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Tioguanine oral

Updated 2 Feb 2023 | Antimetabolites


Oral formulations of tioguanine.

Drugs List

  • tioguanine 40mg tablets
  • Therapeutic Indications




    Whilst the doses stated below are those recommended by the manufacturer, local cancer network protocols for the relevant indication should be consulted.

    The exact dose and duration of administration will depend on the nature and dosage of other cytotoxic drugs given in conjunction with tioguanine.

    Tioguanine may be used at various stages during treatment in short-term cycles. It is not recommended for use during maintenance therapy or similar long-term continuous treatments due to the high risk of hepatotoxicity.


    100 to 200mg/metre squared body surface area per day.


    100 to 200mg/metre squared body surface area per day.


    Plasma levels may be reduced following emesis or intake of food.

    Whilst the tablets are scored, they should only be broken to ease swallowing not to administer specific doses. If tablets are broken, use appropriate personal protective equipment to avoid skin contamination or inhalation of the drug.



    Precautions and Warnings

    Inherited NUDT15 gene mutation
    Inherited thiopurine methyltransferase deficiency
    Glucose-galactose malabsorption syndrome
    Hepatic impairment
    Lactose intolerance
    Lesch-Nyhan syndrome
    Renal impairment
    Uric acid nephropathy

    Administration of live vaccines is not recommended
    Live virus vaccine should not be given for 3 months after treatment
    Not recommended for maintenance therapy
    Maintain adequate hydration of patient prior / during treatment
    Male: Greater risk of developing hepatotoxicity
    Treatment to be prescribed under the supervision of a specialist
    Contains lactose
    Consult local policy on the safe use of oral anti-cancer drugs
    Staff: Not to be handled by pregnant staff
    Monitor blood counts regularly
    Monitor liver function tests weekly
    Monitor patients for signs of tumour lysis syndrome
    Advise patients to report signs of hepatic damage (malaise, jaundice etc.)
    Consider treatments to prevent hyperuricaemia
    Discontinue immediately following signs of acute hepatotoxicity
    Potentially mutagenic and carcinogenic
    Discontinue immediately if any severe fall in blood counts occur
    Consider dose reduction in hepatic impairment
    Consider dose reduction in renal impairment
    Male & female: Ensure adequate contraception during treatment
    Advise patient on appropriate sun protection methods

    Early indications of liver toxicity include portal hypertension (thrombocytopenia out of proportion to neutropenia or splenomegaly). Toxicity can also present as hepatic veno-occlusive disease (hyperbilirubinaemia, tender hepatomegaly, weight gain due to fluid retention and ascites). Elevations of liver enzymes do not always occur.

    Close monitoring is advised in patients with inherited TPMT deficiency as they are prone to developing rapid bone marrow suppression. This risk is further increased by co-administration of drugs that inhibit TPMT (e.g. aminosalicylates). Whilst laboratory tests are available to identify TPMT deficiency, there is potential that the tests will fail to identify some at risk patients. Patients may require substantial dose reductions however at the time of writing there are no standard recommendations for dose modifications. Most patients with heterozygous TPMT deficiency are able to tolerate standard doses.

    During remission induction there is a higher risk of myelosuppression and tumour lysis syndrome (particularly during rapid cell lysis). During this period, monitor full blood counts frequently and ensure adequate precautions to avoid hyperuricaemia, hyperuricosuria and uric acid nephropathy. Patients with acute myelogenous leukaemia may frequently experience periods of relative bone marrow aplasia during remission induction. It is important that adequate supportive facilities are available for these patients.

    Resistance to tioguanine may occur in patients with Lesch-Nyhan syndrome due to a deficiency in the enzyme responsible for converting tioguanine to its active metabolite.

    Dose reduction may be necessary in patients with inherited mutated NUDT15 gene due to an increased risk of severe tioguanine toxicity. Genotypic testing of NUDT15 variants may be considered before initiating tioguanine therapy.

    Pregnancy and Lactation


    Tioguanine is contraindicated during pregnancy.

    The manufacturer advises tioguanine should be avoided during pregnancy, particularly during the first trimester.

    In any individual case the potential hazard to the foetus must be balanced against the expected benefit to the mother. The effect of concurrent therapies must also be considered.


    Tioguanine is contraindicated during breastfeeding.

    The manufacturer does not recommend breastfeeding whilst taking tioguanine.

    It is unknown whether tioguanine or its metabolites are excreted in human breast milk. The effect of concurrent therapies must also be considered.

    Side Effects

    Bone marrow depression
    Gamma glutamyl transferase (GGT) increased
    Gastrointestinal intolerance
    Hepatic necrosis
    Hepatic veno-occlusive disease
    Hepatoportal sclerosis
    Increase in alkaline phosphatase
    Increased susceptibility to infection
    Increases in hepatic enzymes
    Intestinal necrosis
    Nodular regenerative hyperplasia
    Oesophageal varices
    Peliosis hepatis
    Periportal fibrosis
    Portal hypertension
    Weight gain (fluid retention)


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: March 2021

    Reference Sources

    Summary of Product Characteristics: Tioguanine 40mg Tablets. Aspen. Revised November 2017.

    NICE Evidence Services Available at:
    Last accessed: 05 March 2021

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