Salvinorin A is the main active psychotropic molecule in Salvia divinorum. Salvinorin A is considered a dissociative hallucinogen.
The κ-opioid receptor or kappa opioid receptor, abbreviated KOR or KOP for its ligand ketazocine, is a G protein-coupled receptor that in humans is encoded by the OPRK1 gene. The KOR is coupled to the G protein Gi/G0 and is one of four related receptors that bind opioid-like compounds in the brain and are responsible for mediating the effects of these compounds. These effects include altering nociception, consciousness, motor control, and mood. Dysregulation of this receptor system has been implicated in alcohol and drug addiction.
Nalfurafine is an antipruritic that is marketed in Japan for the treatment of uremic pruritus in individuals with chronic kidney disease undergoing hemodialysis. It activates the κ-opioid receptor (KOR) and is potent, selective, and centrally active. It was the first selective KOR agonist approved for clinical use. It has also been dubiously referred to as the "first non-narcotic opioid drug" in history.
Herkinorin is an opioid analgesic that is an analogue of the natural product salvinorin A. It was discovered in 2005 during structure-activity relationship studies into neoclerodane diterpenes, the family of chemical compounds of which salvinorin A is a member.
AMG-3 (part of the AM cannabinoid series) is an analgesic drug which is a cannabinoid agonist. It is a derivative of Δ8THC substituted with a dithiolane group on the 3-position side chain. AMG-3 is a potent agonist at both CB1 and CB2 receptors with a Ki of 0.32nM at CB1 and 0.52nM at CB2, and its particularly high binding affinity has led to it being used as a template for further structural development of novel cannabinoid drugs. It has sedative and analgesic effects, with analgesia lasting for up to 36 hours after administration.
Epiboxidine is a chemical compound which acts as a partial agonist at neural nicotinic acetylcholine receptors, binding to both the α3β4 and the α4β2 subtypes. It was developed as a less toxic analogue of the potent frog-derived alkaloid epibatidine, which is around 200 times stronger than morphine as an analgesic but produces extremely dangerous toxic nicotinic side effects.
HDMP-28 or methylnaphthidate is a piperidine based stimulant drug, closely related to methylphenidate, but with the benzene ring replaced by naphthalene. It is a potent dopamine reuptake inhibitor, with several times the potency of methylphenidate and a short duration of action, and is a structural isomer of another potent dopamine reuptake inhibitor, N,O-Dimethyl-4-(2-naphthyl)piperidine-3-carboxylate. It has been sold as a designer drug since around 2015.
Salvia divinorum is a plant species with transient psychoactive properties when its leaves, or extracts made from the leaves, are administered by smoking, chewing, or drinking. The leaves contain the potent compound salvinorin A and can induce a dissociative state and hallucinations.
JDTic is a selective, long-acting ("inactivating") antagonist of the κ-opioid receptor (KOR). JDTic is a 4-phenylpiperidine derivative, distantly related structurally to analgesics such as pethidine and ketobemidone, and more closely to the MOR antagonist alvimopan. In addition, it is structurally distinct from other KOR antagonists such as norbinaltorphimine. JDTic has been used to create crystal structures of KOR [ PDB: 4DJH, 6VI4].
Salvinorin B methoxymethyl ether is a semi-synthetic analogue of the natural product salvinorin A used in scientific research. It has a longer duration of action of around 2–3 hours, compared to less than 30 minutes for salvinorin A, and has increased affinity and potency at the κ-opioid receptor. It is prepared from salvinorin B. The crystal structure is almost superimposable with that of salvinorin A. Structures bound to the κ-opioid receptor have also been reported.
8-Carboxamidocyclazocine (8-CAC) is an opioid analgesic drug related to cyclazocine, discovered by medicinal chemist Mark P. Wentland and co-workers in Cogswell Laboratory at Rensselaer Polytechnic Institute. Similarly to cyclazocine, 8-CAC acts as an agonist at both the μ- and κ-opioid receptors, but has a much longer duration of action than cyclazocine, and does not have μ antagonist activity. Unexpectedly, it was discovered that the phenolic hydroxyl group of cyclazocine could be replaced by a carboxamido group with only slight loss of potency at opioid receptors, and this discovery has subsequently been used to develop many novel opioid derivatives where the phenolic hydroxy group has been replaced by either carboxamide or a variety of larger groups. Due to their strong κ-opioid agonist activity, these drugs are not suited for use as analgesics in humans, but have instead been researched as potential drugs for the treatment of cocaine addiction.
Conolidine is an indole alkaloid. Preliminary reports suggest that it could provide analgesic effects with few of the detrimental side-effects associated with opioids such as morphine, though at present it has only been evaluated in mouse models.
MN-25 (UR-12) is a drug invented by Bristol-Myers Squibb, that acts as a reasonably selective agonist of peripheral cannabinoid receptors. It has moderate affinity for CB2 receptors with a Ki of 11 nM, but 22x lower affinity for the psychoactive CB1 receptors with a Ki of 245 nM. The indole 2-methyl derivative has the ratio of affinities reversed however, with a Ki of 8 nM at CB1 and 29 nM at CB2, which contrasts with the usual trend of 2-methyl derivatives having increased selectivity for CB2 (cf. JWH-018 vs JWH-007, JWH-081 vs JWH-098).
Biphalin is a dimeric enkephalin endogenous peptide (Tyr-D-Ala-Gly-Phe-NH)2 composed of two tetrapeptides derived from enkephalins, connected 'tail-to-tail' by a hydrazide bridge. The presence of two distinct pharmacophores confers on biphalin a high affinity for both μ and δ opioid receptors (with an EC50 of about 1–5 nM for both μ and δ receptors), therefore it has analgesic activity. Biphalin presents a considerable antinociceptive profile. In fact, when administered intracerebroventricularly in mice, biphalin displays a potency almost 7-fold greater than that of the ultra-potent alkaloid agonist, etorphine and 7000-fold greater than morphine; biphalin and morphine were found to be equipotent after intraperitoneal administration. The extraordinary in vivo potency shown by this compound is coupled with low side-effects, in particular, to produce no dependency in chronic use. For these reasons, several efforts have been carried out in order to obtain more information about structure-activity relationship (SAR). Results clearly indicate that, at least for μ receptor binding, the presence of two pharmacophores is not necessary; Tyr1 is indispensable for analgesic activity, while replacing Phe at the position 4 and 4' with non-aromatic, but lipophilic amino acids does not greatly change the binding properties and in general 4,4' positions are found to be important to design biphalin analogues with increased potency and modified μ/δ selectivity. The hydrazide linker is not fundamental for activity or binding, and it can be conveniently substituted by different conformationally constrained cycloaliphatic diamine linkers.
Buprenorphine/samidorphan is a combination formulation of buprenorphine and samidorphan which is under development as an add on to antidepressants in treatment-resistant depression (TRD).
RB-64 is a semi-synthetic derivative of salvinorin A. It is an irreversible agonist, with a reactive thiocyanate group that forms a bond to the κ-opioid receptor (KOR), resulting in very high potency. It is functionally selective, activating G proteins more potently than β-arrestin-2. RB-64 has a bias factor of up to 96 and is analgesic with fewer of the side-effects associated with unbiased KOR agonists. The analgesia is long-lasting. Compared with unbiased agonists, RB-64 evokes considerably less receptor internalization.
BIM-018 is a synthetic cannabinoid that is the benzimidazole analog of JWH-018. It is presumed to be a potent agonist of the CB2 receptor and has been sold online as a designer drug.
Kurkinorin is a non-nitrogenous, extremely selective centrally acting μ-opioid receptor agonist derived from salvinorin A with no sedating or rewarding effects.
