Is Tabloid affected by genetics?

Yes — the active ingredient is metabolized by a gene known to vary between individuals.

Relevant genes: NUDT15, TPMT

Tabloid is affected by pharmacogenetics through the NUDT15 and TPMT genes. Your genotype for these genes can change how your body processes Tabloid, which can affect both how well it works and how well you tolerate it. The strongest evidence level on this page is Strong, based on CPIC or FDA guidelines.

What's in Tabloid

thioguanine affected by NUDT15, TPMT

Affected by NUDT15, TPMT · CPIC, FDA · Strong evidence

Read the full thioguanine genetics guide →

Thioguanine phenotype recommendations

Published guidance from CPIC and FDA on how thioguanine should be dosed or substituted based on your NUDT15, TPMT phenotype.

Phenotype	What it means	Recommendation	Evidence
Normal Function TPMT	Your body processes thioguanine at a normal rate, so the standard dose should work well for you. Your doctor will monitor your blood counts and adjust the dose as needed.	CPIC Start with normal starting dose (e.g. 40-60 mg/m2/day) and adjust doses of thioguanine and of other myelosuppressive therapy without any special emphasis on thioguanine. Allow 2 weeks to reach steady-state after each dose adjustment. FDA Initiate therapy with recommended starting dose.	Strong
Intermediate Function TPMT	Your body breaks down thioguanine more slowly than usual, which causes higher levels of the drug to build up. Your doctor will likely start you on a lower dose and watch your blood counts closely to reduce the risk of side effects.	CPIC Start with reduced doses (50% to 80% of normal dose) if normal starting dose is > or = 40-60 mg/m2/day (e.g. 20-48 mg/m2/day) and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 2-4 weeks to reach steady-state after each dose adjustment. If myelosuppression occurs, and depending on other therapy, emphasis should be on reducing thioguanine over other agents. FDA Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Possible Intermediate Metabolizer TPMT	Your body may break down thioguanine more slowly than usual, which could cause higher levels of the drug to build up. Your doctor will likely start you on a lower dose and watch your blood counts closely.	CPIC Start with reduced doses (50% to 80% of normal dose) if normal starting dose is > or = 40-60 mg/m2/day (e.g. 20-48 mg/m2/day) and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 2-4 weeks to reach steady-state after each dose adjustment. If myelosuppression occurs, and depending on other therapy, emphasis should be on reducing thioguanine over other agents. FDA Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Poor Function TPMT	Your body breaks down thioguanine very slowly, which can cause dangerously high drug levels and serious side effects like a weakened immune system. You will need a much lower dose than usual, or your doctor may recommend a different medication entirely.	CPIC Start with drastically reduced doses (reduce daily dose by 10-fold and dose thrice weekly instead of daily) and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 4-6 weeks to reach steady-state after each dose adjustment. If myelosuppression occurs, emphasis should be on reducing thioguanine over other agents. For non-malignant conditions, consider alternative non-thiopurine immunosuppressant therapy. FDA Consider an alternative agent or reduce dose to 10% or less of the recommended dosage. Monitor closely for myelosuppression.	Strong
Indeterminate TPMT	Your genetic test result for this gene was unclear, so there is no specific dosing guidance for thioguanine based on your result.	CPIC No recommendation FDA Initiate therapy with recommended starting dose.	—
Not available TPMT	Your genetic information for this gene is not available, so there is no specific dosing guidance for thioguanine.	CPIC No recommendation FDA Initiate therapy with recommended starting dose.	—
Normal Metabolizer NUDT15	Your body processes thioguanine at a normal rate based on this gene, so the standard dose should be appropriate for you.	CPIC Start with normal starting dose (40-60 mg/day). Adjust doses of thioguanine and of other myelosuppressive therapy without any special emphasis on thioguanine. Allow 2 weeks to reach steady-state after each dose adjustment. FDA Initiate therapy with recommended starting dose.	Strong
Intermediate Metabolizer NUDT15	Your body has a reduced ability to process thioguanine based on your NUDT15 gene, which increases your risk of side effects like low blood cell counts. A lower starting dose is recommended.	CPIC Start with reduced doses (50% to 80% of normal dose) if normal starting dose is > or = 40-60 mg/m2/day) and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 2-4 weeks to reach steady-state after each dose adjustment. If myelosuppression occurs, and depending on other therapy, emphasis should be on reducing thioguanine over other agents. FDA Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Possible Intermediate Metabolizer NUDT15	Your body may have a reduced ability to process thioguanine based on your NUDT15 gene, which could increase your risk of side effects. A lower starting dose is recommended.	CPIC Start with reduced doses (50% to 80% of normal dose) if normal starting dose is > or = 40-60 mg/m2/day) and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 2-4 weeks to reach steady-state after each dose adjustment. If myelosuppression occurs, and depending on other therapy, emphasis should be on reducing thioguanine over other agents. FDA Reduce thioguanine dose based on tolerability and monitor for myelosuppression. Refer to FDA labeling for specific dosing recommendations.	Strong
Poor Metabolizer NUDT15	Your body has great difficulty processing thioguanine based on your NUDT15 gene, putting you at high risk for serious side effects like dangerously low blood cell counts. You will need a much lower dose or a different medication.	CPIC Reduce doses to 25% of normal dose and adjust doses of thioguanine based on degree of myelosuppression and disease-specific guidelines. Allow 4-6 weeks to reach steady-state after each dose adjustment. In setting of myelosuppression, emphasis should be on reducing thioguanine over other agents. For non-malignant conditions, consider alternative non-thiopurine immunosuppressant therapy. FDA Consider an alternative agent or reduce dose to 10% or less of the recommended dosage. Monitor closely for myelosuppression.	Strong
Indeterminate NUDT15	The impact of your genotype on response to this drug is unknown	CPIC + FDA Initiate therapy with recommended starting dose.	—
Not available NUDT15	The impact of your genotype on response to this drug is unknown	CPIC + FDA Initiate therapy with recommended starting dose.	—

Sources: CPIC, FDA

The gene behind the guidance

TPMT Thiopurine S-Methyltransferase

TPMT inactivates thiopurine drugs like azathioprine, mercaptopurine, and thioguanine. About 1 in 300 people of European descent has essentially no TPMT activity, and standard doses can cause life-threatening bone marrow suppression in those people within weeks. Intermediate activity affects around 10 percent of people and still requires dose reduction.

TPMT testing is one of the oldest and most established pharmacogenetic tests. Most rheumatologists, gastroenterologists, and oncologists order it before starting thiopurine therapy.

See all drugs affected by TPMT →

Browse the full drug-class: Chemotherapy agents.

Related medications

Find out how your genetics affect Tabloid

This page describes the general pharmacogenetics. A Gene2Rx report analyzes your own DNA to tell you which metabolizer group you fall into, across every medication.

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Informational only — not medical advice. Pharmacogenetic guidance describes population-level patterns; your individual response depends on many factors. Never start, stop, or change a medication without talking to your prescribing clinician.