Benzodiazepines inverse agonism

Dysfunction of the GABAa receptor complex such that the effects of all benzodiazepine receptor ligands are shifted in the direction of inverse agonism. In this case, fiumazenil (which normally has zero efficacy) should induce anxiety in anxious patients but have no effects in healthy subjects because they have normal receptors. 

Figure 19.8 A schematic representation of the GABAa receptor shift hypothesis. This proposes that patients with panic disorder have dysfunctional GABAa receptors such that the actions of drugs that behave as antagonists in normal subjects are expressed as inverse agonism in panic patients. It is unlikely that this theory extends to generalised anxiety disorder (GAD), for which benzodiazepine agonists are highly effective treatments, but it could explain why these drugs are relatively ineffective at treating panic disorder. (Based on Nutt et al. 1990)...

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