Physiological and pharmacological bases for the diverse properties of benzodiazepines and their congeners.

Benzodiazepines (BZs), which have been marketed by pharmaceutical companies since the sixties, are the most commonly prescribed psychotropic drugs. Diazepam, the prototype of this class of drugs, has a vast spectrum of therapeutic indications. It possesses, over a narrow dose-range, the well-known neuropsychopharmacological profile consisting of anxiolytic, anticonvulsant, sedative, and muscle relaxant effects, and CNS depression. Recently, BZ ligands that retain anxiolytic and antiepileptic properties at doses that are unable to produce a CNS depression have been developed. The pharmacological profiles of these drugs are discussed in light of: the heterogeneity of the structure of the GABAA receptor complex; intrinsic efficacy of the ligand; action of the BZ ligand on the mitochondrial BZ receptor.