Evaluation of Drug Recognition Expert Reports in Marijuana Cases
Explore a study on evaluating Drug Recognition Expert (DRE) reports in marijuana cases to determine the presence of indicators for cannabis and compare THC versus THC-COOH indicators. Discover the methodology, DRE indicators for cannabis category, THC pharmacokinetics, and subjects' data.
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Presentation Transcript
Evaluation of Drug Recognition Expert Reports in Marijuana Cases Brianna Peterson, Ph.D. and Rod Gullberg, M.S. Washington State Patrol September 20, 2011
Goal of study Determine if DRE indicators for cannabis are present in cases with THC detected Compare indicators for subjects with active THC versus THC-COOH only
DRE Matrix Dissociative Anesthetics Inhalants Cannabis Stimulants Narcotic Analgesics Hallucinogens Depressants Horizontal Gaze Nystagmus Vertical Gaze Nystagmus Lack of Convergence Present Present Present None None None None Present Present Present None None None None Present Present Present Present None None None Constricted Normal Normal Normal Dilated Dilated Dilated Pupil size Slow Slow Normal Normal Slow Normal Little to none Reaction to light Down Up Up Up Up Up Down Pulse Up/Down Down Up Up Up Up Down Blood Pressure Normal Up/Down /Normal Up Normal Up Up Down Body Temp
DRE indicators for cannabis category Lack of convergence (LOC) present Pupil size normal to dilated Elevated pulse rate Elevated blood pressure Horizontal gaze nystagmus (HGN) not present Vertical nystagmus (VGN) not present Reaction to light is normal Body temperature is normal
THC pharmacokinetics Highly lipid soluble Short half-life 3 hrs post smoking, THC in serum <5 ng/mL Main metabolite: 11-nor-9 carboxy-THC (THC-COOH)
Methodology DRE cases from 2007-2009; blood sample analyzed Tested for volatiles by Headspace Gas Chromatography EMIT drug screen Cannabinoids cut off = 10 ng/mL THC-COOH THC confirmation by GC/MS (SIM mode) Limits of Detection THC = 1.0 ng/mL THC-COOH = 5.0 ng/mL Cases that were only positive for THC or THC-COOH
Subjects THC/THC-COOH (n=101) 93% male 78% Caucasian Average age: 24 (range: 16-70) THC-COOH only (n=147) 79% male 84% Caucasian Average age: 27 (range: 14-61) Not impaired (n=17) 76% male 94% caucasian Average age: 38 (range: 19-74)
Results 147 THC/THC-COOH cases THC concentration THC-COOH concentration 60 50 Frequency 40 Frequency 30 40 20 10 20 0 0 1 2 3 4 5 10 20 30 More ng/mL ng/mL Mean = 7.3; median = 5.7 Mean = 74.1; median = 61.7 101 THC-COOH only cases THC-COOH concentration 40 Frequency 30 20 10 0 ng/mL Mean = 16.6; median = 13.5
Lack of convergence 70 * 60 50 Percentage 40 Yes No 30 20 10 0 THC/THC-COOH THC-COOH *p=0.003 *p=0.003 *p=0.003
Average pupil size: Room light Normal range: 2.5 5.0 mm 10 9 8 7 6 THC/THC-COOH THC-COOH 5 4 56%, 61% above normal range 3 2 1 0 0 10 20 30 40 50 60 70 80 90 ng/mL
Average pupil size: Dark Normal range: 5.0 - 8.5 mm 10 9 8 7 60%, 58% above normal range 6 THC/THC-COOH THC-COOH 5 4 3 2 1 0 0 10 20 30 40 50 60 70 80 90 ng/mL
Average pupil size: Direct light Normal range: 2.0 4.5 mm 10 9 8 7 6 5 THC/THC-COOH THC-COOH 4 3 49%, 47% above normal range 2 1 0 0 10 20 30 40 50 60 70 80 90 ng/mL
Average pulse Normal range = 60-90 bpm 150 140 130 120 110 100 THC/THC-COOH THC-COOH 90 80 57% above normal range 70 60 50 40 0 10 20 30 40 50 60 70 80 ng/mL
Systolic blood pressure Normal range = 120 140 mm Hg 200 190 180 170 160 150 THC/THC-COOH THC-COOH 140 130 45% above normal range 120 110 100 90 80 0 10 20 30 40 50 60 70 80 ng/mL
Body Temperature Normal range = 98.6 1 F 101 100.6 100.2 99.8 99.4 73, 87% in normal range 99 98.6 98.2 THC/THC-COOH THC-COOH 97.8 97.4 97 96.6 96.2 95.8 95.4 95 0 10 20 30 40 50 60 70 80 ng/mL
Summary Cannabis indicator None THC/THC- COOH 9% THC- COOH 11% Not impaired 6% HGN VGN None 0 2% 0 Lack of convergence Present 66% 47% 6% Pupil Size Normal to dilated Normal 55% 55% 15% Reaction to light 76% 77% 82% Pulse Elevated 57% 57% 25% Blood pressure (Systolic/diastolic) Body Temperature Elevated 45%/22% 45%/25% 41%/12% Normal 73% 87% 77% Not impaired: 17 cases from 2007 - 2009
Summary THC/THC- COOH 86% THC-COOH Not impaired 24% Bloodshot eyes 81% Eyelid tremors 81% 81% 38% 2/8 clues on WAT 72% 81% 25% 2/4 clues on OLS 46% 57% 31%
Other indicators Romberg test: estimation of 30 seconds Normal range = 25 to 35 seconds THC/THC-COOH 60% THC-COOH 51% Not impaired 47%
Other indicators Rebound Dilation THC/THC-COOH 43% THC-COOH 41% Not impaired 6% Reaction to light Normal, slow, little THC/THC-COOH 77% THC-COOH 76% Not impaired 82%
DRE Opinion THC/THC-COOH cases 97% DRE called cannabis Other cases called not impaired 98% subject admitted to marijuana use THC-COOH only cases 97% DRE called cannabis Stimulant/not impaired 88% subject admitted to marijuana use
Conclusions DRE matrix is useful tool for predicting marijuana use Similar indicators for THC/THC-COOH and THC-COOH cases Short half-life, long exam process
Beasley et al. study Examined which indicators best predict substance (n =742) Stimulants versus cannabis Stimulants: less reddening of eyes and rebound dilation, more likely to have hippus, injection sites, slow reaction to light Cannabis: more likely to have lack of convergence Toward a More Parsimonious Approach to Drug Recognition Expert Evaluations. Traffic Injury Prevention 2009;10:513-518
Acknowledgments Rod Gullberg Research Analyst, Washington State Patrol
