What is methotrexate?
Methotrexate is a drug that is only issued with a prescription. It is known to be cytotoxic. This means that it kills all cells that are undergoing cell division. Methotrexate is available in four forms: Injectable IV solution, Self-injectable solution, oral tablet and oral solution.
Uses of methotrexate
This drug is used to treat certain types of cancers, rheumatoid arthritis and psoriasis. Using methotrexate has its dangers and therefore should be only used in those with life-threatening cancer, disabling psoriasis and rheumatoid arthritis.
The mechanism of action
Methotrexate belongs to a group of drugs known as anti-metabolites. These are synthetic analogues of normal metabolites and acts by competition with each other. It is known to be a Folate antagonist. It inhibits the enzyme dihydrofolate reductase & prevents the synthesis of tetrahydrofolic acid, a coenzyme required for the synthesis of amino acid & nucleic acid. Folic acid is an essential component for the synthesis of nucleic acids therefore by inhibiting the production of folic acid will disrupt the synthesis of DNA, RNA, thymidylates and proteins.
1. Depression of the bone marrow. This leads to a decrease in blood cells, especially white blood cells which makes the person more susceptible for infections.
2. Damage to the epithelium of the gastrointestinal tract: oral and GIT ulceration
3. Reversible elevation of hepatic transaminases with high doses
4. In chronic administration: hepatic fibrosis and cirrhosis
5. Pneumonitis – Inflammation of lung tissue.