Randomized study of the treatment of phenobarbital overdose with repeated doses of activated charcoal.

We performed a prospective randomized study of the effectiveness of repeated oral doses of activated charcoal in the treatment of phenobarbital overdose. Ten comatose patients who required intubation and mechanical ventilation completed the protocol. Five patients received repeated doses of activated charcoal and sorbitol. Five other patients who received a single dose of charcoal and cathartic served as control subjects. The serum half-life of phenobarbital (mean +/- SD, 36 +/- 13 hours) during repeated administration of charcoal and sorbitol was significantly shorter than that after charcoal administration was discontinued (93 +/- 7 hours) and shorter than the half-life in the single-dose group (93 +/- 52 hours). The length of time that patients in each group required mechanical ventilation, 39 +/- 24 hours (single-dose group) and 48 +/- 8 hours (repeated-dose group), did not differ significantly, nor did the time spent in the hospital. Although administration of repeated doses of activated charcoal to patients with phenobarbital overdose significantly increased the elimination of phenobarbital, it had no clear effects on the patients' clinical course.