RESEARCH MONOGRAPH · KDC-MN-248
Buspirone
Buspirone (BuSpar) is the first non-benzodiazepine anxiolytic, approved by the FDA in 1986. Mechanistically it is unrelated to any sedative class: it is a partial agonist at the serotonin 5-HT1A receptor, with no GABA-A activity. That means it does not produce sedation, dependence, or withdrawal, and it has no recreational potential. The trade-off is that it works slowly (effects build over 2 to 4 weeks) and does not produce the fast acute relief patients expect from a benzodiazepine, which has limited its uptake despite its safety advantages. It is FDA-approved for generalized anxiety disorder and is widely used as add-on for SSRI-treated depression where some additional anxiolysis is needed. The active metabolite 1-PP is an alpha-2 antagonist contributing to the noradrenergic tone. Not stocked by Kodiac. This monograph is provided for research and educational reference.
Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.
5-HT1A partial agonist anxiolytic
An azapirone 5-HT1A partial agonist; a non-benzodiazepine anxiolytic without dependence or sedation.
Abstract
Buspirone (8-[4-(4-pyrimidin-2-yl-1-piperazinyl)butyl]-8-azaspiro[4.5]decane-7,9-dione; CAS 36505-84-7; molecular formula C21H31N5O2; molecular weight 385.50) is an azapirone 5-HT1A partial agonist developed at Bristol-Myers Squibb and approved by the FDA in 1986 under the trade name BuSpar. The compound is the first clinically approved non-benzodiazepine anxiolytic, distinguished by mechanism (5-HT1A partial agonism rather than GABA-A potentiation), tolerance/dependence profile (none), and absence of sedation. 5-HT1A affinity is approximately 21 nM (intrinsic activity approximately 35 percent); secondary D2 antagonism (Ki approximately 100 nM) is of unclear clinical significance. The active metabolite 1-(2-pyrimidinyl)piperazine (1-PP) is an alpha-2 adrenergic antagonist contributing to noradrenergic effects. Onset of anxiolytic effect is delayed (2 to 4 weeks), reflecting the time course of 5-HT1A autoreceptor desensitization. Plasma half-life is 2 to 3 hours; metabolism is extensive via CYP3A4 with significant first-pass effect (oral bioavailability approximately 4 percent). Approved for generalized anxiety disorder. Used as the canonical 5-HT1A partial agonist in mechanism studies.
Mechanism of action
5-HT1A partial agonism (intrinsic activity ~35 percent); secondary D2 antagonism. No GABA-A activity. Active metabolite 1-PP is an alpha-2 antagonist.
Reported research dose ranges
Clinical 15 to 60 mg per oral administration daily, in divided doses. Rodent studies 1 to 30 mg/kg/day.
References
- Goa KL, Ward A. Buspirone. A preliminary review of its pharmacological properties and therapeutic efficacy as an anxiolytic. Drugs 1986.
- Eison MS, Temple DL. Buspirone: review of its pharmacology and current perspectives on its mechanism of action. Am J Med 1986.
- Loane C, Politis M. Buspirone: what is it all about? Brain Res 2012.
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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.