Failure of intravenous aspirin to increase gastrointestinal blood loss.

Studies of the effect of intravenous sodium acetylsalicylate (aspirin) on gastrointestinal blood loss with (51)Cr-labelled red cells were made on 15 healthy male volunteers. After a control period of five days 1 g. of sodium acetylsalicylate was infused over a period of 100 minutes twice daily for three days. Faecal blood loss was not increased.In a further six subjects 3 g. of sodium acetylsalicylate was infused over a period of 120 minutes. No salicylate or acetylsalicylate was detected in saliva or gastric washings from these six subjects. Hence gastrointestinal blood loss induced by aspirin may be explained by a local effect on mucosa and not by any systemic effect.