Pharmacology of cannabis

Cannabis has been used for recreational purposes around the world. It is derived from the plant cannabis sativa which has various other compounds known as cannabinoids. Most common form of cannabis used for recreational purpose is marijuana, which is prepared from dried flowering tops and leaves. The primary psychoactive component is delta 9- tetrahydrocannabinol (δ-9THC), which exerts its physiological and psychological effects through its interaction with CB1 and CB2 receptors. Smoking is the most commonly used method with onset of effects within minutes after inhalation. Oral ingestion of cannabis has varied absorption with delayed onset but longer duration of action. Urine drug screen is the most common method for detecting cannabis use. Other cannnabionoids such as cannabidiol have been utilized for medicinal purpose and research is ongoing to fully understand its role in treatment of various health conditions. Synthetic cannabis has emerged as drug of abuse over recent years and poses greater challenge due to serious physiological and psychological effects and inability to be detected in standard screening tests. This chapter describes main cannabinoids, their mechanism of action and metabolism in humans.