of the 16 patients given meperidine ( mean dose 4.3 +/- 0.2 ( sem ) mg/kg ) , five ( 31 % ) had clinical signs ( hypotension , tachycardia , erythema ) and elevations in plasma histamine levels ranging from 3.2 to 49.7 ng/ml 1 min after narcotic administration .
C3540840
clinical signs
C0041834
erythema