Absorption, distribution and elimination of alcohol: highway safety aspects.

Key aspects of the pharmacokinetics of alcohol are highly relevant to highway safety. Of particular pertinence are the partition of alcohol between various body tissues and fluids and the resulting alcohol concentration ratios for blood: breath and other body fluids, as well as the irregularity and short-term fluctuations of the blood and breath alcohol curves. Most alcohol pharmacokinetics parameters are subject to wide intersubject variability, as exemplified by peak blood alcohol concentrations reached on ingestion of identical weight-adjusted doses, time to peak after end of drinking and the rate of alcohol elimination from the blood. This great biological intersubject variability, when combined with sex-, age- and time-related differences, makes the blood alcohol information in widely distributed alcohol consumption nomograms and tables based on mean data inappropriate as a guide for the drinking behavior of individuals. Although there is good statistical correlation between the alcohol concentration of different body tissues and fluids in the fully postabsorptive state, wide individual variations from the population mean alcohol partition values exist. It is often impossible to determine whether the postabsorptive state has been reached at any given time. Those factors make it impossible or infeasible to convert the alcohol concentration of breath or urine to the simultaneous blood alcohol concentration with forensically acceptable certainty, especially under per se or absolute alcohol concentration laws. Inclusion of breath alcohol concentrations in drinking-driving statutes, as definitions or per se offense elements, makes unnecessary the conversion of breath alcohol analysis results into equivalent blood alcohol concentrations. Urine alcohol concentrations are inadequately correlated with blood alcohol concentrations or with driver impairment, and analysis of bladder urine is, therefore, inappropriate in traffic law enforcement. Significantly large sex-related differences in pharmacokinetic parameters have been demonstrated (e.g., in peak blood alcohol concentrations for weight-adjusted doses). The effects of age and time of day have been less extensively studies and are less clear. Breath and blood alcohol time curves are subject to short-term fluctuations from the trend line and other irregularities, and often do not follow the typical Widmark pattern. From the existing information on pharmacokinetics of alcohol and the characteristics and variability of blood and breath alcohol versus time curves, the following conclusions can be reached.(ABSTRACT TRUNCATED AT 400 WORDS)