Methotrexate is a form of chemotherapy used to treat a wide array of conditions, such as rheumatoid arthritis, psoriasis, Crohn's disease and various cancers including leukemia, lymphoma and bone cancer. It is also employed in the treatment of ectopic pregnancies. This medication works by interfering with the synthesis of DNA and RNA, which are needed for cellular growth and division. Thus, methotrexate is toxic to rapidly dividing cells, which accounts for its usefulness in dissimilar situations. If you are taking methotrexate, it is important to remember its interaction with folate.
Folate
Folate, a B vitamin is the natural form of folic acid and is found in high concentrations in dark green leafy vegetables such as kale, spinach and chard. It is also present in liver, kidney and brewer's yeast. Folate from your diet is eventually converted to its active biological form, tetrahydrofolic acid, by a cellular enzyme called dihydrofolate reductase. Tetrahydrofolic acid is required for manufacturing the building blocks used in the synthesis of DNA and RNA. Without DNA and RNA, your cells cannot grow and reproduce.
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According to scientists at Pennsylvania State University, methotrexate binds to dihydrofolate reductase and prevents it from completing the conversion of folate to tetrahydrofolic acid. This competitive inhibition of dihydrofolate reductase reduces the amount of active folate in your cells and interferes with the production of DNA and RNA. Physicians exploit this property to control the reproduction of cancer cells, over-stimulated immune cells or even the cells of an embryo, which has implanted in a dangerous location.
Folic Acid Supplementation
Methotrexate's interference with the action of folate is the reason for the drug's therapeutic benefits as well as its side effects, which include inflammation and sloughing of the oral mucous membranes, low white blood cell count, infections, hair loss, lung and liver damage and birth defects. Your healthy cells need folate to grow and divide, too, but methotrexate is indiscriminate in its anti-folate activities. Therefore, your doctor may advise you to take a folic acid supplement to counteract methotrexate's effects on your healthy tissues. However, if you take folic acid on the same day as your methotrexate dose, the folic acid will compete for the dihydrofolate reductase enzyme and possibly lessen the effects of your methotrexate.
Considerations
Methotrexate is a folic antagonist. The frequency of administration and dosage of methtrexate may vary, depending on what condition the drug is treating. Supplemental folic acid may ameliorate some of methotrexate's side effects, but taking both folic acid and methotrexate on the same day could interfere with the medication's effectiveness. If you are taking methotrexate, ask your doctor if you should take folic acid supplements as well.
References
- "Canadian Family Physician"; Effect of Methotrexate Treatment of Ectopic Pregnancy on Subsequent Pregnancy; R. Hackmon, et al.; January 2011
- "Proceedings of the National Academy of Sciences of the United States of America"; Interaction of Dihydrofolate Reductase with Methotrexate: Ensemble and Single-Molecule Kinetics; P.T. Ravi Rajagopalan, et al.; October 2002
- MedlinePlus Drug Information; Methotrexate; April 1, 2009
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