N-Methyl-DL-Aspartic Acid (NMDLA) represents a racemic mixture of D and L enantiomers (NMDA; NMLA). Each enantiomer has different biological activities and different natural tissue/species abundances. Therefore, each enantiomer should be considered separately. NMDA is a widely studied neurotoxin which is an agonist of the NMDA receptor and induces brain legions. NMDA is not normally found in tissues, while NMLA can be found naturally in some bivalves.

(S)-SKF-83959 (MCL 201) is enantiomer of D1 receptor agonist SKF-83959. (S)-SKF-83959 is reported to be a functionally selective dopamine D1 receptor ligand with much lower affinity to dopamine D2, D3 and D5 receptors. (R)-SKF-83959 like SKF-83959, produced dose related effects on overt behavior (eye blinking) and schedule-controlled performance in squirrel monkeys. (R)-SKF-83959 increases in eye blinking and decreases in rates of fixed-ratio responding. In contrast to the effects of its S-(-) enantiomer, was relatively devoid of behavioral activity up to doses that were approximately 10-fold greater than (R)-SKF-83959.

SKF83959 is a benzodiazepine derivative which acts as an agonist of D1 receptor. Activation of D1 receptors by SKF83959 fails to stimulate adenylyl cyclase and inhibits the stimulation of adenylyl cyclase induced by dopamine but stimulates phosphatidylinositol 4,5-biphosphate hydrolysis in membranes of frontal cortex. SKF83959 was identified as a specific agonist for the heteromer D1/D2 complex. SKF83959 elicit anti-parkinsonism effects in monkeys and rodents. In lower concentrations, SKF83959 inhibits serotonin, norepinephrine and dopamine transporters and is an allosteric regulator of sigma 1 receptor. The compound has demonstrated activity in a preclinical model of depression.

UR-144 is a potent synthetic cannabinoid designed by Abbott Laboratories as a CB2 selective agonist for pain management and other indications. UR-144 preferentially binds the peripheral CB2 receptor (Ki = 1.8 nM) over the central CB1 receptor (Ki = 150 nM). Pre-clinical studies of nociceptive and neuropathic pain have shown that CB2-selective ligands are analgesics without causing the adverse side effects linked with CB1 receptor activation. However, UR-144 has no therapeutic application. According to the FDA (US Food and Drug Administration) there are currently no approved or on-going drug applications for the medical use of UR-144.

UR-144 N(4-hydroxypentyl) is a potent synthetic cannabinoid designed by Abbott Laboratories as a CB2 selective agonist for pain management. UR-144 N(4-hydroxypentyl) is a metabolite of another CB2-selective cannabinoid UR-144. Pre-clinical studies of nociceptive and neuropathic pain have shown that CB2-selective ligands are analgesics without causing the adverse side effects linked with CB1 receptor activation. However, nor UR-144 nor UR-144 N(4-hydroxypentyl) has no therapeutic application.

UR-144 N-5-Hydroxypentyl is a potent synthetic cannabinoid designed by Abbott Laboratories as a CB2 selective agonist for pain management. UR-144 N-5-Hydroxypentyl is a metabolite of another CB2-selective cannabinoid UR-144. Pre-clinical studies of nociceptive and neuropathic pain have shown that CB2-selective ligands are analgesics without causing the adverse side effects linked with CB1 receptor activation. However, nor UR-144 nor UR-144 N-5-Hydroxypentyl has no therapeutic application.