SALAZOPYRIN EN 500

Indications

• Ulcerative colitis
• Crohn's disease
• Rheumatoid arthritis

Dosage

Children: For children, the dosage must be determined based on the BNF for Children, as specific dosing guidelines depend on the child's age and weight.

Adults: For the treatment of ulcerative colitis, the initial dose is 500 mg daily, increased in steps of 500 mg every week, with a target of 2–3 g daily in divided doses. For maintenance of remission, the dosage is 500 mg twice daily after meals.

Mechanism of action

Sulfasalazine is metabolized in the body to sulfapyridine and 5-aminosalicylic acid (5-ASA). The 5-ASA component is responsible for the drug's anti-inflammatory effects, primarily through the inhibition of leukotriene synthesis, suppression of cytokine production, and scavenging of free radicals. This action reduces the inflammatory process in the intestinal mucosa.

Pharmacodynamics

The pharmacodynamic effects of sulfasalazine are attributed to its metabolites, particularly 5-ASA, which acts locally in the gastrointestinal tract. It inhibits the production of pro-inflammatory cytokines and mediators, thereby alleviating symptoms associated with inflammatory bowel diseases. Sulfasalazine has a dose-dependent efficacy, with higher doses typically providing greater therapeutic results.

Pharmacokinetics

Sulfasalazine is administered orally and is absorbed in the gastrointestinal tract. It undergoes extensive first-pass metabolism, with approximately 15% of the drug reaching systemic circulation as active metabolites. The drug's half-life varies but generally ranges from 5 to 12 hours. Sulfasalazine is primarily excreted in urine and can also affect renal function; dose adjustments may be necessary in patients with renal impairment.