Forensic Toxicology and Illicit Drugs Study Notes
Introduction
Peter Stockholm from Forensic Science South Australia introduces forensic toxicology, focusing on drug analysis in blood samples.
The discussion covers forensic drug chemistry, drug classification, historical remedies now illicit, common illicit drugs, and forensic toxicology aspects.
Forensic Drug Chemistry and Toxicology
Deals with the detection, identification, quantification, and interpretation of drugs.
Forensic drug chemistry focuses on seized materials.
Forensic toxicology analyzes biological samples.
Key Aspects
Detection and Identification: Requires robust and unambiguous methods using sophisticated instrumentation for court defensibility.
Quantification: Determining the amount of substance present.
Forensic chemists determine the amount of controlled substance in seized material.
Forensic toxicologists determine drug concentration to assess its impact on performance, overdose potential, or medication adherence.
Interpretation: Understanding the implications of detected substances and their concentrations.
Forensic chemistry interprets findings against legislation.
Forensic toxicology interprets drug concentrations in terms of toxic, therapeutic, or lethal levels.
Forensic Drug Chemistry
Focuses on seized substance analysis.
Examples include synthetic cannabis and large methamphetamine seizures.
Clandestine Laboratories
Presents a significant global challenge, particularly for methamphetamine production.
Involves the use of dangerous chemicals under unsafe conditions.
Chemists require sophisticated protective gear due to the toxicity of the substances involved.
Synthetic Benzodiazepines
Rise in novel psychoactive substances (NPS) found in tablets like Karma (alprazolam).
These substances pose a growing problem in various regions.
Forensic Toxicology
Focuses on trace analysis in biological specimens.
Deals with very low concentrations of drugs in various samples (liver, urine, blood).
Analyzes both illicit and prescription drugs to determine cause of death or state before an incident.
Drug Classification
Classification can be based on chemical properties, therapeutic effects, or legislation.
Broad Chemical Properties
Classification based on whether a drug is acidic, basic, or neutral.
Basic drugs contain an amine group (RNH2), like amphetamine.
Acidic drugs contain a carboxyl group (COOH), like GHB.
Neutral drugs lack active hydrogens, extractable under various conditions.
Exploits differences in properties by adjusting pH to extract drugs using organic solvents -- at the correct pH, the drug will be soluble in the solvent but not in the biological sample and can be extracted easily.
Key factor: pKa, the concentration at which charged and uncharged molecules are equal.
Drugs can be categorized into acidic or basic classes based on the presence of nitrogen or carboxylic acid. If they have no active hydrogens, they will be neutral.
Therapeutic Class or Action
Classification based on drug effects or receptor action.
Examples include antidepressants, stimulants, sedatives, and analgesics.
Categorization by receptor action includes opioids (acting on mu opioid receptors) and cannabinoids (acting on CB receptors).
Legislation
Classification based on legal status (restricted, unrestricted, prohibited).
Forensic science and law enforcement use this classification.
South Australia uses the Controlled Substances Act to classify drugs.
Regulations are easier to change than acts, allowing for more adaptable control of substances.
Australia uses the Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP) for harmonized classification.
Schedules range from S2 (pharmacy medicine) to S9 (prohibited substance).
S8: Drugs of dependence (e.g., morphine, oxycodone, fentanyl), requiring monitoring but having therapeutic value.
S9: Prohibited substances with no medical use (e.g., heroin, cocaine, LSD).
Regulation of Substances
Regulation aims to ensure safety due to drugs' interaction with receptors.
Drugs can cause psychological, physical, and societal harm (e.g., addiction).
Historical Context
Paracelsus: Dose determines if a substance is a poison.
Example is Fellowes compound syrup, containing strychnine hydrochloride.
Strychnine is a potent poison, but the syrup was meant to be taken in small doses as a tonic.
Historical Remedies
Many current prohibited substances were commonplace in the late 1890s.
Failing's sold coca wine to enhance mental and physical performance.
Sepulks sold Sedna, a mix of coca wine, cola wine, port wine, and beef wine.
Heroin was used for medicinal purposes; consumption doubled after World War II.
Advertisements from the 1940s
Benzedrine (amphetamine sulfate) was advertised for fitness and weight loss.
Cocaine was used as an anesthetic for sore throats and toothaches.
Heroin was used as an analgesic.
Chloridyne: treatment for diarrhea, dysentery, cholera, fever, neuralgia, cramps, and as a sedative (contained morphine, chloroform, cannabis, and hydrocyanic acid).
Chlorodine was a popular drug in the early 20th century, leading to addiction and deaths due to its high morphine content.
Common Illicit Drugs
Methamphetamine and Cannabis (THC) are most common.
MDMA is still present, but less so than before.
These three drugs are frequently detected in drivers/riders killed in road accidents (21%).
GHB is a common drug, especially in Adelaide.
Cocaine is less popular in Adelaide compared to other states.
Opiates are consistently present.
New psychoactive substances (NPS) are chemical analogs of older drugs (legal alternatives or different structures with similar effects).
NPS are frequently based on failed pharmaceuticals
Emergency Department Study in Adelaide
50% of patients with drug intoxication symptoms had methamphetamine.
Most popular drug detected was alcohol, followed by GHB.
Other drugs: diazepam, MDMA, LSD, flualprazolam, and itazolam.
Most cases involved multiple drugs (average 2.9, up to 9).
95% of GHB users also had methamphetamine on board.
Other Illicit Drugs
Methamphetamine, MDMA pills, and cannabis are commonly seen.
About 1 in 10 people test positive on random roadside oral fluid testing.
Roadside tests are 97% accurate.
Opioids and Opiates
Classified under different schedules based on their potential for harm and dependence.
Morphine (S8): Restricted drug of dependence.
Codeine (S4): Prescription drug.
Heroin (S9): Illicit due to chemical modifications (acetyl groups) that enhance its ability to cross the blood-brain barrier.
Oxycodone: Another opiate.
Opioids have similar effects but different chemical structures, acting on the opioid receptor.
Emerging opioid NPS (e.g., Ah7921, U44770, Optafentanil) were failed pharmaceutical trials.
GHB
Causes euphoria, hypnotic effects, amnesia, drowsiness, and central nervous system depression.
GHB itself is an S9 drug.
Butanediol or gamma butadiolactone can be converted into GHB in the body (GBL and butanediol are used in industry).
Bedos Example
In 2007, the manufacturer switched from one-five pentanediol to one-four butanediol, leading to kids eating them and becoming intoxicated.
New Psychoactive Substances
Since 2010, over 1,500 new drugs have emerged.
Presents a challenge for law enforcement and toxicology.
Potential harm is significant because these drugs have not been tested on humans.
Forensic Toxicology: Detection, Quantification, and Interpretation
Involves identifying foreign compounds in forensic samples.
Sample Types
Coronial Cases: Blood, urine, liver, vitreous humor (to determine if drugs contributed to the death).
Police Samples: Urine or blood from suspects or victims (e.g., drug-facilitated assault).
Traffic: Oral fluid samples taken by police tested to confirm the presence of the drugs: methamphetamine, THC, and MDMA by law.
Hospital Blood Samples: By law, if someone is in an accident, blood is taken and tested for alcohol, methamphetamine, and THC.
Sample Preparation
Transforms the sample into a suitable form for instrumentation to concentrate the blood to something that can be detected.
Protein Precipitation: Used for alcohol analysis (precipitates proteins and solids).
Liquid-Liquid Extraction: Adjusts pH, adds solvent, separates drugs, and concentrates the extract
Solid Phase Extraction: Separates drugs from biological matrix using selective adsorption; the blood or urine goes through the sample, all the drugs stick to the columns active sites, the blood and unneeded components are discarded, and another solvent is used to remove the drugs of interest off the column.
Instrumentation
Sophisticated instruments like LC-QTOFs (high-resolution mass spectrometers) are used.
Chromatography
Separates mixtures into components based on their properties.
Mass Spectrometry
Identifies compounds by measuring characteristic fragments of each component.
Combines retention time and mass spectrum for unequivocal identification and accurate quantification.
Gas chromatography is also used widely in illicit drug chemistry because it's ideal for doing samples which do are already very concentrated.
Liquid Chromatography (LC-MS)
Uses accurate mass measurements to identify compounds.
Inject a known amount of substance of the material in a standard, then we compare it to what we find in a sample.
Retention time is consistent.
Provides a characteristic spectrum.
Gas Chromatography (GC-MS)
Sample is injected, the gas pushes that gas and as well as some oven temperature ramping, pushes that mixture through the column as it goes through, depending on the molecule's affinity for the column that separates out into a nice chromatogram.
Retention times are used to determine compounds.
The mass spectrum is compared to a library to match and identify compounds.
Unequivocal identification in forensic tox and illicit drug analysis.
Interpretation
Determines if a drug level is therapeutic, toxic, or lethal.
Values vary among individuals and drugs.
Requires specialist interpretation (pharmacologist or forensic pathologist).
Postmortem concentrations may not reflect antemortem levels due to cellular breakdown and bacterial degradation.
Drug interactions complicate interpretation (e.g., alcohol plus benzodiazepines).
Tolerance influences drug effects, may be lethal for a naive user.
Pharmacologist vs Analytical Toxicologist
Pharmacologist: Provides opinions on drug effects and interactions.
Analytical Toxicologist: They give more general interpretations stating that the drug is an antipsychotic and give therapeutic ranges to people but cannot confirm the precise effect it has on the patient.
Conclusion
Overview of illicit drugs and forensic toxicology.
Consider listening to the Tox Pod podcast.