A comprehensive breath test that confirms recent use of inhaled cannabis within the impairment window

Adverse Ocular Impact and Emerging Therapeutic Potential of Cannabis and Cannabinoids: A Narrative Review

Cannabis is the most used drug worldwide with an estimated 219 million users. This narrative review aims to explore the adverse effects and therapeutic applications of cannabis and cannabinoids on the eye, given its growing clinical and non-clinical uses. The current literature reports several adverse ocular effects of cannabis and cannabinoids, including eyelid tremor, ptosis, reduced corneal endothelial cell density, dry eyes, red eyes, and neuro-retinal dysfunction. Cannabinoids may transiently impair night vision, depth perception, binocular and monocular contrast sensitivity, and dynamic visual acuity. Cannabinoids are not currently considered a first-line treatment option for any ocular conditions. Δ-9-tetrahydrocannabinol been shown to result in short-term intraocular pressure reduction, but insufficient evidence to support its use in treating glaucoma exists. Potential therapeutic applications of cannabinoids include their use as a second-line agent for treatment-refractory blepharospasm, for dry eye disease given corneal anti-inflammatory properties, and for suppression of pendular nystagmus in individuals with multiple sclerosis, which all necessitate further research for informed clinical practices.

Smartphone-based drug testing in the hands of patients with substance-use disorder-a usability study

Aim

A clinical study was performed to test the usability of a smartphone eye-scanning app at a needle exchange facility to detect drug use to support therapy.

Methods

The study recruited 24 subjects who visited the facility one to three times, making a total of 40 visits. During each visit the subjects underwent testing for non-convergence (NC), nystagmus (NY), and pupillary light reflex (PLR) using a smartphone-based eHealth system. The collected eye data were transformed into key features that represent eye characteristics. During each visit, a time-line follow-back interview on recent drug use and a usability questionnaire were completed.

Results

Technical usability of the smartphone eye-scanning app was good for PLR and NC, where key features were generated in 82%-91% of the cases. For NY, only 60% succeeded due to cognitive problems to follow instructions. In most cases, subjects were under the influence of drugs when participating in the tests, with an average of 2.4 different drugs ingested within the last 24 h. The key features from PLR could distinguish use of opioids from central stimulants. The usability questionnaire results indicate that 23 of the 24 subjects could perform the eye-scanning by themselves after a short training, even when under severe influence of drugs. The caregiver assessed that 20 out of the 24 challenging subjects could potentially perform these tests in an indoors, home-like environment.

Conclusions

Smartphone-based eye-scanning is functional in a patient population with heavy drug use, also when under the influence of drugs. The use of central stimulants can be distinguished from the use of opioids.

Complexity of Translating Analytics to Recent Cannabis Use and Impairment

While current analytical methodologies can readily identify cannabis use, definitively establishing recent use within the impairment window has proven to be far more complex, requiring a new approach. Recent studies have shown no direct relationship between impairment and Δ9-tetra-hydrocannabinol (Δ9-THC) concentrations in blood or saliva, making legal "per se" Δ9-THC limits scientifically unjustified. Current methods that focus on Δ9-THC and/or metabolite concentrations in blood, saliva, urine, or exhaled breath can lead to false-positive results for recent use due to the persistence of Δ9-THC well outside of the typical 3-4 h window of potential impairment following cannabis inhalation. There is also the issue of impairment due to other intoxicating substances-just because a subject exhibits signs of impairment and cannabis use is detected does not rule out the involvement of other drugs. Compounding the matter is the increasing popularity of hemp-derived cannabidiol (CBD) products following passage of the 2018 Farm Bill, which legalized industrial hemp in the United States. Many of these products contain varying levels of Δ9-THC, which can lead to false-positive tests for cannabis use. Furthermore, hemp-derived CBD is used to synthesize Δ8-THC, which possesses psychoactive properties similar to Δ9-THC and is surrounded by legal controversy. For accuracy, analytical methods must be able to distinguish the various THC isomers, which have identical masses and exhibit immunological cross-reactivity. A new testing approach has been developed based on exhaled breath and blood sampling that incorporates kinetic changes and the presence of key cannabinoids to detect recent cannabis use within the impairment window without the false-positive results seen with other methods. The complexity of determining recent cannabis use that may lead to impairment demands such a comprehensive method so that irresponsible users can be accurately detected without falsely accusing responsible users who may unjustly suffer harsh, life-changing consequences.

Recent advances in the development of portable technologies and commercial products to detect Δ9-tetrahydrocannabinol in biofluids: a systematic review

BACKGROUND

The primary components driving the current commercial fascination with cannabis products are phytocannabinoids, a diverse group of over 100 lipophilic secondary metabolites derived from the cannabis plant. Although numerous phytocannabinoids exhibit pharmacological effects, the foremost attention has been directed towards Δ9-tetrahydrocannabinol (THC) and cannabidiol, the two most abundant phytocannabinoids, for their potential human applications. Despite their structural similarity, THC and cannabidiol diverge in terms of their psychotropic effects, with THC inducing notable psychological alterations. There is a clear need for accurate and rapid THC measurement methods that offer dependable, readily accessible, and cost-effective analytical information. This review presents a comprehensive view of the present state of alternative technologies that could potentially facilitate the creation of portable devices suitable for on-site usage or as personal monitors, enabling non-intrusive THC measurements.

METHOD

A literature survey from 2017 to 2023 on the development of portable technologies and commercial products to detect THC in biofluids was performed using electronic databases such as PubMed, Scopus, and Google Scholar. A systematic review of available literature was conducted using Preferred Reporting Items for Systematic. Reviews and Meta-analysis (PRISMA) guidelines.

RESULTS

Eighty-nine studies met the selection criteria. Fifty-seven peer-reviewed studies were related to the detection of THC by conventional separation techniques used in analytical laboratories that are still considered the gold standard. Studies using optical (n = 12) and electrochemical (n = 13) portable sensors and biosensors were also identified as well as commercially available devices (n = 7).

DISCUSSION

The landscape of THC detection technology is predominantly shaped by immunoassay tests, owing to their established reliability. However, these methods have distinct drawbacks, particularly for quantitative analysis. Electrochemical sensing technology holds great potential to overcome the challenges of quantification and present a multitude of advantages, encompassing the possibility of miniaturization and diverse modifications to amplify sensitivity and selectivity. Nevertheless, these sensors have considerable limitations, including non-specific interactions and the potential interference of compounds and substances existing in biofluids.

CONCLUSION

The foremost challenge in THC detection involves creating electrochemical sensors that are both stable and long-lasting while exhibiting exceptional selectivity, minimal non-specific interactions, and decreased susceptibility to matrix interferences. These aspects need to be resolved before these sensors can be successfully introduced to the market.

Electrochemical Oxidation of Δ9-Tetrahydrocannabinol at Nanomolar Concentrations

With increasing marijuana legalization, there is a growing need for technology that can determine if an individual is impaired due to recent marijuana usage. The electrochemical oxidation of Δ9-THC to form its corresponding quinones can be used as a framework to develop an electrochemical sensor for Δ9-THC. This study describes an electrochemical oxidation of Δ9-THC that uses a copper anode, a platinum cathode, and an atmosphere of oxygen. The oxidation is feasible at nanomolar concentrations, which approaches the reactivity that is necessary for developing a real-world marijuana breathalyzer. Moreover, we show that vaporized Δ9-THC can be captured directly in an electrolyte medium and subjected to electrochemical oxidation, thus paving the way for use in future technology development.

Feasibility of using breath sampling of non-volatiles to estimate the prevalence of illicit drug use among nightlife attendees

The prevalence of drug use among nightlife attendees needs to be accurately estimated to, for example, evaluate preventive interventions. This study tested the feasibility of using a breath-sampling device to estimate the prevalence of drug use among nightlife attendees. The study was conducted at five nightclubs and a large music festival in Stockholm, Sweden. Participants were invited to participate and microparticles in exhaled breath were sampled and analyzed for 47 compounds using a state-of-the-art analytic method that follows forensic standards. In addition, participants' breath alcohol concentration was measured and they were interviewed about demographics, drinking habits, and drug use. Of the people invited, 73.7% (n = 1223) agreed to participate, and breath samples were collected from 1204 participants. Breath sampling was fast and well-accepted by participants. 13 percent of participants tested positive for an illicit drug, but only 4.3% self-reported drug use during the last 48 h. The most common substances detected were cocaine, amphetamine, and MDMA. There was no agreement between self-reported and measured use of any drug. Breath sampling is a convenient method to test illicit drug use among a large number of participants at events, and can be used as an estimate of drug use prevalence.

A Cannabinoid Fuel Cell Capable of Producing Current by Oxidizing Δ9-Tetrahydrocannabinol

We report the development of a current-producing H-Cell that relies on the oxidation of Δ⁹-tetrahydrocannabinol (THC), which is the primary psychoactive ingredient in marijuana. We found through systematic investigation of several variables that power densities could be improved 5-fold. Moreover, a real-time signal in a rudimentary THC sensor was observed at varying concentrations of THC. Given the growing societal interest in the detection of THC, our studies lay the foundation for the development of a marijuana breathalyzer.

Examining impairment and kinetic patterns associated with recent use of hemp-derived Δ8-tetrahydrocannabinol: case studies

Background

As a result of the legalization of U.S. industrial hemp production in late 2018, products containing hemp-derived Δ⁸-tetrahydrocannabinol (Δ⁸-THC) are increasing in popularity. Little, however, is known regarding Δ⁸-THC’s impairment potential and the associated impacts on roadway and workplace safety, and testing for Δ⁸-THC is not yet common. The present study explored impairment patterns and cannabinoid kinetics associated with recent use of Δ⁸-THC.

Methods

Hemp-derived Δ⁸-THC concentrate was administered by vaporization ad libitum to three male frequent cannabis users aged 23–25 years. In addition to self-assessments of impairment using a 10-point scale, horizontal gaze nystagmus (HGN) was evaluated in each subject as a physical means of assessing impairment before and after vaporization. To examine cannabinoid kinetic patterns, exhaled breath and capillary blood samples were collected prior to vaporization up to 180 min post-vaporization and analyzed by liquid chromatography high-resolution mass spectrometry for cannabinoid content using validated methods. The impairment and cannabinoid kinetic results were then compared to analogous results obtained from the same three subjects after they had smoked a ∆⁹-THC cannabis cigarette ad libitum in a previous study to determine whether any similarities existed.

Results

Patterns of impairment after vaporizing Δ⁸-THC were similar to those observed after smoking cannabis, with self-assessed impairment peaking within the first hour after use, and then declining to zero by 3 h post-use. Likewise, HGN was observed only after vaporizing, and by 3 h post-vaporization, evidence of HGN had dissipated. Cannabinoid kinetic patterns observed after vaporizing Δ⁸-THC (short ∆⁸-THC half-lives of 5.2 to 11.2 min at 20 min post-vaporization, presence of key cannabinoids cannabichromene, cannabigerol, and tetrahydrocannabivarin, and breath/blood Δ⁸-THC ratios > 2 within the first hour post-vaporization) were also analogous to those observed for ∆⁹-THC and the same key cannabinoids within the first hour after the same subjects had smoked cannabis in the previous study.

Conclusions

Hemp-derived Δ⁸-THC and Δ⁹-THC from cannabis display similar impairment profiles, suggesting that recent use of Δ⁸-THC products may carry the same risks as cannabis products. Standard testing methods need to incorporate this emerging, hemp-derived cannabinoid.

Indeterminacy of cannabis impairment and ∆9-tetrahydrocannabinol (∆9-THC) levels in blood and breath

Previous investigators have found no clear relationship between specific blood concentrations of ∆⁹-tetrahydrocannabinol (∆⁹-THC) and impairment, and thus no scientific justification for use of legal “per se” ∆⁹-THC blood concentration limits. Analyzing blood from 30 subjects showed ∆⁹-THC concentrations that exceeded 5 ng/mL in 16 of the 30 subjects following a 12-h period of abstinence in the absence of any impairment. In blood and exhaled breath samples collected from a group of 34 subjects at baseline prior to smoking, increasing breath ∆⁹-THC levels were correlated with increasing blood levels (P < 0.0001) in the absence of impairment, suggesting that single measurements of ∆⁹-THC in breath, as in blood, are not related to impairment. When post-smoking duration of impairment was compared to baseline ∆⁹-THC blood concentrations, subjects with the highest baseline ∆⁹-THC levels tended to have the shortest duration of impairment. It was further shown that subjects with the shortest duration of impairment also had the lowest incidence of horizontal gaze nystagmus at 3 h post-smoking compared to subjects with the longest duration of impairment (P < 0.05). Finally, analysis of breath samples from a group of 44 subjects revealed the presence of transient cannabinoids such as cannabigerol, cannabichromene, and ∆⁹-tetrahydrocannabivarin during the peak impairment window, suggesting that these compounds may be key indicators of recent cannabis use through inhalation. In conclusion, these results provide further evidence that single measurements of ∆⁹-THC in blood, and now in exhaled breath, do not correlate with impairment following inhalation, and that other cannabinoids may be key indicators of recent cannabis inhalation.