Prediction of anti-panic properties of escitalopram in the dorsal periaqueductal grey model of panic anxiety

Escitalopram, the active enantiomer of the selective serotonin reuptake inhibitor (SSRI) citalopram, has effects in animal models for the detection of antidepressant and anxiolytic effect and in patients with major depressive and anxiety disorders. In the present study, the effects of escitalopram in the dorsal periaqueductal grey (dPAG) stimulation model of panic anxiety were investigated and compared to a number of clinically used anti-panic agents. The SSRIs, citalopram (ED50 6.6 mg/kg), fluoxetine (ED50 13.6 mg/kg), paroxetine (ED50 2.9 mg/kg) and the benzodiazepine ligand, alprazolam (ED50 0.3 mg/kg) all reduced the flight-like escape behaviour produced by electrical stimulation of the dPAG in the rat, this is presumed to indicate a reduction in fear and/or physical sensation and is interpreted as an anti-panic effect of the drugs. Escitalopram (ED50 3.1 mg/kg) also significantly reduced flight behaviour indicating the anti-panic potential of the compound; it is suggested that escitalopram will be twice as potent as citalopram in this context.