The ever-changing field of drug detection with bath salts and synthetic cannabinoids

Since 2010, the use of synthetic cathinones (that is, “bath salts”) and synthetic cannabinoids (that is, “spice”) has been on the rise in the United States.^1-3 These two classes of synthetic compounds are unique as their structures are modified rapidly by producers, making detection and identification of these compounds difficult. The use of these drugs has increased over several years for multiple reasons. First, the legal status surrounding these compounds is less clearly defined than that of their non-synthesized counterparts. Second, these products are easily sold as plant food or other substances with the label “not to be taken orally,” and thus can be easily procured by the average consumer. Third, unlike naturally occurring THC from marijuana, synthetic cannabinoids and synthetic cathinones are often missed on routine immunoassay drug screens. All of these factors have contributed to a dramatic rise both in the consumption of synthetic cathinones and cannabinoids and their harmful and sometimes deadly side effects. Laboratories are left with the challenge of how to best detect an ever-changing landscape of synthetic drugs to aid clinicians in identifying the drug responsible for their patient’s symptoms.

Naturally occurring substances

Both cathinones and cannabinoids can be naturally occurring in the form of khat (Catha edulis) and marijuana (Cannabis sativa), respectively. Khat is a plant found in Africa and the Arabian peninsula⁴ and is a Schedule I drug with no current accepted medical or recreational uses in the United States.⁵ Khat has been utilized for its psychoactive properties for centuries, dating as far back as the 11th century.^3,6 In contrast to khat, it is currently legal to use marijuana recreationally in eight states (Alaska, California, Colorado, Maine, Massachusetts, Nevada, Oregon, and Washington) and Washington DC, while 13 additional states have decriminalized the possession of small amounts.⁷ Currently, 29 states also allow legal marijuana use for medical purposes.⁷

The naturally occurring substances have known structures and psychogenic effects that differ very little from one crop to another, while the synthetic versions can vary widely from one production to another, and their structures can be modified rapidly by the the parties responsible for their production. Those producers are continually synthesizing new compounds before legislation is passed to ban the predecessor compound from being sold to consumers. Because of this quick turnaround in synthesis of new compounds, the drug of choice changes very rapidly, and the most popular form may fall out of favor within three months as newer products flood the market.⁸ This trend puts a strain on toxicology and hospital laboratories, making it nearly impossible to design, validate, and implement a new assay for a particular analyte, only to have patients arriving in the Emergency Department (ED) with a new synthetic derivative on board by the time the new assay goes live.

Easy-to-obtain causes problems

The ease of obtaining these products creates an open market from producer to consumer with little regulation or oversight. These products are sold with the label “not to be taken orally” or “not for internal ingestion,” which means these products are not regulated by the FDA and can be sold in any stores and purchased without any identification. As such, each product can vary in the compounds and additives used, potentially leading to adverse reactions. These unregulated compounds might be in part responsible for the increase in ED visits by patients in suspected overdoses observed between 2010 and 2011.⁹ Synthetic cannabinoids often have more potent effects than natural marijuana, as the synthetic cannabinoids bind the cannabinoid receptor with higher affinity.¹⁰ The activation of this receptor is responsible for the psychoactive properties reported to be associated when both THC and the synthetic cannabinoids’ bind. This increased potency may also be responsible for increased numbers of patients seen in the ED, as the psychoactive reaction is greater than expected and potentially life-threatening in comparison to natural cannabinoids.

Test problems due to too-specific assays

As a laboratory, our most common method for identifying drug compounds within a urine or blood sample is to first perform a screen (usually in the form of an immunoassay) and then follow up with confirmation testing (usually a mass spectrometry assay) based upon the screen results. Problems arise with both methods in the case of these synthetic cathinones and cannabinoids, in that our assays are too specific. The antibodies used in drug screen immunoassays are typically very specific for a single drug or single class of drugs, while mass spectrometry methods are designed to look for a single parent drug and the known metabolites on each sample and bypass everything else in the sample. Neither of these systems is good at identifying previously unknown compounds. In some reported cases, synthetic cathinones, specifically mephendrone and 3’,4’-methylenedioxypyrovalerone (MDPV), have been shown to cause false positives on specific immunoassays for methamphetamine¹¹ and PCP drug screens,¹² respectively. There is currently one immunoassay commercially available that screens for two groups of bath salts: mephendrone/metacathionone and MDPV/3’,4’-methylenedioxy-α-pyrrolidinobutiophenone (MDPBP)¹³; however, the utility of this assay is still unclear, and new synthetic classes are continuing to outdate the screen.

Promiscuous antibodies that react with core structural elements of synthetic cathinones and cannabinoids could aid in screening, but the mass spectrometry confirmation would still need to be specific for each analyte in order to properly identify. The pitfall with scanning mass spectrometry-based approaches is that the compound’s initial structure and metabolites must already be within the library in order for the software to identify an analyte of interest. With the rapid development of new compounds monthly, continuous definition of parent compounds and metabolites and addition of these new compounds to a library can be daunting, if not impossible, tasks for any individual laboratory. Large reference laboratories are currently undertaking the task of compiling large libraries of known synthetic cathinones and cannabinoids and creating panels to screen; however, local regions may still have a more diverse drug population that is not yet in the geographic region of these larger laboratories.

Synthetic cathinones and cannabinoids are a growing public health crisis in the U.S. The production and distribution of the compounds is unregulated, and legislation is unable to keep up with the growing supply of new compounds that are being made monthly. This creates a challenge for laboratories that try to aid clinicians in determining what compounds are in a patient sample. In the past, innovation in detection assays as a whole has lagged behind new drugs spiking during epidemics. The development of better screening methods could help the laboratory give the clinician a better idea of the class of substance in a sample in order to provide more accurate information to public health authorities. New activity-based assays are currently being developed for synthetic cannabinoids in which newly synthesized cannabinoids can be recognized through their interaction with the cannabinoid receptor.¹⁴ This will allow for identification of newly synthesized compounds based on their activity rather than their modified structure. Until such assays become more readily available for clinical use, there are a few specialized toxicology laboratories that have a focus on synthetic drug screening methods and surveillance. The expertise of these laboratories is useful for cases that arise in the hospital and clinic setting.

REFERENCES

1. Office of National Drug Control Policy: Synthetic Drugs (aka K2, Spice, Bath Salts, etc.) 2015. https://obamawhitehouse.archives.gov/ondcp/ondcp-fact-sheets/synthetic-drugs-k2-spice-bath-salts.
2. Prosser JM, Nelson LS. The toxicology of bath salts: a review of synthetic
   cathinones. J Med Toxicol. 2012;8(1):33-42.
3. Thornton MD, Baum CR. Bath salts and other emerging toxins. Pediatr Emerg Care. 2014;30(1):47-52; quiz 53-45.
4. Hassan NA, Gunaid AA, Murray-Lyon IM. Khat (Catha edulis): health aspects of khat chewing. East Mediterr Health J. 2007;13(3):706-718.
5. Center NDI. Khat Fast Facts: Questions and Answers. 2008. www.justice.gov/archive/ndic/pubs31/31482.
6. Al-Hebshi NN, Skaug N. Khat (Catha edulis)-an updated review. Addict Biol. 2005;10(4):299-307.
7. Association GHS. Drug-Impaired Driving. 2017 http://www.ghsa.org/sites/default/files/2017-07/GHSA_DruggedDriving2017_FINAL_revised.pdf.
8. Laboratories BLaN. Designer Drug Trends: NMS Labs Trends Report 2017. www.nmslabs.com/services-forensic-Designer-Drug-Trends.
9. Bush DM, Woodwell DA. Update: Drug-related emergency department visits
   involving synthetic cannabinoids. The CBHSQ Report. Rockville (MD)2013.
10. Castaneto MS, Gorelick DA, Desrosiers NA, Hartman RL, Pirard S, Huestis MA.
    Synthetic cannabinoids: epidemiology, pharmacodynamics, and clinical implications. Drug Alcohol Depend. 2014;144:12-41.
11. Torrance H, Cooper G. The detection of mephedrone (4-methylmethcathinone) in 4 fatalities in Scotland. Forensic Sci Int. 2010;202(1-3):e62-63.
12. Macher AM, Penders TM. False-positive phencyclidine immunoassay results caused by 3,4-methylenedioxypyrovalerone (MDPV). Drug Test Anal. 2013;5(2):130-132.
13. Ellefsen KN, Anizan S, Castaneto MS, et al. Validation of the only commercially available immunoassay for synthetic cathinones in urine: Randox Drugs of Abuse V Biochip Array Technology. Drug Test Anal. 2014;6(7-8):728-738.
14. Cannaert A, Storme J, Franz F, Auwarter V, Stove CP. Detection and activity profiling of synthetic cannabinoids and their metabolites with a newly developed bioassay. Anal Chem. 2016;88(23):11476-11485.

Sydney W. Strickland, PhD, is a clinical chemistry fellow at the University of Virginia. Strickland has an interest in assay development within toxicology for drugs-of-abuse testing. She has also given several national talks on topics such as recognition of hemoglobin variants in HbA1c analysis by capillary electrophoresis and warfarin pharmacogenetics.

Lindsay AL Bazydlo, PhD, is an Assistant Professor at the University of Virginia and is Director of the Toxicology and Coagulation Laboratories within the UVA Health System. She has an interest in developing clinical assays using mass spectrometry for both urine drug testing and endocrinology applications.