Adverse effects of superactivated charcoal administered to healthy volunteers

Activated charcoal is frequently administered to drug overdose patients, who may experience nausea and vomiting secondary to the drug overdose. Drinking a charcoal slurry orally may be difficult for them necessitating a gastric tube. The purpose of this study is to report the frequency of adverse effects from oral superactivated charcoal (SAC) given to healthy volunteers.

Healthy adult study subject volunteers were given a single 2000 mg (first 13 subjects) or 3000 mg (remaining 35 subjects) dose of acetaminophen. Subjects were randomized to receive no charcoal (ctrl) or 75 grams of SAC administered orally in a slurry 3 hours following the acetaminophen dose. The adverse effects of both groups were recorded and compared.

There were 48 study subject runs. The mean age was 27.4 years (SD6.5). SAC was administered to 24 subjects. Adverse effect rates were as follows (*one-tail p < 0.05): black stool* (SAC 22/ 24, ctrl 0), constipation or abdominal fullness* (SAC 12/24, ctrl 0), nausea* (SAC 5/24, ctrl 0), vomiting (SAC 2/24, ctrl 0), diarrhea (SAC 2/24, ctrl 0), anal irritation (SAC 2/24, ctrl 0), drowsiness/fatigue (SAC 2/24, ctrl 3/24), dizziness/lightheadedness (SAC 0, ctrl 1/24), headache (SAC 4/24, ctrl 0). 7 of 24 SAC subjects and 20 of 24 ctrl subjects experienced no adverse effects at all* (other than black stools for the SAC subjects). Acetaminophen may have been blunted some adverse effects. Two SAC subjects could not finish the charcoal. For the 22 subjects who finished the charcoal, SAC consumption took a mean of 10.9 minutes (SD 11.8, range 1 to 50 minutes). Thirteen subjects finished it in 7 minutes or less. Six subjects took 19 minutes or longer to finish it. The 12 heavier subjects (> 71kg) completed SAC consumption significantly faster than the 12 lighter subjects (18.7 vs 7.8 minutes, p = 0.04, single sided). This comparison included the two subjects (both lighter) who did not finish SAC consumption, so this difference was no longer significant when these two subjects were removed.

Superactivated charcoal consumption is associated with significant adverse effects in some healthy volunteers, which may impede a drug overdose patient's ability to willingly drink charcoal slurry in a reasonable period of time.