Possible Interaction: Folic Acid and Sulfasalazine

“ Sulphasalazine impairs folic acid absorption and metabolism but rarely leads to folate deficiency in inflammatory bowel disease (IBD).”

“ Sulfasalazine , a compound containing a sulfa drug and a salicylate that is broken down to its active components by the … widely used in the treatment of inflammatory bowel disease and has been shown to impair the absorption of folic acid , polyglutamyl folate, and methyl-tetrahydrofolic … patients with these disorders.”

“Patients on sulfasalazine should take folic acid supplementation to reduce the risk of neural tube defects.”

“Although folic acid supplementation is beneficial in persons on medications such as methotrexate and sulfasalazine , studies are contradictory with regard to folic acid and colon cancer prevention.”

“For example, Franklin and Rosenberg 2 in 1973 found that orally administered sulfasalazine interfered with folic acid absorption both in patients with inflammatory bowel disease and in normal subjects.”

“In resected rats transport of PteGlu was inhibited by the structural analogues 5-methyltetrahydrofolate (5-CH3H4PteGlu) and methotrexate (MTX), by sulfasalazine , and by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and was saturable as a function of concentration (apparent Kt = 18.3 microM).”

“ Sulfasalazine inhibits pteroylglutamate (Ki congruent to 112 microM and amethopterin K congruent to 70 microM) transport competitively and reduces the quantity of pteroylglutamate converted to 5-methyltetrahydrofolate during intestinal transport.”

“The simultaneous administration of sulfasalazine and folic acid is regular practice in the therapy of inflammatory bowel diseases in order to maintain sufficient folate concentration in patients.”