Buspirone
Buspirone is a non-benzodiazepine anxiolytic used in adults for generalised anxiety disorder. It acts as a partial agonist at serotonin 5-HT1A receptors, with minimal sedation, no muscle relaxation and a low risk of dependence.
- Chemical formula
- C21H31N5O2
- CAS number
- 36505-84-7
- ATC code
- N05BE01
- Molecular weight
- 385.50 g/mol
- Drug class
- Azapirone anxiolytic
- Also known as
- MJ 9022, Buspirona
What is it?
Buspirone is an azapirone anxiolytic developed in the 1970s and approved for clinical use in the United States in 1986. Unlike benzodiazepines, it does not bind to GABA-A receptors and does not produce sedation, muscle relaxation or anticonvulsant effects. It is supplied as oral tablets at standard strengths and is dispensed only on prescription. According to international guidelines, buspirone is recommended as one of the maintenance options for chronic generalised anxiety.
Mechanism of action
Buspirone is a partial agonist at the serotonin 5-HT1A receptor and a weak antagonist at dopamine D2 receptors. By stimulating presynaptic 5-HT1A autoreceptors, it modulates serotonergic neurotransmission in regions involved in anxiety, including the dorsal raphe nucleus, hippocampus and amygdala. Clinical effects develop gradually over one to two weeks, in line with serotonergic adaptation, which distinguishes buspirone from rapidly acting benzodiazepines.
Pharmacokinetics
Buspirone is rapidly absorbed but undergoes extensive first-pass metabolism, with absolute bioavailability of about 4%. Peak plasma concentrations are reached within 60 to 90 minutes. Plasma protein binding is approximately 86%. The drug is metabolised in the liver mainly by CYP3A4 to several metabolites, including the moderately active 1-PP. The terminal half-life is approximately two to three hours. Hepatic impairment and CYP3A4 inhibitors significantly increase exposure.
Indications
Buspirone is approved in adults for the treatment of generalised anxiety disorder and for the short-term relief of anxiety symptoms. According to international guidelines, it is most useful in patients who require sustained anxiolytic effect without sedation or risk of dependence, including those with substance use history. It is not indicated for acute panic attacks, primary depression or severe psychiatric disorders without specialist supervision.
Safety profile
Buspirone is generally well tolerated. Common adverse effects include dizziness, nausea, headache, restlessness and gastrointestinal discomfort, usually mild. Sedation is uncommon. Buspirone does not impair psychomotor performance to the same degree as benzodiazepines. Serotonin syndrome has been reported in rare combinations with other serotonergic agents. According to the prescribing information, concurrent use with strong CYP3A4 inhibitors requires dose reduction, and concomitant use with monoamine oxidase inhibitors is contraindicated.
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Frequently asked questions
How quickly does buspirone work? ▾
Unlike benzodiazepines, buspirone does not produce immediate anxiolytic effects. Clinical improvement usually appears after one to two weeks of continuous treatment, with maximum effect after several weeks. According to the prescribing information, this profile suits chronic generalised anxiety disorder rather than the acute relief of panic attacks, where benzodiazepines or other approaches may be considered.
Does buspirone cause dependence? ▾
Buspirone has not been associated with significant tolerance, dependence or withdrawal symptoms in standard clinical use, and it does not produce euphoria. This is one of the main advantages over benzodiazepines, particularly in patients with previous substance use disorders. According to the prescribing information, abrupt discontinuation does not typically require a tapering schedule, although continuation should still be reassessed by the prescriber.
Can buspirone be combined with antidepressants? ▾
Yes, in many cases. Buspirone is sometimes added to selective serotonin reuptake inhibitors or serotonin-noradrenaline reuptake inhibitors as augmentation in generalised anxiety disorder or treatment-resistant depression. The combination requires medical supervision because of the theoretical risk of serotonin syndrome. According to the prescribing information, monoamine oxidase inhibitors and other strongly serotonergic agents are contraindicated.
Why is buspirone taken with or without food consistently? ▾
Food increases the bioavailability of buspirone by reducing first-pass metabolism. Although the absolute change is small, the prescribing information recommends taking the drug consistently with or without food in the same way each day, to keep plasma concentrations more predictable. Grapefruit juice should be avoided because it inhibits CYP3A4 and substantially raises buspirone exposure.
What are the main contraindications for buspirone? ▾
Buspirone is contraindicated in known hypersensitivity to the molecule and in concurrent use with monoamine oxidase inhibitors, including in the two weeks following discontinuation of an MAOI. Caution is required in severe hepatic or renal impairment and in patients receiving strong CYP3A4 inhibitors. According to the prescribing information, the medical history and current medication list must be reviewed by a clinician before any prescription.
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