Cannabis is one of the most widely abused substances throughout the world. The primary psychoactive constituent of cannabis, delta 9- tetrahydrocannabinol (Δ9_THC), produces a myriad of pharmacological effects in animals and humans. Although it is used as a recreational drug, it can potentially lead to dependence and behavioral disturbances and its heavy use may increase the risk for psychotic disorders. Many studies that endeavor to understand the mechanism of action of cannabis concentrate on pharmacokinetics and pharmacodynamics of cannabinoids in humans. However, there is limited research on the chronic adverse effects and retention of cannabinoids in human subjects. Cannabis can be detected in body fluids following exposure through active/passive inhalation and exposure through breastfeeding. Cannabis detection is directly dependent on accurate analytical procedures for detection of metabolites and verification of recent use. In this review, an attempt has been made to summarize the properties of cannabis and its derivatives, and to discuss the implications of its use with emphasis on bioavailability, limit of detection, carry over period and passive inhalation, important factors for detection and diagnosis.
