Azapirones are a class of drugs used as anxiolytics, antidepressants, and antipsychotics. They are commonly used as add-ons to other antidepressants, such as selective serotonin reuptake inhibitors (SSRIs). Medical uses Azapirones have shown benefit in general anxiety and augmenting SSRIs in social anxiety and depression. Evidence is not clear for panic disorder and functional gastrointestinal disorders. Tandospirone has also been used to augment antipsychotics in Japan as it improves cognitive and negative symptoms of schizophrenia. Buspirone is being investigated for this purpose as well. Gepirone was abandoned after FDA rejection. Side effects Side effects of azapirones may include dizziness, headaches, restlessness, nausea, and diarrhea. Azapirones have more tolerable adverse effects than many other available anxiolytics, such as benzodiazepines or SSRIs. Unlike benzodiazepines, azapirones lack abuse potential and are not addictive, do not cause cognitive/memory impairment or sedation, and do not appear to induce appreciable tolerance or physical dependence. However, azapirones are considered less effective with slow onset in controlling symptoms. List of azapirones The azapirones include the following agents: Anxiolytics Alnespirone (S-20,499) Binospirone (MDL-73,005) BMY-7,378 Buspirone (Buspar) Enilospirone (CERM-3,726) Eptapirone (F-11,440) Gepirone (Ariza, Variza) Ipsapirone (TVX-Q-7,821) MJ-7378 [21103-03-7] Revospirone (BAY-VQ-7,813) Tandospirone (Sediel) Zalospirone (WY-47,846) Antipsychotics Perospirone (Lullan) Tiospirone (BMY-13,859) Umespirone (KC-9,172) other SNAP-8719 [255893-38-0] Chemistry Buspirone was originally classified as an azaspirodecanedione, shortened to azapirone or azaspirone due to the fact that its chemical structure contained this moiety, and other drugs with similar structures were labeled as such as well. However, despite all being called azapirones, not all of them actually contain the azapirodecanedione component, and most in fact do not or contain a variation of it. Additionally, many azapirones are also pyrimidinylpiperazines, though again this does not apply to them all. Drugs classed as azapirones can be identified by their -spirone or -pirone suffix. Pharmacology Pharmacodynamics On a pharmacological level, azapirones varyingly possess activity at the following receptors: 5-HT1A receptor (as partial or full agonists) 5-HT2A receptor (as inverse agonists) D2 receptor (as antagonists or partial agonists) α1-adrenergic receptor (as antagonists) α2-adrenergic receptor (as antagonists) Actions at D4, 5-HT2C, 5-HT7, and sigma receptors have also been shown for some azapirones. While some of the listed properties such as 5-HT2A and D2 blockade may be useful in certain indications such as in the treatment of schizophrenia (as with perospirone and tiospirone), all of them except 5-HT1A agonism are generally undesirable in anxiolytics and only contribute to side effects. As a