CBD (Cannabidiol)

"Since several years, other pharmacologically relevant constituents of the Cannabis plant, apart from Δ9-THC, have come into the focus of research and legislation. The most prominent of those is cannabidiol (CBD). In contrast to Δ9-THC, it is nonintoxicating, but exerts a number of beneficial pharmacological effects. For instance, it is anxiolytic, anti-inflammatory, antiemetic, and antipsychotic. Moreover, neuroprotective properties have been shown.1,2 Consequently, it could be used at high doses for the treatment of a variety of conditions ranging in psychiatric disorders such as schizophrenia and dementia, as well as diabetes and nausea.1,2

"At lower doses, it has physiological effects that promote and maintain health, including antioxidative, anti-inflammatory, and neuroprotection effects. For instance, CBD is more effective than vitamin C and E as a neuroprotective antioxidant and can ameliorate skin conditions such as acne.3,4

"The comprehensive review of 132 original studies by Bergamaschi et al. describes the safety profile of CBD, mentioning several properties: catalepsy is not induced and physiological parameters are not altered (heart rate, blood pressure, and body temperature). Moreover, psychological and psychomotor functions are not adversely affected. The same holds true for gastrointestinal transit, food intake, and absence of toxicity for nontransformed cells. Chronic use and high doses of up to 1500 mg per day have been repeatedly shown to be well tolerated by humans.1

"Nonetheless, some side effects have been reported for CBD, but mainly in vitro or in animal studies. They include alterations of cell viability, reduced fertilization capacity, and inhibition of hepatic drug metabolism and drug transporters (e.g., p-glycoprotein).1 Consequently, more human studies have to be conducted to see if these effects also occur in humans. In these studies, a large enough number of subjects have to be enrolled to analyze long-term safety aspects and CBD possible interactions with other substances."

"Cannabidiol (CBD) oil is essentially a concentrated solvent extract made from cannabis flowers or leaves that is dissolved in an edible oil such as sunflower, hemp, or olive oil. Solvents used can vary from relatively innocuous organic solvents (ethanol, isopropyl alcohol) to more harmful ones (petroleum-ether, naphtha), or even supercritical fluids (butane, CO2). The exact conditions and solvents applied have a great impact on, for example, the taste, color, and viscosity of the final product. Because many other plant components are co-extracted with the desired cannabinoids present in the herbal material, these are sometimes removed by a treatment known as “winterization.” By placing the extract in a freezer (–20 to –80°C) for 24–48 h, components with a higher melting point such as waxes and triglycerides, as well as chlorophyll will precipitate, so they can be removed by filtration or centrifugation [1]. This treatment can significantly improve the taste and color of the final product.

"Cannabis oils may contain various concentrations of CBD, tetrahydrocannabinol (THC), and minor cannabinoids, mainly depending on the cannabis variety used for extraction. The most popular product currently is CBD oil, but for example cannabigerol (CBG)-rich oil has been spotted as well [2], and others will very likely follow soon. The THC-rich type of cannabis oil has already been known for some years, and is generally known under the name “Simpson oil” [3]. Terpenes may or may not be present in these products, depending on the preparation method used [4]. Because they are highly volatile, elevated temperatures (such as those applied during drying of plant materials, or during the evaporation of solvents) may result in a significant loss of terpene components [5]. However, it is possible to capture evaporated terpenes by condensation, and reintroduce them back into the final oil. Additional ingredients may be added to further adjust properties such as color, viscosity, taste, or shelf-life stability."

"Recent developments suggest that non-psychotropic phytocannabinoids exert a wide range of pharmacological effects (Figure 1), many of which are of potential therapeutic interest. The most studied among these compounds is CBD, the pharmacological effects of which might be explained, at least in part, by a combination of mechanisms of action (Table 1, Figure 1). CBD has an extremely safe profile in humans, and it has been clinically evaluated (albeit in a preliminary fashion) for the treatment of anxiety, psychosis, and movement disorders. There is good pre-clinical evidence to warrant clinical studies into its use for the treatment of diabetes, ischemia and cancer. The design of further clinical trials should: i) consider the bell-shaped pattern of the dose–response curve that has been observed in pre-clinical pharmacology, and ii) establish if CBD is more effective or has fewer unwanted effects than other medicines. A sublingual spray that is a standardized Cannabis extract containing approximately equal quantities of CBD and D9-THC (Sativex^®), has been shown to be effective in treating neuropathic pain in multiple sclerosis patients [76].
"The pharmacology of D9-THCV (i.e. CB1 antagonism associated with CB2 agonist effects) is also intriguing because it has the potential of application in diseases such as chronic liver disease or obesity—when it is associated with inflammation—in which CB1 blockade together with some CB2 activation is beneficial.
"The plant Cannabis is a source of several other neglected phytocannabinoids such as CBC and CBG. Although the spectrum of pharmacological effects of these compounds is largely unexplored, their potent action at TRPA1 and TRPM8 might make these compounds new and attractive tools for pain management."

"We synthesised available evidence on the safety and efficacy of cannabinoids as an adjunctive treatment to conventional AEDs [Antiepileptic Drugs] in treating drug-resistant epilepsy. In many cases, there was qualitative evidence that cannabinoids reduced seizure frequency in some patients, improved other aspects of the patients’ quality of life and were generally well tolerated with mild-to-moderate AEs [Adverse Events]. We can be much more confident about this statement in the case of children than adults, because the recent, larger, well-conducted RCTs [Randomized Controlled Trials] were performed in children and adolescents.

"In studies where there was greater experimental control over the type and dosage of cannabinoid used, there was evidence that adjuvant use of CBD reduced the frequency of seizures, particularly in treatment-resistant children and adolescents, and that patients were more likely to achieve complete seizure freedom. There was a suggestion that the benefits of adding CBD may be greater when patients were also using clobazam.^{11 12} However because clobazam and CBD are both metabolised in the cytochrome P450 pathway, the pharmacokinetic interactions of these two drugs still need to be fully determined ⁵⁶ Further randomised, double-blind studies with a placebo or active control are needed to strengthen this conclusion.

"Non-RCT evidence was consistent with RCT evidence that suggested cannabinoids may reduce the frequency of seizures. In most of these studies, cannabinoid products and dosages were less well-controlled, and outcomes were based on self-report (often by parents). These studies provide lower quality evidence compared with RCTs due to the potential for selection bias in the study populations, and other weaknesses in study design. There was also some evidence that studies at very high risk of bias had higher reported proportions of participants reporting reductions in seizures and lower proportions reporting AEs. In RCTs, and most of the non-RCTs, cannabinoids were used as an adjunctive therapy rather than as a standalone intervention, so at present there is little evidence to support any recommendation that cannabinoids can be recommended as a replacement for current standard AEDs."

"Some studies indicate that under certain circumstances, CBD acute anxiolytic effects in rats were reversed after repeated 14-day administration of CBD.2 However, this finding might depend on the used animal model of anxiety or depression. This is supported by a study, where CBD was administered in an acute and “chronic” (2 weeks) regimen, which measured anxiolytic/antidepressant effects, using behavioral and operative models (OBX=olfactory bulbectomy as model for depression).18 The only observed side effects were reduced sucrose preference, reduced food consumption and body weight in the nonoperated animals treated with CBD (50 mg/kg). Nonetheless, the behavioral tests (for OBX-induced hyperactivity and anhedonia related to depression and open field test for anxiety) in the CBD-treated OBX animals showed an improved emotional response. Using microdialysis, the researchers could also show elevated 5-HT and glutamate levels in the prefrontal cortex of OBX animals only. This area was previously described to be involved in maladaptive behavioral regulation in depressed patients and is a feature of the OBX animal model of depression. The fact that serotonin levels were only elevated in the OBX mice is similar to CBD differential action under physiological and pathological conditions.

"A similar effect was previously described in anxiety experiments, where CBD proved to be only anxiolytic in subjects where stress had been induced before CBD administration. Elevated glutamate levels have been proposed to be responsible for ketamine's fast antidepressant function and its dysregulation has been described in OBX mice and depressed patients. Chronic CBD treatment did not elicit behavioral changes in the nonoperated mice. In contrast, CBD was able to alleviate the affected functionality of 5HT1A receptors in limbic brain areas of OBX mice.18 and references therein

"Schiavon et al. cite three studies that used chronic CBD administration to demonstrate its anxiolytic effects in chronically stressed rats, which were mostly mediated via hippocampal neurogenesis.19 and references therein For instance, animals received daily i.p. injections of 5 mg/kg CBD. Applying a 5HT1A receptor antagonist in the DPAG (dorsal periaqueductal gray area), it was implied that CBD exerts its antipanic effects via these serotonin receptors. No adverse effects were reported in this study."

"Today, CBD is used for the treatment of a wide range of medical conditions. This started with the somewhat serendipitous discovery (by parents experimenting with self-medication for their children) that CBD had a therapeutic effect on a serious form of epilepsy in children, called Dravet syndrome [8]. This effect is now under clinical investigation with the pharmaceutical CBD product Epidiolex®, which is currently in phase 3 trials with encouraging results [9, 10]. The media attention generated by its effect on severely ill children gave CBD the push needed to become a much desired medicine almost overnight [11]. Other medical indications that may be treated with CBD, and are supported to some extent by clinical proof, include Parkinson’s disease [12], schizophrenia [13], and anxiety disorder [14]. However, although research into the therapeutic effects of CBD is rapidly increasing, most current uses of CBD are not (yet) supported by clinical data. The popular use of these products means that physicians may be confronted with the effects of CBD oil even when they do not prescribe it themselves.

"An excellent example is the use of CBD (and also THC) products for the self-medicating of cancer, with the intention of fully curing it [15]. This is based on an increasing body of preclinical evidence showing cannabinoids to be capable, under some conditions, of inhibiting the development of cancer cells in vitro or in vivo by various mechanisms of action, including induction of apoptosis, inhibition of angiogenesis, and arresting the cell cycle [16]. This is certainly exciting news, and research is ongoing around the world, but there is no solid clinical evidence yet to support that cannabinoids – whether natural or synthetic – can effectively and safely treat cancer in actual humans [17]. In fact, there are indications that certain types of cancer may even accelerate when exposed to cannabinoids [18]. This becomes problematic when patients choose to refuse chemotherapy treatment because they firmly believe in the rumored curative properties of cannabinoids. As a result, recommendation of cannabinoids for treating cancer should be done with great care, and with distinction as to the type of cancer being treated [19]."

"Various studies on CBD and psychosis have been conducted.²⁰ For instance, an animal model of psychosis can be created in mice by using the NMDAR antagonist MK-801. The behavioral changes (tested with the prepulse inhibition [PPI] test) were concomitant with decreased mRNA expression of the NMDAR GluN1 subunit gene (GRN1) in the hippocampus, decreased parvalbumin expression (=a calcium-binding protein expressed in a subclass of GABAergic interneurons), and higher FosB/ΔFosB expression (=markers for neuronal activity). After 6 days of MK-801 treatment, various CBD doses were injected intraperitoneally (15, 30, 60 mg/kg) for 22 days. The two higher CBD doses had beneficial effects comparable to the atypical antipsychotic drug clozapine and also attenuated the MK-801 effects on the three markers mentioned above. The publication did not record any side effects.²¹

"One of the theories trying to explain the etiology of bipolar disorder (BD) is that oxidative stress is crucial in its development. Valvassori et al. therefore used an animal model of amphetamine-induced hyperactivity to model one of the symptoms of mania. Rats were treated for 14 days with various CBD concentrations (15, 30, 60 mg/kg daily i.p.). Whereas CBD did not have an effect on locomotion, it did increase brain-derived neurotrophic factor (BDNF) levels and could protect against amphetamine-induced oxidative damage in proteins of the hippocampus and striatum. No adverse effects were recorded in this study.²²

"Another model for BD and schizophrenia is PPI of the startle reflex both in humans and animals, which is disrupted in these diseases. Peres et al., list five animal studies, where mostly 30 mg/kg CBD was administered and had a positive effect on PPI.20 Nonetheless, some inconsistencies in explaining CBD effects on PPI as model for BD exist. For example, CBD sometimes did not alter MK-801-induced PPI disruption, but disrupted PPI on its own.²⁰ If this effect can be observed in future experiments, it could be considered to be a possible side effect."

"CBD, which is nonhedonic, can reduce heroin-seeking behavior after, for example, cue-induced reinstatement. This was shown in an animal heroin self-administration study, where mice received 5 mg/kg CBD i.p. injections. The observed effect lasted for 2 weeks after CBD administration and could normalize the changes seen after stimulus cue-induced heroin seeking (expression of AMPA, GluR1, and CB1R). In addition, the described study was able to replicate previous findings showing no CBD side effects on locomotor behavior.²³"

"There are various mechanisms underlying neuroprotection, for example, energy metabolism (whose alteration has been implied in several psychiatric disorders) and proper mitochondrial functioning.²⁴ An early study from 1976 found no side effects and no effect of 0.3–300 μg/mg protein CBD after 1 h of incubation on mitochondrial monoamine oxidase activity in porcine brains.²⁵ In hypoischemic newborn pigs, CBD elicited a neuroprotective effect, caused no side effects, and even led to beneficial effects on ventilatory, cardiac, and hemodynamic functions.²⁶

"A study comparing acute and chronic CBD administration in rats suggests an additional mechanism of CBD neuroprotection: Animals received i.p. CBD (15, 30, 60 mg/kg b.w.) or vehicle daily, for 14 days. Mitochondrial activity was measured in the striatum, hippocampus, and the prefrontal cortex.²⁷ Acute and chronic CBD injections led to increased mitochondrial activity (complexes I-V) and creatine kinase, whereas no side effects were documented. Chronic CBD treatment and the higher CBD doses tended to affect more brain regions. The authors hypothesized that CBD changed the intracellular Ca2+ flux to cause these effects. Since the mitochondrial complexes I and II have been implied in various neurodegenerative diseases and also altered ROS (reactive oxygen species) levels, which have also been shown to be altered by CBD, this might be an additional mechanism of CBD-mediated neuroprotection.^1,27

"Interestingly, it has recently been shown that the higher ROS levels observed after CBD treatment were concomitant with higher mRNA and protein levels of heat shock proteins (HSPs). In healthy cells, this can be interpreted as a way to protect against the higher ROS levels resulting from more mitochondrial activity. In addition, it was shown that HSP inhibitors increase the CBD anticancer effect in vitro.²⁸ This is in line with the studies described by Bergamaschi et al., which also imply ROS in CBD effect on (cancer) cell viability in addition to, for example, proapoptotic pathways such as via caspase-8/9 and inhibition of the procarcinogenic lipoxygenase pathway.¹

"Another publication studied the difference of acute and chronic administration of two doses of CBD in nonstressed mice on anxiety. Already an acute i.p. administration of 3 mg/kg was anxiolytic to a degree comparable to 20 mg/kg imipramine (an selective serotonin reuptake inhibitor [SSRI] commonly prescribed for anxiety and depression). Fifteen days of repeated i.p. administration of 3 mg/kg CBD also increased cell proliferation and neurogenesis (using three different markers) in the subventricular zone and the hippocampal dentate gyrus. Interestingly, the repeated administration of 30 mg/kg also led to anxiolytic effects. However, the higher dose caused a decrease in neurogenesis and cell proliferation, indicating dissociation of behavioral and proliferative effects of chronic CBD treatment. The study does not mention adverse effects.¹⁹"

"Numerous studies show the CBD immunomodulatory role in various diseases such as multiple sclerosis, arthritis, and diabetes. These animal and human ex vivo studies have been reviewed extensively elsewhere, but studies with pure CBD are still lacking. Often combinations of THC and CBD were used. It would be especially interesting to study when CBD is proinflammatory and under which circumstances it is anti-inflammatory and whether this leads to side effects (Burstein, 2015: Table 1 shows a summary of its anti-inflammatory actions; McAllister et al. give an extensive overview in Table 1 of the interplay between CBD anticancer effects and inflammation signaling).^29,30

"In case of Alzheimer's disease (AD), studies in mice and rats showed reduced amyloid beta neuroinflammation (linked to reduced interleukin [IL]-6 and microglial activation) after CBD treatment. This led to amelioration of learning effects in a pharmacological model of AD. The chronic study we want to describe in more detail here used a transgenic mouse model of AD, where 2.5-month-old mice were treated with either placebo or daily oral CBD doses of 20 mg/kg for 8 months (mice are relatively old at this point). CBD was able to prevent the development of a social recognition deficit in the AD transgenic mice.

"Moreover, the elevated IL-1 beta and TNF alpha levels observed in the transgenic mice could be reduced to WT (wild-type) levels with CBD treatment. Using statistical analysis by analysis of variance, this was shown to be only a trend. This might have been caused by the high variation in the transgenic mouse group, though. Also, CBD increased cholesterol levels in WT mice but not in CBD-treated transgenic mice. This was probably due to already elevated cholesterol in the transgenic mice. The study observed no side effects.^{31 and references within}

"In nonobese diabetes-prone female mice (NOD), CBD was administered i.p. for 4 weeks (5 days a week) at a dose of 5 mg/kg per day. After CBD treatment was stopped, observation continued until the mice were 24 weeks old. CBD treatment lead to considerable reduction of diabetes development (32% developed glucosuria in the CBD group compared to 100% in untreated controls) and to more intact islet of Langerhans cells. CBD increased IL-10 levels, which is thought to act as an anti-inflammatory cytokine in this context. The IL-12 production of splenocytes was reduced in the CBD group and no side effects were recorded.³²

"After inducing arthritis in rats using Freund's adjuvant, various CBD doses (0.6, 3.1, 6.2, or 62.3 mg/day) were applied daily in a gel for transdermal administration for 4 days. CBD reduced joint swelling, immune cell infiltration. thickening of the synovial membrane, and nociceptive sensitization/spontaneous pain in a dose-dependent manner, after four consecutive days of CBD treatment. Proinflammatory biomarkers were also reduced in a dose-dependent manner in the dorsal root ganglia (TNF alpha) and spinal cord (CGRP, OX42). No side effects were evident and exploratory behavior was not altered (in contrast to Δ9-THC, which caused hypolocomotion).³³"

"Another chemical shared by both industrial hemp and marijuana is Cannabidiol (CBD).⁴⁸ CBD is unique because it is not intoxicating and it also moderates the euphoric effect of THC.⁴⁹ Marijuana, which has disproportionately higher levels of THC than industrial hemp, also contains lower levels of CBD.⁵⁰ The higher THC and lower CBD concentration gives marijuana its psychoactive effect.⁵¹ Conversely, industrial hemp’s low THC levels and comparatively high CBD levels produce none of the intoxicating effects of marijuana.⁵²"