Mercaptopurine

Dosage Forms Available

• Mercaptopurine is available in oral dosage forms (tablet and oral suspension).

Age and Dose Restrictions

• Mercaptopurine is usable by both adults and children.

Contraindications

• This medicine is contraindicated in patients with a known allergy to Mercaptopurine.
• Patients with a genetic metabolic disorder called Lesch-Nyhan syndrome should not use Mercaptopurine.
• Mercaptopurine is contraindicated in patients with significant TPMT (thiopurine methyltransferase) deficiency, as they are at increased risk of severe myelosuppression.

Other Medications to Avoid

• Mercaptopurine can interact with xanthine oxidase inhibitors (such as allopurinol), anticoagulants (like warfarin), NSAIDs (including olsalazine and sulphasalazine), and immunosuppressants (such as azathioprine).

Overdose and Missed Dose

• An overdose of Mercaptopurine may lead to nausea, vomiting, diarrhoea, and severe toxicity, including significant suppression of blood cell production. Immediate medical attention is necessary if an overdose is suspected.
• If you miss a dose of Mercaptopurine, take it as soon as you remember. However, if it is nearly time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for the missed one.

Management of Side Effects

Most side effects are temporary and generally harmless and resolve when discontinuing this medicine. However, if you experience any severe side effects or worsening of any of the symptoms, please consult your doctor.

• If experiencing nausea or loss of appetite, consider taking the medicine with a small amount of water. Ensure you are well-hydrated throughout the day.
• For fatigue or weakness, adjusting the time of day when you take your medication might help manage these effects.

Use in Driving and Operating Machinery

• Mercaptopurine may cause dizziness or fatigue in some individuals. It is prudent to avoid driving or operating heavy machinery until you know how Mercaptopurine affects you.

Use in Pregnancy and Lactation

• Mercaptopurine is not recommended for use during pregnancy or lactation. The potential risks to the unborn child or nursing infant usually outweigh the benefits of use during these periods. Consult your doctor for advice on using this medicine if you are pregnant or breastfeeding.

Caution in Other Conditions

• Caution is advised when using Mercaptopurine in patients with liver disease or reduced liver function, as it may exacerbate liver conditions.
• Patients with impaired kidney function should also be cautious, as Mercaptopurine may accumulate up to toxic levels in the body if kidney function is compromised.

Special Dietary and Lifestyle Recommendations

• Maintaining a balanced diet to support overall health is especially important due to potential appetite loss.
• Manage exposure to infections by avoiding crowds and practicing good hygiene, particularly handwashing, as Mercaptopurine can lower immune defences.
• Protect your skin from sun exposure by wearing protective clothing and using sunscreen, as this medication can increase sensitivity to sunlight.
• Prioritise rest and adequate sleep to help manage fatigue commonly associated with chemotherapy medications like Mercaptopurine.