Rectal absorption from aspirin suppositories in children and adults.

Absorption of salicylate was determined by means of urinary excretion techniques after rectal administration of a commercial aspirin suppository to eight children and four adults. The absorption of drug from the suppository was exceedingly slow; perhaps an order of magnitude slower than that observed after oral administration of conventional tablets. The amount of drug absorbed was highly dependent on the time between insertion and the first defecation (retention time ). Retention times as long as four to five hours resulted in only about 60% of the dose being absorbed. In our judgment the use of aspirin in the form of rectal suppositories provides the clinician with little control over drug therapy.