Concurrent use of opioids, benzodiazepines, and skeletal muscle relaxants potentiates the drug effect and respiratory depression via interactions of μ-opioid and GABA receptors. In the early 2000s when abuse of prescription drugs began to spike, a potent combination including hydrocodone, alprazolam, and carisoprodol, aka the “Houston Cocktail” or “Holy Trinity”, emerged that may give users heroin-like euphoria. This research evaluated driving while intoxicated (DWI) cases that tested positive for hydrocodone, alprazolam, and carisoprodol, between 2015 and 2019. The blood samples were collected from drivers and submitted by the Houston Police Department (HPD). They were subsequently analyzed for alcohol and drugs by reference laboratories or Houston Forensic Science Center (HFSC). Toxicological findings, demographic information, and observed impairment were evaluated for the Houston Cocktail-positive DWI cases. A total of 80 DWI/DUID cases positive for hydrocodone, alprazolam, and carisoprodol in blood in which the traffic offense occurred between May 2015 and December 2019 were identified. Among these Houston Cocktail cases, the mean (median, range) concentrations were 75 (61, 6.9-322) ng/mL for hydrocodone, 58 (48, 5.8-180) ng/mL for alprazolam, and 3.9 (3.0, 0.3-14; n = 68) µg/mL for carisoprodol; 80 (100%) and 23 (29%) cases were also positive for meprobamate (mean 13; range 1.2-41 µg/mL) and hydromorphone (1.8; 1.0-3.3 ng/mL), respectively; carisoprodol and meprobamate in 12 of the cases were qualitatively detected. Forty six percent of those cases were females and 54% were males; 44% were Blacks, 46% were Whites, and 10% were other races as identified by the arresting officer. Mean (median) age of the drivers was 36 (34) years, ranged from 22 to 60 years. Twenty eight percent of the cases were positive for the Houston Cocktail only; 21% had one other drug/metabolite, 28% two, 14% three, and 10% had four or more additional drugs/metabolites. Of the 80 cases, cannabinoids were the most frequently detected analytes (35%), followed by codeine (11%). The drivers exhibited driving problems related to lane position, vigilance, judgment, speed, and/or braking. Many of the drivers (70-84%) had red/glassy eyes, slurred speed, poor balance, HGN and impaired divided attention. The present study showed that despite a traffic safety risk, drivers in Houston continue to use this dangerous drug combination. The risk is further exacerbated by the fact that the many drivers had yet other drugs in the system besides the three drugs.
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