BGC 20761 is an orally active, tryptamine analogue that is being developed by BTG as a procognitive antipsychotic for the treatment of schizophrenia. Preclinical development is underway in the US. This serotonin6 and serotonin2A receptor antagonist has nootropic properties with a balance of serotonergic and dopaminergic antagonist activity; BGC 20761 has moderate to low affinity for dopamine2, serotonin2C, histamine1, muscarinic M1-5, and α1 adrenergic receptors, indicating a potentially low propensity to cause serious adverse events.

2,5-Dimethoxy-4-trifluoromethylamphetamine (DOTFM) is the alpha-methylated analogue of 2C-TFM, a psychedelic drug of the phenethylamine and amphetamine chemical classes. 2,5-Dimethoxy-4-trifluoromethylamphetamine acts as an nanomolar agonist at the 5HT2A and 5HT2C receptors and possess hallucinogenic effects in humans.

SB-228357 was originally developed by scientists at Smith Kline Beecham (now merged with Glaxo Welcome to form GlaxoSmithKline). SB-228357 was identified as an antagonist of the serotonin receptors 5-HT2a/b/c with the highest affinity exhibited towards the 5-HT2C receptor. SB-228357 was identified for preclinical development as a treatment for depression, anxiety, and cataplexy but has not progressed beyond animal trials.

P-88-8991, (-)- is a metabolite of Iloperidone. It has functional affinity for noradrenergic, dopaminergic and serotoninergic receptors. Humans produce only one enantiomer stereospecifically following administration of Iloperidone. Preclinical studies revealed that P-88-8991, (-)- might be useful for the treatment of psychotic disorders such as schizophrenia and bipolar disorders.

P-88-8991, (+)- is a metabolite of Iloperidone. It has functional affinity for noradrenergic, dopaminergic and serotoninergic receptors. Humans produce only one enantiomer stereospecifically following administration of Iloperidone. Preclinical studies revealed that P-88-8991, (+)- might be useful for the treatment of psychotic disorders such as schizophrenia and bipolar disorders.

The selective serotonin reuptake inhibitor fluoxetine consists of equal amounts of R and S stereoisomers (antidepressant Prozac (racemic fluoxetine). Binding to the transporter confirmed selectivity of R- and S-fluoxetine for the 5-HT transporter versus the dopamine (DA) and norepinephrine (NE) human transporters. In addition, receptor binding studies demonstrated significant affinity of R-fluoxetine, but not S-fluoxetine, for human 5-HT(2A) and 5-HT(2C) receptor subtypes. R-fluoxetine acts as an antagonist at 5-HT(2A) and 5-HT(2C) receptors. The attempt to develop a single-enantiomer formulation of fluoxetine for the treatment of depression was unsuccessful. Eli Lilly has terminated its licensing and development agreement with Marlborough, Mass.-based Sepracor for (R)-fluoxetine, the single-isomer version of Lilly's antidepressant Prozac.R-enantiomer of fluoxetine, at its highest administered dose, led to statistically significant prolongation of cardiac repolarization in phase II studies; the studies were subsequently stopped.