Medication primarily used to treat anxiety disorders, particularly generalized anxiety disorder.



A serotonin 5-HT1A receptor agonist.



Sold under the brand name Buspar.



Benefits support its short term use.



Taken by mouth, and it may take up to four weeks to have an effect.



Pregnancy category AU: B1



Bioavailability 3.9%.



Protein binding 86–95%.



Metabolism by Liver via CYP3A4



Metabolites – multiple



Elimination half-life 2.5 hours






Urine: 29–63%



Feces: 18–38%






Common side effects:  include nausea, headaches, dizziness, and difficulty concentrating.



Serious side effects may include hallucinations, serotonin syndrome, and seizures.



Its use in pregnancy appears to be safe.



Use during breastfeeding is not recommended.



It is used for the short-term treatment of anxiety disorders or symptoms of anxiety.



Generally less used  than selective serotonin reuptake inhibitors (SSRIs).



Does not have an immediate anxiolytic effect.



It has a delayed onset of action.



Clinical effectiveness may require 2–4 weeks.



It has similar  effective in the treatment of generalized anxiety disorder to benzodiazepines including diazepam, alprazolam, lorazepam, and clorazepate.



There is limited evidence that it may be useful in the treatment of social phobia as an adjunct to selective serotonin reuptake inhibitors (SSRIs), in the treatment of hypoactive sexual desire disorder (HSDD) in women.



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



Useful in treating bruxism on SSRI/SNRI-induced jaw clenching.









Metabolic acidosis



MAO inhibitors



Severely compromised liver and/or kidney function



Side effects: dizziness, headaches, nausea, nervousness, and paresthesia.



It  is relatively well tolerated, and is not associated with sedation, cognitive and psychomotor impairment, muscle relaxation, physical dependence, or anticonvulsant effects.



It  does not produce euphoria and is not associated with drug of abuse.



Metabolized by the enzyme CYP3A4.



Drug interactions observed between buspirone and these inhibitors or inducers of cytochrome P450 3A4: 



Itraconazole: Increased plasma level of buspirone



Rifampicin: Decreased plasma levels of buspirone



Haloperidol: Increased plasma levels of haloperidol



Carbamazepine: Decreased plasma levels of buspirone



Grapefruit: Significantly increases the plasma levels of buspirone.



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).



It acts as an agonist of the serotonin 5-HT1A receptor and has high affinity.



It is a partial agonist of both presynaptic 5-HT1A receptors, which are inhibitory autoreceptors, and postsynaptic 5-HT1A receptors.



Its main effects are mediated via its interaction with the presynaptic 5-HT1A receptor, thus reducing the firing of serotonin-producing neurons.



It also has lower affinities for the serotonin 5-HT2A, 5-HT2B, 5-HT2C, 5-HT6, and 5-HT7 receptors.



It binds to serotonin receptors, and  is an antagonist of the dopamine D2 receptor with weak affinity.



A major metabolite of buspirone, 1-(2-pyrimidinyl)piperazine (1-PP), occurs at higher circulating levels than buspirone, and  may play an important role in the antidepressant effects of buspirone.



Unlike benzodiazepines, it does not interact with the GABAA receptor complex.



Buspirone has a low oral bioavailability of 3.9% relative to intravenous injection due to extensive first-pass metabolism.



Peak plasma levels following ingestion is 0.9 to 1.5 hours.



Has an elimination half-life of 2.8 hours, 


with a mean terminal half-life ranged between 2 and 11 hours.



It is metabolized primarily by CYP3A4, and prominent drug interactions with inhibitors and inducers of this enzyme occur.



Major metabolites of buspirone includes 6-Hydroxybuspirone 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.



It is likely to play an important role in the therapeutic effects of buspirone.



Buspar (buspirone) 10-mg tablets.





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