L2 Forensics Alcohol Dr Peter Moult 24_25

Page 1: Overview

  • Title: University of Glasgow Toxicology - Alcohol: The Twelve SINGLE MALTS of Christmas

  • Notable brands:

    • MTM Laphroaig

    • Lengrowmore

    • Ardbeg 10

    • Glenlivet

    • Lenfidd

    • Highland Macleods 12 Years Old

    • Ark 12

  • Contact: Dr. Peter Moult, Peter.Moult@glasgow.ac.uk, Sir James Black Building 341

Page 2: Lecture Aims

  • Explain the effects of alcohol and describe its clearance from the body.

  • Describe how alcohol concentrations are determined.

  • Detail effects of drugs of abuse, including prescription medications.

  • Explain how drugs are detected within the body.

Page 3: Pharmacology

Pharmacodynamics

  • Focuses on what the drug does to the body.

  • Involves:

    • Receptor binding

    • Post-receptor effects

    • Chemical interactions

Pharmacokinetics

  • Focuses on what the body does to a drug.

  • Elements include:

    • Absorption

    • Distribution

    • Metabolism

    • Elimination

Page 4: Introduction to Alcohol

  • Alcohol definition: Ethyl alcohol (ethanol).

  • Characteristics:

    • Clear and colorless, miscible with water.

    • Contains by-products/additives for color and flavor.

  • Production process: Fermentation from grapes/cereal grains.

    • Chemical equation: C6H12O6 + H2O → C2H5OH + CO2 (using yeast)

Page 5: Alcohol Absorption & Distribution

  • Pathway:

    • Mouth → Oesophagus → Stomach → Small Intestine → Circulatory System → Brain → Kidneys → Lungs → Liver

Page 6: Factors Affecting Absorption

  • Key factors:

    • Quantity of alcohol consumed

    • Concentration of the drink

    • Contact time in the gastrointestinal tract (GIT)

    • Presence of food

    • Rate of stomach emptying

Page 7: Alcohol Distribution

  • Characteristics:

    • Rapid distribution to all organs, directly related to water content of these compartments.

    • Majority of body organs/fluids remain in equilibrium with blood.

Page 8: Blood Alcohol Levels and Effects

  • Blood Alcohol Concentration (BAC) levels in mg/100ml and effects:

    • Under 50: Not obvious, talkative

    • 50 - 100: Slurred speech, bravado, coordination loss

    • 100 - 150: Marked loss of gait, possible nausea

    • 150 - 200: Nausea, non-cooperative, total loss of interest

    • 200 - 300: Probable coma

    • 300 - 400: Coma, impaired respiration

    • 400+: Death may ensue from respiratory paralysis

Page 9: Elimination of Alcohol

  • Metabolism Process:

    • Over 90% of ethanol metabolized into acetaldehyde, followed by conversion to carbon dioxide and water.

    • Average reduction in BAC: 15 mg/100ml - 18 mg/100ml/hour (0.015 - 0.018 %/hour)

Page 10: Enzymatic Pathway - Alcohol Dehydrogenase

  • Reaction:

    • CH3CH2OH + NAD+ → CH3CHO + NADH

    • CH3CHO + NAD+ + H2O → CH3COO- + NADH

  • Key enzyme involved: Alcohol Dehydrogenase

Page 11: Human ADH Isozymes

  • Genetic Aspect:

    • Various isozymes with distinct properties affecting alcohol metabolism.

    • Individuals may be fast or slow metabolizers.

  • Pharmacokinetics:

    • Zero-order kinetics: clearance rate regardless of concentration.

  • Influencing factors: liver size and body mass.

Page 12: Oxidative Pathways of Alcohol Metabolism

  • Involves:

    • Peroxisomes, catalase, and cytochrome P450.

    • MEOS (microsomal ethanol-oxidizing system) plays a significant role.

    • Free radicals may cause tissue damage.

    • Result in increased reactive oxygen species (ROS) formation.

Page 13: Road Traffic Act 1988

  • Sections of interest:

    • Section 4(1): Driving while unfit due to alcohol or drugs

    • Section 4(2): In charge of a vehicle while unfit through alcohol or drugs

    • Section 5(1)(a): Driving after exceeding prescribed alcohol limits

  • Purpose: Safety regulations in driving concerning alcohol consumption.

Page 14: Legal Limits of Alcohol

England, Wales, Northern Ireland

  • Legal blood alcohol limit: 80 mg/100 ml

  • Breath alcohol limit: 35 µg/100 ml

  • Urine alcohol limit: 107 mg/100 ml

Scotland

  • Legal blood alcohol limit: 50 mg/100 ml

  • Breath alcohol limit: 22 µg/100 ml

  • Urine alcohol limit: 67 mg/100 ml

Page 15: Correlation of Alcohol Concentrations

Blood Alcohol Concentration (BAC)

  • Quick equilibration across the blood-brain barrier: accurate measure of brain alcohol influence.

Urine Alcohol Concentration

  • Provides a mean value over excretion period.

Breath Alcohol Concentration

  • Equilibrium with blood concentration (about 1:2300).

  • Alcohol excretion can also occur through breath, urine, perspiration, and saliva.

Page 16: Correlation & Conversion Factors

  • URINE ALCOHOL CONCENTRATION: Blood Alcohol x 1.3 = Urine Alcohol (mg/100 ml)

  • BREATH ALCOHOL CONCENTRATION: Blood Alcohol / 2300 = Breath Alcohol (mg/100 ml)

Page 17: Analysis of Alcohol

Biochemical Methods

  • Enzymatic measurement of alcohol concentration utilizing ADH and NAD+.

  • Reaction: CH3CH2OH + NAD+ → CH3CHO + NADH + H+

Page 18: Chemical Analysis Techniques

  • Various breathalyzer methods:

    • Electrochemical fuel cell

    • Infrared optical sensor

    • Dual sensor breathalyzers

  • Gas chromatography analysis for precise measurements.

Page 19: Detailed Analysis of Alcohol Detection

Electrochemical Method

  • System employs electric current to measure alcohol levels through a fuel cell.

  • Components: anode, cathode, platinum catalysts, etc.

Page 20: Infrared Optical Sensor

  • Infrared sensing methods for breath alcohol detection.

    • Example: Breath shows 120 mg/100ml.

Page 21: Alcohol Elimination Rate Calculation

  • Formula: Blood alcohol concentration = Cmax - (t x elimination rate).

  • Average elimination: 18 mg/100mL/hour.

  • Individual variations may range from 9 - 27 mg/100mL/hour.

Page 22: Elimination Example Calculation

  • Example:

    • If Cmax = 120 mg/100 ml and 4 hours have passed, elimination calculated as follows:

    • Slow metabolizers: 120 - (4 x 9) = 84 mg/100 ml

    • Fast metabolizers: 120 - (4 x 27) = 12 mg/100 ml

Page 23: Determining Time Below Legal Limit

  • Alcohol level found in blood sample: 160 mg/100 mL.

  • Determining time to drop below legal blood alcohol limit in Scotland (50 mg/100 mL).

Page 24: Calculation for Elimination Time

  • Required drop: 160 mg/100 mL to 50 mg/100 mL, needs a decrease of 110 mg/100 mL.

  • Elimination time calculated: Average value 6.11 hours.

  • Variability: 4.07 hours (fast metabolizers) to 12.2 hours (slow metabolizers).

Page 25: Summary & Key Takeaways

  • Key learning outcomes:

    • Explain effects of alcohol.

    • Understand alcohol metabolism enzymes.

    • Recognize factors determining metabolic variance.

    • Describe alcohol clearance from the body.

    • Explain methods of determining alcohol concentration in body.

Detailed Revision Notes on Alcohol and Drugs

Intended Learning Outcomes

  1. Effects of Alcohol and Clearance from the Human Body

    • Effects of Alcohol

      • Blood Alcohol Concentration (BAC) levels and corresponding effects:

        • Under 50 mg/100ml: Not obvious, talkative

        • 50 - 100 mg/100ml: Slurred speech, bravado, coordination loss

        • 100 - 150 mg/100ml: Marked loss of gait, possible nausea

        • 150 - 200 mg/100ml: Nausea, non-cooperative, total loss of interest

        • 200 - 300 mg/100ml: Probable coma

        • 300 - 400 mg/100ml: Coma, impaired respiration

        • 400 mg/100ml and above: Death may ensue from respiratory paralysis

    • Clearance of Alcohol from the Body

      • Metabolism Process: Over 90% of ethanol is metabolized into acetaldehyde, which is further converted into carbon dioxide and water

      • Average reduction in BAC: 15 mg/100ml - 18 mg/100ml/hour (0.015 - 0.018 %/hour)

  2. Determining Alcohol Concentrations in the Body

    • Blood Alcohol Concentration (BAC): Quick equilibration across the blood-brain barrier, serves as an accurate measure of brain alcohol influence

    • Urine Alcohol Concentration: Provides a mean value over the excretion period

    • Breath Alcohol Concentration: Equilibrium with blood concentration (approximately 1:2300 ratio)

    • Conversion Factors:

      • Urine Alcohol Concentration = Blood Alcohol x 1.3

      • Breath Alcohol Concentration = Blood Alcohol / 2300

  3. Effects of Drugs of Abuse and Prescription Drugs

    • Key Drugs of Abuse: Various substances including illicit drugs and misuse of prescription medications

    • Drug Effects: Vary widely based on drug type, dosage, and individual physiology

    • Pharmacodynamics & Pharmacokinetics:

      • Pharmacodynamics: What the drug does to the body (receptor binding, post-receptor effects, chemical interactions)

      • Pharmacokinetics: What the body does to the drug (absorption, distribution, metabolism, elimination)

  4. Detection of Drugs in the Body

    • Detection Methods:

      • Biochemical Methods: Enzymatic measurements utilizing Alcohol Dehydrogenase and NAD+ for alcohol concentration

      • Chemical Analysis Techniques: Various methods including breathalyzer techniques (electrochemical fuel cells, infrared optical sensors) and gas chromatography for precise measurements

      • Average Elimination Rate: Influences how long drugs and alcohol remain detectable in the body, with variations by individual metabolism rates.