Buspirone (Buspar)

Mechanism of Action: Activates Serotonin (5-HT1A) receptors in brain.

Therapeutic Use: 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.

Absorption: Well absorbed after oral administration but low bioavailability . Peak blood levels reached in 60-90 min. after administration. Metabolism: Liver; oxidation

Half-life: Average 2.5 hour

Average Daily Dose (adult): 20-30 mg

Adverse Effects: Dizziness, light headedness and headache

Drug Interaction: Monoamine oxidase inhibitors (increases blood pressure). Increases blood level of haloperidol if co-administered.

Contraindication: Buspirone is contraindicated in patients hypersensitive to buspirone hydrochloride.

References:

• Holzer, J., Gitelman, D., & Price, B. (1995). Buspirone (Buspar) eliminates aggression in dementia. Brain Injury Update. 10(8), 60.
  
• Gualtieri, C.T. (1992). Buspirone: Neuropsychiatric effects. Journal of Head Trauma Rehabilitation. 6(1), 90-92.
  
• Levine, A.M. (1988). Buspirone and agitation in head injury: Case report. Brain Injury. 2(2), 165-167.

Lorazepam (Ativan)

Mechanism of Action: Like all drugs in this chemical family, (i.e. benzodiazepines), lorazepam enhances the action of the inhibitory neurotransmitter GABA by acting at the GABAA receptor.

Therapeutic Use: To relieve (or prevent) anxiety, relax muscles and to treat insomnia.

Absorption: Well absorbed after oral administration. Reaches peak plasma level in 1-2 hours and peak effect in 1-6 hours.

Metabolism: Conjugation with glucuronic acid in liver.

Half-Life: 10-20 hours

Average Daily Dose (adults): 2-6 mg (orally)

Adverse Effects: Dizziness, ataxia, drowsiness, tolerance, physical dependence, confusion, amnesia (memory loss).

Drug Interaction: Additive sedation with other depressants such as alcohol. Smokers may require higher doses.

Contraindication: Known allergy.

Diazepam (Valium)

Mechanism of Action: Same as for Lorazepam

Therapeutic Use: Same as for Lorazepam; and it can be given I.V. for status epilepticus.

Absorption: Well absorbed after oral administration. Peak plasma levels, 30-90 minutes.

Metabolism: Demethylated in the liver by P-450 enzymes and conjugated with glucuronic acid.

Half-life: 20-60 hours.

Average Daily Dose (adults) : 4-40 mg.

Adverse Effects: Same as Lorazepam

Drug Interaction: Same as Lorazepam, and with other drugs metabolized by P-450 enzymes in liver.

Contraindication: Same as Lorazepam

Alprazolam (Xanax)

Mechanism of Action: Same as Lorazepam, plus antidepressant action of unknown mechanism.

Therapeutic Use: Same as Lorazepam for anxiety. Can also be used in patients with panic disorder due to its antidepressant effects. May also be used in patients with depression.

Absorption: Well absorbed after oral administration. Peak blood levels reached in 1-2 hours.

Half-life: 12 -15 hours.

Average Daily Dose (adult dose): 0.75-1.5 mg

Adverse Effects: Same as Lorazepam

Drug Interaction: Same as Lorazepam, and with other drugs metabolized by P-450 enzymes.

Contraindication: Same as Lorazepam

References:

• Baldessarini, R.J. Drugs and the Treatment of Psychiatric Disorders. In: The Pharmacological Basis of Therapeutics 9th Edition. J.G. Hardman et al (eds.) McGraw Hill, N.Y. pp.399-430, 1996.
  
• Dailey, J.W. Sedative-Hypnotic and Anxiolytic Drugs. In: Modern Pharmacology with Clinical Applications. 5th Edition. C.R. Craig and R.E. Stitzel (eds.) Little Brown, Boston. pp. 373-380, 1997.