Английская Википедия:Buspirone

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Buspirone, sold under the brand name Buspar, among others, is an anxiolytic, a medication primarily used to treat anxiety disorders, particularly generalized anxiety disorder. It is a serotonin 5-HT_1A receptor agonist, increasing action at serotonin receptors in the brain. It is taken orally, and takes two to six weeks to be fully effective.

Common side effects of buspirone include nausea, headaches, dizziness, and difficulty concentrating. Serious side effects may include movement disorders, serotonin syndrome, and seizures. Its use in pregnancy appears to be safe but has not been well studied, and use during breastfeeding has not been well studied.

Buspirone was developed in 1968 and approved for medical use in the United States in 1986. It is available as a generic medication. In 2021, it was the 53rd most-commonly prescribed medication in the United States, with more than 12Шаблон:Nbspmillion prescriptions. Шаблон:TOC limit

Medical uses

Anxiety

Buspirone is used for the short-term and long-term treatment of anxiety disorders or symptoms of anxiety. It is generally preferred over benzodiazepines because it does not activate the receptors that make drugs like alprazolam addictive.

Buspirone has no immediate anxiolytic effects, and hence has a delayed onset of action; its full clinical effectiveness may require 2–4 weeks to manifest itself. The drug has been shown to be similarly effective in the treatment of generalized anxiety disorder (GAD) to benzodiazepines including diazepam, alprazolam, lorazepam, and clorazepate. Buspirone is not known to be effective in the treatment of other anxiety disorders besides GAD, although there is some limited evidence that it may be useful in the treatment of social phobia as an adjunct to selective serotonin reuptake inhibitors (SSRIs).

Other uses

Sexual dysfunction

There is some evidence that buspirone on its own may be useful in the treatment of hypoactive sexual desire disorder (HSDD) in women. Buspirone may also be effective in treating antidepressant-induced sexual dysfunction.

Miscellaneous

Buspirone is not effective as a treatment for benzodiazepine withdrawal, barbiturate withdrawal, or alcohol withdrawal/delirium tremens.

SSRI and SNRI antidepressants such as paroxetine and venlafaxine may cause jaw pain/jaw spasm reversible syndrome (although it is not common), and buspirone appears to be successful in treating bruxism on SSRI/SNRI-induced jaw clenching.

Contraindications

Buspirone has these contraindications:

• Hypersensitivity to buspirone
• Metabolic acidosis, as in diabetes
• Should not be used with MAO inhibitors
• Severely compromised liver and/or kidney function

Side effects

Known side effects associated with buspirone include dizziness, headaches, nausea, tinnitus, and paresthesia. Buspirone is relatively well tolerated, and is not associated with sedation, cognitive and psychomotor impairment, muscle relaxation, physical dependence, or anticonvulsant effects. In addition, buspirone does not produce euphoria and is not a drug of abuse. Dyskinesia, akathisia, myoclonus, parkinsonism, and dystonia were reported associated with buspirone. It is unclear if there is a risk of tardive dyskinesia or other movement disorders with buspirone.

Overdose

Buspirone appears to be relatively benign in cases of single-drug overdose, although no definitive data on this subject appear to be available. 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

Site	Ki (nM)	Action	Species	Ref
5-HT1A	3.98–214 21 (median)	Agonist	Human
5-HT1B	>100,000	Agonist ?	Rat
5-HT1D	22,000–42,700	Agonist ?	Human
5-HT2C	1,100–6,026	Antagonist ?	Rat/pig
5-HT7	375–381 840	Antagonist ?	Rat Human
α1	1,000	Antagonist	Rat
α2	6,000	Antagonist	Rat
α2A	7.3 (Шаблон:Abbrlink)	Antagonist	Human
β	8,800	Antagonist	Rat
D1	33,000	Antagonist	Rat
D2	484 240	Antagonist	Human Rat
D3	98	Antagonist	Human
D4	29	Antagonist	Human
Шаблон:Abbrlink	38,000	?	Rat
[[GABAA receptor#Benzodiazepine site|GABAA (Шаблон:Abbr)]]	>100,000	-	Rat
Values are Ki (nM). The smaller the value, the more strongly the drug binds to the site.

Buspirone acts as an agonist of the serotonin 5-HT_1A receptor with high affinity. It is a partial agonist of both presynaptic 5-HT_1A receptors, which are inhibitory autoreceptors, and postsynaptic 5-HT_1A receptors. It is thought that the main effects of buspirone are mediated via its interaction with the presynaptic 5-HT_1A receptor, thus reducing the firing of serotonin-producing neurons. Buspirone also seems to have lower affinities for the serotonin 5-HT_2A, 5-HT_2B, 5-HT_2C, 5-HT₆, 5-HT₇ receptors probably as an antagonist.

In addition to binding to serotonin receptors, buspirone is an antagonist of the dopamine D₂ receptor with weak affinity. It preferentially blocks inhibitory presynaptic D₂ autoreceptors, and antagonizes postsynaptic D₂ receptors only at higher doses. In accordance, buspirone has been found to increase dopaminergic neurotransmission in the nigrostriatal pathway at low doses, whereas at higher doses, postsynaptic D₂ receptors are blocked and antidopaminergic effects such as hypoactivity and reduced stereotypy, though notably not catalepsy, are observed in animals. Buspirone has also been found to bind with much higher affinity to the dopamine D₃ and D₄ receptors, where it is similarly an antagonist.

A major metabolite of buspirone, 1-(2-pyrimidinyl)piperazine (1-PP), occurs at higher circulating levels than buspirone itself and is known to act as a potent α₂-adrenergic receptor antagonist. This metabolite may be responsible for the increased noradrenergic and dopaminergic activity observed with buspirone in animals. In addition, 1-PP may play an important role in the antidepressant effects of buspirone. Buspirone also has very weak and probably clinically unimportant affinity for the α₁-adrenergic receptor. However, buspirone has been reported to have shown "significant and selective intrinsic efficacy" at the α₁-adrenergic receptor expressed in a "tissue- and species-dependent manner".

Unlike benzodiazepines, buspirone does not interact with the GABA_A receptor complex.

Pharmacokinetics

Buspirone has a low oral bioavailability of 3.9% relative to intravenous injection due to extensive first-pass metabolism. The time to peak plasma levels following ingestion is 0.9 to 1.5 hours. It is reported to have an elimination half-life of 2.8 hours, although a review of 14 studies found that the mean terminal half-life ranged between 2 and 11 hours, and one study even reported a terminal half-life of 33 hours. Buspirone is metabolized primarily by CYP3A4, and prominent drug interactions with inhibitors and inducers of this enzyme have been observed. Major metabolites of buspirone include 5-hydroxybuspirone, 6-hydroxybuspirone, 8-hydroxybuspirone, and 1-PP. 6-Hydroxybuspirone has been identified as the predominant hepatic metabolite of buspirone, with plasma levels that are 40-fold greater than those of buspirone after oral administration of buspirone to humans. The metabolite is a high-affinity partial agonist of the 5-HT_1A receptor (K_i=25 nM) similarly to buspirone, and has demonstrated occupancy of the 5-HT_1A receptor in vivo. As such, it is likely to play an important role in the therapeutic effects of buspirone. 1-PP has also been found to circulate at higher levels than those of buspirone itself and may similarly play a significant role in the clinical effects of buspirone.

Файл:Buspirone metabolism.png

Phase I Metabolism of buspirone in humans

Chemistry

Buspirone is a member of the azapirone chemical class, and consists of azaspirodecanedione and pyrimidinylpiperazine components linked together by a butyl chain.

Analogues

Structural analogues of buspirone include other azapirones like gepirone, ipsapirone, perospirone, and tandospirone.

A number of analogues are recorded.

Synthesis

A number of more modern methods of synthesis have also been reported (list not exhaustive):

Файл:Buspirone-synthesis.svg

Synthesis: Patents: Polymorphic crystalline form:

Alkylation of 1-(2-pyrimidyl)piperazine [20980-22-7] (1) with 3-chloro-1-cyanopropane (4-chlorobutyronitrile) [628-20-6] (2) gives [33386-14-0] (3). the reduction of the nitrile group is performed either by catalytic hydrogenation or with LAH giving [33386-20-8] (4). The primary amine is then reacted with 3,3-tetramethyleneglutaric anhydride [5662-95-3] (5) in order to yield Шаблон:Highlight (6).

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

Файл:Buspar.jpg

Buspar (buspirone) 10-mg tablets

Generic names

Buspirone is the Шаблон:Abbrlink, Шаблон:Abbrlink, Шаблон:Abbrlink, and Шаблон:Abbrlink of buspirone, while buspirone hydrochloride is its Шаблон:Abbrlink, Шаблон:Abbrlink, and Шаблон:Abbrlink.

Brand names

Buspirone was primarily sold under the brand name Buspar. Buspar is currently listed as discontinued by the US Food and 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

Шаблон:Anchor Due to interrupted production at a Mylan Pharmaceuticals plant in Morgantown, West Virginia, the United States experienced a shortage of buspirone in 2019.

External links

• Шаблон:Commons category-inline