Evaluation of activated charcoal and magnesium citrate in the prevention of aspirin absorption in humans.

Inhibition of aspirin absorption by activated charcoal and magnesium citrate solution was compared with the inhibition produced by activated charcoal alone. Following an overnight fast, eight healthy male volunteers were given three 325-mg aspirin tablets under four study regimens: (1) water 360 ml; (2) water 300 ml and activated charcoal 10 g in water 60 ml; (3) water 105 ml, activated charcoal 10 g in water 60 ml, and magnesium citrate solution 200 ml; and (4) same as (3) except that administration of magnesium citrate was delayed 30 minutes. At least one week separated each regimen. Urine samples were collected at 0, 2, 4, 8, 12, 24, 36, and 48 hours, and percent of the aspirin dose excreted in the urine was determined. The data were analyzed using analysis of variance for Latin-square design and Newman-Keuls test. The salicylate excreted with regimens 2, 3, and 4 was each significantly less compared with that excreted following regimen 1 (p less than 0.001). Salicylate excretion percentages when magnesium citrate was given with activated charcoal in regimens 3 and 4 were not significantly different from each other or the salicylate excretion with activated charcoal alone (p greater than 0.05). These findings apply only to the dose of aspirin tested, and it is possible that magnesium citrate and activated charcoal may decrease aspirin absorption to a greater extent when aspirin is taken in overdose. Hence, it is recommended that this study not be used to justify discontinuing the combined use of magnesium citrate and activated charcoal to treat aspirin overdose.