Compared to the control area under the serum concentration vs. time curve , a single dose of activated charcoal 1 h after drug ingestion reduced acetaminophen bioavailability by 20 % ( 95 % CI 4-36 % ) and by 47 % ( 95 % CI 35-59 % ) in the presence of atropine ( P < 0.05 atropine plus charcoal vs. charcoal alone ) .
