The novel vasopressin receptor (V1aR) antagonist SRX246 reduces anxiety in an experimental model in humans: a randomized proof-of-concept study.

RATIONALE Arginine vasopressin (AVP) is a neuropeptide that modulates both physiological and emotional responses to threat. Until recently, drugs that target vasopressin receptors (V1a) in the human central nervous system were unavailable. The development of a novel V1a receptor antagonist, SRX246, permits the experimental validation of vasopressin's role in the regulation of anxiety and fear in humans. OBJECTIVES Here, we examined the effects of SRX246 in a proof-of-concept translational paradigm of fear (phasic response to imminent threat) and anxiety (prolonged response to potential threat). METHODS Healthy volunteers received both SRX246 and placebo in a randomized, double-blind, counter-balanced order separated by a 5-7-day wash-out period. Threat consisted of unpleasant electric shocks. The "NPU" threat test probed startle reactivity during predictable threat (i.e., fear-potentiated startle) and unpredictable threat (i.e., anxiety-potentiated startle). RESULTS As predicted, SRX246 decreased anxiety-potentiated startle independent of fear-potentiated startle. CONCLUSIONS As anxiety-potentiated startle is elevated in anxiety and trauma-associated disorders and decreased by traditional anxiolytics such as SSRIs and benzodiazepines, the V1a receptor is a promising novel treatment target.