Agranulocytosis associated with sulphasalazine therapy.

A case report of a patient with agranulocytosis associated with sulphasalazine therapy is described. Recovery followed supportive therapy and withdrawal of the drug. Investigations including tests for leucocyte antibodies, the presence of which might have suggested an immunological cause for the drug reaction, were negative; an acetylation study, however, characterized the patient as a 'slow' acetylator phenotype, suggesting that the drug reaction was more likely to have been toxic in nature. It is suggested that acetylation studies be performed in patients who have previously shown serious side effects to sulphasalazine to assess the incidence of 'slow' acetylators.