Medicines & Supplements A to Z > Methotrexate
Last updated on 14/07/2021.
GENERIC NAME: Methotrexate
CHINESE NAME: 甲氨蝶呤
BRAND NAME(S) IN HONG KONG: Methotrexate Sandoz, Methotrexate-Ebewe
DRUG CLASS: Antineoplastics
SUB CLASS: Antimetabolites
USED FOR: Rheumatoid arthritis, Psoriasis, Treatment of cancers
AVAILABLE DOSAGE FORMS:
– 2.5 mg (tablets)
– 25 mg/ml, 50 mg/2ml, 100 mg/ml, 1 g/10ml (injections)
What is Methotrexate for?
Methotrexate is a folate antimetabolite that inhibits an enzyme dihydrofolate reductase to suppress the synthesis of DNA and thus cell growth. Therefore, it can be used in the treatment of rheumatoid arthritis, psoriasis and cancers.
How to use it?
Methotrexate is to be injected into the veins, muscles, spinal cord or the subarachnoid space, or orally taken as tablets. The dose may be adjusted based on the body surface area estimated by the physicians. Methotrexate is usually accompanied by the use of Leucovorin to reduce side effects.
Oral: 7.5 mg once weekly. Adjust based on response to a dose not more than 20 mg weekly.
Oral: 10-25 mg once weekly. Adjust subsequent doses based on response.
Intramuscular or intravenous: 10-25 mg once weekly. Adjust subsequent doses based on response.
Acute lymphoblastic leukaemia
Oral: 15 mg/m2 once or twice weekly, with other agents for maintenance.
Intravenous: 2.5 mg/kg every 14 days for maintenance.
Intravenous: 10-60 mg/m2 often with cyclophosphamide and fluorouracil.
What are the side effects of Methotrexate?
Common side effects of Methotrexate include, but not limited to, diarrhoea, nausea, vomiting, increased liver enzymes, hair loss, skin photosensitivity, osteoporosis, venous thromboembolism, pigmentary changes, increased risk of infection and lung problems including chronic obstructive pulmonary disease and pulmonary fibrosis.
Who should not take Methotrexate?
– People allergic to Methotrexate or any component of the formulation.
– Patients with severe renal impairment
– Pregnant women or those who plan to be pregnant
– People on nitrous oxide anesthesia
There are some other contraindications. Please notify the physician of your condition before being administered with Methotrexate.
– Methotrexate can cause bone marrow suppression, slowing down the formation of white blood cells. Signs like pale skin, lips and nail beds, fatigue and shortness of breath will be observed. This will increase the risk of infection. Report all signs of infection like fever, shortness of breath and sore throat to your physician as soon as possible.
– Leucovorin (Folinic acid) should be used together to reduce the side effects.
– Chest X-ray, liver function test, blood test and breathing test will be carried to confirm your body is able to withstand the side effects of Methotrexate.
Common dosing schedule:
Methotrexate injections are prescribed in institutions by the physicians.
Oral Methotrexate is to be taken once weekly. Bear in mind that the same day of the week should be chosen to take the tablets and the days should be separated as far as possible.
This schedule is for reference only, adjustments may be made according to individual needs.
Some common medications Methotrexate may interact with:
– Hepatotoxic medications, e.g. Rifampin, Terbinafine, Felbamate
– 5-aminosalicylic acid derivatives, e.g. Balsalazide, Mesalamine, Sulfasalazine
– NSAIDs, e.g. Ibuprofen, Diclofenac, Celecoxib, Aspirin
– Proton pump inhibitors, e.g. Esomeprazole, Omeprazole, Pantoprazole
– Antibiotics, e.g. Tacrolimus, Trimethoprim, Vancomycin
Methotrexate may interact with many other medications. Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.
Where to buy Methotrexate in Hong Kong?
In Hong Kong, Methotrexate is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.
For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk
Need more information?
For detailed information about the use of Methotrexate in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.
Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.