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Drugged Driving Dr Morris Odell Victorian Institute of Forensic Medicine. Drugged Driving – the issues. Legislative approaches Research methodology Prevalence Detection Impairment “Differential diagnosis” Prescribed drugs Specific Drugs. Driving – an unnatural act.

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drugged driving the issues
Drugged Driving – the issues
  • Legislative approaches
  • Research methodology
  • Prevalence
  • Detection
  • Impairment
  • “Differential diagnosis”
  • Prescribed drugs
  • Specific Drugs
driving an unnatural act
Driving – an unnatural act
  • High speed decision making
  • Vision, Reaction time, cognition, all at limits of capability
  • Physical demands of the task
  • Doing several things at once – divided attention
  • Injury risk is high
  • Greatest non-homicide cause of unnatural death
legislative approaches
Legislative Approaches
  • DUI – loosely defined prohibition of driving under the influence. Problems obtaining proof of intoxication
  • “Per se” laws – similar to 0.05% alcohol law –strict liability based on toxicology tests eg: saliva testing
  • DWI - Impairment based assessment – refinement of DUI to systematize observations (+/- toxicology)
research into drugs driving
Research into Drugs & Driving
  • Laboratory studies
    • Standard psychomotor tests
    • Driving simulators
    • Problems – doses not realistic
    • Cannot realistically determine crash risk
  • Epidemiological studies
    • Require huge sample size
    • Need to control for vast number of drugs & combinations
    • data from fatalities vs. data from live drivers
prevalence of drugs on roads
Prevalence of drugs on Roads
  • Very Difficult to determine
  • Injury study SA 2000
    • Alcohol 8.6%, THC 7.1%, Alc + THC 3%
  • Alfred Hospital study 2001-2
    • THC 39%, BZD 16%, Stim 12%, Opioid 7%
  • Vic Police DWI cases VIFM 2000-2
    • BZD 64%, Op 43%, THC 30%, Stim 13%, Alc 3%

Victorian Oral Fluid testing program 2005-10

    • Overall prevalence 2-3% BUT only 3 drugs and highly targeted testing
apprehension by police source of bias
Apprehension by Police –source of bias
  • Screening eg: Booze buses
  • On road behaviour
  • “Dob ins” from the Public
  • Breath tests to exclude alcohol
  • Roadside observations of impairment
  • Systematic method for recording observations
assessment of impairment
Assessment of Impairment
  • Observations
    • Interview
    • Physical signs eg: pupils, nystagmus, pulse, BP
    • Psychomotor tests eg: walk & turn, one leg stand
  • Toxicology
    • Urine, blood, saliva, other
    • Qualitative vs. quantitative
potential problems
Potential Problems
  • Serious medical conditions requiring attention
  • Non-serious conditions affecting assessment
  • Impairment due to illness being treated
  • Technical problems with examination
  • Drug effect worn off by time of exam
  • Conflicting effects of different drugs
other causes of impairment
Other Causes of Impairment
  • Medical conditions
    • long standing
    • acute or emergencies
  • Disabilities and/or deformities
  • Side effects of legitimately prescribed drugs
  • Psychiatric conditions
  • Acute stress - “pseudo impairment”
acute anxiety panic
Acute Anxiety - Panic
  • May be triggered by distress of apprehension
  • Similarities to amphetamine effect
  • Can co-exist with drug effect
  • Release of adrenaline - “fight or flight”
    • tremor
    • sweaty
    • dilated pupils
serious medical conditions
Serious Medical Conditions
  • Head injury
  • Internal injuries with haemorrhage
  • Over-dosage & severe intoxication
  • Epilepsy & post ictal states
  • Hypoglycaemia
  • Should be obvious on observation and interview
chronic medical conditions
Chronic Medical Conditions
  • Neurological problems
    • old strokes
    • degenerative diseases - MS, Parkinson’s, Huntington’s
  • Eye problems
    • licensing criteria allow one eyed drivers etc
  • Physical disabilities
    • deformities
    • gait disorders
prescription drugs
Prescription Drugs
  • Vast number capable of affecting driving
  • In practice they are rarely a problem if used properly
    • Medical & pharmacy advice
    • Compliance with doses
  • Allow time to develop tolerance
  • May be a valid defence to charges
  • Effects of condition being treated
drugged driving toxicology
Drugged Driving Toxicology
  • Specimen – blood vs. urine vs. saliva
    • Specified in relevant laws
    • Practicalities
  • Timing
    • Effect of delay on drug levels
    • “readbacks” not usually possible
  • Interpretation
    • Cutoff levels for qualitative tests
    • Correlation of levels with doses/effects !!!!!
legal drugs
Legal Drugs
  • Enormous number of substances in legal use
    • OTC
    • Prescribed
  • “Therapeutic” - used in treatment
  • Condition being treated may cause problems
  • “Use” and “Abuse”
specific drugs
Specific drugs
  • Tobacco & Alcohol
  • Cannabis
  • Amphetamines (Cocaine)
  • Opioids
  • Benzodiazepines
  • Other prescribed drugs
  • Others
cannabis
Cannabis
  • Product of Cannabis sativa
    • marijuana
    • hash(ish)
    • mull
    • grass
    • dope
    • etc
effects of cannabis
Effects of Cannabis
  • Nervous system
    • Euphoria
    • Disorientation
    • Altered perception
    • Relaxation
    • Slowing of time perception
    • Hunger
  • Physical
    • increased heart rate
    • red eyes
    • pupils dilated
    • dry mouth
    • balance
cannabis toxicology
Cannabis toxicology
  • Active component is delta-9 THC
  • Short redistribution time 1-4 hours.
  • Thiopentone-like pharmacokinetics
  • Peak effect about 30 minutes
  • Long elimination half life - weeks
  • Metabolite is carboxy-THC
  • Long elimination half-life - days/weeks
tests for cannabis
Tests for Cannabis
  • Urine - “cannabinoids” - mostly metabolites
  • Positive up to 1-2 weeks
  • Blood – snapshot of THC at the time of collection
  • Saliva – short window of detection likely to correlate with clinical effects
  • Post mortem – extremely variable – THC levels may change in either direction after death
interpretation of thc levels
Interpretation of THC levels
  • Unusual to get specimens during the peak
  • Baseline levels due to slow elimination - up to 5 ng/ml (cf 0.05% = 500,000ng/ml)
  • What is a realistic baseline in Australia in 2012?
  • Levels above baseline - are they evidence of impairment and if so how much?
  • Review - 11 ng/ml ~0.073% alcohol – is this realistic?
prescription drugs opioids narcotics
Prescription drugs - Opioids (Narcotics)
  • One of the oldest known groups of drugs (4000 BC)
  • Great number of different derivatives
  • Widespread medical and illegal use
effects of narcotics
Effects of Narcotics
  • Nervous effects
    • relaxation
    • sedation, coma
    • pain relief
    • euphoria
    • mental clouding
    • reduced aggression
    • reduced libido
  • Physical effects
    • pinpoint pupils
    • respiratory depression
    • constipation
    • nausea/vomiting
    • flushing
    • cough suppression
opiates signs of intoxication
Opiates - Signs of Intoxication
  • Interview & Observation
    • Drowsy - “on the nod”
    • Needle tracks
    • Rouseable but falls asleep rapidly
    • Droopy eyelids
    • Pinpoint pupils
    • Slow speech
  • Withdrawal
    • Nasty but rarely fatal
prescribed opiates
Prescribed opiates
  • Very commonly found in combination with other sedating drugs
  • Codeine, tramadol alone – not associated with impairment (Bachs 2009)
  • Methadone, buprenorphine – not impairing if tolerance established and used as directed (Lenne 2003, Bernard 2010)
  • Methadone, buprenorphine – associated with increased crash risk due to “risky behaviour” (Corsenac 2011)
benzodiazepines
Benzodiazepines
  • “Minor tranquillizers”
  • Widely available
  • Widely used
  • Widely abused
  • Many types all with similar properties
  • Classic CNS depressants
benzodiazepines1
Benzodiazepines
  • Many types differ in duration of action
  • Times range from hours to days
    • Diazepam (Valium)
    • Temazepam (Normison)
    • Oxazepam (Serepax)
    • Flunitrazepam (Rohypnol)
    • Clonazepam (Rivotril)
    • Alprazolam (Xanax)
    • Midazolam (Hypnovel) - liquid form
pharmacology of benzodiazepines
Pharmacology of Benzodiazepines
  • Complex metabolism
  • Converted to other benzos in the body
  • Long lived products
  • Metabolic products may interact with other drugs after original drug effect has worn off
effects of benzodiazepines
Effects of Benzodiazepines
  • Interview & Observation
    • Drowsiness, “Drunk”, Slurred speech
    • Paradoxical excitement
      • “Taking off the brakes”
  • Clinical signs
    • nystagmus the classic indicator
    • pupils not usually affected
    • Incoordination
benzodiazepines and driving
Benzodiazepines and driving
  • The one drug group consistently found to affect driving & crash risk
  • BUT
  • Very few studies differentiate between prescribed and excessive dosing
  • Increased risk with long acting prescribed benzos in first few weeks of treatment (Smink 2010, Dubois 2008)
  • Different situation to excessive use of short acting benzos
  • Enormous potential to interact with other sedatives especially opiates
antidepressants
Antidepressants
  • 3 main groupings
    • SSRI
    • tricyclics
    • MAO inhibitors
  • Common in community
  • Often in combination with other drugs
  • Modern SSRIs rarely cause impairment
  • Rarely abused except in suicide attempts
antidepressants effects
Antidepressants - effects
  • Early effects
    • sedation
    • cholinergic
    • Cardiotoxicity with older types
  • Effects of depression
    • psychomotor retardation
  • Interactions - alcohol, other drugs, serotonin syndrome
  • ? Mania
other drugs
Other drugs
  • Infinite number of drugs and combinations of drugs
  • OTC drugs
  • Rarely a problem with prescribed drugs
  • Rave scene
  • IV anaesthetics
  • Need to consider the reason why they were prescribed
  • Drugs in combination
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