Randomized controlled study on the use of multiple-dose activated charcoal in patients with supratherapeutic phenytoin levels.

INTRODUCTION: We conducted a prospective randomized controlled study on the influence of multiple doses of activated charcoal (MDAC) in patients with supratherapeutic serum phenytoin levels;

METHODS: Patients with serum phenytoin levels greater than 30 mg/L upon presentation to the ED were recruited from two urban teaching hospitals. Patients enrolled were older than 18, nonpregnant, able to tolerate activated charcoal by mouth and able to give written consent. They were randomized to receive 50 g activated charcoal by mouth every 4 hours or no activated charcoal. They continued in the study until the patient was discharged or the serum level was <25 mg/L. Serum levels were drawn every 6 hours initially, then every 24 hours after the 1st day. The presence of gait abnormalities and nystagmus was recorded and mini-mental status exam (MMSE) scores were collected from each patient enrolled. Time to reach subtoxic levels was recorded;

RESULTS: Seventeen patients were enrolled in the study. Seven patients received MDAC, eight patients served as controls and two patients who were initially enrolled as controls inadvertently received one dose of activated charcoal and were excluded from the analysis. Both groups were comparable in age and all were male. The median time to reach a subtoxic level was 41.1 hours (range, 11.6-196) and 19.3 hours (range, 13-33) in the control and charcoal groups, respectively (p = 0.049). The median and range peak serum levels were 40.0 hours (range, 32.0-47.6) and 35.6 hours (range, 32.5-40.0) in the control and charcoal groups, respectively (p = 0.082). The median and range MMSE scores were 20 points (range, 12-30) and 19.5 points (range, 16-29) in the control and charcoal groups, respectively;

CONCLUSION: Further study is needed to determine if MDAC decreases the time to reach a subtoxic level of phenytoin in patients with supratherapeutic phenytoin levels.