Sulfasalazine
Mechanism :
The mode of action of sulfasalazine or its metabolites, 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP), is still under investigation, but may be related to the anti-inflammatory and/or immunomodulatory properties and to its affinity for connective tissue, and/or to the relatively high concentration it reaches in serous fluids, the liver and intestinal walls.
Indication :
- Inflammatory bowel disease
- Juvenile idiopathic arthritis
Contraindications :
Hypersensitivity to sulfasalazine, its metabolites, sulfonamides or salicylate in patients with intestinal or urinary obstruction and in patients with porphyria, as the sulfonamides have been reported to precipitate an acute attack. Contraindicated in children <2 years of age and caution in patients with G6PD deficiency.
Dosing :
<2 years:
Safety and efficacy not established.
≥2 years:
Acute Attack or relapse: 40-60 mg/kg/day PO in divided doses, Maintenance Dosage: 20-30 mg/kg/day PO in divided doses.
Adverse Effect :
Cyanosis, hemolytic anemia, stomatitis, elevated hepatic enzymes, leukopenia, thrombocytopenia, hypoglycemia, goitre, nausea, anorexia, vomiting, oligospermia, headache, dyspepsia, rash, abdominal pain, fever, pruritus, dizziness, urticaria, exacerbation of colitis
Interaction :
Digoxin and Folic Acid: May reduce gastrointestinal absorption.
Antibiotics: That alter intestinal flora may interfere with conversion of sulfasalazine to sulfapyridine and 5-aminosalicylic acid (5-ASA) decreasing its effectiveness.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function. Use with caution |
| 10-20 | Dose as in normal renal function. Use with caution |
| <10 | Start at very low dose and monitor. Use with caution |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unlikely to be dialysed. Dose as in GFR<10 mL/min |
| HD | Unlikely to be dialysed. Dose as in GFR<10 mL/min |
| HDF/High flux | Unlikely to be dialysed. Dose as in GFR<10 mL/min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
Dose adjustment guidelines are not available. In the setting of impaired liver function, extreme caution should be taken when using this drug. Discontinue drug as soon as signs of liver toxicity or jaundice develops. Hepatic necrosis can occur. Slow acetylators are at an increased incidence of adverse effects, perhaps due to increased sulfapyridine concentrations.