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Composition of unapproved cannabinoid products directly marketed to Canadian pet owners
On October 17, 2018 the Cannabis Act came into effect in Canada legalizing activities associated with the production, distribution, sale, and consumption of cannabis. A legal framework exists for physicians to authorize cannabis under the Access to Cannabis for Medical Purposes Regulations (ACMPR). However, this option is currently unavailable to Canadian veterinarians despite calls for revision by the Canadian Veterinary Medical Association (CVMA) (https://www.canadianveterinarians.net/documents/cvma-letter-to-hc-proposed-approach-to-regulation-of-cannabis). Therefore Canadian veterinarians are currently unable to authorize the use of cannabis-derived products for their patients, despite apparent interest from Canadian pet owners (1).
Meanwhile, various cannabis formulations have been marketed directly to pet owners through pet stores or cannabis dispensaries (online or physical storefront). Veterinary Health Products (VHPs) containing hemp may legally be sold, but only if the formulation is derived from approved strains of Cannabis sativa (also known as hemp), dried or extracted from the non-viable seed, and contains ≤ 10 ppm (0.01 mg/mL) of delta-9-tetrahydro-cannabinol (Δ9-THC; https://www.canada.ca/en/public-health/services/antibiotic-antimicrobial-resistance/animals/veterinary-health-products/list-c.html). In addition, VHPs must refrain from specific claims of safety and efficacy. However, cannabis-derived formulations marketed to pet owners as “CBD (cannabidiol) oil” or “phytocannabinoid tinctures” do not meet the criteria for classification as VHPs, as any product containing appreciable CBD or THC would not be obtained from hemp seed. Furthermore, such unapproved, non-VHP cannabis products may have incomplete labeling and/or marketing materials, making it difficult for veterinarians to provide adequate guidance to clients regarding their validity or appropriate use. Given the unregulated nature of these products, our study objective was to analytically quantify the phytocannabinoid levels of various cannabis-derived formulations marketed to pet owners and compare our results to label information. The authors performed independent assessments using separate analytical methods of products purchased in Ontario (JH, JC, IS) and Saskatchewan (AC, KI, SV). The results were combined to provide a more extensive evaluation of cannabis product composition marketed to pet owners across Canada.
Materials and methods
Acquisition of cannabis-derived products: for the Ontario assessment, 4 cannabis liquid formulations (Liquids A to D) and 2 solid treat products (Treats A and B) marketed for veterinary use were obtained via Canadian online retailers. All products were obtained online between March and May 2019. None required a prescription or proof of veterinary licensure. For the Saskatoon assessment, 9 cannabis-derived oil formulations (Liquids E to L) from 4 separate brands were purchased from 2 local pet stores in July and December, 2019. All products were held at room temperature in the stores, with the exception of 1 product (Liquid H) which was kept refrigerated according to manufacturer instructions. Upon purchase, all products were kept refrigerated until they were analyzed.
Products purchased in Ontario were analyzed at a Health Canada accredited GMP-compliant laboratory. For cannabinoid extraction, products were dissolved in 100% methanol, centrifuged, and filtered. Solid samples were ground to increase the surface area for dissolution. The cannabinoid assay was performed via high performance liquid chromatography (HPLC) with changes to the general method made as needed to improve chromatography and separate overlapping peaks. The calibration curve for CBD analysis consisted of 6 standard points, with lower limits of quantification (LLOQ) and upper limits of quantification (ULOQ) of 500 and 50 000 ng/mL, respectively. Presence or absence of THC in the products was determined via inclusion of single point standards for THC (Δ8-THC at 10 000 ng/mL, Δ9-THC at 50 000 mg/mL).
The pesticides assay was run via gas chromatography — tandem mass spectrometry (GC-MS/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). As with the HPLC work, samples were extracted using a combination of grinding, dissolving product in acetonitrile, centrifugation, and filtration. Samples were analyzed on the requisite equipment while comparing to an oil sample spiked with reference pesticides at 10, 50, and 200 ng/mL.
The heavy metal assay was run via inductively coupled plasma mass spectrometry (ICP/MS). The general process for this involved weighing the sample, running it through an acid digestion until it was fully broken down, and then running the samples per United States pharmacopeia (USP). Because the method was not validated, samples were run as-is and compared to samples spiked with known quantities of the elemental impurities. Results were then back-calculated as required.
Liquid products purchased in Saskatoon were analyzed for cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) concentrations using an LC-MS/MS method adapted from a published method in plasma (2). An Agilent 1290 Infinity liquid chromatography system (Agilent Technologies Canada, Mississauga, Ontario) and SCIEX QTrap 6500 triple quadrupole mass spectrometer with electrospray ionization in positive ionization mode (Sciex, Concord, Ontario) were used. Samples were introduced into a Zorbax Eclipse XDB C-18 column (Agilent Technologies Canada) with a flow rate of 700 μL/min. Mobile phase consisted of 0.1 mM ammonium formate in LCMS grade water (mobile phase A) and methanol (mobile phase B), with mobile phase B held at 90% for a sample run time of 12 minutes.
The LC-MS/MS method was validated based on the 2018 FDA Bioanalytical Method Validation guidelines (https://www.fda.gov/files/drugs/published/Bioanalytical-Method-Validation-Guidance-for-Industry.pdf). A calibration curve consisting of 7 standard points, ranging from 10 to 250 ng/mL and weighted 1/x, displayed linearity (R 2 values ≥ 0.98). For both CBD and Δ9-THC, the limit of detection (LOD) and LLOQ were 5 and 10 ng/mL, respectively. The low-quality control (LQC), middle-quality control (MQC), and high-quality control (HQC) concentrations were established as 15 ng/mL, 150 ng/mL, and 225 ng/mL, respectively. Intra- and inter-day accuracy and precision was conducted over 3 days in triplicate, demonstrating all observed LLOQ and QC concentrations were within ± 20% and ± 15% of the nominal concentrations, respectively. Deuterated internal standards were used for accurate quantification of cannabinoids.
Because the stated cannabinoid concentrations of the oil formulations exceeded calibration curve upper limits suitable for the mass spectrometry, all products were diluted 40 000× to enable accurate interpolation of CBD and Δ9-THC concentrations. To mimic use by animal owners, products were vigorously mixed by hand before withdrawing samples for dilution. Liquids G and H were initially outside of the standard curve and were re-analyzed with dilution factors of 500 000× and 5000×, respectively. Dilution integrity was confirmed in triplicate for all dilution factors, remaining within ± 15% of the nominal concentration. Based on the diluted sample LLOQ (10 ng/mL) and a dilution factor of 40 000, the LLOQ of CBD and Δ9-THC in the undiluted liquid products was 0.4 mg/mL (5 and 0.05 mg/mL for Liquids G and H, respectively, due to revised dilution factors). All samples were assayed in triplicate; mean ± standard deviation (SD) results are reported.
The compositions of cannabis-derived products are reported in Tables 1 (Ontario) and and2 2 (Saskatchewan). The specific parameters reported vary due to differences in analytical methods used and formulations assessed at each laboratory. Figure 1 illustrates the label-claimed cannabinoid versus assayed CBD concentrations; there is no correlation (R 2 = 0.014) between claimed cannabinoid and actual CBD concentration.
Stated cannabinoid concentration (on label) versus assayed CBD concentration for various cannabis-derived products.
Composition of cannabis formulations purchased in Ontario.
|Product||Label description||Assay results (mg/mL)||CBD Potency (as % of claimed cannabinoids)||Heavy metals/Pesticides detected||Label recommendations|
|Liquid A||30 mg/mL hemp terpenes||8.7||ND||Det (1)||29%||None found||For dogs and cats, but no directions for use.|
|Liquid B||8.3 mg/mL CBD||3.4||ND||ND||41%||None found||For dogs and cats. Up to 2.27 kg: 10 drops (2.5 mg); 2.27 to 6.8 kg: 20 drops (5 mg); 7 to 11.4 kg: 30 drops (7.5 mg); 11.4 to 15.5 kg: 40 drops (10 mg).|
|Liquid C||none||0.15||Det (40 * )||Det (0.1)||N/A||Pesticides: Metalaxyl, Myclobutanil, Pyrethrin I, Imidacloprid, Cyfluthrin I–IV, Permethrin-cis, Permethrin-trans||Use as needed orally or topically.|
|Liquid D||4 mg/mL CBD||5.3||Det (0.01)||ND||132%||Pesticides: Cyfluthrin I–IV, Permethrin-cis, Permethrin-trans||No directions for use.|
|Treat A||none||4||ND||ND||N/A||Heavy metals: 1.650 μg/g arsenic **||Apply 1 packet per day with food.|
|Treat B||none||2.1||ND||ND||N/A||None found||Administer 2 treats per day.|
ND — Not detected. Actual limit of detection not possible due to single-point standard used.
Det — Cannabinoid detected, but accurate concentration cannot be determined due to single point standard used. Value in parentheses are approximate concentrations only, based on ratio with single point standard.
N/A — Not applicable.
4000× times the maximum concentration for a NHP (10 ppm).
160× the maximum permissible level in water, and 8× the maximum permissible amount in food.
Undiluted cannabinoid composition of cannabis products purchased in Saskatoon, Saskatchewan.
|Product||Label description a||CBD conc. (mg/mL) (mean ± SD)||Δ9-THCConc(mg/mL)||CBD Potency (as % of claimed cannabinoids)||Label recommendations|
|Liquid E1 b||4 mg/mL hemp terpenes||4.65 ± 0.10||< LOD||116.3||0.1 mg per kg BW c|
|Liquid E2 b||4 mg/mL hemp terpenes||3.11 ± 0.07||< LOD||77.7|
|Liquid F||10 mg/mL hemp terpenes||9.24 ± 0.14||< LOD||92.4|
|Liquid G||20 mg/mL hemp terpenes||36.25 ± 0.49||< LOD *||181.3|
|Liquid H||133.3 mg/mL phytocannabinoid tincture in hemp oil||0.52 ± 0.03||< LOD **||0.4||Chronic = 2 drops per 4.5 kg BW, q12h
Acute = 4 drops per 4.5 kg BW, q12h
|Liquid I||10 mg/mL hemp oil (unknown)||3.07 ± 0.18||< LOD||30.7||1 to 3 drops d per 2.27 kg BW|
|Liquid J||16.7 mg/mL hemp oil (unknown)||2.76 ± 0.12||< LOD||16.6|
|Liquid K||5.0 mg/mL hemp isolate in coconut oil||4.58 ± 0.05||< LOD||91.5||0.1 mg per kg BW|
|Liquid L||6.0 mg/mL hemp isolate in coconut oil||4.59 ± 0.16||< LOD||76.5|
Conc — Concentration; SD — Standard deviation; BW — Body weight; LOD — limit of detection; diluted sample LOD = 5 ng/mL; undiluted sample LOD = 0.2 mg/mL.
The use of cannabis-derived products is an emerging field of veterinary therapeutics. A recent preliminary study demonstrated potential efficacy for CBD treatment of canine osteoarthritis (3), and CBD use for control of seizures in epileptic dogs may demonstrate dose-dependent effects (4). Numerous pharmacokinetic studies using various cannabinoid formulations for dogs and cats have been published (3,5–7). However, no cannabis-derived products are currently approved by Health Canada for use in animals. Therefore, cannabis-derived formulations currently marketed to pet owners have not been independently assessed for product quality, efficacy, or safety; any such claims made by the manufacturer are unsubstantiated.