Buspirone is a non benzodiazepine non sedating anxiolytic. It has slow onset of action. No hypnotic, anti convulsant or muscle relaxant properties are present.
Mechanism of Action:
It acts as partial agonist at brain 5-HT1A receptors
- Causes rebound anxiety after sudden cessation of high doses
- Minimal abuse liability
- Rapidly absorbed orally, undergoes Ist pass metabolism
- Active metabolites are formed after hydroxylation & dealkylation
- Active metabolite (I-PP) has alpha2 adrenergic action in CNS
- Half life of Buspirone is 2-4 hrs
- no rebound anxiety
- no withdrawal symptoms
- minimal abuse liability
- cause less psychomotor impairment than benzodiazepines and does not effect driving skills
- does not potentiate effects of sedatives/hypnotics, ethanol and TCAs
- elderly people do not appear to be more sensitive to its actions
Onset of action is delayed. It takes about 7 days. In generalized anxiety disorders, as action is comparable to benzodiazepines, it may be used. It does not interact with other CNS depressants except ethanol.
Acts by inhibiting presynaptic receptors, increasing serotonin.
Less troublesome than benzodiazepines
- GI distress
- Dose dependent pupillary constriction
- Monoamine oxidase inhibitors antidepressants + Buspirone increase blood pressure
- Macrolyte antibiotics (Erythromycin [enzyme inhibitor], Ketoconazole) increase plasma levels
- Rifampin decreases plasma level