There are several medications available in the treatment of rheumatoid arthritis, a systemic inflammatory disease. Steroids and TNF-alpha antagonists slow the damage to the bones, while steroids can also lower the inflammation. Biologic agent medications attack the immune system cells, and nonsteroidal anti-inflammation drugs and disease-modifying anti-rheumatic drugs lower the inflammation caused by the disease. Folic acid is recommended when taking one of the disease-modifying anti-rheumatic drugs to reduce the side effects.
Rheumatoid Arthritis
Rheumatoid arthritis is an autoimmune disease that primarily causes inflammation in the joints. It is called an autoimmune disorder because the immune system mistakenly attacks its own tissues instead of attacking foreign substances. Why this happens is not known, but scientists have discovered some genes that are involved. Approximately 1 percent of the population has rheumatoid arthritis, women three times more than men, according to Dr. David Hellmann, professor of medicine at John Hopkins University School of Medicine in "Current Medical Diagnosis & Treatment." If this arthritis is not treated, it will destroy the joints.
Disease-modifying Anti-rheumatic Drugs
The treatment for rheumatoid arthritis includes good nutrition, exercise, physical therapy, medications and perhaps surgery. Disease-modifying anti-rheumatic drugs, or DMARDs, are prescribed as soon as the diagnosis has been made because this type of medication is anti-inflammatory and suppresses the immune system. The DMARDs include methotrexate, sulfasalazine, leflunomide and hydroxychloroquine, but according to the University of Maryland Medical Center, methotrexate is the most common DMARD prescribed. Methotrexate does have some side effects, however. It may suppress the bone marrow and cause liver abnormalities, a lung infection, nausea and an infection in the mouth. Folic acid may decrease some of the side effects.
Methotrexate
Methotrexate interferes with an enzyme called dihydrofolate reductase. Enzymes are proteins that the cells must use to make a biochemical reaction go faster. Interfering with this enzyme means the cells make less amino acids and substances called purines that they must use to make DNA, according to "Goodman & Gilman's The Pharmacological Basis of Therapeutics" by Dr. Bruce Chabner, professor of medicine at Harvard Medical School. Methotrexate interferes with the metabolism of protein and with DNA production. In addition, it changes inside the cells to a substance that is even more powerful. The result of all of its actions is a decrease in the number of the immune cells.
Folic Acid and Methotrexate
The cells use folic acid to make DNA. To do so, however, they must first change folic acid to tetrahydrofolate, and making this change requires the dihydrofolate reductase enzyme, explains Gerhard Meisenberg of the Department of Biochemistry at Ross University School of Medicine in the "Principles of Medical Biochemistry." This is the same enzyme that is inhibited by methotrexate, which explains why cells that divide quickly, such as the blood cells in the bone marrow, do not have enough tetrahydrofolate to make DNA. This causes the bone marrow suppression of methotrexate and is why folic acid is prescribed to reduce the side effects.
References
- "Current Medical Diagnosis & Treatment 2011"; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2011
- "Goodman & Gilman's The Pharmacological Basis of Therapeutics"; Laurence Brunton, Ph.D.; 2011
- "Principles of Medical Biochemistry"; Gerhard Meisenberg, Ph.D., William Simmons, Ph.D.; 1998
- "University of Maryland Medical Center"; Rheumatoid Arthritis; Mark Borigini; 2010
- "The Washington Manual of Medical Therapeutics"; Gopa Green, M.D., Ian Harris, M.D., Grace Lin, M.D., Kyle Moylan, M.D.; 2004
