Buspirone (Buspar®) vs Clonazepam (Klonopin®)

Based on "Essential Psychopharmacology"
written by Stephen M. Stahl, MD, PhD

Key differences between Buspirone and Clonazepam

  • Buspirone is an anxiolytic with a unique structure and pharmacology.
  • Buspirone alleviates anxiety without causing sedation or functional impairment.
  • Buspirone is NOT a controlled substance and does not promote abuse or physical dependence.
  • In contrast to clonazepam, buspirone lacks anticonvulsant and muscle relaxant properties.
  • The onset of anxiolytic effect is much more pronounced and rapid with clonazepam. Buspirone is ineffective when taken irregularly.
  • Buspirone is ineffective for occasional use and is useless for acute situational anxiety or insomnia.
  • It may take 1-2 weeks for beneficial antianxiety effects become noticeable.


Buspirone Clonazepam
• Buspar®
• Klonopin®
Drug class
• Azapirone (azaspirodecanedione) derivative, structurally unrelated to benzodiazepines • Benzodiazepine, long acting
Legal status
• Rx only • Rx only
Schedule IV
Controlled substance
Dose formulations
• Oral tablets • Oral tablets
• Oral disintegrating wafers
FDA-approved indications
• Generalized Anxiety Disorder (GAD)
• Short-term relief of anxiety symptoms
• Panic disorder
• Lennox-Gastaut syndrome
• Akinetic seizure
• Myoclonic seizure
• Acute mania
• Acute psychosis
"Off-label" uses
• Depression4, mainly as augmenting agent to antidepressants
• Smoking cessation3
• Behavioural disturbances (agitation, aggression)
• Insomnia5
• Anxiety disorders
Therapeutic actions
• Delayed anxiolytic effect, useful mainly for GAD
• Buspirone lacks an immediate anti-anxiety effects.
• Rapid anxiolytic effect, works for a wide range of anxiety disorders
• Anticonvulsant
• Muscle-relaxant
• Hypnotic (sleep inducing)
• 2-3 hours • 30-40 hours
Oral bioavailability
• 5% • 90%
• History of sensitivity to buspirone • History of sensitivity to benzodiazepines
• Acute narrow angle glaucoma
• Significant liver disease
Side effects
• Dizziness
• Nausea
• Drowsiness
• Headache

• Buspirone does NOT impair cognitive performance, memory, or driving skills
• NO withdrawal symptoms after buspirone discontinuation
• Sedation
• Performance impairment
• Memory impairment
• Dizziness
• Fatigue
• Physical dependence
• Potentiates effects of alcohol and CNS
• Withdrawal symptoms after clonazepam discontinuation
Pregnancy category
• B D
Onset of therapeutic effect
• After 4-6 weeks
• Rapid onset of antianxiety action, within 1-5 min.

Further reading


  • 1. Prescribing Information for Buspar® (Buspirone)
  • 2. Prescribing Information for Klonopin® (Clonazepam)
  • 3. Farid P, Abate MA. Buspirone use for smoking cessation. Ann Pharmacother. 1998 Dec;32(12):1362-4.
  • 4. Rickels K, Amsterdam JD, Clary C, Puzzuoli G, Schweizer E. Buspirone in major depression: a controlled study. J Clin Psychiatry. 1991 Jan;52(1):34-8. PubMed
  • 5. Minkel J, Krystal AD. Optimizing the Pharmacologic Treatment of Insomnia: Current Status and Future Horizons. Sleep Med Clin. 2013 Sep 1;8(3):333-350. PubMed

Published: December 20, 2018
Last reviewed: December 20, 2018


Interesting facts
  • Buspirone may have a major advantage over benzodiazepines for patients who cannot afford impairment in psychomotor skills.
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