5-aminosalicylic acid drugs

Sulphasalazine (5-aminosalicylic acid conjugated to sulphapyridine)
Mesalazine (5-aminosalicylic acid)
Olsalazine (dimeric 5-aminosalicylic acid)

Indications

Ulcerative colitis, remission and maintenance. May be useful in remission in Crohn's.

Mechanism of action

Unknown.

Adverse effects

Sulphapyridine—nausea, morbilliform/urticarial rash, blood discrasias (agranulocytosis, aplastic anaemia, haemolytic anaemia—esp. G6PD deficiency). Olsalazine—watery diarrhoea.

Contraindications

G6PD (for sulfasalazine).