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Drug Impaired Driving
Dwain C. Fuller, D-FTCB, TC-NRCCTechnical Director of Toxicology, VANTHCSPrivate Practice Forensic Toxicology [email protected]
Traffic Safety Initiative Conference, Austin, TexasApril 2014
Overview
Types of Toxicology
Human Performance Toxicology
Laboratory Testing
Interpretation Challenges
Limitations
New Drugs
Copyright 2014, Dwain C. Fuller, D-FTCB
Forensic Toxicology
Forensic Urine Drug Testing
Postmortem Forensic Toxicology
Human Performance Toxicology
Copyright 2014, Dwain C. Fuller, D-FTCB
Drugs and poisons in human biological specimens with legal implications.
Three sub-disciplines:
Forensic Toxicology
Forensic Urine Drug Testing
Postmortem Forensic Toxicology
Human Performance Toxicology
Copyright 2014, Dwain C. Fuller, D-FTCB
Drugs and poisons in human biological specimens with legal implications.
Three sub-disciplines:
Forensic Toxicology
Forensic Urine Drug Testing
Postmortem Forensic Toxicology
Human Performance Toxicology
Copyright 2014, Dwain C. Fuller, D-FTCB
Drugs and poisons in human biological specimens with legal implications.
Three sub-disciplines:
Forensic Toxicology
Forensic Urine Drug Testing
Postmortem Forensic Toxicology
Human Performance Toxicology
Copyright 2014, Dwain C. Fuller, D-FTCB
Drugs and poisons in human biological specimens with legal implications.
Three sub-disciplines:
Human Performance Toxicology
Effects of drugs on living humans
Performance of what? Driving
Walking
Making judgments
Drug Facilitated Sexual Assault
Other
Copyright 2014, Dwain C. Fuller, D-FTCB
The Role of the Toxicologist
Testing Alcohol
Drugs
Other intoxicants
Interpretation Substance
Concentration
Context
Other factors
Testimony
Copyright 2014, Dwain C. Fuller, D-FTCB
Testing - Alcohol
Usually dual column gas chromatography-flame ionization-headspace Identifies analytes by differing retention times on two different
chromatographic columns
Well-established and specific
Sometimes enzymatic analysis (hospital specimens) Doesn’t directly measure ethanol
Measures an enzyme/substrate/cofactor reaction
May produce false or elevated results under certain conditions
Rarely gas chromatography/mass spectrometry (GC/MS) Highly defensible
Probably “overkill”
Copyright 2014, Dwain C. Fuller, D-FTCB
Testing - Drugs
Two step process Screening Typically “immunoassay” Based on antibody-antigen reactions Non-specific Limited in scope Must meet threshold requirement Not forensically defensible without confirmation
Confirmation/Quantitation Typically mass spectrometric (GC/MS, LC/MS, LC/MS/MS, etc.) Usually qualitative and quantitative for DUID Must meet LOD requirement Wide scope possible, but usually restricted to limited menu Labor intensive = time consuming = expensive Often different analytical scheme and analyses for different drugs
Copyright 2014, Dwain C. Fuller, D-FTCB
Side Note: New Technologies
Copyright 2014, Dwain C. Fuller, D-FTCB
The Dream!
Side Note: New Technologies
Copyright 2014, Dwain C. Fuller, D-FTCB
The Reality!
Alcohol Drugs
Copyright 2014, Dwain C. Fuller, D-FTCB
Alcohol vs. Drugs in Driving
The most prevalent “drug”
Extremely well-studied and understood
Reasonably dependable dose-response relationship
“Per se” concentration
Hundreds of potential drugs
Prevalence not well-understood May be over or underestimated Less studied in a controlled fashion
Dose-response relationships less understood and more diverse
Proof of impairment usually required
Challenges for the Toxicologist
Combatting “cum hoc ergo propter hoc” logic. Understanding and appreciating literature biases. Drug impairment is often different to alcohol impairment. Motor skills Drowsiness Cognitive impairment
Drugs with different “phases” of action. Tolerance Stimulant use and abuse
How much is too much? (What equals 0.08 EtOH?) Polypharmacy and drug-alcohol interactions How can the report be negative? Forensic toxicology is not practiced in a vacuum!
Copyright 2014, Dwain C. Fuller, D-FTCB
The Burden of Proof
Copyright 2014, Dwain C. Fuller, D-FTCB
Impairment
DR
E/S
FS
T/O
bser
vatio
ns
Driving Behavior
Copyright 2014, Dwain C. Fuller, D-FTCB
Too fast
Too slow
Weaving
At cause accident Hitting fixed object
Hitting other vehicles or pedestrians
Hit and run
Failure to abide by traffic rules Traffic signs or signals
Wrong way driving
Stopped on road
SFST and DRE
Copyright 2014, Dwain C. Fuller, D-FTCB
SFST – Standardized Field Sobriety Test HGN – Horizontal Gaze Nystagmus WAT – Walk and Turn OLS – One Leg Stand
DRE – Drug Recognition Exam (or Expert) DRE examinations, as opposed to SFST, are best conducted under a
controlled environment rather than roadside. HGN – Horizontal Gaze Nystagmus VGN – Vertical Gaze Nystagmus Lack of Convergence Pupil Size Reaction to Light Pulse Blood Pressure Temperature Muscle Tone
DRE 12 Steps
1. Breath alcohol test Does alcohol account for the observed impairment? Usually no DRE eval if BAC>0.08
2. Interview of Arresting Officer3. Preliminary Examination Eye examinations and subject is questioned for any
evidence of medical complication4. Eye Examination HGN VGN Lack of convergence
Slide Courtesy of Laura Liddicoat, Wisconsin State Laboratory of Hygiene
DRE 12 Steps
5. Divided Attention Psychophysical Tests Romberg Balance Finger to Nose WAT OLS
6. Vital Signs Pulse (x3) Body temperature Blood Pressure
7. Dark Room Pupil size in room light, near total darkness, direct light
8. Muscle Tone
Slide Courtesy of Laura Liddicoat, Wisconsin State Laboratory of Hygiene
DRE 12 Steps
9. Examination for injection sites
10. Suspect’s Statements / Other Observations
11. Opinion of Evaluator DRE documents conclusions and category(s) of
drugs causing the impairment
12. Toxicological Examination Specimen for Toxicology testing is obtained and
sent to laboratory for analysis
Slide Courtesy of Laura Liddicoat, Wisconsin State Laboratory of Hygiene
DRE Matrix
Copyright 2014, Dwain C. Fuller, D-FTCB
Pupils
Copyright 2014, Dwain C. Fuller, D-FTCB
Horizontal Gaze Nystagmus
Copyright 2011, Dwain C. Fuller
Involuntary jerking of the eyes as angle of horizontal gaze increases
Caused by alcohol and CNS depressants
Angle of onset is related to BAC
Which Drugs Can Impair Driving?
Any drug that changes the way we perceive or react to the environment. (Perception, tracking, coordination, reaction time, attention, judgment, etc.) CNS depressants Multiple effects
Cannabinoids Chiefly cognitive
Stimulants Can enhance driving in some doses
Risk-taking
Exhaustion
Opioids drowsiness
Copyright 2014, Dwain C. Fuller, D-FTCB
Copyright 2014, Dwain C. Fuller, D-FTCB
CNS Depressants
HGN
Confusion
Sedation
Drowsiness
Droopy eyelids
Slurred speech
Poor balance
Poor coordination
Disorientation
Memory loss
Slowed reaction time
Low blood pressure
Slowed pulse
Poor divided attention performance
Benzodiazepines and Tolerance
Copyright 2014, Dwain C. Fuller, D-FTCB
Benzodiazepines are CNS depressants with activity ranging from anesthetic induction to sleep enhancement to anti-anxiety.
All benzodiazepines can impair driving.
Not all drivers with benzodiazepines on board are necessarily impaired.
Tolerance to the psychomotor and sedative effects of short half-life benzodiazepines can develop within a matter of days to a few weeks.
Supra-therapeutic and acute doses of short half-life benzodiazepines are the most impairing.
Copyright 2014, Dwain C. Fuller, D-FTCB
CNS Stimulants
Improved reaction time
Relief from fatigue
Improved vigilance
Increased risk taking
Increased blood pressure
Increased pulse
Increased body temperature
Agitation
Hyperactivity
Irritability
Confusion
Suspiciousness
Paranoia
Delusions
Hallucination
Violence
Exhaustion
Fatigue
Hypersomnolence
Depression
Stimulants
Copyright 2014, Dwain C. Fuller, D-FTCBLogan, BK. Journal of Forensic Sciences. 41(3) 1996, 457-64
So does the number mean anything?
Copyright 2014, Dwain C. Fuller, D-FTCB
Provides the toxicologist with a starting point.
With some limitations, can be compared to normal therapeutic ranges.
Should be interpreted with caution.
Should never be interpreted without context.
Toxicologist should understand the limitations of his/her interpretative paradigm. Naturalistic studies
Controlled studies
Naturalistic studies
Copyright 2014, Dwain C. Fuller, D-FTCB
Studies often report the drug concentration of people who are stopped for poor driving, wrecks, or some other behavior that bring them in contact with law enforcement.
This produces a selection bias toward those who are impaired by a substance, and omits, perhaps even a majority of, subjects who may be unimpaired at the same concentrations.
These studies typically provide no information about how many people were stopped or came into contact with law enforcement for these same reasons in which no drugs were detected.
Naturalistic studies
Copyright 2014, Dwain C. Fuller, D-FTCB
Controlled Studies
Copyright 2014, Dwain C. Fuller, D-FTCB
The preferred studies are those which are placebo controlled and double blind. At times, actual driving performance (SDLP) Behavioral tests < Simulated driving < Actual driving Even at best, not real world
Limitation on controlled studies Institutional Review Board Issues Ethics Safety
Cost and Logistics Food Housing Compensation
SDLP – Standard Deviation of Lateral Position
Copyright Dwain C. Fuller 2012
Verster JC, Roth T. Int J Gen Med. 2011; 4: 359–371.
So why not use “per se” concentrations?
Copyright 2014, Dwain C. Fuller, D-FTCB
18 states have some form of “per se” concentrations for commonly abused illicit drugs ranging from no tolerance to specific concentrations Pros Eases interpretative burden
May discourage illicit drug use
Cons Choosing the per se concentration
Some drugs share metabolites with legitimate drugs
Legal THC use Marinol
Sativex
Prescription medications?
Synthetic Cannabinoids “Bath Salts”
Copyright 2014, Dwain C. Fuller, D-FTCB
New Drugs
Spice, K2, etc. Amphetamine analogs sold as “bath salts”, “plant food”, etc.
Synthetic Cannabinoids
Copyright 2014, Dwain C. Fuller, D-FTCB
Sold as incense or potpourri, “Not for Human Consumption”
Most were developed for pharmaceutical research on the cannabinoid receptor
Some are DEA scheduled
Ever moving target
“Bath Salts” - Cathinones
Copyright 2014, Dwain C. Fuller, D-FTCB
Widely varied synthetic stimulants and hallucinogens similar to amphetamine
Based on cathinone or “Khat” Native to Africa
Leaves chewed or made into tea
Some are DEA scheduled
Ever moving target
Questions and Discussion
Copyright 2014, Dwain C. Fuller, D-FTCB