Toxicology

• Drugs and pharmaceuticals


  Have complicated structures built from a backbone of carbon atoms in a chain or a ring
• Carbon chain lengths


  • Oct: 8 carbons
  • Non: 9 carbons
  • Dec: 10 carbons
• Alkanes


  Carbon chains with only single bonds between the carbons

  
• Zig zag chains


  Each corner has a CH2 and the end has a CH3
• Rings


  Most common is 6 carbons, some drugs have 5 or 7 carbons. Naturally occurring compounds like steroids have 5 or 6 carbon rings
• Cyclo-


  Added to the name to indicate a ring structure, e.g. cyclohexane, cycloheptane

  
• Ends in -ene


  Indicates the carbon chain contains a double bond
• Underdoses of medical concern

  • Risk of infection due to antibiotic resistance
  • Asthma
  • Blood pressure = cardiac arrest
  • Mental Health Psychosis and cancer
• Overdoses of medical concern

  Too high of a dose taken which affects the heart, lungs and brain. Kidney and liver organs attempt to eliminate the high drug load
• Toxic metabolites


  Can cause liver and kidney damage, healthy organs are destroyed if the drug is not removed
• Causes of overdose


  • Accidental (clinical settings) children eating tables, elderly can't remember the correct dosage
  • Intentional (forensic settings) call for help, suicide, poisoning
• Poison


  A substance which, taken into or formed in the body, destroys or impairs health
• Xenobiotic


  A foreign body (drug, pesticide, dietary supplement)
• Prescription drugs


  Legal to have, but if you have too much on you then you would be under suspicion of intending to deal
• Plasma drug concentration


  • Max in blood plasma, begins to be excreted at 2, takes then 3 or 4 days to get to the therapeutic range
  • If dose is taken correctly you will be in between the minimum and max needed to kill the bug
• Underdose


  Depends on the dose, as if given in a high enough doses can be toxic including salt, water and oxygen
• How drugs are eliminated from the body

  • Absorption: ability to cross the membrane
  • Metabolism: chemically altered with enzymes, gastrointestinal tract, hydrolysis. Prodrug or reactive metabolism
  • Excretion: lungs, kidneys and feaces
• MDMA


  Also known as ecstasy
• Chronic drug use


  Low level substances taken over a while, takes time to build up
• Acute drug use


  Short and lots (toxic and ischemic injury)
• Kidney function


  Most drugs are lipid soluble so they can cross membranes, but kidneys can only excrete water soluble drugs, so drugs are metabolised by the liver from fat soluble drugs to water soluble drugs
• Reasons for drug abuse

  • Behavioural
  • Genetic predisposition
  • Access
  • Addiction
  • Long term damaging effects
  • Links to criminal activity
• Identification of drug misuse

  Suspected by behaviour, vital signs, pulse rate and diluted pupils. The identification of suspected drug classes like amphetamines can occur through bodily fluids and hair

  
• Drug detection in hair

  Some drugs can be detected as they become chemically embedded
• Visible signs of drug use

  • Locomotor problems like slurred speech, aroma of alcohol
  • Excited, confident, insomnia, continuously running nose, nose bleed
  • Subdued, blood shot eyes
• Diagnostic techniques


  • Invasive (biopsy)
  • Non-invasive techniques
• Analytical techniques


  • Thin layer chromatography
  • FTIR (not good for biological samples)
  • Immunoassay: Biological fluids
  • Urine: 1 step test, non invasive
  • Blood: invasive
  • Saliva: non invasive
  • Hair: non invasive
• Screening at the scene

  Low cost test, fast, semi quantitative, high sensitivity, low specificity
• Confirmation in a lab

  High cost test, slow, quantitative, high sensitivity and specificity
• Toxicology in the living

  • Drunk/drug driving
  • Clinical forensic toxicology
  • Victims and offenders of assault
  • Drug facilitated crime
  • Child welfare
  • Drunkenness in office
  • Drug testing programs (Workplace, Schools, Armed forces, Prisons and correctional facilities)

  
• Forensic Toxicology investigations Post mortem

  • Autopsy findings suggesting poison
  • Homicides and suspicious cases
  • Suspicion of malpractice
  • Need to confirm apparent cause of test
  • Traffic accident
• Forensic Toxicologists


  • Analyse poisons in bodily fluids and specimens at an autopsy
  • Interpret the results and work with coroners/pathologists to determine the cause of death

  
• Drugs


  Originally defined as any substance of animal or vegetable or mineral origin used as an ingredient in pharmacy, chemistry, dyeing or various manufacturing processes. Now defined as a natural or synthetic substance used in the prevention and treatment of disease
• Narcotics


  A drug which when swallowed, inhaled or injected causes drowsiness, stupor or insensibility according to the dosage
• How drugs can enter the body


  • Accident
  • Substance being misused or abused
  • Used to treat medical symptoms
• Crimes involving drugs


  • Driving under the influence of drugs
  • Assault —>spiking/ drug facilitated sexual assault
  • Supply
  • Manslaughter/murder
  • Possession
  • Robbery
  • Suicide
  • Human trafficking
  • Money laundering
  • Production
  • Organised crime
  • Rape
  • Manufacturing drugs
  • Hit and run
• Psychological Dependence


  Drug seeking behaviour, strong desire to use again for certain effects, not necessarily associated with physical dependency
• Physical dependence


  Withdrawal symptoms occur when a drug is no longer used suddenly, produces symptoms that are the opposite of the effects you desire
• Dependence


  Doesn't necessarily lead to addiction as you can stop
• Tolerance


  Take a particular dose for an effect, after repeated use you take the same dose again which causes a reduced effect, the body gets used to the drug. Can lead to overdosing as you take more and more to get the same affect, this becomes toxic