To the Editor.—
As medical director of Glenbrook Laboratories, which markets timed-release aspirin, I was somewhat surprised that Dr. James Hoon (229:841, 1974) reported uncontrolled observations, which are, of course, open to interpretation, based on data from only three patients.In the interest of furthering scientific inquiry, I would like to discuss a previously unpublished study on this subject that is in our files. In a well-controlled crossover study of 18 subjects who each received 250 microcuries of radioactive chromium to determine gastrointestinal blood loss from sustained-release aspirin, the mean blood loss did not reach any level of clinical significance. In real values, the mean average blood loss for the 18 subjects in the control period was 0.51 ml, whereas the mean for regular aspirin was 4.11 ml, and for sustained-release aspirin, 3.09 ml. The difference between the latter two figures is statistically significant, but the losses are clinically insignificant.