What is the information about Buspirone (Anxiolytic medication)?

From the Guidelines

Buspirone is a recommended medication for the treatment of anxiety disorders, particularly generalized anxiety disorder (GAD), due to its favorable side effect profile and lack of physical dependence or withdrawal symptoms, as noted in the guideline adaptation by the American Society of Clinical Oncology 1.

Key Characteristics of Buspirone

• Belongs to the class of drugs called azapirones
• Works by affecting certain neurotransmitters in the brain, particularly serotonin
• Exact mechanism differs from SSRIs

Dosage and Administration

• Typically prescribed at a starting dose of 5 mg taken three times daily
• Gradual increases up to 20-30 mg total daily dose divided into multiple administrations, with a maximum dose of 20 mg three times daily as suggested by the American Family Physician guideline 1
• Should be taken consistently, preferably with food to minimize stomach upset

Advantages and Considerations

• Doesn't cause sedation, physical dependence, or withdrawal symptoms, making it suitable for longer-term anxiety management
• Doesn't interact with alcohol the way other anti-anxiety medications do
• Takes 2-4 weeks to reach full effectiveness, unlike the immediate relief provided by benzodiazepines
• Common side effects include dizziness, headaches, nausea, and nervousness
• Shouldn't be stopped abruptly, and patients should inform their doctor about all other medications they're taking, as buspirone can interact with certain drugs, particularly MAOIs and some antifungal medications

Clinical Use

• Useful only in patients with mild to moderate agitation, as stated in the American Family Physician guideline 1
• May be considered as part of a comprehensive treatment plan for anxiety disorders, taking into account the patient's individual needs and medical history, as recommended by the American Society of Clinical Oncology 1

From the FDA Drug Label

The mechanism of action of buspirone is unknown. 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. 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. Buspirone hydrochloride tablets are rapidly absorbed in man and undergo extensive first-pass metabolism. Buspirone is metabolized primarily by oxidation, which in vitro has been shown to be mediated by cytochrome P450 3A4 (CYP3A4).

Buspirone is an antianxiety agent that is not chemically or pharmacologically related to the benzodiazepines, barbiturates, or other sedative/anxiolytic drugs 2.

• Mechanism of Action: The mechanism of action of buspirone is unknown, but it has a high affinity for serotonin (5-HT1A) receptors and moderate affinity for brain D2-dopamine receptors.
• Pharmacokinetics: Buspirone hydrochloride tablets are rapidly absorbed in man and undergo extensive first-pass metabolism. Buspirone is metabolized primarily by oxidation, which in vitro has been shown to be mediated by cytochrome P450 3A4 (CYP3A4) 2.
• Description: Buspirone hydrochloride tablets, USP are supplied as tablets for oral administration, contains 5 mg, 7.5 mg, 10 mg, 15 mg, or 30 mg of buspirone hydrochloride, USP (equivalent to 4.6 mg, 6.9 mg, 9.1 mg, 13.7 mg, and 27.4 mg of buspirone free base, respectively) 2.

From the Research

Mechanism of Action

• Buspirone is a partial agonist for the serotonin 5-HT(1A) receptors and has low affinity as an antagonist for the dopamine D(2) autoreceptors, with some evidence of a weak affinity to 5-HT(2) receptors 3.
• The underlying mechanism of action of buspirone is not clear, but it is thought that its main pharmacology is mediated via the 5-HT(1A) receptors 3.
• Buspirone's mechanism of action is extremely complex, and current investigations indicate that its main neuropharmacologic effects are mediated by the 5-HT1A receptors, with other neuroreceptor systems potentially involved 4.

Indications and Efficacy

• Buspirone is indicated in the treatment of generalized anxiety disorders, with efficacy comparable to benzodiazepines 4, 5.
• It may be useful in various other neurological and psychiatric disorders, such as attenuating side effects of Parkinson's disease therapy, ataxia, depression, social phobia, and behavior disturbances following brain injury, and those accompanying Alzheimer's disease, dementia, and attention deficit disorder 3.
• Buspirone has been shown to be effective in the long-term treatment of generalized anxiety disorder, with a significant reduction in anxiety symptoms and a low incidence of patient discontinuation due to side effects or insufficient improvement 6.

Safety and Tolerability

• Buspirone lacks anticonvulsant and muscle-relaxant properties and causes only minimal sedation 4.
• The frequency of adverse effects is low, with the most common effects being headaches, dizziness, nervousness, and lightheadedness 4.
• Buspirone is well tolerated for maintenance therapy, with a low incidence of patient discontinuation due to side effects or insufficient improvement 6.
• Prior benzodiazepine use may predict a reduced response to buspirone in patients diagnosed with generalized anxiety disorder, and initiation of buspirone therapy in these patients should be undertaken cautiously 7.

Pharmacokinetics

• Buspirone is rapidly absorbed after oral administration, with a mean bioavailability of 3.9% 4.
• The mean elimination half-life of buspirone is 2.1 hours, and it is mainly bound to albumin and alpha 1-acid glycoprotein 4.
• Buspirone is metabolized to an active metabolite, 1-(2-pyrimidinyl) piperazine (1-PP), with a mean elimination half-life of 6.1 hours 4.