However, e-cigarette’s harm quotient should stay low, provided they are properly regulated in terms of their components, including nicotine. Social influences and attitudes drive harm through stigma, social exclusion and social marginalization; these are often side-effects of drug policies, which can bring more harm than drug use itself.Policies that reduce exposure to drugs are essentially those that limit availability by increasing the price and reducing physical availability.Limits to availability bring a range of co-benefits to educational achievement and productivity, for example, but they can also bring adverse effects – for example, the well documented violence, corruption and loss of public income associated with some existing ‘illegal’ drug policies. Individual choices and behaviour that drive harm from drug use are determined by the environment in which those choices and behaviours operate. Banning commercial communications, increasing price and reducing availability are all incentives that impact individual behaviour. Research and development can be promoted to reduce the potency of existing drugs and their drug delivery packages. Unfortunately, there remain enormous gaps between the supply and demand of evidence-based prevention, advice and treatment programmes. Called for by United Nations Sustainable Development Goal 3.5, their supply can bring many co-benefits to society, including reduced social costs and increased productivity. The harm driven by the gaps is due in large part to insufficient resources and insufficient implementation of effective evidence-based prevention and treatment programmes. Currently these programmes represents less than 1% of all costs incurred to society by drugs.
Similar to medicines agencies that assess and approve drugs,commercial greenhouse supplies prevention agencies could be created. Compounding the gap between supply and demand is the fact that often, considerable marginalization and stigmatization happens in the path to treatment, and this is then further exacerbated by the treatment itself. The use of pharmacotherapy as an adjunct may be further limited due to ideological stances, poorly implemented guidelines, lack of appropriate medication, and even a perceived lack of effect, if the drug is available. The private sector is a core driver of harm, through commercial communications which include all actions undertaken by producers of drugs to persuade consumers to buy and consume more. There are international models encouraging better control of commercial communications in the public health interest, the most notable being the Framework Convention on Tobacco Control. In addition to commercial communications, the private sector drives harm through shaping drug policies, leading to more drug-related deaths. Governance structures thus need to have the capability and expertise to supervise industry movements that shape drug-related legislation and regulations, including regulating and restricting political lobbying. One of the difficulties here is that politically driven change in difficult areas, such as drug policies, is highly dependent on collective decisions and influenced by what has been termed specular interaction, in which a politician’s actions may be less determined by their own conviction, and more by their evaluation of beliefs of their rivals and friends. The health footprint is the accountability system for who and what causes drug-related harm. Jurisdictional entities can be ranked according to their overall health footprint, in order to identify the countries that contribute most to drug attributable ill-health and premature death, and where the most health gain could be achieved at country level. Jurisdictional footprints could include ‘policy attributable health footprints’ which estimate the health footprint between current policy and ideal health policy. This would address the question: ‘what would be the improvement in the health footprint compared to present policies, were the country to implement strengthened or new policies?’ Conversely, the health footprint can provide accountability for when such evidence-based policy is not implemented correctly.
A range of sectors are involved in nicotine and alcohol related risk factors. These include producer and retail organizations such as large supermarket chains, and service provider companies such as advertising and marketing industries. There is considerable overlap between sectors, and estimates will need to determine appropriate boundaries for health footprint calculations. Companies could report their health footprints and choose to commit to reducing them by a specified amount over a five to ten-year time frame. Direct examples of producer action could include switching from higher to lower alcohol concentration products, and switching from smoked tobacco cigarettes to e-cigarettes.Cannabinoid receptors, the molecular targets of the active principle of cannabis 9 -tetrahydrocannabinol, are activated by a small family of naturally occurring lipids that include anandamide and 2-arachidonylglycerol . As in the case of other lipid mediators, these endogenous cannabis-like compounds may be released from cells upon demand by stimulus-dependent cleavage of membrane phospholipid precursors . After release, anandamide and 2-AG may be eliminated by a two-step mechanism consisting of carrier-mediated transport into cells followed by enzymatic hydrolysis . Because of this rapid deactivation process, the endocannabinoids may primarily act near their sites of synthesis by binding to and activating cannabinoid receptors on the surface of neighboring cells . The development of methods for endocannabinoid analysis and the availability of selective pharmacological probes for cannabinoid receptors have allowed the exploration of the physiopathological functions served by the endocannabinoid system. Although still at their beginnings, these studies indicate that the endocannabinoids may significantly contribute to the regulation of pain processing , motor activity , blood pressure , and tumor cell growth . Furthermore, these investigations point to the endocannabinoid system—with its network of endogenous ligands, receptors, and inactivating mechanisms—as a potentially important arena for drug discovery. In this context, emphasis has been especially placed on the possible roles that CB1 and CB2 receptors may play as drug targets .
Here, we focus our attention on another facet of endocannabinoid pharmacology: the mechanisms by which anandamide and 2-AG are deactivated. We summarize current knowledge on how these mechanisms may function, describe pharmacological agents that interfere with their actions, and highlight the potential applications of these agents to medicine.Extracellular anandamide is rapidly recaptured by neuronal and non-neuronal cells through a mechanism that meets four key criteria of carriermediated transport: fast rate, temperature dependence, saturability, and substrate selectivity . Importantly, and in contrast with transport systems for classical neurotransmitters, [3 H]anandamide reuptake is neither dependent on external Na ions nor affected by metabolic inhibitors, suggesting that it may be mediated by a process of carrier-facilitated diffusion . How selective is anandamide reuptake? Cis-inhibition studies in a human astrocytoma cell line have shown that [ 3 H]anandamide accumulation is not affected by a variety of amino acid transmitters or biogenic amines . Furthermore, [3 H]anandamide reuptake is not prevented by fatty acids , neutral lipids , saturated fatty acyl ethanolamides ,cannabis dry rack prostaglandins, leukotrienes, hydroxyeicosatetraenoic acids, and epoxyeicosatetraenoic acids. Even further, [ 3 H]anandamide accumulation is insensitive to substrates or inhibitors of fatty acid transport , organic anion transport , and P-glycoproteins . By contrast, in the same cells, [3 H]anandamide reuptake is competitively blocked by either of the two endogenous cannabinoids, anandamide or 2-AG . Similar selectivity profiles are observed in primary cultures of rat cortical neurons or astrocytes and rat brain slices . The fact that both anandamide and 2-AG prevent [ 3 H]anandamide transport in cis-inhibition studies suggests that the two compounds compete for the same transport system. This possibility is further supported by three observations: 1) anandamide and 2-AG can mutually displace each other’s transport ; 2) [3 H]anandamide and [3 H]2-AG are accumulated with similar kinetic properties ; and 3) the transports of both compounds are prevented by the endocannabinoid transport inhibitor, N–arachidonylamide. Together, these findings indicate that anandamide and 2-AG may be internalized via a common carrier-mediated process, which displays a substantial degree of substrate and inhibitor selectivity. The molecular structure of this hypothetical transporter remains, however, unknown.The structures of anandamide and 2-AG contain three potential pharmacophores: 1) the hydrophobic carbon chain; 2) the carboxamido/carboxyester group; and 3) the polar head group . Systematic modifications in the carbon chain suggest that the structural requisites for substrate recognition by the putative endocannabinoid transporter may be different from those of substrate translocation. Substrate recognition appears to require the presence of at least one cis double bond in the middle of the fatty acid chain, indicating a preference for substrates whose hydrophobic tail can adopt an extended U-shaped conformation. By contrast, a minimum of four cis nonconjugated double bonds may be required for translocation, suggesting that substrates need to adopt a closed “hairpin” conformation to be transported across the membrane . In agreement with this hypothesis, molecular modeling studies show that transport substrates have both extended and hairpin low-energy conformers . By contrast, extended, but not hairpin, conformations may be thermodynamically favored in pseudosubstrates such as oleylethanolamide , that displace [3 H]anandamide from transport without being themselves internalized .
The impact that modifications of the polar head group exert on endocannabinoid transport has also been investigated . The available data suggest that ligand recognition may be favored 1) by a head group of defined stereochemical configuration containing a hydroxyl moiety at its distal end; and 2) by replacing the ethanolamine group with a 4-hydroxyphenyl or 2-hydroxyphenyl moiety. The latter modification leads to compounds, such as AM404 , that are competitive transport inhibitors of reasonable potency and efficacy .Anatomical studies of endocannabinoid transport are greatly limited by the lack of transporter-specific markers. Nevertheless, biochemical experiments have documented the existence of [3 H]anandamide uptake in primary cultures of rat cortical neurons and astrocytes , rat cerebellar granule cells , human neuroblastoma cells , and human astrocytoma cells . The CNS distribution of endocannabinoid transport was investigated by exposing metabolically active rat brain slices to [14C]anandamide and analyzing the distribution of radioactivity in the tissue by autoradiography . A receptor antagonist was included in the incubations to prevent the binding of [14C]anandamide to CB1 receptors, which are very numerous in certain brain regions , and AM404 was used to differentiate transportmediated [14C]anandamide reuptake from nonspecific binding . Substantial levels of AM404-sensitive [14C]anandamide reuptake were observed in the somatosensory, motor, and limbic areas of the cortex and in the striatum. Additional brain regions showing detectable [14C]anandamide accumulation included the hippocampus, thalamus, septum, substantia nigra, amygdala, and hypothalamus . Thus, endocannabinoid transport may be present in discrete regions of the rat brain that also express CB1 receptors .The endocannabinoid system is not confined to the brain, and it is reasonable to anticipate that mechanisms of endocannabinoid inactivation may also exist in peripheral tissues. In keeping with this expectation, carrier-mediated [ 3 H]anandamide transport was demonstrated in J774 macrophages , RBL-2H3 cells , and human endothelial cells . Although the kinetic and pharmacological properties of endocannabinoid uptake in peripheral cells appear to be generally similar to those reported in the CNS, some important difference have been observed. For example, in contrast to neurons, [3 H]anandamide uptake in RBL-2H3 cells is inhibited by arachidonic acid . Such disparities might reflect the existence in non-neural tissues of mechanisms of endocannabinoid internalization that are distinct from those found in the CNS.A variety of compounds have been tested for their ability to interfere with [3 H]anandamide internalization . Amongever, that AM404 is readily transported inside cells , where it can reach concentrations that may be sufficient to inhibit anandamide hydrolysis . To what extent this effect contributes to the ability of AM404 to prolong anandamide’s life span is at present unclear. The selectivity of AM404 for endocannabinoid transport has been the object of investigation. An initial screening found that AM404 has no affinity for a panel of 36 different pharmacological targets, including G protein-coupled receptors and ligand-gated ion channels . However, additional studies revealed that AM404 activates capsaicin receptor channels at concentrations similar to those necessary to inhibit endocannabinoid transport . The fact that AM404 can produce undesired effects underscores the need to introduce appropriate controls in the design of in vivo experiments with this compound. In particular, the effects of a cannabinoid receptor antagonist should be routinely tested to verify that endogenously produced anandamide and 2-AG are involved in the response to AM404 .AM404 does not display a typical cannabimimetic profile when administered in vivo; this is consistent with its poor affinity for cannabinoid receptors. For example, AM404 has no antinociceptive effect in mice or rats and causes no hypotension in guinea pigs .