Sulfasalazine is a disease-modifying anti-rheumatic drug (DMARD) and an anti-inflammatory agent. It is a prodrug, a conjugate of 5-aminosalicylic acid (5-ASA/mesalamine) and sulfapyridine, linked by an azo bond. It is primarily used in the management of inflammatory bowel diseases (ulcerative colitis, Crohn's disease) and rheumatoid arthritis. In the gut, colonic bacteria cleave the azo bond, releasing the active components. Its anti-inflammatory and immunomodulatory effects are central to its therapeutic action.
Adult: RA & IBD: Start with 500 mg daily, increase gradually over 4-6 weeks to target dose. Maintenance: 2-3 g daily in 2-3 divided doses (e.g., 1000mg twice daily). Max daily dose for IBD: 4-6 g. Max daily dose for RA: 3 g.
Note: Take after food with a full glass of water to reduce GI upset. Swallow tablet whole, do not crush or chew. Maintain adequate hydration. For IBD, enteric-coated tablets are preferred to ensure delivery to colon. Doses should be evenly spaced.
The exact mechanism is multifactorial and disease-specific. In IBD: The active moiety 5-ASA acts locally in the colonic mucosa as an anti-inflammatory, inhibiting cyclooxygenase and lipoxygenase pathways, scavenging reactive oxygen species, and inhibiting cytokine production. In RA: The sulfapyridine moiety is believed to be responsible for systemic immunomodulatory effects, including inhibition of neutrophil chemotaxis, inhibition of inflammatory pathways (NF-ÎșB), and suppression of B-cell activity and antibody production.
Pregnancy: Pregnancy Category B (US FDA). Considered compatible for use in pregnancy for maternal IBD or RA. However, it inhibits dihydrofolate reductase; concomitant folic acid supplementation (5 mg/day) is strongly recommended. Avoid during the last trimester due to risk of neonatal kernicterus (theoretical). Decision should be risk-benefit based.
Driving: May cause dizziness, headache, or vertigo. Patients should not drive or operate machinery until they know how the drug affects them.
| Digoxin | Sulfasalazine may reduce bioavailability of digoxin. | Moderate |
| Folic Acid / Folate Antagonists (e.g., Methotrexate, Trimethoprim) | Sulfasalazine inhibits folate absorption and metabolism; may increase risk of megaloblastic anemia. Concurrent use with methotrexate may increase hepatotoxicity and myelosuppression. | Major |
| Warfarin | Sulfasalazine may potentiate anticoagulant effect by displacing warfarin from protein binding sites and reducing vitamin K production by gut flora. | Major |
| Oral Hypoglycemics (Sulfonylureas) | Increased risk of hypoglycemia due to displacement from protein binding. | Moderate |
| Cyclosporine | Sulfasalazine may reduce cyclosporine levels, risking transplant rejection. | Major |
| Antibiotics (broad-spectrum) | May reduce colonic bacterial cleavage of sulfasalazine, decreasing efficacy in IBD. | Moderate |
Same composition (Sulfasalazine (1000mg)), different brands: