Cannabis and Cannabinoids

Pharmacology, Toxicology, and Therapeutic Potential

Ethan B Russo

• Publisher: Routledge
• Year: 2013
• eBook ISBN: 9781136614934
• Topic: Medicine
• Subtopic: Alternative & Complementary Medicine

Study the latest research findings by international experts!This comprehensive volume presents state-of-the-art scientific research on the therapeutic uses of cannabis and its derivatives. All too often, discussions of the potential medical uses of this substance are distorted by political considerations that have no place in a medical debate. Cannabis and Cannabinoids: Pharmacology, Toxicology, and Therapeutic Potential features fair, equitable discussion of this emerging and controversial medical topic by the world's foremost researchers.Cannabis and Cannabinoids examines the benefits, drawbacks, and side effects of medical marijuana as a treatment for various conditions and diseases. This book discusses the scientific basis for marijuana's use in cases of pain, nausea, anorexia, and cachexia. It also explores its possible benefits in glaucoma, ischemia, spastic disorders, and migraine.Cannabis and Cannabinoids examines all facets of the medical use of marijuana, including:

• botany
• history
• biochemistry
• pharmacology
• clinical use
• toxicology
• side effectsCannabis and Cannabinoids is a reference work that will become indispensable to physicians, psychologists, researchers, biochemists, graduate students, and interested members of the public. No other book available offers this comprehensive, even-handed look at a deeply divisive subject.

PART I: BOTANY, TAXONOMY, CHEMISTRY, AND HISTORY

Chapter 1 Botany of Natural Cannabis Medicines

Robert C. Clarke

David Paul Watson

DOI: 10.4324/9780203479506-1

INTRODUCTION

Cannabis is among the very oldest of economic plants, providing fiber, edible seed, and drug resin. Human selection for varying uses and natural selection pressures imposed by diverse climates have resulted in a wide variety of growth forms and chemical compositions. Innovative classical breeding techniques have been used to improve drug cannabis, resulting in many cannabinoid-rich cultivars suitable for medical use. The production of cannabinoids is unique to Cannabis, and cultivars with specific chemical profiles are being developed for diverse potential pharmaceutical uses.

NATURAL LIFE CYCLE

Cannabis is an annual plant, propagated from seed, and grows vigorously in open sunny environments with light, well-drained soil and ample nutrients and water, and reaches up to five meters (16 feet) in height in a four- to six-month growing season. Feral Cannabis populations are frequently found in association with human habitation. Agricultural lands, roadsides, exposed riverbanks, meadows, and disturbed lands are ideal habitats for wild and feral Cannabis, as they provide adequate sunlight.

Seeds usually germinate in three to seven days. During the first two to three months of growth juvenile plants respond to increasing day length with more vigorous vegetative growth characterized by an increasing number of leaflets on each leaf. Later in the season (after the summer solstice), shorter days (actually longer nights) induce flowering and complete the life cycle (see Figure 1.1). Cannabis begins to flower when exposed to short day lengths of 12 to 14 hours or less (long nights of 10 to 12 hours or more) depending on its latitude of origin. However, a single evening of interrupted darkness can disrupt flowering and delay maturation. If an individual plant is not crowded by its neighbors, as is the case for the crops intended for seed or drug production, flower-bearing limbs will grow from small buds located at the base of the leaf petioles originating from nodes along the main stalk. The flowering period is characterized by leaves bearing decreasing numbers of leaflets.¹

Figure 1.1. Close-Up Photo of a Cannabis Inflorescence, with Each Seed Concealed Within a Perigonal Bract Covered with Glandular Trichomes

Cannabis is normally a dioecious plant, with male and female flowers developing on separate plants. The sexes of Cannabis are anatomically indistinguishable before they begin flowering. However, Mandolino and Ranalli⁷ report success using RAPD analysis to identify male-specific DNA markers. The development of male and female plants varies greatly. The male flowers hang in loose clusters along a relatively leafless upright branch, in contrast to crowded clusters of individual female flowers at the base of each leaf along the branch. Male Cannabis flowers require air currents to carry pollen grains to the female flowers, which results in fertilization and consequent seed formation. The male plants finish shedding pollen and die before the seeds in the female plants ripen four to eight weeks after being fertilized. Pollen has been frozen and successfully used for seed production up to three years later.

The single seed in each female flower ripens in about three to eight weeks and will either be harvested by humans, eaten by birds or rodents, or drop to the ground. A large female plant can produce over one kilogram of seed. This completes the natural four to six month life cycle. If the seeds are not consumed by birds or rodents, they may germinate the following spring. Cannabis seeds are a balanced source of essential fatty acids (EFAs), and easily digestible protein and are usable as human food or animal feed (see chapter 38). EFAs have been shown to have many important physiological roles and hemp seed oil is a valuable nutraceutical.³

AGRICULTURAL FIELD PRODUCTION

For hemp crops grown for fiber or seed, both male and female plants are usually left in the field until harvest. The male plants pollinate the females and then die before the seeds ripen. In the early 1970s, a handful of North American marijuana cultivators began to grow sinsemilla (Spanish for “without seed”) marijuana. The sinsemilla effect is achieved by eliminating staminate plants from the fields, leaving only the unfertilized pistillate plants to mature for later harvest. In lieu of setting seed in the earliest flowers, the pistillate plants continue to produce additional flowers, which are covered by resin glands, thus increasing the percentage of psychoactive and medically valuable Δ⁹-tetrahydrocannabinol (THC) or other cannabinoids. This technique was originally developed in India, but historians are unsure of its history prior to 1800. Since 1975, sinsemilla has been the primary style of North American and European marijuana production.

Throughout the 1980s, the vast majority of domestically produced North American drug cannabis was grown outdoors, but in the 1990s the popularity of growing in greenhouses and indoors under artificial lights rapidly expanded. Crops grown from seed make large plants of both genders that take up a lot of space, and exhibit a range of characteristics. A Cannabis breeder relies on this variation as potential to improve varieties. However, a drug cannabis producer wants a profitable and uniform crop, and uses female clones that improve grow room yields, but preclude the possibility of seed production and varietal improvement.

VEGETATIVE CROP PRODUCTION

Much of the Cannabis presently used for medical purposes is grown indoors under artificial lights. Metal halide and sodium vapor light systems are most often set up in attics, bedrooms, or basements. Most modern indoor growers produce vegetatively propagated crops. Only female drug Cannabis plants are economically valuable, and garden space is limited. It is both difficult and expensive to purchase reliable drug Cannabis seed, sales of which are prohibited in many nations. In addition, the legal systems of many nations penalize growers of large quantities of cannabis with harsher penalties. Under artificial growing conditions, crops are reproduced vegetatively by rooting cuttings of only female plants, transplanting and inducing flowering almost immediately. Cuttings taken from one plant are all identical members of a single clone and they will all respond in the same way to environmental inputs. Given that environmental influences are constant, the clone will yield a uniform crop of nearly identical seedless females each time it is grown.

Female “mother” plants are maintained in a constantly vegetative state under 18 hour or longer day lengths. Serial cuttings can be removed, rooted, grown under long day length and used to replace older mother plants, indefinitely. If the cutting material remains free of viruses or other pathogens there is no loss of vigor after multiple rounds of vegetative propagation. Whenever they are required, rooted small cuttings (10 to 30 cm tall) are moved into a flowering room with a day length of 10 to 13 hours, to mature 7 to 14 weeks later.

Cloned plants can mature fully, form flowers from top to bottom and look like a rooted branch from a large plant grown from seed when they are less than one meter tall...

Table of contents

• Cover
• Half-Title Page
• Title Page
• Copyright Page
• Table of Contents
• About the Editors
• Contributors
• Foreword
• Preface
• Definitions and Explanations
• PART I: BOTANY, TAXONOMY, CHEMISTRY, AND HISTORY
• PART II: PHARMACOLOGY AND PHARMACOKINETICS
• PART III: INDICATIONS FOR CANNABIS AND THC
• PART IV: RISKS AND SIDE EFFECTS
• PART V: OTHER CANNABINOIDS
• PART VI: OTHER CONSTITUENTS OF CANNABIS
• Resources
• Index