MEDICAL CANNABIS STRAINS
Many people are aware that medical cannabis is a medicine that can be used to treat a wide range of conditions. What is less well known, however, is that there are many different varieties of medical cannabis that have different effects and can thus be used for different diseases. About 700 varieties have been named and described (1). Which cannabis strain is best for a patient depends on factors such as the cannabinoid and terpene profile of the strain and the condition being treated.
What is a medical cannabis strain?
A cannabis strain can be defined as either a pure or hybrid strain of a plant from the plant genus Cannabis, which is commonly divided into the species Cannabis sativa, Cannabis indica and Cannabis ruderalis. Even though about 700 varieties have already been described, the total number remains a topic of controversy among experts (1). Hybrid varieties that are bred and stabilized over several generations can become a new strain themselves. Therefore, some databases estimate that the total number of varieties could be as high as 3,600 (2). Furthermore, the commonly used terms “varieties” and “strain” are not the most accurate, since in the botanical sciences, the term “cultivar” is more commonly used (3).
You may also have heard that the names sativa, indica and hybrid are used as a classification system to describe the effect of cannabis varieties. Sativa strains are said to be invigorating and energising, helping to increase creativity and focus, while indica strains are typically associated with more physical effects, such as increasing deep relaxation and reducing insomnia. Hybrid strains are attributed with a mixture of both. However, this classification is generally not accepted by the scientific community, as this classification system is not very helpful in terms of chemical composition, apart from giving clues to the physical properties and physiology of a plant. There are currently no identifiable biochemical characteristics that would support a classification into indica, sativa and hybrid. A more reliable classification system is the cannabinoid and terpene profile.(4)
Cannabinoids
Cannabinoids, in this case also referred to as phytocannabinoids, i.e. cannabinoids of plant origin, are a broad group of active compounds in cannabis that have different chemical structures and pharmacological functions. They are mainly produced in the glandular trichomes of the plant. To date, about 120 have been identified and described (5). These cannabinoids are chemically similar to the body’s own endocannabinoids, which allows them to interact with the receptors of the endocannabinoid system (ECS). The ECS is a nerve cell modulating system that plays an important role in the transmission of signals between cells and in the central nervous system. These include CB1 and CB2 receptors found in the body and immune cells, respectively (6). The two best known and researched cannabinoids are THC and CBD, but other cannabinoids are also currently being studied for their unique effects.
Tetrahydrocannabinol (THC)
Δ-9-Tetrahydrocannabinol, also known as THC and dronabinol, is the main source of the psychotropic effects associated with cannabis use (7). It binds to the CB1 and CB2 receptors of the endocannabinoid system, and thus can stimulate appetite and relax muscles, among other effects.
Cannabidiol (CBD)
CBD, cannabidiol, on the other hand, is not psychoactive and its biological mechanism of action is not fully understood. Despite its low affinity for CB1 and CB2 receptors, CBD has been shown to influence the effects of THC by antagonizing these receptors, thereby reducing side effects of THC (7). The list of ailments for which CBD can help is growing. However, more research is needed to better understand the efficacy and range of benefits of CBD.
Other cannabinoids
Besides CBD and THC, there are other cannabinoids that have recently come under closer scrutiny by scientists due to their special properties. These include cannabichromene (CBC), which seems to have antidepressant and analgesic effects (8,9), cannabigerol (CBG), which has been shown to have antifungal and antibacterial effects (10), and cannabinol CBN, which has antispasmodic properties and may be therapeutic in the treatment of burns (11,12).
Terpenes
Terpenes are different chemical compounds that are mostly formed by plants as so-called secondary metabolites. They are the main components of essential oils that give cannabis its unique, unmistakable smell. Some are used as food additives, while others have been shown to have psychoactive effects. Interestingly, terpenes share a chemical precursor with cannabinoids. The combination of cannabinoids and terpenes may be therapeutically beneficial, according to evidence in the literature(13). Over 100 terpenes have been found in cannabis, such as myrcene, the most abundant terpene, as well as limonene, known for its citrus-like smell, and linalool, which gives off a floral smell. The combination of different terpenes provides the unique aromas of the various medical cannabis strains.(14)
When combined with the cannabinoids, terpenes can lead to synergistic effects and interactions that have been speculated about for several decades. This phytocannabinoid-terpene synergy, commonly referred to as the “entourage effect”, could increase the functionality of cannabis’ medical properties and possibly its potency.(15)
What strains of medical cannabis are available in dispensaries?
Despite the wide variety of medical cannabis strains, there are generally 3 categories into which strains can be divided:
- High THC and low CBD strains (e.g. 10-30% THC, traces of CBD).
- Varieties with high CBD and low THC content (e.g. 5-20% CBD, THC below 5%).
- Varieties with a balanced CBD and THC ratio (e.g. 5-15% THC and 5-15% CBD).
Medical cannabis strains with high THC and low CBD include White Lemon, White Widow and Hindu Kush. High CBD, low THC strains include God Bud and Cannatonic. Varieties with a balanced CBD and THC ratio, sometimes called 1:1 varieties, include Equiposa and Warlock CBD.(16,17)
Which medical cannabis strain is suitable for whom?
Which strains of cannabis are most suitable for medical use depends on the chemical composition of the plant and the patient’s condition. The cannabinoid and terpene profiles are most useful as a classification to differentiate between the hundreds, possibly thousands, of cannabis varieties. Ultimately, the decision as to which strain is most beneficial and should therefore be used always rests with the treating physician.
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