Different modes of action of alprazolam in the treatment of panic attacks.

Alprazolam (a benzodiazepine in the group of the triazolo-benzodiazepines) is a potent drug for the treatment of panic disorder. This is possible due to four different interactions with neurotransmitter systems. First, it facilitates, as all diazepines, the inhibitory acitivity of gamma-amino-butyricacid (GABA). The chemical structure differs from the benzodiazepines by incorporation of the triazoloring. Due to this triazoloring, the drug has three additional modes of action. These modes of action inhibit the locus coeruleus which plays a role in the origin of panic disorder. A first specific action is a stimulation of the serotonergic system. Triazolobenzodiazepines are also α2-adrenoreceptor agonists. Both mechanisms are responsible for inhibition of the locus coeruleus. Triazolo-benzodiazepines inhibit the platelet-activating-factor (PAF). PAF stimulates the corticotropin-releasing-hormone (CRH). This hormone stimulates the locus coeruleus. CRH in patients with panic attacks is elevated. This could be a result of hyperactive metabolism of the right parahippocampal area, which is observed in patients with panic attacks. Triazolo-benzodiazepines decrease the activity of the locus coeruleus because of a low CRH-level due to inhibited PAF.