe interactions with no other drugs.
• Thioguanine has serious interactions with the following drugs:
  • adenovirus types 4 and 7 live, oral
  • axicabtagene ciloleucel
  • brexucabtagene autoleucel
  • ciltacabtagene autoleucel
  • deferiprone
  • idecabtagene vicleucel
  • influenza virus vaccine quadrivalent, adjuvanted
  • influenza virus vaccine trivalent, adjuvanted
  • lisocabtagene maraleucel
  • palifermin
  • pexidartinib
  • pretomanid
  • ropeginterferon alfa 2b
  • tisagenlecleucel
  • tofacitinib
• Thioguanine has moderate interactions with the following drugs:
  • acalabrutinib
  • allopurinol
  • belatacept
  • busulfan
  • cholera vaccine
  • dengue vaccine
  • fingolimod
  • hydroxyurea
  • influenza A (H5N1) vaccine
  • influenza virus vaccine (H5N1), adjuvanted
  • mechlorethamine
  • meningococcal group B vaccine
  • ofatumumab SC
  • olaparib
  • siponimod
  • sipuleucel-T
  • trastuzumab
  • trastuzumab deruxtecan
• Thioguanine has minor interactions with the following drugs:
  • maitake
  • taurine
  • vitamin A
  • vitamin E

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

Contraindications

• Hypersensitivity; prior resistance to 6-thioguanine or mercaptopurine

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Thioguanine?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Thioguanine?”

Cautions

• Therapy should be administered only by physicians experienced with the risks of therapy and with knowledge of the natural history of acute nonlymphocytic leukemias
• Long-term continuous therapy associated with high risk for hepatotoxicity, portal hypertension, or sinusoidal obstruction syndrome; monitor liver function closely and discontinue therapy if patient experiences symptoms of hepatotoxicity, including hyperbilirubinemia, hepatomegaly, portal hypertension such as thrombocytopenia out of proportion with neutropenia and splenomegaly; elevations of liver enzymes have also been reported in association with liver toxicity but do not always occur
• The most consistent, dose-related toxicity is bone marrow suppression, which may be manifested by anemia, leukopenia, thrombocytopenia, or any combination of these; any one of these findings may also reflect the progression of underlying disease; since thioguanine may have a delayed effect, it is important to withdraw medication temporarily at the first sign of an abnormally large fall in any of formed elements of blood
• Evaluate patients with repeated severe myelosuppression for thiopurine S-methyltransferase (TPMT) or nucleotide diphosphatase (NUDT15) deficiency; TPMT genotyping or phenotyping (red blood cell TPMT activity) and NUDT15 genotyping can identify patients who have reduced activity of these enzymes; patients with homozygous TPMT or NUDT15 deficiency require substantial dosage reductions; bone marrow suppression could be exacerbated by co-administration with drugs that inhibit TPMT, such as olsalazine, mesalazine, or sulphasalazine
• Obtain evaluation of the hemoglobin concentration or hematocrit, total white blood cell count and differential count, and quantitative platelet count frequently while on thioguanine therapy; in cases where the cause of fluctuations in formed elements in peripheral blood is obscure, bone marrow examination may be useful for evaluation of marrow status; the decision to increase, decrease, continue, or discontinue a given dosage of thioguanine must be based not only on the absolute hematologic values but also upon the rapidity with which changes are occurring; in many instances, particularly during the induction phase of acute leukemia, complete blood counts will need to be done more frequently in order to evaluate the effect of therapy; dosage of thioguanine may need to be reduced when combined wi
• Myelosuppression is often unavoidable during the induction phase of adult acute nonlymphocytic leukemias if remission induction is to be successful; whether or not this demands modification or cessation of dosage depends both upon the response of underlying disease and careful consideration of supportive facilities (granulocyte and platelet transfusions) which may be available; life-threatening infections and bleeding have been observed as consequences of thioguanine-induced granulocytopenia and thrombocytopenia
• Therapy is potentially carcinogenic
  • Institute adequate hydration and administer allopurinol prophylactically to minimize the risk of hyperuricemia, which commonly occurs with treatment
  • Monitor for infections (leukopenia)
  • Monitor for bleeding (thrombocytopenia)

Pregnancy and Lactation

• Use in LIFE-THREATENING emergencies when no safer drug is available
• Lactation
  • Not known if excreted in breast milk, do not nurse