Abstract
Oral fluid (OF) offers non-invasive sample collection for on-site drug testing, but performance of on-site tests with occasional and frequent smokers’ OF to identify cannabinoid intake requires further evaluation. Furthermore, to our knowledge, no studies evaluate differences in cannabinoid disposition among OF collection devices with authentic OF samples after controlled cannabis administration.
14 frequent (≥4x/week) and 10 occasional (<2x/week) adult cannabis smokers smoked one 6.8% Δ9-tetrahydrocannabinol (THC) cigarette ad libitum over 10 min. OF was collected with the StatSure Saliva Sampler™, Oral-Eze®, and Draeger DrugTest® 5000 test cassette before and up to 30h after cannabis smoking. Test cassettes were analyzed within 15 min and gas chromatography-mass spectrometry cannabinoid results obtained within 24h. Cannabinoid concentrations with the StatSure and Oral-Eze devices were compared and last cannabinoid detection times (tlast) and DrugTest 5000 test performance were assessed at different cannabinoid cutoffs.
11-nor-9-carboxy-THC (THCCOOH) and cannabinol concentrations were significantly higher in Oral-Eze than Stat-Sure samples. DrugTest 5000 tlast for a positive cannabinoid test were median (range) 12h (4-24h) and 21h (1-≥30h) for occasional and frequent smokers, respectively. Detection windows in screening and confirmatory tests were generally shorter in occasional than frequent smokers, especially when including THCCOOH ≥20ng/L in confirmation criteria. No differences in tlast were observed between collection devices, except for THC ≥2μg/L.
We report significant differences in THCCOOH and cannabinol, but not THC, concentrations between OF collection devices, which may influence OF data interpretation. The DrugTest 5000 on-site device had high diagnostic sensitivity, specificity and efficiency for cannabinoids.
Keywords: Cannabinoid, Oral Fluid, On-site test, Draeger DrugTest 5000
Introduction
Cannabis is the most commonly used illicit drug worldwide, with 2.8-5.0% (129-230 million people) of 15-64 year-olds consuming cannabis at least once in 2011 [1]. Δ9-Tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, was the most prevalent illicit drug detected in injured drivers in Victoria, Australia (9.8%) [2]. Cannabinoids were found in 8.6% of nighttime drivers’ blood and/or oral fluid (OF) in the 2007 US Roadside Survey [3].
With changes to drug policy for recreational and medicinal cannabis intake, increased recreational and medicinal cannabis use [1,4-5] and decreased perceived risk [3], rapid and accurate on-site cannabinoid testing is required. OF is increasingly utilized for on-site drug testing in drug treatment, workplace, pain management, and driving under the influence of drugs (DUID) testing. OF advantages include non-invasiveness, observed specimen collection, and lower potential for adulteration compared to urine. Optimal OF on-site devices require rapid analysis times, OF collection volume indicators, objective result interpretation, and quality control parameters such as adequacy of lateral flow. However, differences in device formulation including elution buffers, sample collection volume, buffer dilution, cannabinoid antibodies, and detection mechanisms make performance comparison among devices difficult. Furthermore, manufacturers make frequent device reformulations to improve cannabinoid sensitivity. Many previously available on-site devices failed to meet the 80% diagnostic sensitivity, specificity, and efficiency criteria proposed by the Driving under the Influence of Drugs, Alcohol and Medicines (DRUID) project for OF drug detection [6-15]. On-site OF cannabinoid efficiencies were 80% for OraLine® IV s.a.t. [8], 57.5-92.8% for Drugwipe 5 [10-13,16], 60-94.3% for Cozart DDSV [14,12,17], 66-93.0% for RapidStat® [12,15,13,17,16], 94.3% for A-Concateno DDS® [16], 68-96.1% for DrugTest 5000® [12-13,17,16], and 78-90.9% for OrAlert™ [12,17]. Although the OraLine IV s.a.t. and A-Concateno DDS devices achieved ≥80% efficiency, sensitivity was only 69.2% and 37.8%, respectively. Overall, the authors concluded that the DrugTest 5000 achieved the best diagnostic efficiency for OF cannabinoids detection [13,17,16,18].
We recently documented high diagnostic sensitivity (90.7%), specificity (75.0%), and efficiency (87.9%) for the DrugTest 5000 with the manufacturer's 5 μg/L screening cutoff and a 2 μg/L THC confirmation cutoff [19]. However, that study included only frequent smokers and monitored cannabinoids for only 22h after smoking, leading to overall high cannabinoid concentrations and too few true negatives to evaluate specificity. Others also evaluated this newest DrugTest 5000 version (5 μg/L THC screening cutoff) and reported diagnostic sensitivity, specificity, and efficiency of 53-93, 71-99 and 84-94.3%, respectively, with OF THC confirmation cutoffs of 1-10 μg/L [12-13,16-17]. Recency of smoking was shown to impact diagnostic sensitivity and efficiency [12,18].
To our knowledge, no studies evaluate differences among OF collection devices following controlled smoking and with authentic OF samples, although significantly higher concentrations were found in expectorated OF from Dutch “Coffee Shop” patrons compared to samples consecutively collected from the same individuals with the StatSure device [20]. Furthermore, OF THC concentrations in consecutively collected duplicate expectorated samples were much more variable than samples collected with the StatSure device. No significant differences between simultaneously collected OF samples with the Quantisal [21] or Intercept devices [22] were noted.
To address these knowledge gaps, we evaluated performance characteristics and OF detection windows with the on-site DrugTest 5000 and the StatSure and Oral-Eze devices in occasional and frequent cannabis users following smoking of a 6.8% THC cigarette. THC, 11-nor-9-carboxy-THC (THCCOOH), 11-hydroxy-THC (11-OH-THC), cannabidiol (CBD), and cannabinol (CBN) were quantified by two-dimensional gas chromatography-mass spectrometry (2D-GC-MS) [23] to investigate different cannabinoid markers and windows of cannabinoid detection to meet the goals of diverse drug testing programs.
Methods
Participants
Healthy male and female cannabis smokers provided written informed consent to participate in this National Institute on Drug Abuse Intramural Research Program Institutional Review Board-approved study. Individuals were recruited by television, radio and newspaper advertisements, flyers, and participant referrals. Participants received a comprehensive medical and psychological evaluation to verify compliance with eligibility criteria. Inclusion criteria were ages 18 to 45 years and self-reported average frequency of cannabis smoked of less than twice per week (occasional smoker) or at least four times per week (frequent smoker) in the past 3 months. History of cannabis use was confirmed by a positive urine cannabinoid test for chronic frequent smokers. Exclusion criteria included breastfeeding or pregnant women; current clinically significant medical condition or history of neurological illness; history of a clinically significant adverse event associated with cannabis intoxication; >450mL blood donation within 30 days of drug administration; clinically significant anemia; increased systolic or diastolic blood pressure or heart rate >100 bpm after 5 min rest; clinically significant electrocardiogram abnormality; or interest in drug abuse treatment within 60 days of study screening. Pregnancy tests were administered at screening and on study admission to women with reproductive potential.
Study Design
Participants entered the secure research unit approximately 19h prior to smoking to preclude intoxication at the time of cannabis dosing. Participants smoked one (average±SD) 6.8±0.2% (54mg) THC, 0.25±0.08 CBD (2mg), and 0.21±0.02% CBN (1.6mg) cannabis cigarette ad libitum for up to 10min. OF was collected with the StatSure Saliva Sampler™ (StatSure Diagnostics Systems, Inc., Framingham, MA), followed by the Oral-Eze® (Quest Diagnostics, Madison, NJ) and the DrugTest 5000 (Draeger Safety Diagnostics, Lübeck, Germany). The StatSure device consists of an absorptive cellulose pad placed below the tongue, a volume adequacy indicator that turns blue upon collection of 1.0mL OF, and a polypropylene tube containing 1mL elution/stabilizing buffer, yielding a 1:2 OF dilution. The Oral-Eze device has an absorptive cotton pad positioned between the lower cheek and gum (with plastic shield against the cheek), a volume adequacy indicator that turns blue upon collection of 1.0mL OF, and a plastic tube containing 2mL stabilizing buffer, yielding a 1:3 OF dilution. The DrugTest 5000 test cassette is equipped with a polymeric non-compressible pad for OF collection. OF was collected by swiping the test cassette on the tongue and side of the cheeks. The test cassette collects 270μL±15% OF, as indicated by the volume adequacy indicator. Oral intake (eating, drinking, cigarette smoking) was prohibited 10min before OF collection. Samples were collected on admission, 1h before, and 0.5, 1, 2, 3, 4, 5, 6, 8, 10.5, 13.5, 21, 24, 26, 28, and 30h after the start of smoking. OF was collected until the volume indicator turned blue or for a maximum of 10 min. StatSure samples were stored upright at 4°C and Oral-Eze samples stored horizontally at room temperature according to manufacturers’ recommendations; all (except 5 Oral-Eze samples analyzed within 96h) were analyzed within 24h of collection. Participants remained on the secure residential unit until the end of the study.
Sample Analysis
THC, 11-OH-THC, THCCOOH, CBN, and CBD were quantified by 2D-GC-MS according to a previously published method [23], with minor modifications. For the StatSure, calibrators and quality controls were prepared in 0.25mL blank OF and 0.25mL StatSure buffer to account for OF dilution. For the Oral-Eze, calibrators and quality controls were prepared with 0.25mL blank OF and 0.5mL Oral-Eze buffer. The GC column configuration for neutral cannabinoid analysis was changed, with the DB-1MS (Agilent Technologies, Wilmington, DE) column as the primary and the ZB-50 (Phenomenex, Torrance, CA) as the secondary column. Before loading the first elution solvent, 0.4mL methanol (StatSure) or hexane (Oral-Eze) was added to the solid phase extraction columns. Limits of quantification (LOQ) were 0.5μg/L for THC, 11-OH-THC, and CBD; 0.5μg/L (StatSure) or 1μg/L (Oral-Eze) for CBN; and 15ng/L for THCCOOH. For StatSure, the linear range was 0.5-50μg/L (THC, CBD, CBN, and 11-OH-THC), and 10-500ng/L (THCCOOH), and for Oral-Eze, 0.5-50μg/L (THC, CBD, and 11-OH-THC), 1-50μg/L (CBN), and 15-500ng/L (THCCOOH). Intra-assay imprecision were 1.0-2.7% (n=6) and 1.0%-4.7% (n=6) for StatSure and Oral-Eze devices, respectively; inter-assay imprecision was <7.6% for both. OF specimens were diluted with drug free OF-buffer mixture if analyte concentrations exceeded the upper LOQ.
Data Analysis
Qualitative OF DrugTest 5000 cannabinoid results at the preprogrammed 5 μg/L THC cutoff were evaluated against quantitative StatSure and Oral-Eze OF 2D-GC-MS results. True positive (TP, DrugTest 5000 and GC-MS positive), true negative (TN, DrugTest 5000 and GCMS negative), false positive (FP, positive DrugTest 5000, but negative GC-MS) and false negative (FN, negative DrugTest 5000, but positive GC-MS) results were calculated at DrugTest 5000 screening cutoffs of 5 μg/L THC and GC-MS THC confirmation cutoffs of 1 μg/L (DRUID), and 2 μg/L (Substance Abuse and Mental Health Services Administration, SAMHSA), as well as confirmation cutoffs of THC and/or THCCOOH (20 ng/L). Sensitivity (100×(TP/[TP+FN])), specificity (100×(TN/[TN+FP])), and efficiency (100×([TP+TN]/[TP+TN+FP+FN])) were calculated at multiple confirmation cutoffs. Rates of detection and windows of detection were evaluated with the DrugTest 5000 screen and different confirmation analytes and cutoffs.
Mann-Whitney U test was utilized to compare time of last detection between occasional and frequent smokers at various screening and confirmation cutoffs; detection ≥30h was assigned as 30h for statistical purposes. Wilcoxon Signed Rank test was applied to compare Oral-Eze and StatSure concentrations and times of last detection (tlast) between devices; a 1 μg/L cutoff was employed for CBN to keep consistency between devices. Any pair where the StatSure or Oral-Eze volume adequacy indicator did not turn blue was excluded. All analyses were done with SPSS Version 20 (IBM, Armonk, NY), with two-tailed p<0.05 considered significant.
Results
Human Participants
Fourteen healthy frequent and 10 occasional smokers (17 men, 7 women), ages 19-41 years, participated in the study (Table 1). Frequent smokers were significantly younger, had smoked for a significantly shorter period of their lifetime, and smoked significantly more recently, more joints or joint-equivalents (empirically-normalized joint consumption, to account for different smoking methods [i.e. bowl, pipe, blunt]) in the last 14 days and more frequently compared to occasional smokers. Two participants (M and N) were originally classified as occasional smokers by self-report, but following analysis of multiple biological (blood, urine, and oral fluid) samples, were reclassified as chronic frequent smokers.
Table 1.
Demographic characteristics and smoking histories for 14 frequent and 10 occasional cannabis smokers
| Participant | Group | Race & Ethnicity | Gender | Age* | BMI* | Age 1st use* | Lifetime years smoked* | Time between last use and admission in h or d** | Number of days used in last 14** | Average joint or joint equivalent/day or /month** |
|---|---|---|---|---|---|---|---|---|---|---|
| A | Frequent | AA | M | 29.6 | 27.6 | 12 | 17.6 | 7.4 h | 11 | 4/d |
| B | Frequent | AA | M | 19.4 | 22.6 | 15 | 4.4 | 4.3 h | 13 | 5/d |
| C | Frequent | AA | M | 22.6 | 31.4 | 14 | 8.6 | 5.1 h | 12 | 3/d |
| D | Frequent | W | M | 25.5 | 23.0 | 13 | 12.5 | 3.9 h | 14 | 20/d |
| E | Frequent | AA | F | 19.9 | 32.4 | 11 | 8.9 | 2.6 h | 14 | 3.5/d |
| F | Frequent | AA | M | 24.2 | 27.4 | 13 | 11.2 | 23.2 h | 12 | 1.5/d |
| G | Frequent | W | F | 22.9 | 24.8 | 16 | 6.9 | 17.2 h | 14 | 6/d |
| H | Frequent | AA | M | 37.3 | 23.0 | 25 | 12.3 | 1.6 h | 14 | 3/d |
| I | Frequent | AA | F | 27.6 | 35.4 | 18 | 9.6 | 2.4 h | 14 | 4/d |
| J | Frequent | AA | F | 26.9 | 20.4 | 14 | 12.9 | 3.8 h | 14 | 21/d |
| K | Frequent | AA | M | 23.4 | 24.3 | 19 | 4.4 | 1.2 h | 14 | 6/d |
| L | Frequent | AA | M | 28.7 | 28.1 | 14 | 14.7 | 9.5 h | 14 | 6/d |
| M | Frequent | AA | M | 28.0 | 19.4 | 14 | 14.0 | 67.4 h† | 2† | 2/m† |
| N | Frequent | AA | M | 23.8 | 30.7 | 14 | 9.8 | 273 h† | 1† | 4/m† |
| O | Occasional | W | M | 25.6 | 29.4 | 16 | 9.6 | 16 d | 0 | 2/m |
| P | Occasional | W | M | 25.4 | 23.7 | 13 | 12.4 | 31 d | 0 | 2/m |
| Q | Occasional | W | M | 23.7 | 24.1 | 16 | 7.7 | 10 d | 2 | 7/m |
| R | Occasional | AA | M | 38.2 | 21.0 | 19 | 19.2 | 2 d | 2 | 2/m |
| S | Occasional | M | M | 41.3 | 22.0 | 16 | 25.3 | 7 d | 5 | 10/m‡ |
| T | Occasional | U | F | 34.9 | 31.7 | 13 | 21.9 | 9 d | 1 | 2/m |
| U | Occasional | AA | F | 36.5 | 47.8 | 18 | 18.5 | 2 d | 2 | 4/m |
| V | Occasional | M, H | M | 22.5 | 25.2 | 13 | 9.5 | 86 d | 0 | 6/m |
| W | Occasional | W | F | 34.2 | 26.6 | 14 | 20.2 | 3 d | 1 | 0.25/m |
| X | Occasional | AA | M | 31.7 | 21.8 | 16 | 15.7 | 18 d | 0 | 8/m |
| Frequent | Mean | 25.7 | 26.4 | 15.1 | 10.6 | - | 13.3 | - | ||
| StdDev | 4.6 | 4.8 | 3.5 | 3.8 | - | 1.1 | - | |||
| Median | 24.8 | 26.1 | 14.0 | 10.5 | 4.1 h | 14.0 | 4.5/d | |||
| Occasional | Mean | 31.4 | 27.3 | 15.4 | 16.0 | - | - | |||
| StdDev | 6.7 | 8.0 | 2.1 | 6.0 | - | - | ||||
| Median | 33.01 | 24.7 | 16.0 | 17.11 | 9.51 | 1.01 | 3/m1 | |||
Data collected at screening
Data collected prior to smoking
Self-reported data inconsistent with biological sample concentrations. Data excluded from mean and median
Self-reported average use at screening of 0.5 joints, 3-4 times per month
Significant difference between groups (p<0.05)
AA: African American, W: White, M: Mixed, U: Unknown, H: Hispanic or Latino
Sample Analysis
Participant B withdrew from the study after the 26h sample collection; 28 and 30h OF samples were not collected. Additional Oral-Eze and DrugTest 5000 samples were missed for participant C at 0.5h due to an adverse event, and for participant E at 30h due to a broken Oral-Eze tube. There were 404 DrugTest 5000-StatSure sample pairs and 403 DrugTest 5000-Oral-Eze sample pairs. Nine DrugTest 5000 samples (2.2%) produced invalid results, yielding 395 OF pairs for comparison with StatSure and 394 OF pairs for comparison with Oral-Eze. Quantitative cannabinoid disposition in OF collected with the StatSure and Oral-Eze devices were previously published [24-25].
StatSure and Oral-Eze Cannabinoid Concentration Comparison
StatSure and Oral-Eze THC and CBD concentrations were not significantly different between devices (Z=−1.500, p=0.134 for THC and Z=−1.551, p=0.121 for CBD) in consecutively collected samples. However, StatSure and Oral-Eze THCCOOH and CBN concentrations differed significantly by device (Z=−11.439, p<0.001 for THCCOOH and Z=−2.520, p<0.05 for CBN), with THCCOOH and CBN concentrations being generally higher in Oral-Eze samples. Given the low THCCOOH detection rate in occasional smokers [24-25], we also compared THCCOOH concentrations between devices for frequent smokers only; concentrations remained significantly different (Z=−10.380, p<0.001).
Detection Rates and Windows of Detection
StatSure and Oral-Eze OF detection rates, with and without DrugTest 5000 results, for THC ≥1 and ≥2μg/L, THCCOOH ≥20ng/L, THC ≥2μg/L or THCCOOH ≥20ng/L, and THC ≥2μg/L and THCCOOH ≥20ng/L are shown in Figures 1 and 2. All occasional smokers were negative on admission for all analytes and cutoffs, while 85.7-100% of frequent smokers were positive on admission, depending on the collection device and cutoff. Adding the DrugTest 5000 results generally reduced detection rates (Figures 1 and 2).
Fig 1.
Cannabinoid detection rates in Oral-Eze and StatSure oral fluid collection devices in occasional and frequent smokers following controlled smoking of a 6.8% Δ9-tetrahydrocannabinol (THC) cannabis cigarette
Fig 2.
Cannabinoid detection rates in DrugTest 5000 with Oral-Eze or StatSure oral fluid confirmation in occasional and frequent smokers following controlled smoking of a 6.8% Δ9-tetrahydrocannabinol (THC) cannabis cigarette
Detection windows were generally shorter in occasional smokers compared to frequent smokers, especially when including THCCOOH ≥20ng/L in the confirmation criteria (Table 2). Three frequent smokers were still DrugTest 5000 positive at 30h, but had 1, 5, and 5 negative samples prior to 30h. Cannabinoid tlast values were not significantly different between devices, except for THC ≥2μg/L (Table 3).
Table 2.
Median (range) time of last cannabinoid detection by screening and confirmation tests for 14 frequent and 10 occasional cannabis smokers following controlled smoking of 6.8% Δ9-tetrahydrocannabinol (THC) cigarette
| Occasional Smokers (h) | Frequent Smokers (h) | Mann Whitney (U) | Effect Size (r) | p | |
|---|---|---|---|---|---|
| DrugTest 5000 Positive | 12 (4 – 24) | 21 (1 – ≥30a) | 43.5 | −0.319 | 0.12 |
| Oral-Eze THC ≥ 1 μg/L (DRUID) | 21 (8 – 28) | 28 (10.5 – ≥30) | 29.5 | −0.473 | <0.05 |
| Oral-Eze THC ≥ 2 μg/L (SAMHSA) | 13.5 (5 – 26) | 21 (6 – ≥30) | 34 | −0.406 | 0.051 |
| Oral-Eze THCCOOH ≥ 20 ng/L | 8 (1 – 21) | ≥30 | 0 | −0.923 | <0.001 |
| Oral-Eze THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | 21 (13.5 – 28) | ≥30 | 0 | −0.932 | <0.001 |
| Oral-Eze THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | 6.5 (1 – 13.5) | ≥30 | 2.0 | −0.822 | <0.001 |
| Oral-Eze THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | 13.5 (6 – 26) | ≥30 | 0 | −0.932 | <0.001 |
| Oral-Eze THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | 6.5 (1 – 13.5) | 26 (6 – ≥30) | 10.5 | −0.711 | <0.001 |
| DrugTest 5000 Positive, Oral-Eze THC ≥ 1 μg/L | 8.25 (2 – 21) | 21 (1 – ≥30) | 34 | −0.404 | 0.053 |
| DrugTest 5000 Positive, Oral-Eze THC ≥ 2 μg/L | 7 (2 – 13.5) | 12 (1 – 26) | 38 | −0.312 | 0.15 |
| DrugTest 5000 Positive, Oral-Eze THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | 8.25 (2 – 21) | 21 (1 – ≥30) | 36.5 | −0.371 | 0.078 |
| DrugTest 5000 Positive, Oral-Eze THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | 4.5 (1 – 13.5) | 21 (1 – ≥30) | 19.0 | −0.600 | <0.01 |
| DrugTest 5000 Positive, Oral-Eze THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | 7 (2 – 13.5) | 21 (1 – ≥30) | 26.0 | −0.508 | <0.05 |
| DrugTest 5000 Positive, Oral-Eze THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | 4.5 (1 – 13.5) | 12 (1 – 26) | 27.0 | −0.467 | <0.05 |
| StatSure THC ≥ 1 μg/L (DRUID) | 21 (10.5 – 28) | 28 (10.5 – ≥30) | 27.5 | −0.494 | <0.05 |
| StatSure THC ≥ 2 μg/L (SAMHSA) | 12 (8 – 24) | 24 (6 – ≥30) | 27 | −0.520 | <0.01 |
| StatSure THCCOOH ≥ 20 ng/L | 4 (0 – 24) | ≥30 (10.5 – ≥30) | 5.0 | −0.802 | <0.001 |
| StatSure THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | 21 (10.5 – 28) | ≥30 (28 – ≥30) | 2.0 | −0.868 | <0.001 |
| StatSure THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | 4 (0 – 13.5) | 25 (10.5 – ≥30) | 9.0 | −0.732 | <0.001 |
| StatSure THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | 13.5 (8 – 24) | ≥30 (21 – ≥30) | 5.0 | −0.803 | <0.001 |
| StatSure THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | 4 (0 – 13.5) | 24 (6 – ≥30) | 10.5 | −0.715 | <0.001 |
| DrugTest 5000 Positive, StatSure THC ≥ 1 μg/L | 5.5 (2 – 21) | 13.5 (1 – ≥30) | 37.5 | −0.359 | 0.09 |
| DrugTest 5000 Positive, StatSure THC ≥ 2 μg/L | 5.5 (2 – 21) | 13.5 (1 – ≥30) | 37.5 | −0.359 | 0.09 |
| DrugTest 5000 Positive, StatSure THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | 5.5 (2 – 21) | 21 (1 – ≥30) | 29.5 | −0.462 | <0.05 |
| DrugTest 5000 Positive, StatSure THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | 2 (0 – 13.5) | 13.5 (1 – ≥30) | 22.0 | −0.559 | <0.01 |
| DrugTest 5000 Positive, StatSure THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | 5.5 (2 – 21) | 21 (1 – >30) | 29.5 | −0.462 | <0.05 |
| DrugTest 5000 Positive, StatSure THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | 2 (0 – 13.5) | 13.5 (1 – ≥30) | 22.0 | −0.559 | <0.01 |
≥30h assigned as 30h for statistical purposes
Table 3.
Median (range) times of last detection between Oral-Eze and StatSure oral fluid collection devices following controlled smoked cannabis of a 6.8% Δ9-tetrahydrocannabinol (THC) cigarette in 14 frequent and 10 occasional cannabis smokers
| Cutoff | Oral-Eze tlast (h) | StatSture tlast (h) | Z | p |
|---|---|---|---|---|
| THC ≥ 1 μg/L (DRUID) | 24 (8 – ≥30) | 26 (10.5 – ≥30) | −0.448 | 0.688 |
| THC ≥ 2 μg/L (SAMHSA) | 13.5 (5 – ≥30) | 21 (6 – ≥30) | −1.980 | <0.05 |
| THCCOOH ≥ 20 ng/L | 30 (1 – ≥30) | 24 (0 – ≥30) | −1.260 | 0.221 |
| THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | 30 (13.5 – ≥30) | 28 (10.5 – ≥30) | 0 | 1.0 |
| THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | 21 (1 – ≥30) | 13.5 (0 – ≥30) | −0.748 | 0.469 |
| THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | 30 (6 – ≥30) | 24 (8 – ≥30) | −0.597 | 0.594 |
| THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | 13.5 (1 – ≥30) | 13.5 (0 – ≥30) | −1.067 | 0.298 |
| DrugTest 5000 Positive, THC ≥ 1 μg/L | 13.5 (1 – ≥30) | 10.5 (1 – ≥30) | −2.023 | 0.063 |
| DrugTest 5000 Positive, THC ≥ 2 μg/L | 9.25 (1 – 26) | 10.5 (1 – ≥30) | 0 | 1.0 |
| DrugTest 5000 Positive, THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | 13.5 (1 – ≥30) | 10.5 (1 – ≥30) | −0.267 | 0.832 |
| DrugTest 5000 Positive, THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | 8 (1 – ≥30) | 8 (0 – ≥30) | −0.682 | 0.514 |
| DrugTest 5000 Positive, THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | 13.5 (1 – ≥30) | 10.5 (1 – ≥30) | −1.381 | 0.178 |
| DrugTest 5000 Positive, THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | 8 (1 – 26) | 8 (0 – ≥30) | −0.039 | 0.988 |
DrugTest 5000 and Confirmation Comparison
Diagnostic sensitivity, specificity and efficiency at multiple confirmation cutoffs are shown in Table 4. When confirming for THC only, diagnostic sensitivity was 5.7-11.0 percentage points higher in frequent as compared to occasional smokers, due to longer detection windows and higher true positive rates (e.g., 70.6% vs. 59.6% in frequent and occasional smokers, respectively, at the 1μg/L Oral-Eze cutoff). Similarly, increased diagnostic sensitivity, specificity, and efficiency were generally documented when considering only 6 or 8h post-smoking, due to higher concentrations and higher true positive rates in occasional and frequent smokers.
Table 4.
Performance characteristics for the Draeger DrugTest 5000 on-site test with a 5 μg/L Δ9-tetrahydrocannabinol (THC) screening cutoff in oral fluid with different confirmation cutoffs
| TP | TN | FP | FN | Total | Sensitivity | Specificity | Efficiency | ||
|---|---|---|---|---|---|---|---|---|---|
| Oral-Eze THC ≥ 1 μg/L (DRUID) | Overall | 202 | 90 | 1 | 101 | 394 | 66.7 | 98.9 | 74.1 |
| Occasional | 65 | 56 | 1 | 44 | 166 | 59.6 | 98.2 | 72.9 | |
| Frequent | 137 | 34 | 0 | 57 | 228 | 70.6 | 100 | 75.0 | |
| Oral-Eze THC ≥ 2 μg/L (SAMHSA) | Overall | 195 | 128 | 8 | 63 | 394 | 75.6 | 94.1 | 82.0 |
| Occasional | 64 | 74 | 2 | 26 | 166 | 71.1 | 97.4 | 83.1 | |
| Frequent | 131 | 54 | 6 | 37 | 228 | 78.0 | 90.0 | 81.1 | |
| Oral-Eze THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | Overall | 202 | 55 | 1 | 136 | 394 | 59.8 | 98.2 | 65.2 |
| Occasional | 65 | 54 | 1 | 46 | 166 | 58.6 | 98.2 | 71.7 | |
| Frequent | 137 | 0 | 1 | 90 | 228 | 60.4 | 100 | 60.5 | |
| Oral-Eze THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | Overall | 167 | 125 | 36 | 66 | 394 | 71.7 | 77.6 | 74.1 |
| Occasional | 31 | 90 | 35 | 10 | 166 | 75.6 | 72.0 | 72.9 | |
| Frequent | 136 | 35 | 1 | 56 | 228 | 70.8 | 97.2 | 75.0 | |
| Oral-Eze THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | Overall | 201 | 70 | 2 | 121 | 394 | 62.4 | 97.2 | 68.8 |
| Occasional | 64 | 68 | 2 | 32 | 166 | 66.7 | 97.1 | 79.5 | |
| Frequent | 137 | 2 | 0 | 89 | 228 | 60.6 | 100 | 61.0 | |
| Oral-Eze THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | Overall | 161 | 148 | 42 | 43 | 394 | 78.9 | 77.9 | 78.4 |
| Occasional | 31 | 94 | 35 | 6 | 166 | 83.8 | 72.9 | 75.3 | |
| Frequent | 130 | 54 | 7 | 37 | 228 | 77.8 | 88.5 | 80.7 | |
| Oral-Eze THC ≥ 2 μg/L (6h post-smoking) | Overall | 160 | 25 | 0 | 27 | 212 | 85.6 | 100 | 87.3 |
| Occasional | 54 | 20 | 0 | 14 | 88 | 79.4 | 100 | 84.1 | |
| Frequent | 106 | 5 | 0 | 13 | 124 | 89.1 | 100 | 89.5 | |
| Oral-Eze THC ≥ 2 μg/L (8h post-smoking) | Overall | 173 | 28 | 1 | 33 | 235 | 84.0 | 96.6 | 85.5 |
| Occasional | 58 | 22 | 0 | 18 | 98 | 76.3 | 100 | 81.6 | |
| Frequent | 115 | 6 | 1 | 15 | 137 | 88.5 | 85.7 | 88.3 | |
| StatSure THC ≥ 1 μg/L (DRUID) | Overall | 196 | 94 | 7 | 98 | 395 | 66.7 | 93.1 | 73.4 |
| Occasional | 64 | 58 | 2 | 42 | 166 | 60.4 | 96.7 | 73.5 | |
| Frequent | 132 | 36 | 5 | 56 | 229 | 70.2 | 87.8 | 73.3 | |
| StatSure THC ≥ 2 μg/L (SAMHSA) | Overall | 191 | 125 | 12 | 67 | 395 | 74.0 | 91.2 | 80.0 |
| Occasional | 64 | 73 | 2 | 27 | 166 | 70.3 | 97.3 | 82.5 | |
| Frequent | 127 | 52 | 10 | 40 | 229 | 76.0 | 83.8 | 78.2 | |
| StatSure THC ≥ 1 μg/L or THCCOOH ≥ 20 ng/L | Overall | 200 | 66 | 3 | 126 | 395 | 61.3 | 95.7 | 67.3 |
| Occasional | 64 | 57 | 2 | 43 | 166 | 59.8 | 96.6 | 81.9 | |
| Frequent | 136 | 9 | 1 | 83 | 229 | 62.1 | 90 | 63.3 | |
| StatSure THC ≥ 1 μg/L and THCCOOH ≥ 20 ng/L | Overall | 140 | 144 | 63 | 48 | 395 | 74.5 | 69.6 | 71.9 |
| Occasional | 11 | 97 | 55 | 3 | 166 | 78.6 | 63.8 | 65.1 | |
| Frequent | 129 | 47 | 8 | 45 | 229 | 74.1 | 85.5 | 76.8 | |
| StatSure THC ≥ 2 μg/L or THCCOOH ≥ 20 ng/L | Overall | 200 | 86 | 3 | 106 | 395 | 65.4 | 96.6 | 72.4 |
| Occasional | 64 | 72 | 2 | 28 | 166 | 69.6 | 97.3 | 81.9 | |
| Frequent | 136 | 14 | 1 | 78 | 229 | 63.6 | 93.3 | 65.5 | |
| StatSure THC ≥ 2 μg/L and THCCOOH ≥ 20 ng/L | Overall | 135 | 155 | 68 | 37 | 395 | 78.5 | 69.5 | 73.4 |
| Occasional | 11 | 97 | 55 | 3 | 166 | 78.6 | 63.8 | 65.1 | |
| Frequent | 124 | 58 | 13 | 34 | 229 | 78.5 | 81.7 | 79.5 | |
| StatSure THC ≥ 2 μg/L (6h post-smoking) | Overall | 158 | 26 | 2 | 26 | 212 | 85.9 | 92.9 | 86.8 |
| Occasional | 54 | 19 | 0 | 15 | 88 | 78.3 | 100 | 82.6 | |
| Frequent | 104 | 7 | 2 | 11 | 124 | 90.4 | 77.8 | 89.5 | |
| StatSure THC ≥ 2 μg/L (8h post-smoking) | Overall | 172 | 28 | 2 | 33 | 235 | 83.9 | 93.3 | 85.1 |
| Occasional | 58 | 20 | 0 | 20 | 98 | 74.4 | 100 | 79.6 | |
| Frequent | 114 | 8 | 2 | 13 | 137 | 89.8 | 80.0 | 89.1 |
TN: True positive; TN: True negative; FP: False positive; FN: False negative; THC: Δ9-tetrahydrocannabinol; DRUID: Driving under the Influence of Drugs, Alcohol and Medicines; SAMHSA: Substance Abuse and Mental Health Services Administration; THCCOOH: 11-nor-9-carboxy-THC.
Discussion
To our knowledge, no other studies compare cannabinoid concentrations among OF collection devices from authentic OF samples after controlled cannabis smoking. In addition, we evaluated detection windows of one screening and two confirmation OF collection devices for cannabinoids in OF from occasional and frequent smokers.
THCCOOH and CBN concentrations were significantly higher in Oral-Eze devices. StatSure samples were collected immediately before Oral-Eze samples. Perhaps the presence of the StatSure device in the mouth stimulated OF excretion, but it is unclear how this could have resulted in higher THCCOOH and CBN concentrations with the Oral-Eze device. Although both devices theoretically collect 1 mL, actual OF volume collected might vary. Previous work documented (based on weight) a mean (RSD) of 0.952mL (11.97%) OF for OF collected with the StatSure device [26]; no data are available for the Oral-Eze device. Differences in collected OF volume could potentially explain the differences in THCCOOH and CBN concentrations. The low CBD prevalence and high THC variability immediately after smoking may contribute to the lack of significant differences for these analytes. Differences in cannabinoid recovery from the pad do not explain differences in concentrations. For the StatSure device, cannabinoid recoveries from the pad were 65.5-68.1%, 62.2-65.9%, 71.3-73.9%, and 65.1-71.2% for THC, CBD, CBN, and THCCOOH, respectively. For the Oral-Eze device, cannabinoid recoveries from the pad were 42.5-48.8%, 33.5-47.7%, 35.6-58.7%, and 68.1-86.2% for THC, CBD, CBN, and THCCOOH, respectively [25]. The lower cannabinoid recoveries for THC, CBD, and CBN from the Oral-Eze pads are inconsistent with higher Oral-Eze concentrations. Other potential explanations for the differences in concentrations are placement of the device in the mouth (under the tongue for the StatSure and between the gum and the cheek for the Oral-Eze), differences in pad composition and thickness, differences in elution/stabilizing buffer, and sequential (rather than simultaneous) OF collections. Concentrations differences due to analyte instability are not expected, as all but 5 Oral-Eze samples were analyzed within 24h of collection.
To our knowledge, no other study evaluated differences in authentic cannabinoid OF concentrations among collection devices after cannabis smoking. Langel et al. evaluated analyte recovery from fortified samples and collected OF volume from 8 OF devices; however, concentrations from authentic OF samples were not evaluated [26]. One study compared expectorated and StatSure OF samples and reported high concentration differences between the two collection methods [20]. In general expectorated THC concentrations were 6 times higher than StatSure concentrations, and consecutively collected expectorated samples varied much more in concentration than consecutively collected StatSure samples. The authors suggest that THC adsorption to cell debris in the OF could explain higher concentrations in expectorated OF, and that inhomogeneous THC distribution in the mouth could explain the higher variability in the expectorated OF compared to the StatSure (which is always placed under the tongue). Others documented no significant differences between simultaneously collected OF with the Quantisal [21] or Intercept devices [22].
Given the higher THCCOOH concentrations in the Oral-Eze samples, it is not surprising that THCCOOH detection rates are higher with this device (Figures 1 and 2). THC ≥1μg/L or THCCOOH ≥20ng/L provided the longest detection times in occasional and frequent smokers (Oral-Eze and StatSure). Due to low THCCOOH prevalence in occasional smokers, requiring a positive THCCOOH ≥20ng/L (e.g. THC ≥1μg/L and THCCOOH ≥20ng/L) greatly reduced detection rates in this cohort for the Oral-Eze and StatSure devices (Figure 1). We previously reported that higher THCCOOH OF concentrations in frequent smokers were due to their frequent past self-administered cannabis intake and high THC body burden [24].
No differences between tlast were observed between collection devices, except for THC ≥2μg/L. In this case, StatSure OF samples had a later tlast. It is unclear why there was a significant difference for this cutoff, as Oral-Eze concentrations were not significantly different. However, in one participant (participant K), THC concentrations were just above the 2μg/L cutoff with the StatSure device, but just below the 2μg/L cutoff with the Oral-Eze between 8-21h post smoking, possibly explaining the significantly later tlast for StatSure samples . Frequent smokers’ tlast were generally later; had we captured the true tlast and not had to assign ≥30h assigned as 30h for statistical purposes, group differences could have differed.
When considering screening and THC confirmation tests, the DrugTest 5000 was generally the limiting factor in the positivity rate due to its higher 5μg/L cutoff compared to GCMS 1 and 2μg/ cutoffs (Figure 2). The only exception was in occasional smokers when THCCOOH ≥20ng/L was required for positive confirmation due to low THCCOOH OF prevalence in this group. These data are consistent with our previously reported evaluation of the DrugTest 5000 in chronic frequent cannabis smokers [19]. Similarly, detection times were reduced with the DrugTest 5000 (Table 2), and differences between occasional and frequent smokers’ tlast were reduced except when THCCOOH was a required confirmation analyte.
Diagnostic sensitivity and efficiency following controlled smoked cannabis were slightly lower than previously reported; however, diagnostic specificity was higher [19]. This can be explained by the higher proportion of true negatives in this study compared to our previous study. Others reported diagnostic sensitivity, specificity, and efficiency of 53-93, 71-99 and 84-94.3%, respectively, (confirmation cutoffs of 1-10μg/L OF THC) [12-13,16-17]. Our data are consistent with our previously published data, indicating that the highest diagnostic efficiency was achieved with a 2μg/L THC confirmation cutoff. Occasional smokers had a lower sensitivity than frequent smokers (when considering only THC for confirmation) due to the generally higher concentrations in frequent smokers’ OF at the later time points. This resulted in a lower incidence of true positives in occasional smokers. Similarly, diagnostic sensitivity, specificity, and efficiency improved in occasional and frequent smokers when considering samples collected up to 6 or 8h post dose, due to the higher incidence of true positive tests. This is consistent with two prior studies that documented higher sensitivities in samples collected recently after smoking [18,12].
Requiring THCCOOH (THC and THCCOOH statement) for confirmation generally reduced diagnostic specificity and efficiency, as it increased the number of DrugTest 5000 false positives, especially in frequent smokers. Due to the low LOQ for THCCOOH and high cannabinoid body burden in frequent smokers, THCCOOH remained positive when THC was no longer detected in OF, increasing the detection rate and window of detection [27].
Conclusion
We document for the first time OF cannabinoid disposition in occasional and chronic frequent cannabis smokers with an on-site screening device and with two OF collection devices following controlled smoked cannabis. We report significant differences in THCCOOH and cannabinol, but not THC concentrations between OF collection devices, which may influence OF data interpretation. The DrugTest 5000 on-site device has high diagnostic sensitivity, specificity, and efficiency for OF cannabinoid detection.
Acknowledgments
We acknowledge the contributions of the clinical staffs of the National Institute on Drug Abuse, Intramural Research Program, and Behavioral Pharmacology Research Unit and Clinical Research Unit, Johns Hopkins Bayview Medical Center, as well as Dr. Sébastien Anizan, Dr. David M. Schwope for protocol assistance, the Graduate Partnership Program, NIH and the “Fondation Baxter et Alma Ricard”. The Draeger DrugTest 5000, Oral-Eze and StatSure devices were provided by the manufacturers to NIH through Materials Transfer Agreements. This research was funded by the Intramural Research Program, National Institute on Drug Abuse, NIH.
Nonstandard abbreviations
- OF
Oral fluid
- THC
Δ9-tetrahydrocannabinol
- THCCOOH
11-nor-9-carboxy-THC
- DUID
Driving under the influence of drugs
- DRUID
Driving under the Influence of Drugs, Alcohol and Medicines
- 11-OH-THC
11-hydroxy-THC
- CBD
cannabidiol
- CBN
cannabinol
- 2D-GC-MS
two dimensional gas chromatography mass spectrometry
- LOQ
Limit of quantification
- TP
True positive
- TN
True negative
- FP
False positive
- FN
False negative
- SAMHSA
Substance Abuse and Mental Health Services Administration
- tlast
time of last detection
References
- 1.United Nations Office on Drugs and Crime . World Drug Report 2013. United Nations, Vienna: 2013. [2 Mar 2014]. http://www.unodc.org/unodc/secured/wdr/wdr2013/World_Drug_Report_2013.pdf. [Google Scholar]
- 2.Drummer OH, Kourtis I, Beyer J, Tayler P, Boorman M, Gerostamoulos D. The prevalence of drugs in injured drivers. Forensic Sci Int. 2012;215(1–3):14–17. doi: 10.1016/j.forsciint.2011.01.040. [DOI] [PubMed] [Google Scholar]
- 3.Lacey JH, Kelley-Baker T, Furr-Holden D, Voas RB, Romano E, Ramirez A, Brainard K, Moore C, Torres P, Berning A. 2007 National Roadside Survey of Alcohol and Drug Use by Drivers: Drug Results. National Highway Traffic Safety Administration Office of Behavioral Safety Research; Washington DC: 2009. [2 Mar 2014]. http://www.nhtsa.gov/Driving+Safety/Research+&+Evaluation/2007+National+Roadside+Survey+of+Alcohol+and+Drug+Use+by+Drivers. [Google Scholar]
- 4.Bostwick JM. Blurred Boundaries: The Therapeutics and Politics of Medical Marijuana. Mayo Clinic Proceedings. 2012;87(2):172–186. doi: 10.1016/j.mayocp.2011.10.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.O'Connell TJ, Bou-Matar CB. Long term marijuana users seeking medical cannabis in California (2001-2007): demographics, social characteristics, patterns of cannabis and other drug use of 4117 applicants. Harm Reduct J. 2007;4:16. doi: 10.1186/1477-7517-4-16. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Crouch DJ, Walsh JM, Flegel R, Cangianelli L, Baudys J, Atkins R. An evaluation of selected oral fluid point-of-collection drug-testing devices. J Anal Toxicol. 2005;29(4):244–248. doi: 10.1093/jat/29.4.244. [DOI] [PubMed] [Google Scholar]
- 7.Laloup M, Del Mar Ramirez Fernandez M, Wood M, De Boeck G, Maes V, Samyn N. Correlation of Delta9-tetrahydrocannabinol concentrations determined by LC-MS-MS in oral fluid and plasma from impaired drivers and evaluation of the on-site Drager DrugTest. Forensic Sci Int. 2006;161(2-3):175–179. doi: 10.1016/j.forsciint.2006.03.033. [DOI] [PubMed] [Google Scholar]
- 8.Cirimele V, Villain M, Mura P, Bernard M, Kintz P. Oral fluid testing for cannabis: on- site OraLine IV s.a.t. device versus GC/MS. Forensic Sci Int. 2006;161(2-3):180–184. doi: 10.1016/j.forsciint.2006.01.020. [DOI] [PubMed] [Google Scholar]
- 9.Walsh JM, Crouch DJ, Danaceau JP, Cangianelli L, Liddicoat L, Adkins R. Evaluation of ten oral fluid point-of-collection drug-testing devices. J Anal Toxicol. 2007;31(1):44–54. doi: 10.1093/jat/31.1.44. [DOI] [PubMed] [Google Scholar]
- 10.Pehrsson A, Gunnar T, Engblom C, Seppa H, Jama A, Lillsunde P. Roadside oral fluid testing: Comparison of the results of Drugwipe 5 and Drugwipe Benzodiazepines on-site tests with laboratory confirmation results of oral fluid and whole blood. Forensic Sci Int. 2008;175(2-3):140–148. doi: 10.1016/j.forsciint.2007.05.022. [DOI] [PubMed] [Google Scholar]
- 11.Crouch DJ, Walsh JM, Cangianelli L, Quintela O. Laboratory evaluation and field application of roadside oral fluid collectors and drug testing devices. Ther Drug Monit. 2008;30(2):188–195. doi: 10.1097/FTD.0b013e3181679249. [DOI] [PubMed] [Google Scholar]
- 12.Blencowe T, Pehrsson A, Lillsunde P, Vimpari K, Houwing S, Smink B, Mathijssen R, Van der Linden T, Legrand S-A, Pil K, Verstraete A. An analytical evaluation of eight on-site oral fluid drug screening devices using laboratory confirmation results from oral fluid. Forensic Sci Int. 2011;208(1-3):173–179. doi: 10.1016/j.forsciint.2010.11.026. [DOI] [PubMed] [Google Scholar]
- 13.Wille SMR, Samyn N, Ramírez-Fernández MdM, De Boeck G. Evaluation of on-site oral fluid screening using Drugwipe-5+®, RapidSTAT® and Drug Test 5000® for the detection of drugs of abuse in drivers. Forensic Sci Int. 2010;198(1-3):2–6. doi: 10.1016/j.forsciint.2009.10.012. [DOI] [PubMed] [Google Scholar]
- 14.Kintz P, Brunet B, Muller JF, Serra W, Villain M, Cirimele V, Mura P. Evaluation of the Cozart DDSV test for cannabis in oral fluid. Ther Drug Monit. 2009;31(1):131–134. doi: 10.1097/FTD.0b013e3181947916. [DOI] [PubMed] [Google Scholar]
- 15.Röhrich J, Zörntlein S, Becker J, Urban R. Detection of Delta9-Tetrahydrocannabinol and Amphetamine-Type Stimulants in Oral Fluid Using the Rapid Stat Point-of-Collection Drug- Testing Device. J Anal Toxicol. 2010;34:155–161. doi: 10.1093/jat/34.3.155. [DOI] [PubMed] [Google Scholar]
- 16.Strano-Rossi S, Castrignano E, Anzillotti L, Serpelloni G, Mollica R, Tagliaro F, Pascali JP, di Stefano D, Sgalla R, Chiarotti M. Evaluation of four oral fluid devices (DDS®), Drugtest 5000®, Drugwipe 5+® and RapidSTAT® for on-site monitoring drugged driving in comparison with UHPLC-MS/MS analysis. Forensic Sci Int. 2012;221(1-3):70–76. doi: 10.1016/j.forsciint.2012.04.003. [DOI] [PubMed] [Google Scholar]
- 17.Vanstechelman S, Isalberti C, Van der Linden T, Pil K, Legrand SA, Verstraete AG. Analytical evaluation of four on-site oral fluid drug testing devices. J Anal Toxicol. 2012;36(2):136–140. doi: 10.1093/jat/bkr016. [DOI] [PubMed] [Google Scholar]
- 18.Bosker WM, Theunissen EL, Conen S, Kuypers KP, Jeffery WK, Walls HC, Kauert GF, Toennes SW, Moeller MR, Ramaekers JG. A placebo-controlled study to assess Standardized Field Sobriety Tests performance during alcohol and cannabis intoxication in heavy cannabis users and accuracy of point of collection testing devices for detecting THC in oral fluid. Psychopharmacology (Berl) 2012;223(4):439–446. doi: 10.1007/s00213-012-2732-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Desrosiers NA, Lee D, Schwope DM, Milman G, Barnes AJ, Gorelick DA, Huestis MA. On-Site Test for Cannabinoids in Oral Fluid. Clin Chem. 2012;58(10):1418–1425. doi: 10.1373/clinchem.2012.189001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Houwing S, Smink BE, Legrand SA, Mathijssen RP, Verstraete AG, Brookhuis KA. Repeatability of oral fluid collection methods for THC measurement. Forensic Sci Int. 2012;223(1-3):266–272. doi: 10.1016/j.forsciint.2012.09.017. [DOI] [PubMed] [Google Scholar]
- 21.Milman G, Barnes AJ, Schwope DM, Schwilke EW, Darwin WD, Goodwin RS, Kelly DL, Gorelick DA, Huestis MA. Disposition of Cannabinoids in Oral Fluid after Controlled Around-the-Clock Oral THC Administration. Clin Chem. 2010;56(8):1261–1269. doi: 10.1373/clinchem.2009.141853. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Niedbala RS, Kardos KW, Fritch DF, Kardos S, Fries T, Waga J, Robb J, Cone EJ. Detection of marijuana use by oral fluid and urine analysis following single-dose administration of smoked and oral marijuana. J Anal Toxicol. 2001;25(5):289–303. doi: 10.1093/jat/25.5.289. [DOI] [PubMed] [Google Scholar]
- 23.Milman G, Barnes AJ, Lowe RH, Huestis MA. Simultaneous quantification of cannabinoids and metabolites in oral fluid by two-dimensional gas chromatography mass spectrometry. J Chromatogr A. 2010;1217(9):1513–1521. doi: 10.1016/j.chroma.2009.12.053. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Anizan S, Milman G, Desrosiers N, Barnes AJ, Gorelick DA, Huestis MA. Oral fluid cannabinoid concentrations following controlled smoked cannabis in chronic frequent and occasional smokers. Anal Bioanal Chem. 2013;405(26):8451–8461. doi: 10.1007/s00216-013-7291-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Newmeyer MN, Desrosiers NA, Lee D, Mendu DR, Barnes AJ, Gorelick DA, Huestis MA. Cannabinoid Disposition in Oral Fluid after Controlled Cannabis Smoking in Frequent and Occasional Smokers Drug Test Anal. Drug Test Anal. 2014 doi: 10.1002/dta.1632. DOI: 10.1002/dta.1632. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Langel K, Engblom C, Pehrsson A, Gunnar T, Ariniemi K, Lillsunde P. Drug testing in oral fluid-evaluation of sample collection devices. J Anal Toxicol. 2008;32(6):393–401. doi: 10.1093/jat/32.6.393. [DOI] [PubMed] [Google Scholar]
- 27.Lee D, Milman G, Barnes AJ, Goodwin RS, Hirvonen J, Huestis MA. Oral Fluid Cannabinoids in Chronic, Daily Cannabis Smokers During Sustained. Monitored Abstinence. 2011;57(8):1127–1136. doi: 10.1373/clinchem.2011.164822. [DOI] [PubMed] [Google Scholar]