NHS-Reimbursed Cannabis Flowers for Cancer Palliative Care and the Management of Chemotherapy-Induced Nausea and Vomiting: An Autobiographical Case Report.

Chemotherapy-induced nausea and vomiting (CINV) is a debilitating side effect of cancer treatment, affecting many patients. Cannabinoid agonists, such as nabilone and Δ9-tetrahydrocannabinol (THC), the main psychoactive component of Cannabis sativa L., have shown efficacy as antiemetics. Here, we report the case of Michael Roberts (MR), who we believe is the first British patient reimbursed by the National Health Service (NHS) England for the cost of medicinal cannabis flowers to manage CINV. Medical data were obtained from NHS records and individual funding request (IFR) forms. Patient-reported outcome measures (PROMs) were collected using validated questionnaires as part of the standard of care at the specialized private clinics where the prescription of medicinal cannabis was initiated. The patient presented with rectosigmoid adenocarcinoma with lung metastases. He received FOLFIRI (folinic acid, fluorouracil, and irinotecan) chemotherapy and underwent an emergency Hartmann's procedure with subsequent second-line FOLFOX (folinic acid, fluorouracil, and oxaliplatin) chemotherapy and lung ablation. MR reported severe nausea and vomiting associated with the initial FOLFIRI treatment. Antiemetics metoclopramide and aprepitant demonstrated moderated efficacy. Antiemetics ondansetron, levomepromazine, and nabilone were associated with intolerable side effects. Inhalation of THC-predominant cannabis flowers in association with standard medication improved CINV, anxiety, sleep quality, appetite, overall mood, and quality of life. Our results add to the available evidence suggesting that medicinal cannabis flowers may offer valuable support in cancer palliative care integrated with standard-of-care oncology treatment. The successful individual funding request in this case demonstrates a pathway for other patients to gain access to these treatments, advocating for broader awareness and integration of cannabis-based medicinal products in national healthcare services.

Cannabis-Based Medicinal Products in the Management of Emotionally Unstable Personality Disorder (EUPD): A Narrative Review and Case Series.

Emotionally unstable personality disorder (EUPD) is a common mental health disorder, manifesting with a range of chronic and debilitating symptoms, including impaired social functioning, unstable mood, and risky impulsive or self-injurious behaviour. Whilst the exact aetiology has not been fully elucidated, implicated factors seem to include genetic factors, environmental causes such as trauma, and neurotransmitter deficits. The literature suggests that impaired functioning of the endocannabinoid system in key brain regions responsible for emotional processing and stress response may underlie the manifestation of EUPD symptoms. The National Institute for Health and Care Excellence (NICE) 2009 guidelines state that "no drugs have established efficacy in treating or managing EUPD", and yet, patients are commonly prescribed medication which includes antipsychotics, antidepressants, and mood stabilisers. Here we present a case series of seven participants diagnosed with EUPD and treated with cannabis-based medicinal products (CBMPs). Participants were given an initial assessment and followed up one month after CBMPs prescription. Improvement in symptoms was assessed by the completion of ratified rating scales by the participant and psychiatrist. Our results indicate that CBMPs were effective and well tolerated, as six participants reported a noticeable improvement in their symptoms and functioning. Although promising, further research is needed to ascertain the long-term tolerability, efficacy, and dosing strategy for CBMPs in EUPD.

"Flower Power": Controlled Inhalation of THC-Predominant Cannabis Flos Improves Health-Related Quality of Life and Symptoms of Chronic Pain and Anxiety in Eligible UK Patients.

In November 2018, the UK's Home Office established a legal route for eligible patients to be prescribed cannabis-based products for medicinal use in humans (CBPMs) as unlicensed medicines. These include liquid cannabis extracts for oral administration ("oils") and dried flowers for inhalation ("flos"). Smoking of CBPMs is expressly prohibited. To date, THC-predominant cannabis flowers remain the most prescribed CBPMs in project Twenty21 (T21), the first multi-center, prospective, observational UK cannabis patient registry. This observational, prospective data review analyzes patient-reported outcome measures (PROMS) collected by T21 associated with the inhalation of KHIRON 20/1, the most prescribed CBPM in the project. PROMS collected at baseline and at subsequent 3-month follow-up included health-related quality of life (HRQoL), general mood, and sleep. Condition-specific measures of illness severity were performed with the Brief Pain Inventory Short Form (BPI-SF) and the Generalized Anxiety Disorder 7-Item Scale (GAD-7). Participants (N = 344) were mostly males (77.6%, average age = 38.3) diagnosed mainly with chronic pain (50.9%) and anxiety-related disorders (25.3%). Inhalation of KHIRON 20/1 was associated with a marked increase in self-reported HRQoL, general mood, and sleep (N = 344; p < 0.001). Condition-specific assessments showed significant improvements in pain severity (T = 6.67; p < 0.001) and interference (T = 7.19; p < 0.001) in patients using KHIRON 20/1 for chronic pain (N = 174). Similar results were found for patients diagnosed with anxiety-related disorders (N = 107; T = 12.9; p < 0.001). Our results indicate that controlled inhalation of pharmaceutical grade, THC-predominant cannabis flos is associated with a significant improvement in patient-reported pain scores, mood, anxiety, sleep disturbances and overall HRQoL in a treatment-resistant clinical population.

Sex-Dependent Prescription Patterns and Clinical Outcomes Associated With the Use of Two Oral Cannabis Formulations in the Multimodal Management of Chronic Pain Patients in Colombia.

To date, the therapeutic use of cannabinoids in chronic pain management remains controversial owing to the limited clinical evidence found in randomized clinical trials (RCTs), the heterogeneous nature of the clinical indication, and the broad range of cannabis-based medicinal products (CBMPs) used in both experimental and observational clinical studies. Here we evaluate patient-reported clinical outcomes (PROMS) in a cohort of adult patients, diagnosed with chronic pain of diverse etiology, who received adjuvant treatment with oral, cannabis-based, magistral formulations between May and September 2021 at the Latin American Institute of Neurology and Nervous System (ILANS-Zerenia) in Bogotá, Colombia. During this period, 2,112 patients completed a PROMS questionnaire aimed at capturing the degree of clinical improvement of their primary symptom and any potential side effects. Most participants were female (76.1%) with an average age of 58.7 years old, and 92.5% (1,955 patients) reported some improvement in their primary symptom (p < 0.001). Two monovarietal, full-spectrum, cannabis formulations containing either cannabidiol (CBD 30 mg/mL; THC <2 mg/mL) or a balanced composition (THC 12 mg/mL; CBD 14 mg/mL) accounted for more than 99% of all prescriptions (59.5 and 39.8%, respectively). The degree of improvement was similar between both formulations, although males reported less effectiveness in the first 4 weeks of treatment. Sex-specific differences were also found in prescription patterns, with male patients increasing the intake of the balanced chemotype overtime. For many patients (71.7%) there were no adverse side effects associated to the treatment and those most reported were mild, such as somnolence (13.0%), dizziness (8.1%) and dry mouth (4.2%), which also appeared to fade over time. Our results constitute the first real-world evidence on the clinical use of medicinal cannabis in Colombia and suggest that cannabis-based oral magistral formulations represent a safe and efficacious adjuvant therapeutic option in the management of chronic pain.

Self-Reported Effectiveness and Safety of Trokie® Lozenges: A Standardized Formulation for the Buccal Delivery of Cannabis Extracts.

Therapeutic use of cannabinoids, the main active ingredients of Cannabissativa L., is often hindered by their limited bioavailability and undesirable psychoactivity. We conducted an observational study in December 2016 and another one in February 2018 to investigate respectively: (i) the effectiveness of Trokie® lozenges, a standardized formulation containing cannabis extracts, to deliver cannabinoids via buccal absorption and (ii) its long-term safety. Participants were members of the Palliative Care Corporation health clinic, registered California cannabis patients, and had a diagnosis of chronic non-cancer pain. For the effectiveness study, 49 participants were asked to self-report pain perception before and after 1-12 weeks of taking Trokie® lozenges, using an 11-point pain intensity numeric rating scale (PI-NRS). A mean reduction in PI-NRS score of 4.9 ± 2.0 points was observed. Onset of analgesia typically varied between 5 and 40 min, which seems consistent with, at least partial, buccal absorption. In the safety study, 35 participants were asked to complete a questionnaire about adverse events (AEs) associated with Trokie® lozenges. AEs were reported by 16 subjects (46%), the most common being dizziness/unsteadiness (N = 7), bad taste (N = 5), and throat irritation/dry mouth (N = 4). None of the self-reported AEs resulted in a serious medical situation and most of them had limited impact on daily functions. Despite the AEs, 90% of participants reported being "satisfied" or "very satisfied" with the product. These observations suggest that buccal administration of standardized extracts via Trokie® lozenges may represent an efficacious and safe approach to cannabis administration.

Suppression of acute and anticipatory nausea by peripherally restricted fatty acid amide hydrolase inhibitor in animal models: role of PPARα and CB1 receptors.

BACKGROUND AND PURPOSE: Effective treatments of nausea are limited. In this study we evaluated the ability of the peripherally restricted fatty acid amide hydrolase (FAAH) inhibitor, URB937, to suppress acute and anticipatory nausea in rats and examined the pharmacological mechanism of this effect. EXPERIMENTAL APPROACH: We investigated the potential of URB937 (administered i.p.) to reduce the establishment of lithium chloride-induced conditioned gaping (model of acute nausea) and to reduce the expression of contextually-elicited conditioned gaping (model of anticipatory nausea) in rats. The role of CB1 receptors, CB2 receptors and PPARα in the anti-nausea effect of URB937 was examined. The potential of URB937 to suppress FAAH activity in tissue collected from the area postrema (AP), prefrontal cortex (PFC), liver and duodenum and to elevate levels of FAAH substrates - anandamide (AEA), N-oleoylethanolamide (OEO) and N-palmitoylethanolamide (PEA) - in the AP was also evaluated. KEY RESULTS: URB937 reduced acute nausea by a PPARα-dependent mechanism and reduced anticipatory nausea by a CB1 receptor-dependent mechanism. The PPARα agonist, GW7647, similarly attenuated acute nausea. URB937 reduced FAAH activity in the liver and the duodenum but not in the PFC. In addition, URB937 reduced FAAH activity and elevated levels of fatty-acid ethanolamides in the AP, a brain region that is not protected by the blood-brain barrier. CONCLUSIONS AND IMPLICATIONS: The anti-nausea action of URB937 may occur in the AP and may involve PPARα to suppress acute nausea and CB1 receptors to suppress anticipatory nausea.

Endogenous N-acyl taurines regulate skin wound healing.

The intracellular serine amidase, fatty acid amide hydrolase (FAAH), degrades a heterogeneous family of lipid-derived bioactive molecules that include amides of long-chain fatty acids with taurine [N-acyl-taurines (NATs)]. The physiological functions of the NATs are unknown. Here we show that genetic or pharmacological disruption of FAAH activity accelerates skin wound healing in mice and stimulates motogenesis of human keratinocytes and differentiation of human fibroblasts in primary cultures. Using untargeted and targeted lipidomics strategies, we identify two long-chain saturated NATs-N-tetracosanoyl-taurine [NAT(24:0)] and N-eicosanoyl-taurine [NAT(20:0)]-as primary substrates for FAAH in mouse skin, and show that the levels of these substances sharply decrease at the margins of a freshly inflicted wound to increase again as healing begins. Additionally, we demonstrate that local administration of synthetic NATs accelerates wound closure in mice and stimulates repair-associated responses in primary cultures of human keratinocytes and fibroblasts, through a mechanism that involves tyrosine phosphorylation of the epidermal growth factor receptor and an increase in intracellular calcium levels, under the permissive control of transient receptor potential vanilloid-1 receptors. The results point to FAAH-regulated NAT signaling as an unprecedented lipid-based mechanism of wound-healing control in mammalian skin, which might be targeted for chronic wound therapy.

Enhancement of Anandamide-Mediated Endocannabinoid Signaling Corrects Autism-Related Social Impairment.

Introduction: We recently uncovered a signaling mechanism by which the endocannabinoid anandamide mediates the action of oxytocin, a neuropeptide that is crucial for social behavior, to control social reward. Oxytocin signaling has been implicated in autism spectrum disorder (ASD), and social reward is a key aspect of social functioning that is thought to be disrupted in ASD. Therefore, as a proof of principle for the core component of ASD-social impairment-we tested an endocannabinoid-enhancing compound on two widely studied mouse models of ASD, the BTBR and fmr1-/- (model of Fragile X Syndrome). Methods: We used the established three-chambered social approach test. We specifically increased the activity of anandamide by administering the compound URB597, a selective inhibitor of fatty acid amide hydrolase (FAAH), the hydrolytic enzyme for anandamide. Results: Remarkably, we found that FAAH blockade completely reversed the social impairment in both mouse models. CB1 receptor blockade prevented the prosocial action of FAAH inhibition in BTBR mice. These results were likely independent of effects on anxiety, as FAAH inhibition did not alter the performance of BTBR mice in the elevated plus maze. Conclusions: The results suggest that increasing anandamide activity at CB1 receptors improves ASD-related social impairment and identify FAAH as a novel therapeutic target for ASD.

Can You Pass the Acid Test? Critical Review and Novel Therapeutic Perspectives of Δ9-Tetrahydrocannabinolic Acid A.

Δ9-tetrahydrocannabinolic acid A (THCA-A) is the acidic precursor of Δ9-tetrahydrocannabinol (THC), the main psychoactive compound found in Cannabis sativa. THCA-A is biosynthesized and accumulated in glandular trichomes present on flowers and leaves, where it serves protective functions and can represent up to 90% of the total THC contained in the plant. THCA-A slowly decarboxylates to form THC during storage and fermentation and can further degrade to cannabinol. Decarboxylation also occurs rapidly during baking of edibles, smoking, or vaporizing, the most common ways in which the general population consumes Cannabis. Contrary to THC, THCA-A does not elicit psychoactive effects in humans and, perhaps for this reason, its pharmacological value is often neglected. In fact, many studies use the term "THCA" to refer indistinctly to several acid derivatives of THC. Despite this perception, many in vitro studies seem to indicate that THCA-A interacts with a number of molecular targets and displays a robust pharmacological profile that includes potential anti-inflammatory, immunomodulatory, neuroprotective, and antineoplastic properties. Moreover, the few in vivo studies performed with THCA-A indicate that this compound exerts pharmacological actions in rodents, likely by engaging type-1 cannabinoid (CB1) receptors. Although these findings may seem counterintuitive due to the lack of cannabinoid-related psychoactivity, a careful perusal of the available literature yields a plausible explanation to this conundrum and points toward novel therapeutic perspectives for raw, unheated Cannabis preparations in humans.

Increased Renal 2-Arachidonoylglycerol Level Is Associated with Improved Renal Function in a Mouse Model of Acute Kidney Injury.

Background: Acute kidney injury (AKI) is associated with a significantly increased risk of morbidity and mortality. Ischemia-reperfusion injury (IRI) is a major cause of AKI. In this study, we investigated the role of the endocannabinoid (EC) system in renal IRI using a well-established mouse model. Materials and Methods: Renal ischemia was induced in male C57BL/6 mice by clamping both kidney pedicles for 30 min followed by 24 h of reperfusion. To increase renal 2-arachidonoylglycerol (2-AG) levels, mice were pretreated with JZL184 (16 mg/kg), 30 min before IRI. Serum creatinine and blood urea nitrogen (BUN), renal tubular damage, renal content of ECs and renal expression of markers of inflammation and oxidative stress were measured. Results: Renal IRI was associated with significantly increased serum BUN and creatinine, increased tubular damage score, increased expression of renal markers of inflammation and oxidative stress and elevated renal 2-AG content. Pretreatment with JZL184 was associated with a significant increase in renal 2-AG content and there was also improved serum BUN, creatinine and tubular damage score. However, renal expression of inflammation and oxidative stress markers remained unchanged. Conclusions: This is the first report documenting that renal IRI is associated with an increase in kidney 2-AG content. Further enhancement of 2-AG levels using JZL184 improved indices of renal function and histology, but did not lower renal expression of markers of inflammation and oxidative stress. Further studies are needed to determine the mechanisms responsible for the effects observed and the potential value of 2-AG as a therapeutic target in renal IRI.

A Potent Systemically Active N-Acylethanolamine Acid Amidase Inhibitor that Suppresses Inflammation and Human Macrophage Activation.

Fatty acid ethanolamides such as palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) are lipid-derived mediators that potently inhibit pain and inflammation by ligating type-α peroxisome proliferator-activated receptors (PPAR-α). These bioactive substances are preferentially degraded by the cysteine hydrolase, N-acylethanolamine acid amidase (NAAA), which is highly expressed in macrophages. Here, we describe a new class of ß-lactam derivatives that are potent, selective, and systemically active inhibitors of intracellular NAAA activity. The prototype of this class deactivates NAAA by covalently binding the enzyme's catalytic cysteine and exerts profound anti-inflammatory effects in both mouse models and human macrophages. This agent may be used to probe the functions of NAAA in health and disease and as a starting point to discover better anti-inflammatory drugs.

Multitarget fatty acid amide hydrolase/cyclooxygenase blockade suppresses intestinal inflammation and protects against nonsteroidal anti-inflammatory drug-dependent gastrointestinal damage.

The ability of nonsteroidal anti-inflammatory drugs (NSAIDs) to inhibit cyclooxygenase (Cox)-1 and Cox-2 underlies the therapeutic efficacy of these drugs, as well as their propensity to damage the gastrointestinal (GI) epithelium. This toxic action greatly limits the use of NSAIDs in inflammatory bowel disease (IBD) and other chronic pathologies. Fatty acid amide hydrolase (FAAH) degrades the endocannabinoid anandamide, which attenuates inflammation and promotes GI healing. Here, we describe the first class of systemically active agents that simultaneously inhibit FAAH, Cox-1, and Cox-2 with high potency and selectivity. The class prototype 4: (ARN2508) is potent at inhibiting FAAH, Cox-1, and Cox-2 (median inhibitory concentration: FAAH, 0.031 ± 0.002 µM; Cox-1, 0.012 ± 0.002 µM; and Cox-2, 0.43 ± 0.025 µM) but does not significantly interact with a panel of >100 off targets. After oral administration in mice, ARN2508 engages its intended targets and exerts profound therapeutic effects in models of intestinal inflammation. Unlike NSAIDs, ARN2508 causes no gastric damage and indeed protects the GI from NSAID-induced damage through a mechanism that requires FAAH inhibition. Multitarget FAAH/Cox blockade may provide a transformative approach to IBD and other pathologies in which FAAH and Cox are overactive.

Effects of Fatty Acid Amide Hydrolase (FAAH) Inhibitors in Non-Human Primate Models of Nicotine Reward and Relapse.

Inhibition of the enzyme fatty acid amide hydrolase (FAAH) counteracts reward-related effects of nicotine in rats, but it has not been tested for this purpose in non-human primates. Therefore, we studied the effects of the first- and second-generation O-arylcarbamate-based FAAH inhibitors, URB597 (cyclohexyl carbamic acid 3'-carbamoyl-3-yl ester) and URB694 (6-hydroxy-[1,1'-biphenyl]-3-yl-cyclohexylcarbamate), in squirrel monkeys. Both FAAH inhibitors: (1) blocked FAAH activity in brain and liver, increasing levels of endogenous ligands for cannabinoid and α-type peroxisome proliferator-activated (PPAR-α) receptors; (2) shifted nicotine self-administration dose-response functions in a manner consistent with reduced nicotine reward; (3) blocked reinstatement of nicotine seeking induced by reexposure to either nicotine priming or nicotine-associated cues; and (4) had no effect on cocaine or food self-administration. The effects of FAAH inhibition on nicotine self-administration and nicotine priming-induced reinstatement were reversed by the PPAR-α antagonist, MK886. Unlike URB597, which was not self-administered by monkeys in an earlier study, URB694 was self-administered at a moderate rate. URB694 self-administration was blocked by pretreatment with an antagonist for either PPAR-α (MK886) or cannabinoid CB1 receptors (rimonabant). In additional experiments in rats, URB694 was devoid of THC-like or nicotine-like interoceptive effects under drug-discrimination procedures, and neither of the FAAH inhibitors induced dopamine release in the nucleus accumbens shell--consistent with their lack of robust reinforcing effects in monkeys. Overall, both URB597 and URB694 show promise for the initialization and maintenance of smoking cessation because of their ability to block the rewarding effects of nicotine and prevent nicotine priming-induced and cue-induced reinstatement.

Structural determinants of peripheral O-arylcarbamate FAAH inhibitors render them dual substrates for Abcb1 and Abcg2 and restrict their access to the brain.

The blood-brain barrier (BBB) is the main entry route for chemicals into the mammalian central nervous system (CNS). Two transmembrane transporters of the ATP-binding cassette (ABC) family - breast cancer resistance protein (ABCG2 in humans, Abcg2 in rodents) and P-glycoprotein (ABCB1 in humans, Abcb1 in rodents) - play a key role in mediating this process. Pharmacological and genetic evidence suggests that Abcg2 prevents CNS access to a group of highly potent and selective O-arylcarbamate fatty-acid amidohydrolase (FAAH) inhibitors, which include the compound URB937 (cyclohexylcarbamic acid 3'-carbamoyl-6-hydroxybiphenyl-3-yl ester). To define structure-activity relationships of the interaction of these molecules with Abcg2, in the present study we tested various peripherally restricted and non-restricted O-arylcarbamate FAAH inhibitors for their ability to serve as transport substrates in monolayer cultures of Madin-Darby Canine Kidney-II (MDCKII) cells over-expressing Abcg2. Surprisingly, we found that the majority of compounds tested - even those able to enter the CNS in vivo - were substrates for Abcg2 in vitro. Additional experiments in MDCKII cells overexpressing ABCB1 revealed that only those compounds that were dual substrates for ABCB1 and Abcg2 in vitro were also peripherally restricted in vivo. The extent of such restriction seems to depend upon other physicochemical features of the compounds, in particular the polar surface area. Consistent with these in vitro results, we found that URB937 readily enters the brain in dual knockout mice lacking both Abcg2 and Abcb1, whereas it is either partially or completely excluded from the brain of mice lacking either transporter alone. The results suggest that Abcg2 and Abcb1 act together to restrict the access of URB937 to the CNS.

Synthesis and structure-activity relationship studies of O-biphenyl-3-yl carbamates as peripherally restricted fatty acid amide hydrolase inhibitors.

The peripherally restricted fatty acid amide hydrolase (FAAH) inhibitor URB937 (3, cyclohexylcarbamic acid 3'-carbamoyl-6-hydroxybiphenyl-3-yl ester) is extruded from the brain and spinal cord by the Abcg2 efflux transporter. Despite its inability to enter the central nervous system (CNS), 3 exerts profound antinociceptive effects in mice and rats, which result from the inhibition of FAAH in peripheral tissues and the consequent enhancement of anandamide signaling at CB1 cannabinoid receptors localized on sensory nerve endings. In the present study, we examined the structure-activity relationships (SAR) for the biphenyl region of compound 3, focusing on the carbamoyl and hydroxyl groups in the distal and proximal phenyl rings. Our SAR studies generated a new series of peripherally restricted FAAH inhibitors and identified compound 35 (cyclohexylcarbamic acid 3'-carbamoyl-5-hydroxybiphenyl-3-yl ester) as the most potent brain-impermeant FAAH inhibitor disclosed to date.

Antinociceptive effects of the N-acylethanolamine acid amidase inhibitor ARN077 in rodent pain models.

Fatty acid ethanolamides (FAEs), which include palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), are endogenous agonists of peroxisome proliferator-activated receptor-α (PPAR-α) and important regulators of the inflammatory response. They are degraded in macrophages by the lysosomal cysteine amidase, N-acylethanolamine acid amidase (NAAA). Previous studies have shown that pharmacological inhibition of NAAA activity suppresses macrophage activation in vitro and causes marked anti-inflammatory effects in vivo, which is suggestive of a role for NAAA in the control of inflammation. It is still unknown, however, whether NAAA-mediated FAE deactivation might regulate pain signaling. The present study examined the effects of ARN077, a potent and selective NAAA inhibitor recently disclosed by our group, in rodent models of hyperalgesia and allodynia caused by inflammation or nerve damage. Topical administration of ARN077 attenuated, in a dose-dependent manner, heat hyperalgesia and mechanical allodynia elicited in mice by carrageenan injection or sciatic nerve ligation. The antinociceptive effects of ARN077 were prevented by the selective PPAR-α antagonist GW6471 and did not occur in PPAR-α-deficient mice. Furthermore, topical ARN077 reversed the allodynia caused by ultraviolet B radiation in rats, and this effect was blocked by pretreatment with GW6471. Sciatic nerve ligation or application of the proinflammatory phorbol ester 12-O-tetradecanoylphorbol 13-acetate decreased FAE levels in sciatic nerve and skin tissue, respectively. ARN077 reversed these biochemical effects. The results identify ARN077 as a potent inhibitor of intracellular NAAA activity, which is active in vivo by topical administration. The findings further suggest that NAAA regulates peripheral pain initiation by interrupting endogenous FAE signaling at PPAR-α.

Peripheral FAAH inhibition causes profound antinociception and protects against indomethacin-induced gastric lesions.

Fatty-acid amide hydrolase (FAAH) catalyzes the intracellular hydrolysis of the endocannabinoid anandamide and other bioactive lipid amides. In the present study, we conducted a comparative characterization of the effects of the newly identified brain-impermeant FAAH inhibitor, URB937 ([3-(3-carbamoylphenyl)-4-hydroxy-phenyl] N-cyclohexylcarbamate), in various rodent models of acute and persistent pain. When administered by the oral route in mice, URB937 was highly active (median effective dose, ED(50), to inhibit liver FAAH activity: 0.3mgkg(-1)) and had a bioavailability of 5.3%. The antinociceptive effects of oral URB937 were investigated in mouse models of acute inflammation (carrageenan), peripheral nerve injury (chronic sciatic nerve ligation) and arthritis (complete Freund's adjuvant). In all models, URB937 was as effective or more effective than standard analgesic and anti-inflammatory drugs (indomethacin, gabapentin, dexamethasone) and reversed pain-related responses (mechanical hyperalgesia, thermal hyperalgesia, and mechanical allodynia) in a dose-dependent manner. ED(50) values ranged from 0.2 to 10mgkg(-1), depending on model and readout. Importantly, URB937 was significantly more effective than two global FAAH inhibitors, URB597 and PF-04457845, in the complete Freund's adjuvant model. The effects of a combination of URB937 with the non-steroidal anti-inflammatory agent, indomethacin, were examined in the carrageenan and chronic sciatic nerve ligation models. Isobolographic analyses showed that the two compounds interacted synergistically to attenuate pain-related behaviors. Furthermore, URB937 reduced the number and severity of gastric lesions produced by indomethacin, while exerting no ulcerogenic effect when administered alone. The results indicate that the peripheral FAAH inhibitor URB937 is more effective than globally active FAAH inhibitors at inhibiting inflammatory pain. Our findings further suggest that FAAH and cyclooxygenase inhibitors interact functionally in peripheral tissues, to either enhance or hinder each other's actions.

The ABC membrane transporter ABCG2 prevents access of FAAH inhibitor URB937 to the central nervous system.

The O-arylcarbamate URB937 is a potent inhibitor of fatty-acid amide hydrolase (FAAH), an intracellular serine hydrolase responsible for the deactivation of the endocannabinoid anandamide. URB937 is unique among FAAH inhibitors in that is actively extruded from the central nervous system (CNS), and therefore increases anandamide levels exclusively in peripheral tissues. Despite its limited distribution, URB937 exhibits marked analgesic properties in rodent models of pain. Pharmacological evidence suggests that the extrusion of URB937 from the CNS may be mediated by the ABC membrane transporter ABCG2 (also called Breast cancer resistance protein, BCRP). In the present study, we show that URB937 is a substrate for both mouse and human orthologues of ABCG2. The relative transport ratios for URB937 in Madin-Darby canine kidney (MDCKII) cells monolayers over-expressing either mouse Abcg2 or human ABCG2 were significantly higher compared to parental monolayers (13.6 and 13.1 vs. 1.5, respectively). Accumulation of the compound in the luminal/apical side was prevented by co-administration of the selective ABCG2 inhibitor, Ko-143. In vivo studies in mice showed that URB937 (25 mg kg(-1)) readily entered the brain and spinal cord of Abcg2-deficient mice following intraperitoneal administration, whereas the same dose of drug remained restricted to peripheral tissues in wild-type mice. By identifying ABCG2 as a transport mechanism responsible for the extrusion of URB937 from the CNS, the present results should facilitate the rational design of novel peripherally restricted FAAH inhibitors.

Anandamide suppresses pain initiation through a peripheral endocannabinoid mechanism.

Peripheral cannabinoid receptors exert a powerful inhibitory control over pain initiation, but the endocannabinoid signal that normally engages this intrinsic analgesic mechanism is unknown. To address this question, we developed a peripherally restricted inhibitor (URB937) of fatty acid amide hydrolase (FAAH), the enzyme responsible for the degradation of the endocannabinoid anandamide. URB937 suppressed FAAH activity and increased anandamide levels outside the rodent CNS. Despite its inability to access brain and spinal cord, URB937 attenuated behavioral responses indicative of persistent pain in rodent models of peripheral nerve injury and inflammation and prevented noxious stimulus-evoked neuronal activation in spinal cord regions implicated in nociceptive processing. CB1 cannabinoid receptor blockade prevented these effects. These results suggest that anandamide-mediated signaling at peripheral CB1 receptors controls the access of pain-related inputs to the CNS. Brain-impenetrant FAAH inhibitors, which strengthen this gating mechanism, might offer a new approach to pain therapy.

Administration of MDMA to ethanol-deprived rats increases ethanol operant self-administration and dopamine release during reinstatement.

Recreational use of (±)-3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is often associated with other drugs, among which ethanol (EtOH) is one of the most common. However, little is known about how neurochemical sensitization produced by MDMA can modulate EtOH abuse. In this study we used EtOH operant self-administration tasks to investigate the effect of several low doses (0.33, 1.0 and 3.0 mg/kg) of MDMA in Dark Agouti rats. Motor activity was recorded after each MDMA administration. Changes in extracellular dopamine in the nucleus accumbens following a single EtOH injection (1.5 g/kg i.p.) were measured using intracerebral microdialysis in vivo after 1 wk of abstinence from EtOH, in order to mimic the dopaminergic response associated with reinstatement into EtOH consumption. Animals exposed to higher doses of MDMA (1.0 and 3.0 mg/kg) showed significantly enhanced EtOH self-administration during reinstatement and an increased EtOH-induced dopamine efflux. MDMA treatment acutely elevated motor activity after each administration in a dose-dependent manner. These findings suggest that repeated administration of MDMA, a relatively common drug of abuse, even at low doses, can alter subsequent vulnerability to EtOH consumption.