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Combined Dextromethorphan and Chlorpheniramine Intoxication in Impaired Drivers

NCJ Number
Jounal of Forensic Sciences Volume: 54 Issue: 5 Dated: September 2009 Pages: 1176-1180
Barry K. Logan, Ph.D., D-ABFT
Date Published
September 2009
5 pages
This study profiles eight drivers arrested for driving under the influence of the combined effects of dextromethorphan and chlorpheniramine and an additional four drivers under the influence of dextromethorphan alone.
Dextromethorphan is an over-the-counter cough suppressant/antitussive that is present in numerous cough, cold, and flu formulations. It is often taken in combination with analgesics; antihistamines, including chlorpheniramine; and a mucolytic (guaifenesin). Dextromethorphan is also abused for the intoxicating, hallucinogenic, and dissociative effects it produces when taken in high doses. The drivers examined in this study generally displayed symptoms of central nervous system depressant intoxication, and there was clear evidence of driving impairment, including weaving, leaving the lane of travel, failing to obey traffic signals, and involvement in collisions. In the eight drivers under the influence of the combined effects of dextromethorphan and chlorpheniramine, blood dextromethorphan concentrations ranged from 150 to 1,220 ng/ml, and chlorpheniramine concentrations ranged from 70 to 270 ng/ml. The four cases without chlorpheniramine present had blood dextromethorphan concentrations between 190 and 1,000 ng/ml. Some drivers had therapeutic concentrations of other drugs present. No alcohol was present in the systems of any of the drivers. The impairment shown in the driving of these individuals was consistent with that of drivers experiencing central nervous system depressant intoxication with alcohol. Concentrations of dextromethorphan in excess of 150 ng/ml were the result of abuse, not as directed for the symptomatic treatment of coughs, colds, or the flu. Blood was collected subsequent to the arrest and assessment. Toxicological analysis was performed at the Washington State Toxicology Laboratory. 1 table and 25 references