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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 dr morris odell victorian institute of forensic medicine
Drugged DrivingDr Morris OdellVictorian Institute of Forensic Medicine


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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