Forensic Toxicology and Illicit Drugs Notes

Forensic Toxicology and Illicit Drugs

Introduction

  • Peter Stockholm from Forensic Science South Australia, specializing in toxicology.
  • Focus: Analyzing drugs and poisons in blood samples.

Forensic Drug Chemistry and Toxicology

  • Detection, identification, quantification, and interpretation of drugs.
    • Seized materials (forensic drug chemistry).
    • Biological samples (forensic toxicology).
  • Unambiguous identification is crucial for court admissibility.
  • Quantification:
    • Forensic chemistry: determining the amount of controlled substance.
    • Forensic toxicology: determining drug concentration and its effects (driving impairment, overdose, medication compliance).
  • Interpretation:
    • Forensic chemistry: interpreting drug findings against legislation.
    • Forensic toxicology: interpreting drug concentrations (toxic, therapeutic, lethal).

Forensic Drug Chemistry

  • Deals with seized substance analysis.
    • Examples: Synthetic cannabis, methamphetamine.
  • Clandestine laboratories are a significant problem, especially for methamphetamine.
Safety Concerns
  • Chemists require sophisticated protective gear due to toxic substances.
  • Rise in synthetic benzodiazepines.
    • Novel psychoactive substances (NPS) are a growing concern.

Forensic Toxicology

  • Trace analysis in biological specimens.
    • Specimens: Liver (post-mortem), urine, blood, vitreous humor.
  • Analysis includes illicit drugs and prescription drugs.
  • Goal: Determining cause of death or condition during an incident.

Drug Classification

  • Classify by three areas:
    • Broad Chemical Properties (analytical toxicology).
    • Therapeutic class, action or receptor (clinical or interpretive toxicology).
    • Legislation (forensic science and law enforcement).
Chemical Properties Classification
  • Acidic vs. basic drugs.
    • Basic drugs: generally contain an amine group (RNH2RNH_2).
      • Example: Amphetamine.
    • Acidic drugs: generally contain a carboxyl group (CO2HCO_2H).
      • Example: GHB.
    • Neutral drugs: lack active hydrogens.
  • Exploiting differences in properties for extraction.
  • pKa: concentration at which there is an equal number of charged and uncharged molecules.
  • Separation into acidic or basic classes.
Therapeutic Class/Action Classification
  • Based on drug effect on the body.
    • Examples: Antidepressants, stimulants, sedatives, analgesics.
  • Based on receptor action.
    • Examples: Opioids (act on mu opioid receptor), cannabinoids (act on CBD receptors).
Legal Classification
  • Based on legislation and community standards.
  • South Australia uses the Controlled Substances Act (updated regularly).
  • Regulations are easier to change than the act itself.
  • National scheduling (SUSMP) for drug classification.
Schedules
  • S2: Pharmacy medicine.
  • S3: Pharmacist only medicine.
  • S4: Prescription medicine.
  • S8: Drugs of dependence (e.g., morphine, oxycodone, fentanyl).
  • S9: Prohibited substances with no medical use (e.g., heroin, cocaine, LSD).
  • New psychoactive substances (NPS) are often scheduled in S9.
Importance of Regulation
  • Safety is paramount, considering drug interactions with receptors.
  • Drug effects can cause psychological, physical, and societal harm (addiction).

Historical Context

  • Paracelsus: Dose determines if a substance is a poison.
  • Example: Fellowes Compound Syrup containing strychnine.
    • Labeled as poison but considered safe in small doses.
  • Many now-prohibited substances were commonplace.
  • Fouldings: Sold coca wine.
  • Sepulks: Sold Sedna (coca wine, cola wine, port wine, beef wine).
  • Heroin was freely available for medicinal purposes.
Advertisements from the 1940s
  • Benzedrine (amphetamine sulfate).
  • Cocaine for sore throats and toothaches.
  • Heroin as an analgesic.
  • Chlorodyne: Contained morphine, chloroform, cannabis, and hydrocyanic acid.

Common Illicit Drugs

  • Methamphetamine.
  • Cannabis (THC).
  • MDMA.
  • These three drugs were detected in 21% of drivers/riders killed in road accidents.
  • GHB (common in Adelaide).
  • Cocaine (less popular in Adelaide).
  • Opiates.
  • New psychoactive substances (NPS): Chemical analogs of older drugs or completely novel drugs.
Emergency Department Study in Adelaide
  • 50% of patients had methamphetamine.
  • Alcohol was second most common.
  • GHB was surprisingly prevalent.
  • Diazepam and MDMA were also detected.
  • Flualprazolam and etizolam (NPS) were present.
  • Most cases involved multiple drug use (average 2.9 drugs per person, up to 9 in some cases).
  • 95% of GHB users also used methamphetamine.
Other Drug Examples
  • Methamphetamine, MDMA pills, cannabis.
  • Roadside drug testing.
Opioids and Opiates
  • Morphine (S8 drug).
  • Codeine (S4 drug).
  • Heroin (S9 drug).
  • Oxycodone.
Emerging Opioid NPS
  • AH-7921, U47700, ocfentanil, parafluorofentanyl.
  • Some were failed pharmaceuticals from the 80s and 90s.
GHB (Gamma-Hydroxybutyrate)
  • Causes euphoria, hypnosis, amnesia, drowsiness, and CNS depression.
  • S9 drug; often a result of butanediol or GBL.
  • Butanediol, converted to GHB in the body, is found in industrial products.
New Psychoactive Substances (NPS)
  • Since 2010, approximately 1500 new drugs have emerged.
  • Presents a challenge for analysis and harm reduction.

Forensic Toxicology Process

  • Detection, quantification, and interpretation.
Sample Types
  • Coronial cases: Blood, urine, liver, vitreous humor.
  • Police samples: Urine, blood.
  • Traffic: Oral fluid, blood.
Drug Interests
  • Alcohol, prescription drugs, illicit drugs, pesticides, and poisons.
Drug Facilitated Sexual Assault
  • Alcohol, sedatives, prescription drugs, illicit drugs.
Impaired Driving
  • Alcohol, Methamphetamine, THC, MDMA

Drug Detection Methods

  • Sample Preparation.
    • Transforming the sample to a suitable form.
    • Concentrating the sample for analysis on instrumentation.
Sample Preparation Methods
  • Protein precipitation (for alcohol).
  • Liquid-liquid extraction (adjust pH and extract with solvent).
  • Solid-phase extraction (uses columns with selective binding).
Instrumentation
  • Sophisticated, state-of-the-art equipment.
  • Liquid chromatography-mass spectrometry (LC-MS).
  • Gas chromatography-mass spectrometry (GC-MS).
Chromatography
  • Separates mixtures into components.
Mass Spectrometry
  • Measures and identifies characteristic fragments.
LC-QTOF (Quadrupole Time-of-Flight Mass Spectrometry)
  • Accurate mass measurement.
  • Retention time and mass spectrum for identification.
Gas Chromatography (GC)
  • Widely used in illicit drug chemistry.
  • Separates compounds based on affinity for the column.
  • Retention times and mass spectral matching for identification.

Interpretation of Results

  • Determining therapeutic, toxic, or lethal drug levels.
  • Requires specialist expertise (pharmacologist or forensic pathologist).
Postmortem Complications
  • Drug concentrations may change after death due to cellular breakdown and bacterial degradation.
Additional Complexities
  • Drug interactions (e.g., alcohol + benzodiazepines).
  • Tolerance development.
Analytical vs. Forensic Toxicologist
  • Pharmacologist: Provides opinions on drug effects and interactions.
  • Analytical toxicologist: Provides general interpretations and therapeutic ranges.

Conclusion

  • Overview of illicit drugs and forensic toxicology.
  • Contact information for questions.
  • Mention of the "Tox Pod" podcast.