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Background and AimsThe U.S. legal cannabis market is saturated with products containing high levels of tetrahydrocannabinol (THC), with no distinction between medical and recreational programs. This omnipresence of potent cannabis products seems to be driven by the recreational realm, where cannabis with the highest THC content is prized. This prevalence of highly potent cannabis is conveyed to medical programs, which places consumers (patients) at higher risk for over consumption and cannabis use disorder. Thus, understanding what factors influence the market that patients face in medical cannabis programs could shed light on the risks of legal cannabis. The supply and demand dynamic of the US for-profit cannabis market could explain the current market composition; therefore, we postulate that a financial gain could influence the perpetuation of the prevalence of high THC products in legal cannabis dispensaries. We investigate whether THC content in popular cannabis products correlates with higher prices and assess whether some attributes (type of product, chemovars, or presence of cannabidiol (CBD) affect the association of THC with price.MethodsWe focus on the world's largest cannabis market, California. We randomly selected dispensaries across the state, screened for a web presence and product menu, determined the most prevalent product type, and collected THC and CBD concentration, price, and other product attributes.ResultsWe observed that herbal products were more common, they had THC concentrations greater than 10%, and THC concentrations positively correlated with price. This correlation existed in flower and preroll presentations, all chemovar, and independently of the level of CBD. CBD did not correlate with price; however, the presence of CBD diminished the THC and price correlation particularly in products with high THC (>15%).ConclusionsOverall, highly potent herbal cannabis products (>15% THC) are the majority of products offered and more expensive regardless of product type or chemovar in California dispensaries, suggesting that a financial gain contributes to the current market composition. Efforts to limit the availability of highly potent THC products and educate consumers about potential harms are needed.

While cancer patients may have chemotherapeutics to thank for being cured of their malignancy, they are often left to suffer a disabling neuropathy induced by that same cancer treatment. This neuropathy, known as chemotherapy-induced peripheral neuropathy, or CIPN, is one of the most debilitating survivorship concerns for patients, with many citing hallmark symptoms of hyperalgesia, allodynia, and numbness, and subsequently reducing their dose or even ceasing treatment altogether. Investigations into this interplay between the antineoplastic activity of chemotherapeutic agents and the preservation of peripheral nerve health are therefore crucial for the development of CIPN treatment and prevention methods. Responding to need, current literature is inundated with varying preclinical models of CIPN. This chapter thus seeks to provide a detailed and reliable methodology for the induction and assessment of CIPN in mice, using a preclinical model that is both reproducible and translatable to several aspects of the clinical phenotype. Specifically, this chapter lays out a model for intermittent low-dose paclitaxel induction of CIPN in C57BL/6J mice, and a testing of this induction via von Frey filament mechanical hypersensitivity assays, a mechanical hyposensitivity (numbness) assay, and a cold-thermal allodynia assay (acetone test). These protocols can easily be adjusted to fit the needs of individual CIPN experiments, as stated throughout the chapter.

Background: Cannabidiol (CBD) products are increasingly available to consumers in the United States and are subject to regulation by the U.S. Food and Drug Administration (FDA). CBD products cannot be marketed as unapproved new drugs with claims of therapeutic benefit. In addition, because CBD is the active ingredient in a FDA-approved CBD product, Epidiolex, CBD cannot be marketed as, or in, food products or dietary supplements. The FDA has issued Warning Letters to promote voluntary regulatory compliance. These letters provide insights as to the types of violations for CBD products detected in the U.S. market. Objective: The goal of this retrospective study was to content analyze Warning Letters issued by the FDA to identify illicit marketing of CBD products. Design: Warning Letters issued by the FDA between 2015 and 2019 were content analyzed using a deductive approach. We extracted year of issuance, issuing office, and claim types that are currently prohibited by the FDA, including (i) unapproved new drug, (ii) misbranded drug, (iii) false and/or misleading, (iv) FDA-approved/endorsed, (v) dietary supplement, and (vi) adulterated food product. In addition, we documented the disease or conditions the product claimed to affect, pharmacological effects, and location of violation. Results: Of the 39 Warning Letters issued, 97% were for violations made on company websites and 56% were for social media accounts. Almost all letters (97%) cited violations of marketing CBD as an unapproved new drug. These illicit therapeutic claims were made for >125 unique health problems, including cancer (87.2%), diabetes (71.8%), inflammation (66.7%), pain (66.7%), and arthritis (66.7%). The majority of letters (79.5%) also cited illicit marketing of CBD as a dietary supplement or food product. CBD was promoted as having 16 unique pharmacological effects, including anti-inflammatory (53.8%), anticancer (43.6%), and antipsychotic (30.8%). Conclusions: CBD products have been unlawfully advertised online as unauthorized drugs with health claims that promote therapeutic benefits and as dietary supplements. Efforts are needed to regulate and monitor illicit advertising so consumers are not misled about the risks and benefits of CBD use.

Increased public access to cannabis calls for a deeper understanding of cannabis's constituents and how they interact to induce clinical effects. Whereas trans-Δ9 -tetrahydrocannabinol (THC) is considered the main psychoactive component in cannabis, producing the associated "high" or "euphoria," various findings demonstrate medical potential for cannabidiol (CBD), from anxiolytic to antiepileptic implications. This has translated into a public optimism and given way to the popular opinion that CBD can provide countless other therapeutic benefits, including the potential to mitigate some of the adverse side effects of THC, such as intoxication, psychomotor impairment, anxiety, and psychotic symptoms. This is particularly relevant for patients seeking to garner therapeutic benefits from cannabis without experiencing the burden of a significant subjective high. Thus, this article analyzes the scientific evidence available to support or disprove the idea that presence of CBD is beneficial and can exude a protective effect against THC. A thorough review of relevant literature, a basis from which to interpret such evidence through a critical mechanistic discussion, and the implications for patients are presented in this article.

Large tissue damage or wounds cause serious comorbidities and represent a major burden for patients, families, and health systems. Due to the pivotal role of immune cells in the proper resolution of inflammation and tissue repair, we focus our current study on the interaction of macrophages with skin cells, and specifically on the effects of CD163 gene induction in macrophages in wound healing. We hypothesize that the over-expression of the scavenger receptor gene CD163 in human macrophages would result in a more efficient wound healing process. Using 3D human wounded skin organotypic tissues, we observed that CD163 overexpression in THP-1 and human primary macrophages induced a more efficient re-epithelization when compared to control cells. Using human primary skin cells and an in vitro scratch assay we observed that CD163 overexpression in THP-1 macrophages promoted a more rapid and efficient wound healing process through a unique interaction with fibroblasts. The addition of CD163-blocking antibody, but not isotype control, blocked the efficient wound healing process induced by CD163 overexpression in macrophages. We found that the co-culture of skin cells and CD163 overexpressing macrophages reduced monocyte chemoattractant protein (MCP)-1 and enhanced tumor growth factor (TGF)-α, without altering interleukin (IL)-6 or TGF-β. Our findings show that CD163 induces a more efficient wound healing and seems to promote a wound milieu with a pro-resolution molecular profile. Our studies set the foundation to study this approach in in vivo clinically relevant settings to test its effects in wound healing processes such as acute major injuries, large surgeries, or chronic ulcers.

The National Academies of Sciences, Engineering, and Medicine has found substantial evidence that cannabis (plant) is effective for the treatment of chronic pain in adults, and moderate evidence that oromucosal cannabinoids (extracts, especially nabiximols) improve short-term sleep disturbances in chronic pain. The paradoxical superiority of the cannabis plant over cannabinoid molecules represents a challenge for the medical community and the established processes that define modern pharmacy. The expanding and variable legalization of cannabis in multiple states nationwide represents an additional challenge for patients and the medical community because recreational and medicinal cannabis are irresponsibly overlapped. Cannabis designed for recreational use (containing high levels of active ingredients) is increasingly available to patients with chronic pain who do not find relief with current pharmacologic entities, which exposes patients to potential harm. This article analyzes the available scientific evidence to address controversial questions that the current state of cannabis poses for health care professionals and chronic pain patients and sets the basis for a more open discussion about the role of cannabis in modern medicine for pain management. A critical discussion on these points, the legal status of cannabis, and considerations for health care providers is presented.

Macrophages orchestrate the initiation and resolution of inflammation by producing pro- and anti-inflammatory products. An imbalance in these mediators may originate from a deficient or excessive immune response. Therefore, macrophages are valid therapeutic targets to restore homeostasis under inflammatory conditions. We hypothesize that a specific mannosylated nanoparticle effectively induces gene expression in human macrophages under inflammatory conditions without undesirable immunogenic responses. THP-1 macrophages were challenged with lipopolysaccharide (LPS, 5 μg/mL). Polyethylenimine (PEI) nanoparticles grafted with a mannose receptor ligand (Man-PEI) were used as a gene delivery method. Nanoparticle toxicity, Man-PEI cellular uptake rate and gene induction efficiency (GFP, CD14 or CD68) were studied. Potential immunogenic responses were evaluated by measuring the production of tumor necrosis factor-alpha (TNF-α), Interleukin (IL)-6 and IL-10. Man-PEI did not produce cytotoxicity, and it was effectively up-taken by THP-1 macrophages (69%). This approach produced a significant expression of GFP (mRNA and protein), CD14 and CD68 (mRNA), and transiently and mildly reduced IL-6 and IL-10 levels in LPS-challenged macrophages. Our results indicate that Man-PEI is suitable for inducing an efficient gene overexpression in human macrophages under inflammatory conditions with limited immunogenic responses. Our promising results set the foundation to test this technology to induce functional anti-inflammatory genes.

Inositol-requiring enzyme 1[α] (IRE1[α])–X-box binding protein spliced (XBP1) signaling maintains endoplasmic reticulum (ER) homeostasis while controlling immunometabolic processes. Yet, the physiological consequences of IRE1a–XBP1 activation in leukocytes remain unexplored. We found that induction of prostaglandin-endoperoxide synthase 2 (Ptgs2/Cox-2) and prostaglandin E synthase (Ptges/mPGES-1) was compromised in IRE1a-deficient myeloid cells undergoing ER stress or stimulated through pattern recognition receptors. Inducible biosynthesis of prostaglandins, including the pro-algesic mediator prostaglandin E2 (PGE2), was decreased in myeloid cells that lack IRE1a or XBP1 but not other ER stress sensors. Functional XBP1 transactivated the human PTGS2 and PTGES genes to enable optimal PGE2 production. Mice that lack IRE1α–XBP1 in leukocytes, or that were treated with IRE1a inhibitors, demonstrated reduced pain behaviors in PGE2-dependent models of pain. Thus, IRE1a–XBP1 is a mediator of prostaglandin biosynthesis and a potential target to control pain.

Abnormal outgrowth of sensory nerves is one of the important contributors to pain associated with cancer and its treatments. Primary neuronal cultures derived from dorsal root ganglia (DRG) have been widely used to study pain-associated signal transduction and electrical activity of sensory nerves. However, there are only a few studies using primary DRG neuronal culture to investigate neurite outgrowth alterations due to underlying cancer-related factors and chemotherapeutic agents. In this study, primary DRG sensory neurons derived from mouse, non-human primate, and human were established in serum and growth factor-free conditions. A bovine serum albumin gradient centrifugation method improved the separation of sensory neurons from satellite cells. The purified DRG neurons were able to maintain their heterogeneous subpopulations, and displayed an increase in neurite growth when exposed to cancer-derived conditioned medium, while they showed a reduction in neurite length when treated with a neurotoxic chemotherapeutic agent. Additionally, a semi-automated quantification method was developed to measure neurite length in an accurate and time-efficient manner. Finally, these exogenous factors altered the gene expression patterns of murine primary sensory neurons, which are related to nerve growth, and neuro-inflammatory pain and nociceptor development. Together, the primary DRG neuronal culture in combination with a semi-automated quantification method can be a useful tool for further understanding the impact of exogenous factors on the growth of sensory nerve fibers and gene expression changes in sensory neurons.

Cannabis related online searches are associated with positive attitudes toward medical cannabis, particularly when information is obtained from dispensaries. Since pain is the main reason for medicinal cannabis use, information from dispensary websites has the potential to shape the attitude of pain patients towards cannabis. This is relevant because cannabis has demonstrated efficacy in neuropathic pain with low tetrahydrocannabinol (THC) concentrations (< 5–10%), in contrast to potent cannabis (>15% THC), which is highly rewarded in the recreational realm. The role of CBD in pain is not clear, however it has gained popularity. Thus, we hypothesize that the potency of medical cannabis that is advertised online is similar to the cannabis advertised for recreational purposes, which would potentially create a misconception towards medical cannabis. The current lack of knowledge surrounding advertised potencies in the legal cannabis market limits the ability to generate clear policies regarding online advertising to protect patients that are willing to use cannabis for their condition. Thus, we evaluated the advertised THC and CBD content of cannabis products offered online in dispensaries in the United States to determine products’ suitability to medicinal use and compare the strength of products offered in legal medical and recreational programs. We recorded THC and CBD concentrations for all herb cannabis products provided by dispensary websites and compared them between or within states. Four Western states (CA, CO, NM, WA) and five Northeastern states (ME, MA, NH, RI, VT) were included. A total of 8,505 cannabis products across 653 dispensaries were sampled. Despite the clear differences between medicinal and recreational uses of cannabis, the average THC concentration advertised online in medicinal programs was similar (19.2% ±6.2) to recreational programs (21.5% ±6.0) when compared between states with different programs, or between medicinal and recreational programs within the same states (CO or WA). Lower CBD concentrations accompanied higher THC products. The majority of products, regardless of medicinal or recreational programs, were advertised to have >15% THC (70.3% - 91.4% of products). These stated concentrations seem unsuitable for medicinal purposes, particularly for patients with chronic neuropathic pain. Therefore, this information could induce the misconception that high potency cannabis is safe to treat pain. This data is consistent with reports in which THC and CBD in products from legal dispensaries or in nationwide products from the illegal market were actually measured, which indicates that patients consuming these products may be at risk of acute intoxication or long-term side effects. Our study offers grounds to develop policies that help prevent misconceptions toward cannabis and reduce risks in pain patients.

The use of cannabinoids for the treatment of chronic diseases has increased in the United States, with 23 states having legalized the use of marijuana. Although currently available cannabinoid compounds have shown effectiveness in relieving symptoms associated with numerous diseases, the use of cannabis or cannabinoids is still controversial mostly due to their psychotropic effects (e.g., euphoria, laughter) or central nervous system (CNS)-related undesired effects (e.g., tolerance, dependence). A potential strategy to use cannabinoids for medical conditions without inducing psychotropic or CNS-related undesired effects is to avoid their actions in the CNS. This approach could be beneficial for conditions with prominent peripheral pathophysiologic mechanisms (e.g., painful diabetic neuropathy, chemotherapy-induced neuropathy). In this article, we discuss the scientific evidence to target the peripheral cannabinoid system as an alternative to cannabis use for medical purposes, and we review the available literature to determine the pros and cons of potential strategies that can be used to this end.

The purpose of this study was to provide the most up-to-date scientific evidence of the potential analgesic effects, or lack thereof, of the marijuana plant (cannabis) or cannabinoids, and of safety or tolerability of their long-term use. We found that inhaled (smoked or vaporized) cannabis is consistently effective in reducing chronic non-cancer pain. Oral cannabinoids seem to improve some aspects of chronic pain (sleep and general quality of life), or cancer chronic pain, but they do not seem effective in acute postoperative pain, abdominal chronic pain, or rheumatoid pain. The available literature shows that inhaled cannabis seems to be more tolerable and predictable than oral cannabinoids. Cannabis or cannabinoids are not universally effective for pain. Continued research on cannabis constituents and improving bioavailability for oral cannabinoids is needed. Other aspects of pain management in patients using cannabis require further open discussion: concomitant opioid use, medical vs. recreational cannabis, abuse potential, etc.

M1 macrophages release pro-inflammatory factors during inflammation. They transition to an M2 phenotype and release anti-inflammatory factors to resolve inflammation. An imbalance in the transition from M1 to M2 phenotype in macrophages contributes to the development of persistent inflammation. CD163, a member of the scavenger receptor cysteine-rich family, is an M2 macrophage marker. The functional role of CD163 during the resolution of inflammation is not completely known. We postulate that CD163 contributes to the transition from M1 to M2 phenotype in macrophages. We induced CD163 gene in THP-1 and primary human macrophages using polyethylenimine nanoparticles grafted with a mannose ligand (Man-PEI). This nanoparticle specifically targets cells of monocytic origin via mannose receptors. Cells were challenged with a single or a double stimulation of lipopolysaccharide (LPS). A CD163 or empty plasmid was complexed with Man-PEI nanoparticles for cell transfections. Quantitative RT-PCR, immunocytochemistry, and ELISAs were used for molecular assessments. CD163-overexpressing macrophages displayed reduced levels of tumor necrosis factor-alpha (TNF)-α and monocytes chemoattractant protein (MCP)-1 after a single stimulation with LPS. Following a double stimulation paradigm, CD163-overexpressing macrophages showed an increase of interleukin (IL)-10 and IL-1ra, and a reduction of MCP-1. This anti-inflammatory phenotype was partially blocked by an anti-CD163 antibody (effects on IL-10 and IL-1ra). A decrease in the release of TNF-α, IL-1β, and IL-6 was observed in CD163-overexpressing human primary macrophages. The release of IL-6 was blocked by an anti-CD163 antibody in the CD163-overexpressing group. Our data show that the induction of the CD163 gene in human macrophages under inflammatory conditions produces changes in cytokine secretion in favor of an anti-inflammatory phenotype. Targeting macrophages to induce CD163 using cell-directed nanotechnology is an attractive and practical approach for inflammatory conditions that could lead to persistent pain, i.e. major surgeries, burns, rheumatoid arthritis, etc.

The role of central glial cells in the mechanisms underlying pain has been intensively studied in the last two decades. Most studies on glia and pain focused on the potential detrimental role of glial cells following noxious stimulus/insults manifested as an "activation" or a "reactive" state (increase in glial marker expression and production of proinflammatory/nociceptive molecules). Therefore, "activated" or "reactive" glial cells became a target for the future generation of drugs to treat chronic pain. Several glial modulators that reduce the activation of glial cells have shown great efficacy in multiple animal (rodents mostly) models of pain (acute, subacute, chronic, inflammatory, neuropathic, surgical, etc.). These encouraging findings inspired clinical trials that have been completed in the last 5 years. Unfortunately, all clinical trials with these glial modulators have failed to demonstrate efficacy for the treatment of pain. New lines of investigation and elegant experimental designs are shedding light on alternative glial functions, which demonstrate that "glial reactivity" is not necessarily deleterious in some pathological conditions. New strategies to validate findings through our current animal models are necessary to enhance the translational value of our preclinical studies. Also, more studies using human subjects would enhance our understanding of glial cells in the context of pain. This chapter explores the available literature to objectively ponder the potential role of glial cells in human pain conditions.

New generations of cyclooxygenase (COX) inhibitors are more potent and efficacious than their traditional parent compounds. They are also safer than the classic non-steroidal anti-inflammatory drugs (NSAIDs) and are starting to be used not only for low to moderate intensity pain, but also for high intensity pain. Three different strategies have been followed to improve the pharmacological profile of COX inhibitors: 1. Development of COX-2 selective inhibitors. This is based on the initial hypothesis that considered COX-2 as the enzyme responsible for the generation of prostaglandins only in inflammation, and, therefore, uniquely responsible for inflammation, pain and fever. Initial expectations gave rise to controversial results, still under discussion. The second generation of these compounds is being developed and should contribute to clarifying both their efficacy and the specific functions of the COX enzymes. 2. Modified non-selective COX inhibitors. Molecules like nitro-NSAIDs or tromethamine salt derivatives have been synthesized considering that both COX-1 and COX-2 are responsible for the synthesis of prostaglandins involved either in homeostatic functions or inflammation. Nitroaspirin, nitroparacetamol or dexketoprofen trometamol are some examples of molecules that are already showing an important clinical efficacy. The modifications performed in their structures seem to lower the unwanted side effects as well as to enhance their analgesic efficacy. 3. Combined therapy of classic NSAIDs with other drugs. This strategy looks for improvements in the incidence of adverse effects or to take advantage of the synergistic enhancement of their therapeutic effects. Some of the molecules resulting from these strategies are very valuable as therapeutic agents and open a wide range of possibilities in the treatment of high intensity pain, including neuropathic pain, and opiate sparing therapy.

The combination of numerous classic drugs with nitric oxide donors has led to the development of new compounds with promising therapeutic activities in a great variety of situations, including cardiovascular and respiratory systems, ocular pressure, inflammation, and pain. One of the first compounds developed was NCX-701 or nitroparacetamol, resulting from the combination of paracetamol, a classic and popular analgesic used in a great number of over-the-counter medications because of its antipyretic and analgesic properties, and a nitrooxybutyroyl moiety, which releases nitric oxide at a low but steady level. Although paracetamol is devoid of most of the gastrointestinal toxicity associated with aspirin-like drugs, this type of compounds was first designed to take advantage of the cytoprotective properties of nitric oxide when released at low concentrations. However, the combination of these molecules also resulted in an unexpected enhancement of the analgesic activity of paracetamol. In fact, NCX-701 has been shown to be effective in acute nociception as well as in neuropathic pain, situations in which paracetamol and other COX inhibitors are devoid of any effect. In addition, NCX-701 is more potent and, in some circumstances, more effective than its parent compound in different models of inflammatory pain. Furthermore, whereas paracetamol lacks any effective antiinflammatory action, NCX-701 might reduce inflammation. All these results taken together imply that the mechanism of action of NCX-701 is different from that of paracetamol, although it is not yet established for either molecule. NCX-701 appears to be a promising compound in the treatment of different types of pain, with a likely better profile of side effects than its parent molecule, paracetamol. Although recent clinical trials provided data consistent with the preclinical profile of NCX-701, further studies are needed to support its clinical use.