Alcohol Physiology and Pharmacology Vermont Forensic Laboratory

DISCLAIMER  This presentation includes information that is intended to give the students a basic understanding of alcohol physiology and pharmacology.  It is not designed to make the students experts in this subject.

What is Alcohol? It is a drug. It is a poison. It is a Central Nervous System (CNS) Depressant. Any Carbon attached to an OH group. Ethanol, Methanol, Isopropanol etc.

Who Uses Alcohol? Alcohol is the most widely used drug. In 2013, 86.8 percent of people ages 18 or older reported that they drank alcohol at some point in their lifetime; 70.7 percent reported that they drank in the past year; 56.4 percent reported that they drank in the past month.

Alcohol-Related Deaths Nearly 88,000 people die from alcohol- related causes annually, making it the third leading preventable cause of death in the United States. In 2013, alcohol-impaired driving fatalities accounted for 10,076 deaths (30.8 percent of overall driving fatalities).

Alcohol Physiology Absorption Distribution Metabolism Elimination

Absorption Drink is consumed orally (typically) 10-20% of the alcohol is absorbed directly through the stomach wall % is absorbed through the wall of the small intestine. Alcohol is a small molecule and does not require digestion to be absorbed.

What can affect absorption? Stomach emptying (opening of pyloric sphincter) Food Type of beverage Proof of liquor Gastric bypass Speed of consumption

What can affect absorption? In terms of a DUI, we are concerned with alcohol consumed within 30 minutes of operation. Some or all may still remain in the stomach.

Once the alcohol is absorbed it circulates in the blood throughout the body. Observable effects are a reaction to the alcohol in the brain. Distribution

Ethanol is hydrophilic = water loving. Ethanol moves into muscles & organs but not into adipose tissue or bone.

Volume of Distribution (Vd) BAC is affected by the volume of distribution. Vd changes based on size, gender and body mass index.

Volume of Distribution (Vd) Women tend to have higher levels of adipose tissue which means that the Vd is smaller resulting in a higher BAC than would be expected of a man of the same size. Same issue would occur between a lean person and an obese person of the same weight.

Blood Alcohol Concentration The amount of ethanol found in a sampled portion of blood. Typically expressed as a percentage or in terms of g/100ml. AKA: BAC

Breath Alcohol Concentration “Breath Alcohol Concentration” used when concerning a breath test. (BrAC) Breath values reported as grams of alcohol per 210 liters of expired air. (g/210L)

Metabolism Once consumed some alcohol is metabolized in the stomach by an enzyme, ADH. ADH = Alcohol Dehydrogenase, the prime enzyme responsible for metabolism. Main site of metabolism is in the liver. Intestine  Portal Vein  Liver

Elimination Excretion: 2-3% of the alcohol consumed is excreted via sweat, breath and urine. Excretion allows us to measure alcohol in a breath sample.

Elimination Elimination: Includes excretion and the metabolic breakdown of ethanol % of alcohol eliminated is through the breakdown into its metabolites via ADH. The effective dose of alcohol overwhelms the body’s ability to metabolize it away. (Until levels reach below 0.01)

Elimination The rate of elimination is constant and not dose dependent.

Elimination Typical elimination: %/hour Range: %/hour Extreme cases: %/hour (estimates) 0.015%/hour used in calculations as it meets or underestimates the “true” elimination rate of a majority of the population.

What can affect Elimination? Gender: Women tend to eliminate faster Experience: Experienced drinkers eliminate faster. Person to person variability exists as well as inter-day variability for the same person. Some medications and fructose may affect elimination to a minor degree by increasing or decreasing the rate.

What does NOT affect elimination? Coffee Cold showers Exercise Sleep

What is Impairment? Impairment = Deterioration of one’s physical or mental abilities from normal. May be caused by many things. Alcohol impairment = the deterioration is due to alcohol consumption.

Impairment Measurable impairment in laboratory settings as low as Abilities used to operate a vehicle are affected at The ability to drive in all individuals is affected at 0.08 level Per se limit is to reflect this fact. NHTSA 2001

Impairment Legal limit has decreased as scientific understanding has increased. Scientific Communities have urged a reduction to Some countries as low as 0.02.

The Effects of Alcohol 3 2 1

Low Level Impairment Feeling of well-being Relaxation Decreased inhibitions Euphoria Lowering of caution Some minor impairment of reasoning and memory

Mid Level Impairment Impairment of balance, speech, vision, reaction time, and hearing. The ability to multi-task is reduced. Judgment and self-control are reduced. Caution, reason and memory are impaired.

High Level Impairment Gross motor impairment and lack of physical control. Blurred vision and major loss of balance. Judgment and perception are severely impaired. Exaggeration of emotions.

Extremely High Level Impairment Feeling dazed/confused or otherwise disoriented. Limited perception of pain. Blackouts are likely at this level. All mental, physical and sensory functions are severely impaired. Possible onset of coma or death due to respiratory arrest.

Impairment Cognitive skills are affected first and at lower concentrations. Overlap of effects occur between levels. Observable signs may be altered by tolerance.

Impairment Speed at reaching BAC may effect observable signs of impairment. Mellanby Effect: Impairment is greater when BAC is rising as opposed to falling.

Tolerance Behavioral: An individual accustomed to a certain BAC may learn to hide outward signs of intoxication. Walking and talking may seem normal.

Tolerance Physiological: The body is accustomed to the alcohol and has “learned” how to eliminate it quickly. May have increased levels of ADH or higher usage of secondary pathway.

Tolerance Impairment still exists to the same degree in terms of cognitive abilities. Ability to multi-task and react quickly to a changing situation is still impaired. This is well researched and documented.

Tolerance Tolerant ≠ Sober

Heavy Drinkers Some heavy drinkers may rarely reach a zero BAC.

Predicting BAC

Widmark Equation: Used by chemists to determine the impact of a drink to a person’s BAC. Based on type of beverage, weight and gender of individual.

The Standard Drink A standard drink is the equivalent dose of beer, wine and liquor which yield the same BAC.

The Myth of the Standard Drink Why is it a myth? Drinks are not always poured to the same amount. Alcohol concentrations of beer and wine vary. Home mixed drinks are substantially stronger than those served at an establishment.

The Myth of the Standard Drink A “standard” drink will be used by the chemist when no other information is given about what was actually consumed. Keep in mind that a beer is not a beer. There can be great variations.

Retrograde Extrapolation AKA Relation Back A calculation used by chemists to determine what an alcohol concentration would have been at an earlier point in time. Based on test result, time of test, time of operation and any drinking history available.

Retrograde Extrapolation The Widmark equation is used when drinking occurs after or within 30 minutes of operation.

Retrograde Extrapolation A relation back calculation is required: 1) The test occurs more than 2 hours from the time of operation. 2) The test result is below a ) A drink has been consumed after or within 30 minutes of operation.

Things to Remember! Alcohol is a CNS Depressant. Alcohol is eliminated at a constant rate per hour. Absorption and elimination occur simultaneously. Impairment begins at very low BAC. Everyone is impaired to operate a motor vehicle at an level.