Mercaptopurine (PURINETHOL)

Acute lymphoid leukemia and Acute promyelocytic leukemia

Acute lymphoid leukemia and Acute promyelocytic leukemia

• Oral: Multiple dosing schedules and doses exist, such as weight-based dosing, body surface area based dosing, and flat dosing (same dose regardless of patient). Please refer to local protocol being used.
• Given in combination with rituximab or chemotherapy.

Available as 50mg tablets. Tablets contain lactose. Tablets should NOT be crushed or broken. Store at room temperature.

Antimetabolite

Take on empty stomach, at least 1 hour before or 2 hours after any dairy products

If a dose is missed, patients should be instructed to take it as soon as they can if it is within 12 hours of the missed dose. If it is over 12 hours since the missed dose, patients should skip the missed dose and resume with the next scheduled dose.

Common: Hepatotoxicity.

Less Common: Anemia, Leukopenia, Thrombocytopenia, Stomatitis.

The adverse effects listed above are not exhaustive. Please refer to the relevant product monograph for full details.

Baseline before treatment: CBC & differential, AST, ALT, ALP, SCr.

During treatment (weekly to start, then at prescriber descretion): CBC & differential, AST, ALT, ALP, SCr.

If clinically indicated: Consider performing TPMT phenotype/genotype to assess for TPMT activity level in patients who are experiencing a high level of myelosuppression.

Note: Please be advised that this testing is not currently readily accessible in Canada and may need to be sourced elsewhere.

Current drug interaction databases should be consulted for more information.

• Avoid in pregnancy and lactation.
• Milk and dairy products can make mercaptopurine less effective, and thus should be avoided during administration times.

BC Cancer. BC Cancer Drug Manual. Mercaptopurine.  Vancouver, British Columbia: BC Cancer Agency. Available at: http://www.bccancer.bc.ca/drug-database-site/Drug%20Index/Mercaptopurine_monograph.pdf. Updated April 1, 2018.  Accessed February 2, 2024.

Lexicomp. Mercaptopurine Monograph. In: Lexi-Drugs. Hudson, Ohio: Lexi-Comp, Inc. Available at: https://online-lexi-com.qe2a-proxy.mun.ca/lco/action/doc/retrieve/docid/patch_f/7252?cesid=0WqPHM3HOuZ&searchUrl=%2Flco%2Faction%2Fsearch%3Fq%3Dmercaptopurine%26t%3Dname%26acs%3Dtrue%26acq%3Dmercaptop. Updated January 18, 2024. Accessed January 26, 2024.

Cancer Care Ontario. Mercaptopurine Monograph. Drug Formulary. Toronto, Ontario: Cancer Care Ontario. Available at: https://www.cancercareontario.ca/en/drugformulary/drugs/monograph/44091. Updated June 2019. Accessed January 22, 2024.

Novopharm Limited. Mercaptopurine Tablet Product Monograph. Toronto, Ontario. Updated November 19, 2014.