ChemPath: Drug, Forensics and Toxicology Flashcards
What sorts of deaths are reported to the coroner and what act is this under?
Section 3 of the Coroner’s Act 1887
- Violent
- Unnatural or sudden
- Cause of death is unknown
A number of these require analysis for drugs and alcohol in order to establish the cause of death
What sorts of case types are reported to the coroner?
- Addicts / drug use
- Sudden unexplained / natural
- Hanging
- Overdoses
- Road Traffic Collisions
- Train deaths
- Self-inflicted injury
- Fire
What samples do coroners take?
- Ante-mortem serum / blood
- Post-mortem blood
- Heart blood, cavity blood (screening)
- Femoral vein blood (screening and quantitation)
- Urine
- Stomach contents
- Vitreous humor
- Hair
- Liver
- Others – bile, muscle, powders, syringes
What is the most common drug problem?
Alcohol
What are the main problems associated with alcohol?
- OD
- Accidents including RTCs
- Additive effects other respiratory depressant drugs
What are the main problems associated with heroine?
- IV injection, volatilised
- Fatal OD with both routes of ingestion
- Additive effects other respiratory depressant drugs
- Few rapid deaths
- Most respiratory depression or aspiration pneumonitis
- Tolerance
What is toxicology?
Concerned with anaylsing samples of drugs/poisins and interpreting the significance of the results.
What does ‘forensic’ mean?
Results/reports used in court
Why might drug levels appear erroneoously elevated post-mortem?
Tissue breakdown can lead to the release of drugs from various tissues
Where can a sample be taken from for drug concentration measurement?
Femoral vein blood
When is vitreous humour used as a sample?
Used to measure glucose (may be elevated in DKA)
How can heroin overdose kill?
Respiratory depression or aspiration pneumonitis
What are the acute dangers of cocaine?
- Cardiac dysrhythmias
- Acute heart failure
- MI
What is the effectof mixing ethanol with cocaine?
Forms cocaethylene which prolongs the effects of cocaine
What happes to cocaine in post-mortem blood?
Breaks down rapidly so the concentration in post-mortem blood may be considerable lower than at the time of death.
Describe the consequences of amphetamine overdose.
Causes hyperthermia → rhabdomyolysis → renal failure
Also has a direct toxic effect on the heart
List some examples of legal highs.
- Stimulats (e.g. bath salts)
- Synthetic cannabinoids / k2 spice
- Synthetic opioids (e.g. acetylfentanyl)
- Hallucinogenic compounds
How long can drugs be detected for in the:
- Blood and serum
- Urine
- Blood and serum = 12 hours
- Urine = 2-3 days
How are hair samples used in forensic toxicology?
- Demonstrating a history of drug use or lack of it
- Demonstrating tolerance or lack of tolerance to drugs (helps interpret post-mortem drug concentrations)
- Compliance with medications (e.g. antipsychotics)
NOTE: hair samples are rarely used in coroner’s toxicology but it is used in forensic investigations
What are the issues with hair analysis?
- Environmental contamination
- Cosmetic treatment - perm/bleaching/dyeing may remove some drug
- Hair colour - darker hair retains more drug
What are the main drugs used in chemsex?
GHB
Methylamphetamine (crystal meth)
Mephedrone (MCAT)
Where is the most important PM blood sample taken from
Femoral vein
How to differentiate between chronic use and acute OD of a drug in PM blood?
Acute: high metabolite : parent drug ratio
Chronic: high parent drug : metabolite ratio
How fast does hair grow?
1cm / month
What is the gold standard test for identification of toxicological analysis?
GC-MS (gas chromatography/mass spectrometry)
How does GC-MS and LC-MS differ?
GC-MS = gas chromatography/mass spectrometry
LC-MS = liquid chromatography
GCMS is the gold standard
However LCMS is more sensitive and can analyse a wider range of analytes
What test is used to analyse ethanol/solvenets in PM blood?
Headspace GC
When is quantitation of toxins/analytes done?
Done (on blood sample) if the concentration found in the screen is above the therapeutic range
What is heroin measured as in a PM?
Measured as morphine
Because Heroin -> 1-acetylmorphine -> morphine
What factors affect the interpretaation of PM drug concentrations?
Tolerance
Stability of drug e.g. cocaine breaks down rapidly
Volume of distribution (Vd) - tissues breakdown which redistributes drug after death, hence PM blood conc can’t be used to calculate dose
Individual variations in response
