Search Results

This introductory chapter begins with a description of the hemp plant from which the various cannabis products derive. The hemp plant (Cannabis sativa) may have originated in Central Asia but has been distributed widely around the world through man’s activities It has been cultivated as a multipurpose economic plant for thousands of years, and through the process of selection for various desirable characteristics, many different cultivated varieties exist—some growth for their fiber content, others for their psychoactive chemical content. The chapter then discusses the consumption of cannabis through smoking, eating, and drinking. A brief history of the drug is presented.

Humans use nearly every part of the infamous green weed Cannabis sativa. The plant grows quickly in many environments and can reach a height of 20 feet. The leaves consist of five or more narrow leaflets, each radiating from a slender stem attached to a thick, hollow stalk. The jagged edge of each leaflet resembles the blade of a serrated knife. The species is dioecious, meaning that both female and male varieties of the plant exist. The stalks help produce fiber; the seeds provide food and oil. The flowers, leaves, and resin appear in medical and intoxicating preparations. Each day, smiling teens buy hemp shirts. Retailers sell snacks made from the seed. Glaucoma patients puff cannabis cigarettes in hope of saving their sight, and many people worldwide inhale marijuana smoke in an effort to alter consciousness. These industrial, medical, and recreational uses for the plant go back thousands of years, contributing to its spread from Taiwan throughout the world. This chapter presents the histories of industrial hemp, medical marijuana, and cannabis.

Marijuana (cannabis) is among the most widely used of all psychoactive drugs. Despite the fact that its possession and use is illegal in many countries, cannabis is used regularly by as many as 20 million people in the United States and Europe and by millions more in other areas of the world. Thousands of patients with AIDS, multiple sclerosis, and a variety of other disabling diseases use marijuana in the firm belief that it makes their symptoms better, despite the relative paucity of medical evidence to substantiate this claim. This chapter reviews the long history of cannabis in human societies and its vilification and control in the 20th century. The plants Cannabis sativa and Cannabis indica are described, as are the various cannabis products derived from the plants and the more modern forms of concentrates.

Although cannabis has been used throughout human history, the scientific investigation of its effects only began with the isolation of THC in the 1960’s. Once discovered it was another 20 years before the mechanism by which THC produces its psychoactive effects in the brain, the CB₁ receptor, was discovered. Cannabis contains over 80 cannabinoid compounds, but THC is the only intoxicating compound. Recent preclinical research is being directed towards evaluating the therapeutic potential of other cannabinoid compounds found in cannabis, including CBD. The pharmacokinetics of THC, methods of administration, and dosing issues are explored in Chapter 1.

Dopamine is a neurotransmitter critical for reward processing and is elevated by most addicting drugs. The effect of THC and other CB₁ agonists moderately elevate dopamine in reward related regions of the rodent brain; however, there is less consistent evidence in humans for marijuana-induced changes in dopamine release or for morphological changes in brain reward areas. In humans, cannabis use disorder has been identified, which shows similar features of other substance use disorders, but not in the same extremes as opiates, psychostimulants or alcohol. This chapter discusses the interaction between cannabis and other drugs in relapse to drugs use, with a special case for the interaction between cannabinoids and opiates. Finally, the relationship between cannabinoid effects on men and women in sexual behaviour is discussed.

Was a search for drugs the main motivation that inspired travellers to go to the East? The chapter begins by considering one addict’s experience: however, the argument presented is that this was not typical. A historical contextualisation for drug-taking is given, noting how drugs of all sorts were often linked to Eastern cultures, even when there was no direct connection. Varied attitudes towards drug-taking are identified; in particular, the attitudes of an abstaining minority are considered. The chapter concludes by arguing that the existence of a wide range of considerably different attitudes to drug-taking means that drugs cannot be seen as a single, all-encompassing explanation for travel to the east.

This chapter addresses all preclinical evidence supporting the potential of phytocannabinoids for the treatment of pain. Findings are reviewed with an emphasis on chronic pain since it is still often refractory to conventional pharmacotherapies and since there is mounting evidence that phytocannabinoids may be more efficacious in the treatment of chronic pain conditions rather than acute pain. The aim is to provide a summative review not only of the antinociceptive efficacy of the main phytocannabinoids when given alone but also of the preclinical data now available on these agents when they are administered in combination. In fact emerging evidence highlights greater beneficial effects of whole cannabis extracts than of single components of these extracts, justifying further exploration both of the therapeutic potential of cannabis-based medicines and of pharmacological interactions between some of its constituents. Finally, the molecular mechanisms that could explain phytocannabinoids-induced relief of chronic pain are fully discussed.

Sleep is a universal phenomenon that occurs in every species studied so far. A normal sleep period fluctuates in a regular cycle of two basic forms: slow wave sleep (SWS) and rapid eye movement (REM) sleep. The sleep–wake cycle is modulated by diverse brain circuits and neuromodulators as well as by several endogenous and exogenous molecules, including cannabinoids. This chapter describes the effects of certain cannabis-derived and synthetic cannabinoids on sleep. Additionally, it provides an overview of current knowledge about potential uses of natural or synthetic cannabinoids for the treatment of sleep disorders.

Chemical phenotypes (chemotypes) of Cannabis are defined by the content and composition of their cannabinoid fraction. This chapter describes the current diversity of chemotypes and discusses their underlying genetic mechanisms and breeding histories. The role of chemotype in Cannabis classification is addressed. Specific morphological features of the glandular trichomes associated with certain chemotypes are illustrated. The purity, content, and yield levels of the cannabinoids of clones selected in a plant-breeding program at GW Pharmaceuticals are presented. Several of these clones are currently in use for pharmaceutical raw material production. Their crude floral extracts and purified cannabinoids are being investigated for therapeutic potential. The chapter closes with some thoughts on the prospects of molecular breeding to modify cannabinoid biogenesis and further expand the cannabinoid portfolio

This chapter looks at cannabis products and their history in the nineteenth and twentieth centuries. In part this story is about the entry of preparations of the plant into Western medical knowledge and practice. However, the chapter also demonstrates that cannabis was not simply constructed as a medicine in Western circles in this period. The ways in which competing understandings emerged of the plant and the substances that could be manufactured from it is also explored. The purpose of doing this is twofold. In the first instance the chapter begins to provide some answers to the question of ‘what is medical about colonial medicine’. In addressing this question the chapter also addresses a second concern, which is to put plants back into the picture of the history of medicine in the colonial period.