sulfasalazine, Azulfidine (cont.)

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DOSING: Adult doses range from 1000 mg to 4000 mg daily. Sulfasalazine is administered 2 to 4 times daily depending on the disease for which it is used. Sulfasalazine should be taken with a full glass of water after meals or with food to minimize upset stomach. Patients with kidney diseases may need to use lower doses of sulfasalazine.

DRUG INTERACTIONS: Sulfasalazine may cause reduced absorption of folic acid and digoxin (Lanoxin). Reduced folic acid absorption may cause folic acid deficiency and result in anemia. Reduced digoxin absorption may reduce the effectiveness of digoxin. Sulfapyridine (a byproduct of sulfasalazine) is a sulfonamide, and sulfonamides increase blood levels of methotrexate (Rheumatrex, Trexall), resulting in increased methotrexate toxicity. Conversely, methotrexate can increase the occurrence of the anemia caused by sulfonamides because methotrexate also causes folic acid deficiency. Sulfonamides can increase the risk of kidney damage from cyclosporine by an unknown mechanism. They also may increase the blood glucose lowering effect of oral anti-diabetic drugs and potentially cause excessive reductions in blood sugar (hypoglycemia) by decreasing elimination of anti-diabetic drugs by the liver and elevating the levels of the anti-diabetic drugs in the blood.

Combining 5-ASA with drugs that affect kidney function such as nonsteroidal antiinflammatory drugs, for example, ibuprofen (Advil), may increase the likelihood of kidney dysfunction. Concurrent use of 5-ASA and 6-mercaptopurine or azathioprine (Imuran) may increase the likelihood of blood disorders. 5-ASA may increase the blood thinning effect of warfarin (Coumadin).

PREGNANCY: In hundreds of pregnant women with ulcerative colitis or Crohn's disease treated with sulfasalazine, there has been no increase in the risk of fetal malformations relative to other women with these illnesses who have not been treated with sulfasalazine. Additionally, there have not been ill effects on pregnant animals given high doses of sulfasalazine. Thus, sulfasalazine may be used during pregnancy if the physician feels the benefit outweighs the possible risk.



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