The DSM-5 now recognizes a cannabis related disorders category that includes cannabis use disorder (CUD), cannabis intoxication, cannabis withdrawal, other cannabis-induced disorders, and unspecified cannabis related disorder.1 Chronic cannabis use is associated with an increased risk of developing cannabis use disorder. 2 In the DSM-5 cannabis use disorder includes 11 criteria which are like other substance use disorders and they encompass the range of signs and symptoms including physiological signs like tolerance and withdrawal. 3 The DSM-5 defines cannabis dependence as a disorder characterized by a problematic pattern of use leading to clinically significant impairment or distress. Approximately 10% of individuals who regularly use cannabis will develop dependence. In the DSM-5 cannabis abuse and dependence fall under the diagnosis of CUD. 4 Clinical and experimental work spanning the last two decades has indicated that cannabis specifically THC has the potential to be abused. 3 Cannabis has been associated with low abuse potential compared to other drugs of abuse, but it would be inappropriate to underestimate its abuse and dependence liability. Cannabis addiction has been observed in about 9% of users. 5 In human studies of abuse potential, cannabis produces clear subjective reports of pleasurable effects, and these are associated with motivational responses including drug-seeking and drug-taking behavior. Euphoria or a feeling of being high has been identified as a primary factor associated with cannabis use.6 Many factors contribute to the abuse liability of cannabis but one that must be considered is that THC potency has increased steadily over the last four decades. 1 Chronic cannabis users typically experience unpleasant withdrawal symptoms when use is discontinued. Cannabis withdrawal symptoms include restlessness, irritability, and insomnia just to name a few.2,5 Symptoms of cannabis withdrawal also seem to appear in a similar time course and manner as withdrawal from other substances of abuse. These symptoms are much less severe than those associated with withdrawal from opioids but aversive enough to encourage continued cannabis use and interfere with cessation attempts. 1 Whether a drug can influence the dopaminergic system aids in determining if a drug could possess abuse potential through its reinforcing actions. Increased dopamine release in cells of the mesolimbic ventral tegmental area and the nucleus accumbens pathway is a common characteristic of almost all drugs of abuse and THC has been shown to increase dopamine in these areas. ,6 Research indicates that there are interactions between dopamine receptors(D2) and CB1 receptors.5 Although cannabis may have lower abuse liability than other drugs like cocaine or nicotine, once somebody develops dependence quitting becomes extremely difficult. Relapse rates observed for cannabis use disorders are comparable to those for other abused drugs and only 15-37% of patients undergoing psychotherapeutic and pharmacological interventions achieve continued abstinence.1,3 Many individuals use cannabis for its psychoactive effects When drug-associated cues and contexts associated with the initial exposure to a drug are highly rewarding a conditioned dopamine release can occur. 2 Through the process of conditioning and learning these specific cues in the environment gain control of behavior. This activates and guides a complex sequence of actions required to obtain, prepare, and self-administer the drug, and over time this behavior can become increasingly habitual and resistant to change even after a long period of abstinence. 1 References 1. Panlilio, L V et al. “Cannabinoid abuse and addiction: Clinical and preclinical findings.” Clinical pharmacology and therapeutics vol. 97,6 (2015): 616-27. doi:10.1002/cpt.118 2. Zehra, Amna et al. “Cannabis Addiction and the Brain: A Review.” Journal of neuroimmune pharmacology : the official journal of the Society on NeuroImmune Pharmacology vol. 13,4 (2018): 438-452. doi:10.1007/s11481-018-9782-9 3. Piomelli D, Haney M, Budney AJ, Piazza PV. Legal or Illegal, Cannabis Is Still Addictive. Cannabis and Cannabinoid Research 2016; 1: 47-53. https://www.liebertpub.com/doi/pdf/10.1089/can.2015.29004.rtd 4. Siavash J, Tan T. Diagnosis and Treatment of Marijuana Dependence. British Columbia Medical Journal 2016;58(6):315.317. https://www.bcmj.org/articles/diagnosis-and-treatment-marijuana-dependence Accessed June 11, 2020. 5. Jain R, Pal Y, Balhara. Neurobiology of Cannabis Addiction Indian J.Physiol Pharacol 2008;52(3):217-232 https://pdfs.semanticscholar.org/73ec/29608ca979e9ff1423d3e0ed4b4e19ba06ba.pdf Accessed June 11, 2020. 6. White J. Abuse and dependence potential of Cannabis sativa and nabiximols. 2016; 38th ECDD Agenda item 5.1 https://www.who.int/medicines/access/controlled-substances/Abuse_and_dependence_potential.pdf?ua=1 Accessed June 11, 2020.

Kandel and Faust in the 1970s conducted a study with secondary students in New York State where they described a sequence of substance use initiation progressing from alcohol use to tobacco use followed by cannabis and then other substance use. The authors initially cautioned that their findings should not be considered casual but suggested later that some substances are a gateway to others. this became known as the “gateway hypothesis”. 1 The term “gateway drug” was popularized in 1984 by Dr. Robert L. DuPont Jr. who posited that if young people did not use cannabis it was relatively unlikely that they will use other illegal drugs, He did not claim that cannabis use causes young people to use other drugs. Dr. DuPont observed that if young people did not use alcohol or tobacco, they would be less likely to use other drugs such as cannabis. His main conclusion was that a young person’s willingness to use any drug and especially frequent use may remove the psychological barrier to using another drug. 2 Research does not support the theory that cannabis is a “gateway drug”. Cannabis has never been proven to have a gateway effect. 1,2 Association does not prove causation. 2 Individuals who have used drugs such as heroin or cocaine are more likely to have used cannabis than someone who has not used any of these substances. Since cannabis is the most widely obtainable and widely used illicit drug individuals are more likely to have used cannabis before other illicit drugs as a result. If the gateway effect were true, more cannabis users would progress in their drug use which is not the case. The vast majority of people who use cannabis do not go on to use other illicit drugs. 2 Cannabis use may be associated with other substances, but it involves complex relationships with other factors such as adverse childhood experiences, social influences, genetic, environmental factors, and mental health issues. 1 Research suggests that those who use drugs may have an underlying propensity to do so that is not specific to any drug. 2 Most drug users typically begin with underage nicotine and alcohol use before cannabis. 3 Some suggest that adolescents who have a propensity for drug use are exposed to other drugs when purchasing cannabis on the black market which then increases the opportunity to use other illicit drugs. 4 It is important to recognize that most of the research on drug progression has focused on recreational use. Research from states with medical marijuana programs has found that youth rates drop or remain stable after a state passes a medical marijuana law. A study conducted 15 years after the passage of the first medical marijuana law concluded that teens’ cannabis use has generally decreased. 2 References 1. Leece P, Paul N. Q&A:Is cannabis a “gateway drug? Ontario Agency for Health and Promotion(Public Health Ontario) Toronto,ON:Queen’s Printer for Ontario; Published 2019. https://www.publichealthontario.ca/-/media/documents/Q/2019/qa-cannabis-gateway.pdf?la=en Accessed September 26, 2020. 2. Alexander C. Debunking the “Gateway” Myth. Drug Policy Alliance. Published February 2017. https://www.drugpolicy.org/sites/default/files/DebunkingGatewayMyth_NY_0.pdf Accessed September 26, 2020. 3. Scharff C. Marijuana:The Gateway Drug Myth. Psychology Today. Posted Aug 26, 2014. https://www.psychologytoday.com/us/blog/ending-addiction-good/201408/marijuana-the-gateway-drug-myth Accessed September 26, 2020 4. Jaffe A. Is Marijuna a Gateway Drug? Psychology Today .Posted Jul 24, 2018. https://www.psychologytoday.com/us/blog/all-about-addiction/201807/is-marijuana-gateway-drug Accessed September 26, 2020.

There is a need for USP standards for cannabis to be accepted by the medical community it must conform to the same standards and regulations as any other medicine. Cannabis must be tested so patients know what they are using, providers know what to recommend, and product labels need to be accurate. Currently, there is no federal oversight or regulatory control, instead, the laws governing the testing of cannabis have been left up to the states. Some states have very stringent controls in place while others do not, which has put the consumer at risk. Consumers and patients expect quality to be inherent in the products they use, and poor-quality control procedures can lead to adverse events and increased health risks. These standards could also provide access to quality materials for use in clinical trials. These trials are needed to demonstrate the safety and efficacy of cannabis.1 The United States Pharmacopeia (USP) is a scientific nonprofit organization that plays a role in developing and formulating standards for medicines, dietary supplements, and foods based on expert advice from the medical and scientific community. 1 Once the USP determines there is a need for guidance, methodology, or standards for a new industry, product, or process they produce a draft standard and guidance document. Once the draft is approved the monographs, chapters, and other standards are published in the Unites States Pharmacopeia-National Formulary (USP-NF). 2 Monographs are documents that explain the expectations for a food, drug, or material to ensure its identity, purity, strength, and performance. Monographs contain the chemical information for the ingredient or material and outline the tests and procedures that must occur to meet quality criteria and limit impurities. General chapters provide information on accepted processes, tests, and methods to support industry in product development and manufacturing quality controls. General chapters must be referenced in a specific monograph to be enforceable on a legal basis. 2 The 1938 Food Drug and Cosmetic Act decreed that all medicines sold in the United States must meet USP quality standards. USP standards are enforced by the FDA. Since cannabis is a Schedule 1 drug and is illegal at the federal level, USP has not created a formal official compendium. 2,3 Cannabis first appeared in the 1850 edition of the United States Pharmacopoeia and the Extractum Cannabis monograph was published. In 1916, USP published the Cannabis americana monograph. In 1936 USP published an additional monograph, USP XI. Cannabis was removed from the pharmacopeia in 1940.3 With the reemergence of cannabis as a medicinal product, the goal of the USP is to ensure the quality of cannabis intended for medical purposes. It is imperative for public safety that the USP develop standards to address laboratory verification of cannabis identity, quantitative analysis of cannabinoids and terpenes, and measures to limit exposure to contaminants such as mycotoxins, pesticides, and heavy metals.2 One of the first challenges the USP had to address was how to classify the various varieties and subtypes of the plant product. USP has divided the plant material into three main chemotypes based on the amount of THC and CBD present. These three classifications are, THC dominant, CBD dominant, or intermediate containing both THC and CBD. 1,2This classification system is needed since brand names associated with strain names such as Sativa or Indica can be misleading. 1There can be considerable variation in cannabinoid content among specimens of the same strain and the total THC and CBD levels of a given chemotype can be profoundly affected by cultivation methods, processing, and storage conditions. These factors can be altered to produce strains with higher THC levels.3 USP recommends the use of science-based analytical procedures to identify cannabis varieties. These techniques include high-performance liquid chromatography (HPLC) and gas chromatography (GC) to separate and quantify THC, CBD, and 11 other cannabinoids that may have therapeutic potential.1,3 Reference materials or physical standards currently produced by USP can be used to confirm the identity of various cannabinoids by chromatographic techniques. 1,2 Different cannabis varieties can also vary in the composition of terpenes. USP identified five different terpenes that are abundant in cannabis and recommends profiling these terpenes via separate GC procedures. These detailed profiles of cannabinoid and terpene content can help guide prescribers and ensure patients that they are receiving a consistent product.1 USP standards establish guidelines to ensure safety and create analytical limits for possible contamination from pesticides, heavy metals, mycotoxins such as aflatoxin, and adulteration. One of the most cited reasons for the recall of cannabis products was the contamination of products with pesticides due to exceeding state limits or the presence of restricted pesticides.2 Since cannabis is classified as a schedule one drug, there are no federally approved crop protection agents, this is regulated at the state level. With the absence of legal guidance, growers have used pesticides not intended for use with food or medicinal crops. The US Environmental Protection Agency regulates pesticides for food crops but there is no specific tolerance or exemption for cannabis. 1 The USP maximum acceptable exposure limits for each pesticide are 1000-fold lower than the acceptable daily intake established by the Food and Agriculture Organization of the United Nations and the World Health Organization. Also, the nature and extent of risk could differ for a smoked or vaporized product compared to dietary exposure. USP general chapter articles of botanical origin establish pesticide limits based on acceptable daily exposure, body weight consumed, and a safety margin for oral exposure that can be used for the development of pesticide residue standards for inhaled cannabis materials. Cannabis is a concentrator of heavy metals which then accumulate in the plant and pose a health risk. There have been several product recalls that have occurred due to elevated levels of heavy metals 2Potential sources of elemental impurities include environmental pollutants, manufacturing, processing, and delivery sources. There are no federal testing requirements for heavy metals but rather is regulated at the state level. Most states test for four metals, cadmium, arsenic, lead, and mercury but this is not sufficient. There is a need for a federally regulated list of possible elemental containments that should be tested, instead of the patchwork of testing that currently exists at the state level. USP has several chapters on heavy metal limits and testing, which could be applied to cannabis. 2,4 Cannabis plants are susceptible to microbial contamination including molds especially Aspergillus fumigatus and mycotoxins such as aflatoxins during cultivation, harvesting, drying, storage, and/or distribution. Aspergillus spores can survive when cannabis is smoked or vaporized and can subsequently infiltrate the lungs causing infections resulting in respiratory injury which may be fatal for patients with a weakened immune system. Currently, there is no validated test for Aspergillus. There are USP chapters that address standards for monitoring microorganisms and aflatoxins which can be applied to create limits and methodologies for cannabis.1,3 There is also a need for quality standards for medical cannabis that ensures the identity purity and strength of cannabis to reduce the possibility of adulteration. Cannabis has been mixed with synthetic analogs to increase its psychotropic effect. USP has recently addressed this issue with the development of a new general chapter, Adulteration of Dietary Supplements with Drug and Drug Analogs. This approach could be used to develop cannabis standards to detect this type of adulteration. 3 There is also a need to establish guidelines addressing the potential exposure to toxic solvents used to prepare cannabis extracts. Exposure to these solvents poses a significant health risk. USP has developed procedures and general approaches described in the general chapter Residual Solvents that could be applied to address this risk in cannabis products.1,3 Without the availability of references standards produced by the USP it would be difficult to ensure that products available to a consumer are of the appropriate identity, strength, quality, purity or consistency. These standards are used in pharmaceutical development and manufacturing. To ensure that references materials produced by USP meet the highest standards they are evaluated by multiple independent laboratories. 5 Reference standards help to confirm accuracy and reproducibility in testing, they are required so analytical procedures accurately identify and measure the content of constituents in a material. Reference standards may also be used for qualitative applications such as identification tests, system suitability tests, or chromatographic peak markers. 6 The USP produces cannabis reference standards for medicinal cannabis which provide for the consistent characterization of cannabis for medical use. These references standards are used in analytical procedures to verify the identity and determine the constituents of product samples. The USP has developed multiple compounds including USP Delta-Tetrahydrocannabinol 1 mL (l mg/mL), USP Exo-Tetrahydrocannabinol 1 mL, USP cannabinoid Acid Mixture 1 mL (in acetonitrile and triethylamine with stabilizer, USP Cannabinoids Mixture 1 mL (in methanol), USP Cannabidiol Solution 1mL (lmg.ml) and USP Cannabidiol 25 mg. These reference standards can be used for the quantitative measurement of cannabinoids which is vital in the determination of potency. 7 References 1. Eisenstein M, Muldoon Jacobs KL. Cannabis for Medical Use: Consistent Quality to Help Protect Patients. USP. https://cdn2.hubspot.net/hubfs/3402974/USP%20%7C%20Cannabis%20for%20medical%20use%20consistent%20quality%20to%20help%20protect%20patients.pdf Accessed November 12, 2020. 2. Atkins PL. Everything Old is New Again: Cannabis Returns to USP. Cannabis Science and Technology. June 2020;3(5):17-22 https://www.cannabissciencetech.com/view/everything-old-new-again-cannabis-returns-usp 3. Giancaspro GI, Kim NC, Venerna J, et al. The Advisability and Feasibility of Developing USP Standards for Medical Cannabis. In Pharmacopeial Forum 2016;42(1). https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/usp-nf-notices/usp_stim_article_medical_cannabis.pdf Accessed November 12, 2020. 4. Thomas BF, ElSohly MA. Chapter 4: Analytical Methods in Formulation Development and Manufacturing. Thomas BF, ElSohly MA, eds. The Analytical Chemistry of Cannabis: Quality Assessment, Assurance, and Regulation of Medicinal Marijuana and Cannabinoid Preparations. Elsevier; 2015:63-82. 5. USP Reference Standards. https://www.usp.org/reference-standards Accessed November 14, 2020 6. Sarma, ND, et al, Cannabis Inflorescence for Medical Purposes: USP Considerations for Quality Attributes. Journal of Natural Products. 2020; 83(4):1334-1351 https://dx.doi.org/10.1021/acs.jnatprod.9b01200 7. Cannabis References Standards https://www.usp.org/dietary-supplements-herbal-medicines/cannabis Accessed November 14, 2020.

The treatment of pain remains the number one medical use of cannabis. 1 Using either THC or CBD to treat pain many additional factors need to be considered. Regarding pain there are phenotypic and genotypic interindividual variability 2 and different cannabinoids may lead to mechanistically different pain-relieving effects. 3 In addition, using cannabis in pain management can address disturbed sleep 4, anxiety and depression which often present as co- morbidities in pain. Cannabis has been used for the treatment of pain dating back to Chinese texts in 2900 B.C. 5 The three main pain systems are nociceptive, neuropathic and central. Nociceptive pain is caused by damage to body tissues and is usually described as sharp, aching or throbbing. Nociceptive pain has warning and defensive properties. The two other pain systems, neuropathic and central involve non-functional pain signals. Neuropathic pain is caused by damage to sensory nerves which send inaccurate pain messages to higher brain centers. Pain may be present despite a lack of a clear peripheral cause. 5 Clinical trials lasting from days to months involving more than 1000 patients have shown efficacy in different categories of chronic pain, but the vast majority of controlled trials have involved patients with chronic neuropathic pain. 4 “Neuropathic pain is a severe chronic, debilitating condition associated with nerve injury that develops following lesions to the central and peripheral nervous systems. Neuropathic pain often manifests as spontaneous burning, tingling, or a shooting sensation which can be amplified by noxious stimuli. 6 Recently it has been recognized that cannabinoids both endogenous and plant derived act simultaneously on multiple pain targets within the peripheral and central nervous systems. “In addition to working on CB1 and CB2 receptors, cannabinoids may reduce pain through interaction with non CB1/CB2 cannabinoid G protein coupled receptors such as GPCR 55 or GCPR18, as well as opioid or serotonin(5-HT) receptors. In addition, many studies have reported the ability of certain cannabinoids to modulate peroxisome proliferator activated receptors (PPARs), cys loop ligand gated ion channels or transient receptor potential (TRP) channels. Data suggests that there are a variety of interactions between cannabinoid, opioid and TRPV1 receptors in pain modulation. 1 Both CB1 and CB2 receptors have been found to be upregulated in nervous structures involved in pain processing in response to peripheral nerve damage.1 CB1 receptors are found at high levels in the brain but also lower levels in spinal and peripheral nervous tissue including areas important for pain perception.7 CB1 receptors are also found in brain areas involved in nociceptive perception such as the thalamus and amygdala. Data reveals that amygdala activity contributes to inter-individual responses to cannabinoid analgesia. 3 The anatomical distribution of CB1 receptors helps in identifying how these receptors function in modulating pain perception at both peripheral and central levels. 7 In addition, CB1 receptors have been shown to impede pain conduction. 8 CB2 receptors are primarily expressed in immune cells, including myeloid, macrophage, microglia, lymphoid and mast cells. 8 CB2 while commonly reported as confined to lymphoid and immune tissues, is also proving to be an important mediator for suppressing both pain and inflammatory processes. 9 There are about 100 different cannabinoids isolated from the cannabis plant. The main psychoactive compound is delta-9-tetrahydrocannabinol. It is responsible for most of the pharmacological actions of cannabis, including the psychoactive, analgesic, anti-inflammatory, anti-oxidant, antipruritic, bronchodilatory, antispasmodic and muscle relaxant activities. THC exhibits the greatest analgesic activity. 1 In fact, THC administered epidurally produces antinociception like that observed with opioid compounds. 7 THC acts as a partial agonist at CB1 and CB2 receptors. THC when acting at the CB1 receptor has been shown to modulate neural conduction of pain signals by mitigating sensitization and inflammation. 5 THC suppresses proinflammatory cytokines and enhances anti-inflammatory cytokines in both the innate and adaptive immune responses. 6 THC has twenty times the anti-inflammatory potency of aspirin and twice that of hydrocortisone. 9 In neuropathic pain cannabis containing a lower dose (1.29% THC) and higher dose (3.53% THC) delivered by vaporizer demonstrated a significant analgesic response. 6 A study using Nabilone (a synthetic THC analogue) found it to be significantly more effective than placebo in reducing pain in patients with painful diabetic neuropathy. 6 THC may have differing effects on the sensory (intensity, quality) vs affective (unpleasantness, suffering) components of pain. 3 New imaging studies show that THC works in the brain to effectively treat chronic neuropathic pain. A small trial showed that THC induced pain relief was associated with reduced functional connectivity between the anterior cingulate cortex and the sensorimotor cortex. This effect seems to involve a breakdown in functional connectivity between brain regions that process different dimensions that construct the experience of pain. 11 CBD the other major consistent of the Cannabis Sativa plant has therapeutic effects but with a different pharmacologic profile. 7 CBD has virtually no psychoactivity compared to THC. 10 The synergistic contributions of CBD to cannabis pharmacology and specifically analgesia has been scientifically demonstrated. 3 Evidence suggests that CBD alone or combined with THC can suppress chronic neuropathic pain and that CBD may have a protective effect after nerve injury.4 CBD is thought to have significant analgesic, anti-inflammatory, anti-convulsant and anxiolytic activities without the psychoactive effects of THC. CBD has little binding affinity for CB1 or CB2 receptors but is capable of antagonizing them in the presence of THC. 1 CBD regulates the perception of pain by influencing the activity of a significant number of targets (5HT1A, ion channels,TRPV1,TRPA1 ,TPRM8, GlyR, and PPARs )while also inhibiting uptake of the endogenous cannabinoid anandamide(AEA) and weakly inhibiting its hydrolysis by the enzyme fatty acid amide hydrolase(FAAH) thus enhancing the effects of anandamide. 1, 7 CBD is capable of improving the tolerability of THC by reducing THC’s psychoactive effects and antagonizing some of the other effects of THC such as tachycardia, sedation and anxiety. 1 It has low affinity for both CB1 and CB2 receptors. CBD agonist activity at CB2 receptors seems to account for its anti-inflammatory properties and both primary and secondary influences on pain. The few studies done with CBD suggest it inhibits 5-HT reuptake and there is some experimental evidence to support CBD’s activity in other neurotransmitter systems such as dopamine, GABA and the endogenous opioid system. 10 CBD along with THC inhibits glutamate neurotoxicity and displays antioxidant activity.9 It may be presumptuous to assume that the major clinical effectiveness of cannabis is derived solely from THC and CBD. In addition, non-cannabinoid constituents of the cannabis plant such as terpenes and flavonoids may contribute to the analgesic as well as anti-inflammatory effects of cannabis. 1 “The entourage effect is a term used to describe enhancement of efficacy, with related improvement in overall therapeutic effectiveness, derived from combining phytocannabinoids and other plant derived molecules. Terpenes share a precursor molecule with phytocannabinoids. Cannabis derived terpenes include limonene, myrcene, alpha-pinene, linalool, B-caryophyllene, caryophyllene oxide, nerolidol and phytol. Phytocannabinoid-terpene interactions could produce synergy with respect to treatment of pain and inflammation.” 3 Clinical data indicate that cannabinoids administered together are more effective at ameliorating neuropathic pain than the use of a single agent. 3 A controlled cannabis extract containing numerous cannabinoids and other non-cannabinoid fractions such as terpenes and flavonoids demonstrated greater antinociceptive efficacy than a single cannabinoid given alone, indicating synergistic antinoceptive interaction between cannabinoids and non-cannabinoids in a rat model of neuropathic pain. 1 Cannabis terpenoids also display numerous attributes that may be germane to pain treatment. 9 As with many analgesics’ cannabinoids do not seem to be equally effective in the treatment of all pain conditions in humans. This is probably due to the different mechanisms of pain (acute vs chronic, or chronic non-cancer vs chronic cancer pain. 1 When cannabinoids lead to a reported reduction in pain, it remains unclear where the effects are triggered or what aspect of the pain experience is most affected and under what circumstances. 4 In evaluating the indication of using cannabis for pain many of the trials involve the use of a synthetic single molecule of cannabinoid. 2 To truly evaluate cannabis’ medicinal benefit regarding pain the interplay of the various components needs further investigation as opposed to evaluating molecules in isolation. References 1. Vučković, Sonja et al. “Cannabinoids and Pain: New Insights From Old Molecules.” Frontiers in pharmacology vol. 9 1259. 13 Nov. 2018, doi:10.3389/fphar.2018.01259 2. Deshpande A, Mallis A. Medical Cannabis and Pain Management: How Might the Role of Cannabis Be Defined in Pain Medicine? JALM Jan 2018;485-488. doi:10.1373/jalm.2017.023184 3. Fine PG, Rosenfield MJ. Cannabinoids for Neuropathic Pain. Curr Pain Headache Rep 2014; 18:451-459. doi:10.1007/s11916-014-0451-2. 4. Fine PG, Rosenfield MJ. The Endocannabinoid System, Cannabinoids, and Pain. Rambam Maimonides Med J. 2013;4(4). doi:10.5401/RMMJ.10129 5. Hill KP, Palastro MD, Johnson B, Ditre JW. Cannabis and Pain: A Clinical Review. Cannabis and Cannabinoid Research 2017;(2):96-104 http://online.liebertpub.com/ doi:10.1089/can.2017.0017 6. Donvito G, Nass SR, Wilkerson JL, Curry ZA, Schurman LD, Kinsey SG, Lichtman AH. The endogenous Cannabinoid System: A Budding Source of Targets for Treating Inflammatory and Neuropathic Pain. Neuropsychopharmacology Reviews 2018; 43:52-79. doi:10.1038/npp2017.204. 7. Manzanares, J et al. “Role of the cannabinoid system in pain control and therapeutic implications for the management of acute and chronic pain episodes.” Current neuropharmacology vol. 4,3 (2006): 239-57. doi:10.2174/157015906778019527 8. Modesto-Lowe V, Bojka R, Alvardo C. Cannabis for peripheral Neuropathy: The good, the bad, and the unknown. Cleveland Clinic Journal of Medicine.85(12):943-949. Doi.10.3949/ccjm.85a.17115. 9. Russo E. Cannabinoids in the management of difficult to treat pain. Therapeutics and Clinical Risk Management 2008;4(1):245-259. Accessed November 24, 2019. 10. Russon EB, Burnett A, Hall B, Parker KK. Agonistic Properties of Cannabidiol at 5-HT1a Receptors. Neurochemical Research;30(8):1037-1043. Doi:10.1007/s11064-005.6978-1 11. McNamara D. Cannabis for Chronic Nerve Pain: Mechanism Revealed? https://www.medscape.com/viewarticle/901689 September 7, 2018 Accessed November 24, 2019.

Terpenes are organic compounds that are produced by a variety of plants. When terpenes are modified chemically through oxidation or structural rearrangement the resultant compounds are called terpenoids. The term terpene is used to include all terpenoids. The difference between terpenes and terpenoids is that terpenes are hydrocarbons but terpenoids contain additional functional groups such as oxygen moieties or branching methyl groups. More than 200 terpenoids have been identified in cannabis. Terpenoids are pharmacologically active due to their lipophilic nature which enables interaction with cell membranes, neuronal and muscle ion channels, neurotransmitter receptors, G-protein coupled receptors and enzymes. Terpenoids are bioavailable in high percentages due to their lipophilic properties, permitting passive migration across biological membranes. Some of the most common terpenes in cannabis are D-limonene, B-myrcene, Alpha-pinene, D-linalool and Beta-caryophyllene”. 1. When terpenes work with cannabinoids like CBD and THC, they form a synergy. The entourage effect is the term used to describe this biological synergy between cannabinoids and other compounds such as terpenes. which causes enhanced effects than either would achieve on their own, one such effect that is seen is the improvement in the absorption of cannabinoids. 2 It may be presumptuous to assume that the major clinical effectiveness of cannabis is derived solely from THC and CBD. Non-cannabinoid constituents of the cannabis plant such as terpenes and flavonoids may contribute to the analgesic as well as anti-inflammatory effects of cannabis. 3 “The entourage effect is a term used to describe enhancement of efficacy, with related improvement in overall therapeutic effectiveness, derived from combining phytocannabinoids and other plant derived molecules. Terpenes share a precursor molecule with phytocannabinoids. Cannabis derived terpenes include limonene, myrcene, alpha-pinene, linalool, B-caryophyllene, caryophyllene oxide, nerolidol and phytol. Phytocannabinoid-terpene interactions could produce synergy with respect to treatment of pain and inflammation.” 4 Clinical data indicate that cannabinoids administered together are more effective at ameliorating neuropathic pain than the use of a single agent. 4 A controlled cannabis extract containing numerous cannabinoids and other non-cannabinoid fractions such as terpenes and flavonoids demonstrated greater antinociceptive efficacy than a single cannabinoid given alone, indicating synergistic antinoceptive interaction between cannabinoids and non-cannabinoids in a rat model of neuropathic pain. 3 Cannabis terpenoids also display numerous attributes that may be germane to pain treatment. 5 1. Nahitigal I, Blake A, Hand A, Florentius-Mefailoski AF, Hashemi H, Friedberg J. The Pharmacological properties of cannabis. J Pain Manage 2016;9(4):481-491. https://www.researchgate.net/publication/316545895_The_pharmacological_properties_of_cannabis 2. Mannino J. What is CBD Bioavailability and Why Does It Matter? www.anaviimarket.com https://www.anaviimarket.com/blogs/news/what-is-cbd-bioavailability-and-why-does-it-matter Accessed March 20, 2020. 3. Vučković, Sonja et al. “Cannabinoids and Pain: New Insights From Old Molecules.” Frontiers in pharmacology vol. 9 1259. 13 Nov. 2018, doi:10.3389/fphar.2018.01259 4. Fine PG, Rosenfield MJ. Cannabinoids for Neuropathic Pain. Curr Pain Headache Rep 2014; 18:451-459. doi:10.1007/s11916-014-0451-2.