What are the potential side effects of Buspar (buspirone) in adults with a history of anxiety disorders, particularly in the elderly or those with impaired renal or hepatic function?

Side Effects of Buspar (Buspirone)

Buspirone is generally well-tolerated with a favorable safety profile compared to benzodiazepines, with the most common side effects being headache, dizziness, nervousness, and nausea, and notably lacks the risks of dependence, withdrawal, cognitive impairment, or sedation associated with benzodiazepines. 1, 2

Common Side Effects

The most frequently reported adverse effects include:

• Neurological symptoms: Headache, dizziness, nervousness, lightheadedness, and drowsiness are the most common complaints 1, 2
• Gastrointestinal effects: Nausea is particularly notable, especially at higher doses, along with dry mouth, diarrhea, and abdominal discomfort 1, 3
• Other effects: Sweating (diaphoresis), tremor, insomnia, vivid dreams, and fatigue may occur 1

Most adverse effects emerge within the first few weeks of treatment and are generally mild 1. In clinical trials, buspirone-treated patients reported significantly more nausea, dizziness, somnolence, and sweating compared to placebo 3.

Serious but Rare Adverse Effects

While uncommon, clinicians must monitor for potentially serious reactions:

• Serotonin syndrome: Can occur, particularly when combined with other serotonergic agents 4
• Neuroleptic malignant syndrome: Rare but serious reaction requiring immediate discontinuation 4
• Abnormal bleeding: Has been reported with buspirone use 1
• Seizures: Rare occurrence documented in FDA labeling 1

Special Population Considerations

Elderly Patients

Buspirone is particularly well-suited for elderly patients with anxiety 5. In a controlled trial of patients over 65 years receiving multiple concomitant medications for chronic conditions, buspirone at a mean dose of 18 mg/day was well tolerated with only mild adverse experiences 5. The safety and efficacy profiles in 605 elderly patients (mean age 70.8 years) were similar to younger populations 1.

Hepatic Impairment

Buspirone is contraindicated in severe hepatic impairment 1. Pharmacokinetic studies demonstrate that steady-state AUC increases 13-fold in patients with hepatic impairment compared to healthy subjects, with a lengthened half-life 1. Administration to patients with severe hepatic impairment cannot be recommended 1.

Renal Impairment

Buspirone should be used with extreme caution in severe renal impairment 1. In patients with creatinine clearance of 10-70 mL/min/1.73 m², steady-state AUC increased 4-fold compared to healthy subjects 1. The drug is excreted by the kidneys, and administration to patients with severe renal impairment cannot be recommended 1.

Key Safety Advantages

Buspirone has several critical safety advantages over benzodiazepines:

• No dependence or withdrawal: Abuse, dependence, and withdrawal symptoms have not been reported 2, 6
• No cognitive impairment: Does not cause the cognitive dysfunction associated with benzodiazepines 7, 2
• No psychomotor impairment: When combined with alcohol or given alone, psychomotor impairment was not detected 2
• No tolerance development: Unlike benzodiazepines, tolerance does not occur with chronic use 7
• Safer in overdose: Greater margin of safety compared to benzodiazepines, though deaths have been reported with very large ingestions 1

Important Drug Interactions and Precautions

• CYP3A4 interactions: Buspirone is metabolized primarily by CYP3A4, requiring dose adjustments with strong inhibitors or inducers 1
• Protein binding displacement: May displace digoxin from protein binding sites, though clinical significance is unknown 1
• Laboratory interference: Must be discontinued at least 48 hours before urine collection for catecholamines, as it interferes with metanephrine/catecholamine assays and can cause false-positive results for pheochromocytoma 1

Clinical Context

The overall incidence of adverse effects with buspirone is low and comparable to placebo in many studies 2, 5. In elderly patients receiving concomitant medications, mild adverse experiences were reported by five buspirone-treated patients versus nine placebo-treated patients 5. This favorable tolerability profile, combined with lack of dependence risk, makes buspirone particularly appropriate for chronic anxiety management and in elderly populations where benzodiazepines carry increased risks 4, 6.