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Drugged Driving Dr Morris Odell Victorian Institute of Forensic Medicine

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

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  1. Drugged DrivingDr Morris OdellVictorian Institute of Forensic Medicine

  2. Drugged Driving – the issues • Legislative approaches • Research methodology • Prevalence • Detection • Impairment • “Differential diagnosis” • Prescribed drugs • Specific Drugs

  3. 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

  4. 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)

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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”

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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 !!!!!

  16. Urine tests- practical problems

  17. Legal Drugs • Enormous number of substances in legal use • OTC • Prescribed • “Therapeutic” - used in treatment • Condition being treated may cause problems • “Use” and “Abuse”

  18. Specific drugs • Tobacco & Alcohol • Cannabis • Amphetamines (Cocaine) • Opioids • Benzodiazepines • Other prescribed drugs • Others

  19. Cannabis • Product of Cannabis sativa • marijuana • hash(ish) • mull • grass • dope • etc

  20. 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

  21. 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

  22. 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

  23. 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?

  24. Prescription drugs - Opioids (Narcotics) • One of the oldest known groups of drugs (4000 BC) • Great number of different derivatives • Widespread medical and illegal use

  25. 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

  26. 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

  27. 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)

  28. Benzodiazepines • “Minor tranquillizers” • Widely available • Widely used • Widely abused • Many types all with similar properties • Classic CNS depressants

  29. 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

  30. 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

  31. 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

  32. 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

  33. 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

  34. Antidepressants - effects • Early effects • sedation • cholinergic • Cardiotoxicity with older types • Effects of depression • psychomotor retardation • Interactions - alcohol, other drugs, serotonin syndrome • ? Mania

  35. 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

  36. The End!

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