In one clinical trial, buspirone was administered to healthy male volunteers at a dosage of 375 mg/day, and produced side effects including nausea, vomiting, dizziness, drowsiness, miosis, and gastric distress. In early clinical trials, buspirone was given at dosages even as high as 2,400 mg/day, with akathisia, tremor, and muscle rigidity observed. Deliberate overdoses with 250 mg and up to 300 mg buspirone have resulted in drowsiness in about 50% of individuals. One death has been reported in a co-ingestion of 450 mg buspirone with alprazolam, diltiazem, alcohol, cocaine. Interactions
Buspirone has been shown in vitro to be metabolized by the enzyme CYP3A4. This finding is consistent with the in vivo interactions observed between buspirone and these inhibitors or inducers of cytochrome P450 3A4 (CYP3A4), among others:
Itraconazole: Increased plasma level of buspirone
Rifampicin: Decreased plasma levels of buspirone
Nefazodone: Increased plasma levels of buspirone
Haloperidol: Increased plasma levels of buspirone
Carbamazepine: Decreased plasma levels of buspirone
Grapefruit: Significantly increases the plasma levels of buspirone. See grapefruit–drug interactions. Fluvoxamine: Moderately increase plasma levels of buspirone.Elevated blood pressure has been reported when buspirone has been administered to patients taking monoamine oxidase inhibitors (MAOIs). Pharmacology
Pharmacodynamics
Buspirone acts as an agonist of the serotonin 5-HT1A receptor with high affinity. It is a partial agonist of both presynaptic 5-HT1A receptors, which are inhibitory autoreceptors, and postsynaptic 5-HT1A receptors. It is thought that the main effects of buspirone are mediated via its interaction with the presynaptic 5-HT1A receptor, thus reducing the firing of serotonin-producing neurons.
History
Buspirone was first synthesized by a team at Mead Johnson in 1968 but was not patented until 1980. It was initially developed as an antipsychotic acting on the D2 receptor but was found to be ineffective in the treatment of psychosis; it was then used as an anxiolytic instead. In 1986, Bristol-Myers Squibb gained FDA approval for buspirone in the treatment of GAD. The patent expired in 2001, and buspirone is now available as a generic drug. Society and culture
Generic names
Buspirone is the INN, BAN, DCF, and DCIT of buspirone, while buspirone hydrochloride is its USAN, BANM, and JAN. Brand name
Buspirone was primarily sold under the brand name Buspar. Buspar is currently listed as discontinued by the US Federal Drug Administration. In 2010,  in response to a citizen petition, the US FDA determined that Buspar was not withdrawn from sale for reasons of safety or effectiveness. 2019 shortage
Due to interrupted production at a Mylan Pharmaceuticals plant in Morgantown, West Virginia, the United States experienced a shortage of buspirone in 2019. Research
Some tentative research supports other uses such as the treatment of depression and behavioral problems following brain damage. References
External links
 Media related to Buspirone at Wikimedia Commons
"Buspirone". Drug Information Portal. U.S. National Library of Medicine.