EVIDENCE LIBRARY
Does a Drug–Alcohol Safety Trial Establish Fitness to Drive? Lessons From the PT150 Pilot
A ten-man pilot found no significant PT150-related change in breath-derived alcohol exposure or vital signs. Its safety endpoints did not establish preserved driving performance, universal safety or pharmacokinetic equivalence.
No. Finding no additional safety signal from a drug–alcohol combination does not establish that a person can drive safely after alcohol. A ten-man pilot study of the experimental compound PT150 illustrates the distinction between physiological tolerability, alcohol exposure and functional performance.
What was randomized, and what was not
Morice and colleagues studied ten men aged 28–63 who completed a short inpatient protocol. All received PT150, a selective glucocorticoid-receptor antagonist, for five days. The study was an early safety investigation, not an assessment of driving or a treatment recommendation.
Alcohol challenges occurred before PT150 treatment on day one and after repeated treatment on day five. On each challenge day, participants received an alcoholic beverage and a low-alcohol placebo, separated by at least four hours.
Beverage order was randomized on day one and reversed on day five. PT150 exposure itself was always later in the study; there was no separate group receiving placebo medication throughout. Randomized beverage order therefore did not eliminate every possible day, practice or sequence effect.
Alcohol exposure was estimated from breath
The active beverage delivered 0.8 grams of ethanol per kilogram. The beverage placebo contained 1% ethanol, approximately 0.05 grams per kilogram, and was not a zero-ethanol control.
The study used a breath analyzer to estimate blood-alcohol equivalents. It did not directly measure ethanol in blood. Mean observed peak equivalents during active alcohol challenges were approximately 0.104% both before and after PT150.
Peak, time-to-peak and two-hour exposure-area comparisons were not significantly different between those days. The confidence interval for the peak difference extended approximately from −0.03 to +0.03 percentage points. A zero average difference with that interval is not proof of exact equivalence.
The principal safety outcomes were physiological
Heart rate and blood-pressure changes during the alcohol challenge did not differ significantly with PT150 exposure. No clinically significant abnormal electrocardiograms or serious adverse events were reported.
Five mild adverse events occurred in one participant and were assessed as unrelated to the drug. With only ten completers, the study could not reliably exclude uncommon adverse effects or establish safety across other populations, doses or treatment durations.
Some laboratory and questionnaire outcomes did change, including cortisol and selected craving comparisons. The authors discussed baseline differences and limited clinical meaning. It would therefore be inaccurate to summarize the paper as finding no changes in any outcome.
No performance result certified driving ability
The protocol included subjective questionnaires but no driving, braking, lane-control or objective cognitive-performance battery. Normal vital signs and an unremarkable ECG do not supply the missing functional evidence.
Similarly, an unchanged alcohol concentration would mean only that the tested drug did not produce a detected change in that exposure measure. It would not establish absence of alcohol effects at that concentration.
The pilot was designed around detecting relatively large effects, used exploratory analyses without multiplicity adjustment and included only healthy men. Its authors also identified the lack of direct blood-alcohol measurement as a limitation.
How to use the finding in a DUI analysis
The defensible question is which endpoint the research actually tested. Physiological tolerability, concentration, subjective symptoms and driving performance require separate evidence. The site’s laboratory-to-driving calibration analysis explains the additional validation needed before a test result becomes a driving prediction.
Primary source
Morice C and colleagues. A randomized trial of safety and pharmacodynamic interactions between a selective glucocorticoid receptor antagonist, PT150, and ethanol in healthy volunteers. Scientific Reports. 2021;11:9876. https://doi.org/10.1038/s41598-021-88609-6.