Case Review: The Toxicologist in the Marijuana Court › ... › Kosnett_THC_case_review.pdfCase 2: Implications of post-accident urine drug testing • At 1618 hours, a 24 y.o. man

Case Review: The Toxicologist in the Marijuana Court

Moderator:Michael J. Kosnett, MD, MPH, FACMT

Sunday, December 6, 15

Case 1: driving under the influence of cannabis?

• At 0850 hours a policeman stopped a 28 y.o. woman driving a Mazda 3 on a city boulevard with an expired license plate. No erratic driving or speeding

• Officer detected “the very strong odor of burning marijuana.” Driver volunteered she was a daily medical marijuana patient suffering from chronic back pain and muscle spasms who had “medicated” with cannabis at her house a few minutes earlier. “A couple of hits”

• At 0917, roadside testing performed by officer observed “4 of 8” possible clues on one leg stand, and “2 of 8 clues” on walk and turn. No horizontal gaze nystagmus, but “+ eyelid tremors”


• At 0931 driver was arrested for DUI

• Driver consented to a blood test. After failed phlebotomy by EMTs at fire station, blood obtained in ED at 1028

• At 1057, Drug Recognition Expert conducted formal evaluation. Findings included:

• BP 116/80, P 60;

• eyes “bloodshot” with pupils 6.5mm; lack of convergence R eye;

• “30 second” interval estimated as “29 seconds”;

• 2 heel-toe errors on walk and turn; imbalance on one leg stand on L but not R

• 4 misses on 6 finger to nose maneuver

• DRE conclusion: “driver is under the influence of cannabis and would be unable to safely operate a vehicle”


• Blood analysis (LC-MS/MS) THC: 19 ng/ml THC-COOH: 93 ng/ml

• Defendant declined plea bargain that would have required 2 years of abstinence

• At trial, defendant testified in her defense that daily medical marijuana improved her driving by relieving distraction of chronic pain

• No trial testimony by any toxicologists

• Defense also argued that performance on DRE maneuvers not conclusive evidence of impairment, and no actual driving impairment was observed

• Jury instruction: blood THC ≥ 5 ng/ml is “permissible inference” of impairment but jurors can reach their own opinion based on all the evidence

• 6 member jury acquitted defendant of DUI


Case 1 Video clips


Case 1 discussion questions:

• What criteria adequately assess DUID in chronic daily cannabis users?

• What is positive predictive value of blood THC ≥ 5 ng/ml in this group?

• What is sensitivity and specificity of DRE evaluation in this group?

• What tests or criteria may be useful to prospectively assess whether a daily cannabis user can safely drive?

• What about retrospective assessment of a DUID defendant?


• [Insert photos / video of MiniSim; other tests]


Case 2: Implications of post-accident urine drug testing

• At 1618 hours, a 24 y.o. man driving a company delivery truck was texting on his cell phone and failed to observe that freeway traffic in front had stopped. His truck rear-ended a passenger car, causing severe permanent spinal cord injury to the occupant.

• Officers spoke with the driver and did not consider him intoxicated; no breathalyzer, no roadside sobriety test

• At 1740, a post accident urine drug test, performed per company protocol, revealed THC-COOH of 562 ng/mL (confirmatory LC-MS/MS analysis with + cut-off 15 ng/mL)

• Urine creatinine was 506 mg/dL


• The driver admitted to recreational smoking of a joint or blunt most evenings, but claimed he had abstained for ≈ 3 days prior to accident because of acute flu-like illness

• The injured occupant of the passenger filed a lawsuit against the furniture company, seeking tens of millions of dollars under a state law allowing punitive damages when an accident was caused by an intoxicated driver

• At trial, the plaintiff ’s toxicology expert testified that the THC-COOH value of 562 ng/ml was so high it likely represented very recent use, not residua from 3 days ago; and that it supported plaintiff ’s argument the defendant was intoxicated


Case 2 discussion questions

• Does post-accident urine drug testing provide useful information concerning the role of cannabis in an accident?

• Can a level of urine THC-COOH indicate impairment? Time of last use? Chronic cannabis use?

• What is the implication of a very high urine creatinine in a drug test (i.e. 506 mg/dL)?

• Is it advisable for companies to conduct routine post-accident drug testing for cannabis in employees involved in accidents, and if so, what protocol is recommended?


creatinine

THC-COOH

Adjusting the amount of THC-COOH present in the urine by the amount of creatinine present accounts for any process that may have caused the urine to become concentrated or diluted.

A very high creatinine concentration can be a sign that a urine is very concentrated, and a low creatinine concentration may be a sign of dilution.


Relationship between male and female urinary creatinine concentrations and age.

Cocker J et al. Occup Med (Lond) 2011;61:349-353

© Crown copyright 2011.

Driver’s urine creatinine


THC-COOHCr

Driver’s urine = 562 ng THC-COOH/ml ÷ 5.06 mg creatinine/ml = 111 ng THC-COOH/mg creatinine

Days of abstinence from marijuana useSunday, December 6, 15

Case 3: urine THC-COOH tests to monitor abstinence

• In a family court divorce/child custody hearing, the wife contended that heavy cannabis use by the husband should prevent him from having custody or visitation rights. The husband replied that he had recently quit cannabis use.

• The court ordered the husband to demonstrate abstinence by thrice-weekly urine drug testing for approximately 4 to 6 weeks. The husband submitted specimens at his expense, on days he selected, during this interval.

• Upon reviewing the results (see table), counsel for the wife argued to the court that abstinence had not been demonstrated.


Sequential Day

Urine THC-COOH

(ng/ml)*

1 136

6 ND

8 128

14 152

14 60

19 ND

22 88

27 108

30 ND

33 ND

35 ND

ND = lab report read “not detected” or “negative”

* analysis by EIA without confirmation. Reporting limit was 50 ng/ml


Case 3 discussion questions

• Does urine drug testing have a role in monitoring abstinence from cannabis?

• If so, what is a recommended approach to interpreting sequential samples in various settings (e.g. drug treatment programs; forensic or legal settings)?


Sequential Day

Urine THC-COOH

(ng/ml)*

Urine Creatinine

(mg/ml)

THC-COOH

(ng/mg Cr)Ratio of sequential

values (U2÷U1)

Does ratio exceed

1.5?

1 136 0.448 304

6 ND 0.258

8 128 1.22 105 105÷304 = 0.35 No

14 152 1.633 93 93÷105 = 0.90 No

14 60 1.336 45 45÷93 = 0.48 No

19 ND 0.548

22 88 1.584 55 55÷45 = 1.22 No

27 108 2.137 50 50÷55 = 0.90 No

30 ND 0.389

33 ND 1.46

35 ND 0.201

ND = lab report read “not detected” or “negative”

* analysis by EIA without confirmation; reporting limit was 50 ng/ml


0"

50"

100"

150"

200"

250"

300"

350"

0" 5" 10" 15" 20" 25" 30"

Creatinine-Normalized Urine THC-COOH Immunoassay Results

Sequential Day of Test

Urin

e T

HC

-CO

OH

(ng

/mg

Cre

atin

e)

Text

Bars = possible range of creatine adjusted value if actual THC-COOH was 0 - 49 ng/mL


case 4: forensic implications of cannabinoid metabolite profiles

• A 28 y.o. driver was involved in a fatal motor vehicle accident in which he and other survivors were injured and promptly transported to an ED

• Whole blood drawn in the ED ≈ 40 minutes after the accident was analyzed for THC and metabolites

• The driver was a chronic daily marijuana user who recalled smoking earlier in the day, but had poor recollection of intake in the hours preceding the accident

• Whole blood analysis (ng/ml) by LC-MS/MS:THC 12

11-OH-THC 4

THC-COOH 32

CBD ND

CBN 1.5


case 4 discussion questions

• Does the pattern of cannabinoid metabolites in blood support inferences regarding the frequency of cannabis use, the time since last use, and/or the presence of impairment?

• What is the “cannabis influence factor” and does it offer forensic value?


Documents

Case Review: The Toxicologist in the Marijuana Court › ... › Kosnett_THC_case_review.pdfCase 2: Implications of post-accident urine drug testing • At 1618 hours, a 24 y.o. man