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Combinations of Ethanol and Prescription Drugs While Driving: Factoring Out the Effects of Ethanol

by David M. Benjamin

By David M. Benjamin, PhD  Email:

The combined pharmacologic effects of prescription drugs with CNS depressant actions and their interactions with ethanol can cause impairment of an individual's ability to safely operate a motor vehicle. Operators of motor vehicles may not have been fully informed of the effects of their prescription medications on driving by their physicians, which may predispose them towards operating a motor vehicle unsafely. When ethanol has also been consumed, impairment may be greater than one might predict from the additive effects of ethanol and medication alone. In the Commonwealth of Massachusetts (COM), OUI ethanol and OUI medications are two separate charges which may be brought against an operator stopped by law enforcement for apparent unsafe operation of a motor vehicle. In COM v. Stathopoulous, 401 Mass. 453 (1988) 517 N.E.2d 450, the MA Supreme Judicial Court (SJC) clearly annunciated that the standard required to "prove" OUI ethanol was that the "liquor diminished the defendant's capacity to operate a motor vehicle safely". Therefore, in the courtroom, separating the effects of ethanol from the effects of prescription medications is critical to helping the jury reach a correct verdict regarding the alleged charges. This author presents an approach to factor out the effects of ethanol from those of concomitant ingestion of prescription medications.

Facts of the case: CH was a 32 year old white female, 5'4", 120 lbs., with an established history of a bi-polar psychiatric disorder. On the day she was stopped, her medication and ethanol-ingestion history was as follows: 11am - lithium, 300 mg, nortriptyline, 50 mg, (non-impairing beta-blocker and thyroid medication); 7:30 pm - one "Pete's Wicked Ale", 8:30 pm - one "Pete's Wicked Ale"; 8:45 pm - lithium,600 mg and nortriptyline 50 mg. Based on CH's height and weight and using the "EZ ALC" computer program, utilizing the Widmark formula, this author was able to calculate a reasonable estimate of CH's BAC at 10:05 pm, the time she was stopped by local law enforcement. This estimate was based on the fact that according to the manufacturer, Pete's Wicked Ale contains 4.2% ethanol (w/v), and that each container of Ale contained 12 oz. to yield a total volume of pure ethanol of 0.50 oz. per container. er several days on the medication, the patient developed a coughing paroxysm and fainted. He reported this to his physician who noted it in the patient's chart, and told the patient that if it happened again, he would have to change the medication. Several days later while the patient was towing his prize racehorse in a trailer behind his car, he again began to cough, lost consciousness and overturned his vehicle, fatally injuring the racehorse, which had to be euthanized at the scene. This author testified at a Bench Trial in District Court on behalf of the injured plaintiff regarding the pharmacology of alpha adrenergic blockade and sudden, insidious drops in blood pressure, especially during valsalva maneuvers and following abrupt changes in position normally requiring compensatory sympathetic reflexes to sustain blood pressure, as well as the need for physicians to provide patients with an adequate informed consent about the material, foreseeable risks associated with taking alpha adrenergic blockering agents. The court found in favor of the plaintiff, but the decision was appealed to a jury session in Superior Court and in the re-trial, the jury found no negligence on the part of the treating physician. The plaintiff received no monetary award for any of his physical or emotional injuries, or the loss of his racehorse.

Case 2 involved a 72 year old non-insulin dependent diabetic male who "blacked out" while driving and crashed into a police car. After not eating during the day, at least two hours earlier that evening, the subject had ingested two mixed drinks after a low calorie dinner. He then walked for about 30-45 minutes before returning to his car. The subject stated that he got into his car, light a cigarette, took a deep inhalation and began to drive. The next thing he knew, he was being taken out of his car by police officers, and was subsequently charged with driving under the influence of alcohol and several other related infractions. Upon exiting the vehicle, the subject noticed that he had burnt a hole in his trousers and had lost control of his bladder. The subject had been receiving doxazosin for the treatment of difficulty in urinating due to benign prostatic hyperplasia (BPH), but had not taken the medication regularly and had just re-initiated doxazosin therapy that day. In addition to doxazosin, the subject was also taking the potent oral anti-diabetic agent glyburide, a sulfonylurea associated with a high incidence of acute hypoglycemic reactions and also known to produce a "Disulfiram-like" reaction which blocks the metabolism of ethanol and potentiates its effects. The case was dismissed by the judge for procedural reasons; however, the injuries sustained by the police officers and the driver were very real, as were the expenses to the Commonwealth of Massachusetts to retain public counsel, retain an expert to advise defense counsel, and have the matter heard by the court. Many of these injuries and the associated costs could have been obviated by an adequate instruction from the treating physician to the patient about the dangers of the concomitant ingestion of alcohol when taking sulfonylureas, the dangers of hypoglycemia following an inadequate caloric intake accompanied by increased exercise, and the potential for an individual to experience sudden, precipitous drops in blood pressure accompanied by syncope, especially following dosage increase or re-initiation of alpha adrenergic blocker therapy.