Inhibition of leucocyte motility by drugs used in ulcerative colitis.

The effects on leucocyte motility of sulphasalazine (Salazopyrin) and its metabolites sulphapyridine and 5 amino-salicylic acid have been compared with those of prednisolone and indomethacin. Sulphasalazine, its active metabolite 5 amino-salicylic acid, and prednisolone are all potent inhibitors of leucocyte motility. Sulphapyridine and indomethacin are non-inhibitory. Inhibition of leucocyte motility may explain why sulphasalazine and 5 amino-salicylic acid are effective in ulcerative colitis while sulphapyridine is not. The lack of effect of indomethacin suggests that this action of sulphasalazine does not involve inhibition of prostaglandin synthesis.