Sulfasalazine

Indications

Sulfasalazine is used for: Inflammatory bowel disease, Rheumatoid arthritis

Adult Dose

Oral Inflammatory bowel disease Adult: Initially, 1-2 g 4 times daily until remission occurs. Maintenance: 2 g/day in divided doses. Rheumatoid arthritis Adult: As enteric-coated tablet: Initially, 500 mg daily for the 1st wk increased by 500 mg every wk. Max: 3 g daily in 2-4 divided doses. Rectal Inflammatory bowel disease Adult: As suppository: 0.5-1 g in the morning and night, either alone or as an adjunct to oral treatment. Hepatic impairment: Avoid use.

Child Dose

Oral Inflammatory bowel disease Child: >2 yr: 40-60 mg/kg/day in divided doses. Maintenance: 20-30 mg/kg/day in divided doses. Rheumatoid arthritis Child: For polyarticular juvenile rheumatoid arthritis: >6 yr: As enteric-coated tablet: 30-50 mg/kg/day in 2 divided doses. Begin treatment with 1/4 to 2/3 of expected maintenance dose and increase wkly to reach maintenance dose in 1 mth. Max: 2 g daily. Rectal Inflammatory bowel disease Child: As suppository (may be given as divided doses): 5-8 yr: 500 mg bid; 8-12 yr: 500 mg in the morning and 1 g at night; 12-18 yr: 1 g bid.

Renal Dose

Renal impairment: CrCl (ml/min) Dosage Recommendation 10-30ml/min Admin twice daily. <10ml/min Admin once daily.

Administration

Should be taken with food. Take after meals. Ensure adequate fluid intake.

Contra Indications

Hypersensitivity to sulphonamides or salicylates, porphyria, <2 yr of age, intestinal or urinary obstruction, blood dycrasias, history of leucopenia with gold therapy.

Precautions

Hepatic/renal impairment, G6PD deficiency, allergic bronchial asthma, lactation. Lactation: Excreted into human breast milk; caution with breastfeeding, some reports of bloody stools or diarrhea in human milk fed infants of mothers taking sulfasalazine

Pregnancy-Lactation

Pregnancy category: B; D if used for prolonged periods or near term; increased potential for kernicterus in the newborn Oral sulfasalazine inhibits the absorption and metabolism of folic acid which may interfere with folic acid supplementation and protection from neural tube defects Lactation: Excreted into human breast milk; caution with breastfeeding, some reports of bloody stools or diarrhea in human milk fed infants of mothers taking sulfasalazine

Interactions

Plasma levels reduced by rifampicin and ethambutol. Interferes with absorption of folic acid. Additive leucopaenia with gold therapy for rheumatoid arthritis. Increased haematological toxicity with azathioprine. Reduced serum levels of digoxin.

Adverse Effects

Side effects of Sulfasalazine : >10% Anorexia (~33%), Headache (~33%), Nausea (~33%), Vomiting (~33%), Gastric distress (~33%), Apparently reversible oligospermia (~33%) <1% Skin rash, Pruritus, Urticaria, Fever, Heinz body anemia, Hemolytic anemia, Cyanosis Potentially Fatal: Severe hypersensitivity reactions, blood dyscrasias, renal and hepatic toxicity, fibrosing alveolitis.

Mechanism of Action

Actual mechanism not determined. Sulphasalazine may have direct anti-inflammatory action in the colon. It also systemically interferes with secretion by prostaglandin synthesis inhibition.