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Sulfasalazine
Sulfasalazine is a disease-modifying antirheumatic drug (DMARD) and anti-inflammatory medication used to treat inflammatory bowel disease (IBD) and rheumatoid arthritis (RA). It is a prodrug composed of sulfapyridine and 5-aminosalicylic acid (5-ASA), which work synergistically to reduce inflammation. This article synthesizes information from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to provide a detailed overview of sulfasalazine, including its mechanism, uses, dosing, side effects, precautions, and drug interactions.
Sulfasalazine is a prodrug that is metabolized by gut bacteria into its active components:
- Sulfapyridine: Exerts systemic anti-inflammatory and immunosuppressive effects.
- 5-Aminosalicylic Acid (5-ASA): Acts locally in the colon to reduce inflammation by inhibiting prostaglandin and leukotriene synthesis and scavenging reactive oxygen species (Lippincott, Lange).
The combined effects of these metabolites reduce inflammation and modulate the immune response, making sulfasalazine effective in treating IBD and RA (BNF).
- Ulcerative Colitis:
- Induces and maintains remission in mild to moderate ulcerative colitis (BNF).
- Crohn’s Disease:
- Used for mild to moderate Crohn’s disease, particularly affecting the colon (Lippincott).
- Rheumatoid Arthritis (RA):
- Reduces joint inflammation and slows disease progression (Lange).
- Juvenile Idiopathic Arthritis (JIA):
- Used in children with polyarticular JIA (BNF).
- Adults:
- Ulcerative Colitis/Crohn’s Disease: Start with 500 mg twice daily, increasing gradually to 3–4 g/day in divided doses (BNF).
- Rheumatoid Arthritis: Start with 500 mg daily, increasing gradually to 2–3 g/day in divided doses (Lippincott).
- Children (≥6 years):
- Juvenile Idiopathic Arthritis: 30–50 mg/kg/day in divided doses, up to a maximum of 2 g/day (Lange).
Administration:
- Take with or after food to minimize gastrointestinal side effects.
- Ensure adequate hydration to reduce the risk of crystalluria (BNF).
- Common: Nausea, vomiting, headache, and rash (Lippincott).
- Serious:
- Hematologic Toxicity: Leukopenia, thrombocytopenia, and hemolytic anemia (Lange).
- Hepatotoxicity: Elevated liver enzymes and rare cases of hepatitis (BNF).
- Hypersensitivity Reactions: Stevens-Johnson syndrome and drug rash with eosinophilia and systemic symptoms (DRESS) (Lippincott).
- Renal Toxicity: Interstitial nephritis and crystalluria (Lange).
- Sulfonamide Allergy: Contraindicated in patients with known hypersensitivity to sulfonamides or salicylates (BNF).
- Pregnancy and Lactation: Generally considered safe for use in pregnancy, but consult a healthcare provider (Lippincott).
- G6PD Deficiency: Increased risk of hemolytic anemia; avoid use (Lange).
- Monitoring: Regular full blood counts, liver function tests (LFTs), and renal function tests (BNF).
- Warfarin: Sulfasalazine may increase the risk of bleeding (Lippincott).
- Methotrexate: Increased risk of myelosuppression (Lange).
- Digoxin: Sulfasalazine may reduce digoxin absorption (BNF).
- Live Vaccines: Avoid concurrent use due to immunosuppression (Lippincott).
Sulfasalazine is the generic name for this medication. It is marketed under the brand name Azulfidine®. Generic versions are widely available and cost-effective
