PNU-22394 is a drug which acts as an agonist at serotonin

Serotonin

Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...

 5-HT₂ receptor

Receptor (biochemistry)

In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...

s, with strongest binding affinity for 5-HT_2A

5-HT2A receptor

The mammalian 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor . This is the main excitatory receptor subtype among the GPCRs for serotonin , although 5-HT2A may also have an inhibitory effect on certain areas such...

 and 5-HT_2C

5-HT2C receptor

The 5-HT2C receptor is a subtype of 5-HT receptor that binds the endogenous neurotransmitter serotonin . It is a G protein-coupled receptor that is coupled to Gq/G11 and mediates excitatory neurotransmission. HTR2C denotes the human gene encoding for the receptor, that in humans is located at the...

 and slightly weaker at 5-HT_2B

5-HT2B receptor

5-hydroxytryptamine receptor 2B, also known as HTR2B, is a 5-HT2 receptor, but also denotes the human gene encoding it.-Function:...

, although it is only a full agonist at 5-HT_2C, but partial agonist at 5-HT_2A and 5-HT_2B. It has anorectic

Anorectic

An anorectic or anorexic , also known as anorexigenic or appetite suppressant, is a dietary supplement and/or drug which reduces appetite, food consumption, and as a result, causes weight loss to occur.-List of anorectics:Numerous pharmaceutical compounds are marketed as appetite suppressants.The...

effects in both animal studies and human trials, although it has never been developed for medical use.