Screening of Antianxiety Drugs

Screening of Antianxiety Drugs

1. Definition, scope and rationale of anxiolytic screening

• Anxiolytic screening is the experimental (in vitro + in vivo) evaluation of candidate compounds for the ability to reduce experimentally-induced or spontaneously-expressed anxiety-like behaviour in laboratory animals, before clinical development (Vogel 4e Part V, Tests for Anxiolytic Activity, pp.1069–70).
• The terms "anxiolytic" / "antianxiety" are historically coined from clinical activity of specific classes (as with "neuroleptic"); older synonyms are "ataractic" and "psycholeptic"; the modern lineage runs from tranquilizers such as meprobamate (widely used until the advent of benzodiazepines) to the benzodiazepines (Vogel 4e, p.1069).
• "Antianxiety" vs "antipsychotic" is a qualitative distinction in clinical use and mode of action — anxiolytics treat the minor (nonpsychotic/neurotic) disorders, antipsychotics (phenothiazines, butyrophenones) the severe psychotic/schizophrenic reactions (Vogel 4e, p.1069).
• Pathological anxiety in humans is defined by interference with normal function, somatic manifestations, emotional discomfort, and reduced work productivity; this complexity makes any single animal model an imperfect surrogate — hence no single test suffices and a battery of tests must be run to establish a spectrum of activity predictive of clinical efficacy (Vogel 4e, p.1069).
• The standard in-vivo battery historically combines anticonvulsant tests, antiaggressive tests, and conditioned-behaviour (conflict) evaluation, later broadened by ethological exploratory models (Vogel 4e, p.1070).
• Screening serves two directions: identifying anxiolytic activity (e.g. increased punished responding, increased open-arm exploration) AND detecting anxiogenic activity (opposite effects), since the same paradigms are bidirectional (Vogel 4e, pp.1127, 1143).
• The screening assays are conventionally grouped as (a) in-vitro / receptor-binding mechanistic screens, (b) unconditioned ethological (exploration-conflict) tests, (c) conditioned (operant) conflict/punishment tests, and (d) physiological / endocrine readouts — mirroring Vogel's own contents structure (Vogel 4e, pp.1069–70).