Mechanism of action The actions of Delta-9-THC result from its partial agonist activity at the cannabinoid receptor CB1 (Ki = 40.7 nM), located mainly in the central nervous system, and the CB2 receptor (Ki = 36 nM), mainly expressed in cells of the immune system. The psychoactive effects of<unk>  are primarily mediated by the activation of cannabinoid receptors, which result in a decrease in the concentration of the second messenger molecule cAMP through inhibition of adenylate cyclase. The presence of these specialized cannabinoid receptors in the brain led researchers to the discovery of endocannabinoids, such as anandamide and 2-arachidonoyl glyceride (2-AG).<unk>  is a lipophilic molecule and may bind non-specifically to a variety of entities in the brain and body, such as adipose tissue (fat).<unk> , as well as other cannabinoids that contain a phenol group, possess mild antioxidant activity sufficient to protect neurons against oxidative stress, such as that produced by glutamate-induced excitotoxicity.<unk>  targets receptors in a manner far less selective than endocannabinoid molecules released during retrograde signaling, as the drug has a relatively low cannabinoid receptor affinity.<unk>  is also limited in its efficacy compared to other cannabinoids due to its partial agonistic activity, as<unk>  appears to result in greater downregulation of cannabinoid receptors than endocannabinoids. Furthermore, in populations of low cannabinoid receptor density,<unk>  may even act to antagonize endogenous agonists that possess greater receptor efficacy. However while<unk> 's pharmacodynamic tolerance may limit the maximal effects of certain drugs, evidence suggests that this tolerance mitigates undesirable effects, thus enhancing the drug's therapeutic window. Pharmacokinetics<unk>  is metabolized mainly to 11-OH-THC by the body. This metabolite is still psychoactive and is further oxidized to 11-nor-9-carboxy-THC <unk> -COOH). In animals, more than 100 metabolites could be identified, but 11-OH-THC and<unk> -COOH are the dominating metabolites. Metabolism occurs mainly in the liver by cytochrome P450 enzymes CYP2C9, CYP2C19, CYP2D6, and CYP3A4. More than 55% of<unk>  is excreted in the feces and ≈20% in the urine. The main metabolite in urine is the ester of glucuronic acid and 11-OH-THC and free<unk> -COOH. In the feces, mainly 11-OH-THC was detected.
Tetrahydrocannabinol
Cannabis 
Cannabis
Alpha-Hexachlorocyclohexane
Smokeless tobacco
Beta-Hexachlorocyclohexane
Squalene
N-Nitrosodimethylamine