Aminosalicylates

Mechanism of Action

• Active component is 5-aminosalicylic acide (5-ASA, or mesalazine)
  • Other forms include
    • Sulfasalazine- older; combination of 5-ASA and sulfapyridine (which acts as a carrier although causes side effects)
    • Balsalazide and Olsalazine
• Mechanism of action not fully understood
  • Thought to ‘scavenge’ free oxygen radicals locally, and blocks production of prostaglandins and chemotaxis of leukotrienes (immune system modulation)

Indications

• Mainly used in patients with Ulcerative colitis.  Also used, but to a lesser degree, in patients with Crohn’s disease (mainly ileocaecal disease).
  • Topically used for active proctitis
  • Can be used systemically if the patient has a poor response to topical treatment

Cautions/Contraindications

• MONITOR RENAL FUNCTION before, 3 months into and annually during treatment
  • Avoid in CKD 4/5 if possible (eGFR<20)
• Avoid in severe liver disease
• Avoid if allergic

Side effects

• Blood disorders (dyscrasia)- quite rare but serious
  • Any patient should report any bleeding, bruising, purpura, sore throat, fever, malaise etc
  • Stop immediately if thought to be dyscrasia (perform FBC)
• Lupus like syndrome
• Other side effects include:
  • Diarrhoea, nausea, vomiting, abdominal pain, exacerbation of symptoms of colitis, headache, allergy
  • Rarer effects include: acute pancreatitis, hepatitis, myocarditis/pericarditis; Lung disorder (eosinophilia/fibrosing alveolitis); peripheral neuropathy, myalgia, arthralgia
  • Renal dysfunction (interstitial nephritis, nephrotic syndrome)
  • Skin reactions (lupus-like syndrome (malar rash); rarely Stevens-Johnson syndrome); alopecia