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Active ingredient: Buspirone - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Anti-anxiety Agents
  • Serotonin Agonists
  • Anxiolytics sedatives and hypnotics

Dosage Forms

  • Tablet (5 mg, 10 mg)

Brands / Synonyms

Ansial; Ansiced; Anxiron; Axoren; Bespar; Buspar; Buspimen; Buspinol; Buspirona [INN-Spanish]; Buspirone; Buspirone HCL; Buspironum [INN-Latin]; Buspisal; Censpar; Lucelan; Narol; Travin

Indications

For the management of anxiety disorders or the short-term relief of the symptoms of anxiety, and also as an augmention of SSRI-treatment against depression.

Pharmacology

Buspirone is used in the treatment of generalized anxiety where it has advantages over other antianxiety drugs because it does not cause sedation (drowsiness) and does not cause tolerance or physical dependence. Buspirone differs from typical benzodiazepine anxiolytics in that it does not exert anticonvulsant or muscle relaxant effects. It also lacks the prominent sedative effect that is associated with more typical anxiolytics. in vitro preclinical studies have shown that buspirone has a high affinity for serotonin (5-HT1A) receptors. Buspirone has no significant affinity for benzodiazepine receptors and does not affect GABA binding in vitro or in vivo when tested in preclinical models. Buspirone has moderate affinity for brain D2-dopamine receptors. Some studies do suggest that buspirone may have indirect effects on other neurotransmitter systems.

Mechanism of Action

Buspirone binds to 5-HT type 1A serotonin receptors on presynaptic neurons in the dorsal raphe and on postsynaptic neurons in the hippocampus, thus inhibiting the firing rate of 5-HT-containing neurons in the dorsal raphe. Buspirone also binds at dopamine type 2 (DA2) receptors, blocking presynaptic dopamine receptors. Buspirone increases firing in the locus ceruleus, an area of brain where norepinephrine cell bodies are found in high concentration. The net result of buspirone actions is that serotonergic activity is suppressed while noradrenergic and dopaminergic cell firing is enhanced.

Absorption

Rapidly absorbed in man. Bioavailability is low and variable (approximately 5%) due to extensive first pass metabolism.

Toxicity

Oral, rat LD50 = 136 mg/kg. Symptoms of overdose include dizziness, drowsiness, nausea or vomiting, severe stomach upset, and unusually small pupils.

Biotrnasformation / Drug Metabolism

Metabolized hepatically, primarily by oxidation by cytochrome P450 3A4 producing several hydroxylated derivatives and a pharmacologically active metabolite, 1-pyrimidinylpiperazine (1-PP)

Contraindications

Buspirone HCl is contraindicated in patients hypersensitive to buspirone hydrochloride.

Drug Interactions

It is recommended that buspirone hydrochloride not be used concomitantly with MAO inhibitors Because the effects of concomitant administration of buspirone HCl with most other psychotropic drugs have not been studied, the concomitant use of buspirone HCl with other CNS-active drugs should be approached with caution.

There is one report suggesting that the concomitant use of trazodone hydrochloride (Desyrel) and buspirone HCl may have caused 3- to 6-fold elevations on SGPT (ALT) in a few patients. In a similar study, attempting to replicate this finding, no interactive effect on hepatic transaminases was identified.

In a study in normal volunteers, concomitant administration of buspirone HCl and haloperidol resulted in increased serum haloperidol concentrations. The clinical significance of this finding is not clear.

In vitro, buspirone does not displace tightly bound drugs like phenytoin, propranolol, and warfarin from serum proteins. However, there has been one report of prolonged prothrombin time when buspirone was added to the regimen of a patient treated with warfarin. The patient was also chronically receiving phenytoin, phenobarbital, digoxin, and levothyroxine sodium. In vitro, buspirone may displace less firmly bound drugs like digoxin. The clinical significance of this property is unknown.

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