Charcoal for tolbutamide intoxications

Six healthy adult volunteers entered a study testing the claim that activated charcoal is ineffective in tolbutamide intoxication, due to the poor aqueous solubility of sulphonylureas at gastric pH. Each volunteer swallowed tolbutamide SOOmg and sodium valproate 300mg (as a reference) with SOml water I hour after a light breakfast. Within 5 min they randomly received either a 400ml slIspension of 50mg activated charcoal or water. Food was taken 2 hours after the drugs. Charcoal reduced the absorption of tolbutamide (calculated as the peak concentration and the AVe over 0-48h) by 90%, For sodium va I proate, both the peak concentration and AVe over 48 hours were significantly reduced by charcoal. but the average inhibition of absorption (65%) was significantly lower when compared with tolbutamide. These results suggest that high doses of activated charcoal can be useful for preventing absorption of sulphonylureas in acute intoxications and that ' ... the poor aqueous wiubility of these substances at gastric pH prohably delays their gastrointestinal absorption. so that they may be adsorhed onto charcoal even given severa! hours later ..

,",,'u'onen. P.J. ~t al: European JournaJ of ClInIcal Pharmacolog~ 24: ~43 ,,-.J ~. I<}~JI.

2 ReactIons 1 Apr 1983 0157-7271/83/0401-0002/0$01.00/0 ADIS Press