The effect of charcoal on mefenamic acid elimination

Mefenamic acid suppository 500 mg was administered by rectum to eight healthy adult volunteers followed by either activated charcoal 5 g orally at hourly intervals for 7 h or an equal volume of water on two separate occasions 7 days apart. Administration of charcoal did not significantly affect the pharmacokinetic variables of mefenamic acid. Thus the beneficial effects of charcoal in the treatment of mefenamic acid overdose are largely due to interference with absorption, rather than enhancement of elimination of the drug.