Generic Name: Methotrexate
Product Name: Ledertrexate
Methotrexate has a number of uses. It is used in the treatment of the following cancers:
- Breast cancer.
- A number of cancers that arise during pregnancy.
- It is used in the palliative treatment of acute and subacute lymphocytic leukaemia.
- When used in combination with corticosteroids, Methotrexate can induce remission in acute lymphoblastic leukaemia, and is commonly used for maintenance of this remission.
- Methotrexate can also be used in the symptomatic treatment of severe, disabling psoriasis that has not been responsive to other therapies.
- It is also useful in the treatment of severe, recalcitrant, active rheumatoid arthritis that is not responsive to NSAIDs and other disease modifying drugs. Other treatments (aspirin, physiotherapy) should be continued.
Methotrexate is an anticancer drug known as an antimetabolite. It interferes with the replication of rapidly dividing cells (including cancer cells) by preventing the conversion of folic acid to folinic acid, a building block for new DNA. Methotrexate aims to reduce tumour size and prolong life for cancer sufferers. Its mechanism of action in rheumatoid arthritis is unknown.
Initial treatment with Methotrexate should be started in hospital. All personnel involved in handling and administration should be properly trained.
Choriocarcinoma and other cancers associated with pregnancy:
- 15-30mg daily for five days.
- Repeat 3-5 times with breaks of at least one week between treatments.
- 24 hour urinary chorionic gonadotrophin levels should return to normal by the 3rd-4th course.
- 2 courses should be continued after this point.
- 3.3mg/m2 Methotrexate + 60mg/m2 prednisone is successful at inducing remission in 50% of cases of acute lymphoblastic leukaemia.
- This treatment is more successful in children and young adolescents than in adults.
- 4-6 weeks of treatment is usually adequate to induce remission.
- Maintenance treatment is 30mg/m2 twice weekly.
- Different doses and combinations with other agents are being researched for different types of leukaemias.
- 10-25mg/day for 4-8 days may induce remission in low grade Burkitt’s lymphoma.
- Combination therapy is used for cases of grade III or higher.
- 10-25mg/week (not exceeding 50mg/week) until adequate response is achieved; OR
- 2.5mg at 12-hourly intervals for three doses, or at 8-hourly intervals for four doses each week (not exceeding 30mg/week).
- Once optimum condition has been achieved, reduce dose to lowest effective.
- 7.5mg once weekly; OR
- 2.5mg at 12-hourly intervals for three doses once weekly
- Therapeutic response is usually seen in 6 weeks, but improvement may continue for up to 12 weeks.
- 15mg/week may be required in non-responsive patients.
- Weekly dosage of 20mg should not be exceeded.
Common side effects
The most common toxicities of Methotrexate include:
- Bone marrow suppression resulting in decreased numbers of white blood cells, red blood cells and platelets and resultant increased risk of infection and bleeding.
- Nausea and vomiting (mild with low doses and moderate with high doses).
- Mucositis (inflammation of mucosal surfaces).
- Lung toxicity (usually presents as dry cough).
- Transient changes in liver function tests which may herald more severe liver damage.
- Increased sensitivity to sunlight.
- Haematological – Leukocytes are inhibited more than platelets.
- Mucositis- Depending on dosage schedule, the lining of the digestive tract can be damaged causing diarrhoea and mouth sores.
- Nausea, vomiting and weight loss – Usually only with high dose methotrexate treatment.
Uncommon side effects
Some less common reactions include:
- Blurred vision.
- Hair loss.
- Eye irritation.
- Inflammation of the lining of the brain (intrathecal administration).
For further information talk to your doctor.