Cannabinoids are pharmacological agents of endogenous (endocannabinoids), botanical (phytocannabinoids), or synthetic origin; Cannabinoids alleviate pain through a variety ofreceptor and non-receptor mechanisms including direct analgesic and anti-in fl ammatory effects, modulatory actions on neurotransmitters, and interactions with endogenous and administered opioids; Cannabinoid agents are currently available in various countries for pain treatment, and even cannabinoids of botanical origin may be approvable by FDA, although this is distinctly unlikely for smoked cannabis; An impressive body of literature supports cannabinoid analgesia, and recently, this has been supplemented by an increasing number of phase I–III clinical trials.

Using 8-hour human laboratory experiments, we evaluated the analgesic efficacy of vaporized cannabis in patients with neuropathic pain related to injury or disease of the spinal cord, most of whom were experiencing pain despite traditional treatment. After obtaining baseline data, 42 participants underwent a standardized procedure for inhaling 4 puffs of vaporized cannabis containing either placebo, 2.9%, or 6.7% delta 9-THC on 3 separate occasions. A second dosing occurred 3 hours later; participants chose to inhale 4 to 8 puffs. This flexible dosing was used to attempt to reduce the placebo effect. Using an 11-point numerical pain intensity rating scale as the primary outcome,...

AIM Experimental pain models may help to evaluate the mechanisms of analgesics and target the clinical indications for their use. This review, the second in a series of two, addresses how the efficacy of non-opioid analgesics have been assessed in human volunteers using experimental pain models. METHODS A literature search was completed for randomized controlled studies that included human experimental pain models, healthy volunteers and non-opioid analgesics. RESULTS Nonsteroidal anti-inflammatory drugs worked against various types of acute pain as well as in hyperalgesia. Analgesia from paracetamol was difficult to detect in experimental pain and the pain needed to be assessed with very sensitive methods...

Cannabidiol (CBD), a major phytocannabinoid constituent of cannabis, is attracting growing attention in medicine for its anxiolytic, antipsychotic, antiemetic and anti-inflammatory properties. However, up to this point, a comprehensive literature review of the effects of CBD in humans is lacking. The aim of the present systematic review is to examine the randomized and crossover studies that administered CBD to healthy controls and to clinical patients. A systematic search was performed in the electronic databases PubMed and EMBASE using the key word “cannabidiol”. Both monotherapy and combination studies (e.g., CBD + ∆9-THC) were included. A total of 34 studies were identified: 16 of these were...

Abstract Background and purpose: Paclitaxel (PAC) is associated with chemotherapy-induced neuropathic pain (CIPN) that can lead to the cessation of treatment in cancer patients even in the absence of alternate therapies. We previously reported that chronic administration of the non-psychoactive cannabinoid cannabidiol (CBD) prevents PAC-induced mechanical and thermal sensitivity in mice. Hence, we sought to determine receptor mechanisms by which CBD inhibits CIPN and whether CBD negatively effects nervous system function or chemotherapy efficacy. Experimental approach: The ability of acute CBD pretreatment to prevent PAC-induced mechanical sensitivity was assessed, as was the effect of CBD on place conditioning and on an operant-conditioned learning and memory task....

Osteoarthritis (OA) of the joint is a prevalent disease accompanied by chronic, debilitating pain. Recent clinical evidence has demonstrated that central sensitization contributes to OA pain. An improved understanding of how OA joint pathology impacts upon the central processing of pain is crucial for the identification of novel analgesic targets/new therapeutic strategies. Inhibitory cannabinoid 2 (CB2) receptors attenuate peripheral immune cell function and modulate central neuro-immune responses in models of neurodegeneration. Systemic administration of the CB2 receptor agonist JWH133 attenuated OAinduced pain behaviour, and the changes in circulating pro- and anti-inflammatory cytokines exhibited in this model. Electrophysiological studies revealed that spinal administration of JWH133...

Abstract Activation of both cannabinoid 1 (CB1) and cannabinoid 2 (CB2) receptors reduces nociceptive processing in acute and chronic animal models of pain. In addition, nociceptive processing is tonically modulated by endogenous cannabinoids (endocannabinoids, ECs). This review examines the role of cannabinoids and ECs in the brain stem–spinal pathway of pain inhibition. Preclinical studies evaluating cannabinoids in neuropathic pain management are also reviewed. Pharmacological tools modulating the interaction of cannabinoids with its receptors and the treatment of pain by the augmentation of EC levels, specifically anandamide, are discussed. Particular attention is attributed to neuropathic pain in which pharmacological manipulation resulting in EC accumulation can...

Cannabinoids and opioids share several pharmacologic properties and may act synergistically. The potential pharmacokinetics and the safety of the combination in humans are unknown. We therefore undertook a study to answer these questions. Twenty-one individuals with chronic pain, on a regimen of twice-daily doses of sustainedrelease morphine or oxycodone were enrolled in the study and admitted for a 5-day inpatient stay. Participants were asked to inhale vaporized cannabis in the evening of day 1, three times a day on days 2–4, and in the morning of day 5. Blood sampling was performed at 12-h intervals on days 1 and 5. The extent of chronic...