BMA Concise Guide to Medicine & Drugs

Methotrexate

Brand names Maxtrex, Metoject

Used in the following combined preparations None

QUICK REFERENCE

Drug group Anticancer drug

Overdose danger rating High

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Methotrexate is an anticancer drug used, together with other anticancer drugs, in the treatment of leukaemia, lymphoma, and solid cancers such as those of the breast, bladder, head, and neck. It is also used alone to treat inflammatory conditions such as severe uncontrolled psoriasis, rheumatoid arthritis, and Crohn’s disease.

As with most anticancer drugs, methotrexate affects both healthy and cancerous cells, so that its usefulness is limited by its adverse effects and toxicity. Folic acid supplements may reduce its toxicity, and when methotrexate is given in high doses, it is usually given with folinic acid to prevent it from destroying bone marrow cells. Because of its toxicity and adverse effects it is very important that you do not take methotrexate more often than prescribed by your doctor.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, injection.

Frequency and timing of doses Cancer Single dose once weekly or every 3 weeks. Other conditions Single dose once weekly.

Adult dosage range Cancer Dosage is determined individually according to the nature of the condition, body weight, and response. Rheumatoid arthritis 7.5–20mg weekly. Psoriasis 10–25mg weekly.

Onset of effect 30–60 minutes.

Duration of action Short-term effects last up to 24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children. Wash your hands after handling the tablets.

Missed dose Take as soon as you remember and consult your doctor.

Stopping the drug Do not stop taking the drug without consulting your doctor. Stopping the drug may lead to worsening of the underlying condition.

OVERDOSE ACTION

Seek immediate medical advice in all cases. Take emergency action if breathing problems or loss of consciousness occur.

POSSIBLE ADVERSE EFFECTS

Methotrexate may cause a wide range of adverse effects. Common ones include dry cough; chest pain; nausea and vomiting (which may occur within a few hours of taking the drug); and diarrhoea and mouth ulcers (which may occur a few days after starting treatment). Notify your doctor if dry cough or chest pain are severe or if you experience any of the other effects; if you develop mouth ulcers, the drug should also be stopped. Less common adverse effects include mood changes, confusion, rash, jaundice, sore throat, fever, easy bleeding or bruising, and breathlessness. If you experience mood changes or confusion, you should notify your doctor. If you develop any of these other less common symptoms, you should stop taking the drug and contact your doctor without delay.

INTERACTIONS

General note Many drugs, including NSAIDs, diuretics, ciclosporin, phenytoin, and probenecid, may increase blood levels and toxicity of methotrexate.

Co-trimoxazole, trimethoprim, and certain antimalarial drugs These drugs may enhance the effects of methotrexate.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have liver or kidney problems.

· You have porphyria.

· You have a problem with alcohol abuse.

· You have a peptic or other digestive-tract ulcer.

· You are taking other medicines, especially NSAIDs or antibiotics.

Pregnancy Not prescribed. Methotrexate may cause birth defects in the unborn baby.

Breast-feeding Not advised. The drug passes into the breast milk and may affect the baby adversely.

Infants and children For cancer treatment only. Reduced dose necessary.

Over 60 Increased likelihood of adverse effects. Reduced doses necessary.

Driving and hazardous work No special problems.

Alcohol Avoid. Alcohol may increase the adverse effects of methotrexate.

PROLONGED USE

Long-term treatment may be needed for rheumatoid arthritis. Once the condition is controlled, the drug is reduced as much as possible to the lowest effective dose. Long-term methotrexate treatment may occasionally lead to breathing problems due to scarring of the lungs or, rarely, unusual respiratory infections, such as pneumocystis pneumonia.

Monitoring Full blood counts and kidney and liver function tests will be performed before treatment starts and at intervals during treatment.