Category Archives: Pain

Medical Marijuana and Chronic Pain: a Review of Basic Science and Clinical Evidence.

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“Cannabinoid compounds include phytocannabinoids, endocannabinoids, and synthetics.

The two primary phytocannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), with CB1 receptors in the brain and peripheral tissue and CB2 receptors in the immune and hematopoietic systems.

The route of delivery of cannabis is important as the bioavailability and metabolism are very different for smoking versus oral/sublingual routes.

Gold standard clinical trials are limited; however, some studies have thus far shown evidence to support the use of cannabinoids for some cancer, neuropathic, spasticity, acute pain, and chronic pain conditions.”

http://www.ncbi.nlm.nih.gov/pubmed/26325482

Neuropeptide VF Enhances Cannabinoid Agonist WIN55,212-2-Induced Antinociception in Mice.

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“Cannabinoids produce analgesia in several pain models, but the undesirable side effects from high doses of cannabinoid drugs limit their clinic use.

Our recent results indicate that cannabinoid-induced antinociception was enhanced by neuropeptide VF (NPVF).

Here, we investigate whether low-dose cannabinoid agonists combined with NPVF can produce effective antinociception with limited side effects…

These data suggest that the cannabinoid agonist combined with NPVF produces effective antinociception-lacking tolerance via both cannabinoid receptor type 1 and neuropeptide FF receptors in the brain.”

http://www.ncbi.nlm.nih.gov/pubmed/26273748

[Clinical pharmacology of medical cannabinoids in chronic pain].

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“In Switzerland, medical cannabinoids can be prescribed under compassionate use after special authorization in justified indications such as refractory pain. Evidence of efficacy in pain is limited and the clinical benefit seems to be modest. Their drug-drug interactions (DDI) profile is poorly documented. Cytochromes P450 (CYP) 2C9 and 3A4 are involved in the metabolism of tetrahydrocannabinol and cannabidiol, which implies possible DDI with CYP450 inhibitor and inducer, such as anticonvulsivants and HIV protease inhibitors, which may be prescribed in patients with neuropathic pain.”

http://www.ncbi.nlm.nih.gov/pubmed/26267945

Microinjection of orexin-A into the rat locus coeruleus nucleus induces analgesia via cannabinoid type-1 receptors.

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“Locus coeruleus (LC) nucleus is involved in noradrenergic descending pain modulation.

LC receives dense orexinergic projections from the lateral hypothalamus. Orexin-A and -B are hypothalamic peptides which modulate a variety of brain functions via orexin type-1 (OX1) and orexin type-2 (OX2) receptors.

Previous studies have shown that activation of OX1 receptors induces endocannabinoid synthesis and alters synaptic neurotransmission by retrograde signaling via affecting cannabinoid type-1 (CB1) receptors.

In the present study the interaction of orexin-A and endocannabinoids was examined at the LC level in a rat model of inflammatory pain…

This data show that, activation of OX1 receptors in the LC can induce analgesia and also the blockade of OX1 or CB1 receptors is associated with hyperalgesia during formalin test.

Our findings also suggest that CB1 receptors may modulate the analgesic effect of orexin-A.

These results outline a new mechanism by which orexin-A modulates the nociceptive processing in the LC nucleus.”

http://www.ncbi.nlm.nih.gov/pubmed/26254729

Therapeutic potential of cannabis-related drugs.

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“In this review, I will consider the dual nature of Cannabis and cannabinoids.

The duality arises from the potential and actuality of cannabinoids in the laboratory and clinic and the ‘abuse’ of Cannabis outside the clinic.

The therapeutic areas currently best associated with exploitation of Cannabis-related medicines include pain, epilepsy, feeding disorders, multiple sclerosis and glaucoma.

As with every other medicinal drug of course, the ‘trick’ will be to maximise the benefit and minimise the cost.

After millennia of proximity and exploitation of the Cannabis plant, we are still playing catch up with an understanding of its potential influence for medicinal benefit.”

http://www.ncbi.nlm.nih.gov/pubmed/26216862

Cross-tolerance to cannabinoids in morphine-tolerant rhesus monkeys.

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“Opioids remain the drugs of choice for treating moderate to severe pain, although adverse effects limit their use. Therapeutic utility might be improved by combining opioids with other drugs to enhance analgesic effects, but only if adverse effects are not similarly changed.

Cannabinoids have been shown to enhance the antinociceptive potency of opioids without increasing other effects; this study examined whether the effectiveness of cannabinoids is altered in morphine-dependent monkeys.

Tolerance developed to the antinociceptive effects of morphine and cross-tolerance developed to cannabinoids under conditions that produced modest physical dependence.

Compared with the doses examined in this study, much smaller doses of opioids have antinociceptive effects when given with cannabinoids; it is possible that tolerance will not develop to chronic treatment with opioid/cannabinoid mixtures.”

http://www.ncbi.nlm.nih.gov/pubmed/26202613

Endocannabinoid 2-arachidonylglycerol protects primary cultured neurons against LPS-induced impairments in rat caudate nucleus.

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“Inflammation plays a pivotal role in the pathogenesis of many diseases in the central nervous system.

Caudate nucleus (CN), the largest nucleus in the brain, is also implicated in many neurological disorders.

2-Arachidonoylglycerol (2-AG), the most abundant endogenous cannabinoid and the true natural ligand for CB1 receptors, has been shown to exhibit neuroprotective effects through its anti-inflammatory action from proinflammatory stimuli in hippocampus.

In the present study, we discovered that 2-AG significantly protects CN neurons in culture against lipopolysaccharide (LPS)-induced inflammatory response.

Our study suggests the therapeutic potential of 2-AG for the treatment of some inflammation-induced neurological disorders and pain.”

http://www.ncbi.nlm.nih.gov/pubmed/24510751

Selective Reduction of THC’s Unwanted Effects through Serotonin Receptor Inhibition

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“While recreational marijuana users may seek the full range of its effects, broad medical use of THC—including for pain, nausea, and anxiety—is hindered by them.

In a new study, Xavier Viñals, Estefania Moreno, Peter McCormick, Rafael Maldonado, Patricia Robledo, and colleagues demonstrate that the cognitive effects of THC are triggered by a pathway separate from some of its other effects.

That pathway involves both a cannabinoid receptor and a serotonin receptor, and when this pathway is blocked, THC can still exert several beneficial effects, including analgesia, while avoiding impairment of memory.

The results of this study are potentially highly important, in that they identify a way to reduce some of what are usually thought of as THC’s unwanted side effects when used for medicinal purposes while maintaining several important benefits, including pain relief.

The widening acceptance of a role for THC in medicine may be accelerated by the option to reduce those side effects by selective pharmacological disruption or blocking of the heteromer.”

http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002193

Signaling Mechanism of Cannabinoid Receptor-2 Activation-Induced β-Endorphin Release.

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“Activation of cannabinoid receptor-2 (CB2) results in β-endorphin release from keratinocytes, which then acts on primary afferent neurons to inhibit nociception.

Our data also suggest that stimulation of MAPK contributes to the peripheral analgesic effect of CB2 receptor agonists.”

http://www.ncbi.nlm.nih.gov/pubmed/26108183

Medical Marijuana for Treatment of Chronic Pain and Other Medical and Psychiatric Problems: A Clinical Review.

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“Use of marijuana for chronic pain, neuropathic pain, and spasticity due to multiple sclerosis is supported by high-quality evidence.

Several of these trials had positive results, suggesting that marijuana or cannabinoids may be efficacious for these indications.

CONCLUSIONS AND RELEVANCE:

Medical marijuana is used to treat a host of indications, a few of which have evidence to support treatment with marijuana and many that do not. Physicians should educate patients about medical marijuana to ensure that it is used appropriately and that patients will benefit from its use.”

http://www.ncbi.nlm.nih.gov/pubmed/26103031