Effect of fasedienol (PH94B) pherine nasal spray and steroidal hormones on electrogram responses and autonomic nervous system activity in healthy adult volunteers.

OBJECTIVE: Fasedienol (PH94B) is a pherine compound formulated as a nasal spray that is hypothesized to regulate olfactory-amygdala circuits of fear and anxiety. Fasedienol's effect on the local electrogram of nasal chemosensory neurons (EGNR) and autonomic nervous system (ANS) responses versus steroidal hormones and controls in healthy adults is reported. METHODS: Eight males and 8 females randomly received aerosolized control (propylene glycol) and study drugs (fasedienol, 17ß-estradiol, progesterone, cortisol, and testosterone, 0.4 µg each in propylene glycol) onto the nasal septum mucosal lining at 30-min intervals over 2 sessions. EGNR was continuously monitored; autonomic parameters were recorded before and after administration. RESULTS: Fasedienol significantly increased EGNR amplitude (males: 5.0 vs. 0.6 mV, p < 0.001; females:5.7 vs. 0.6 mV, p < 0.001), and rapidly reduced respiratory rate (p < 0.05), heart rate (p < 0.01), and electrodermal activity (p < 0.05) versus control. EGNR and ANS responses after steroidal hormone administration were similar to control. 81% reported feeling less tense/more relaxed after receiving fasedienol, but not after receiving either control or steroidal hormones. CONCLUSIONS: Intranasal fasedienol, but not control or steroidal hormones, activated EGNR and rapidly reduced ANS responses, consistent with sympatholytic effects. Combined with subjective reports, results suggest fasedienol may provide acute relief in anxiety conditions.

Neural circuits of anxiolytic and antidepressant pherine molecules.

In this review, we describe proposed circuits mediating the mechanism of action of pherines, a new class of synthetic neuroactive steroids with demonstrated antianxiety and antidepressant properties, that engage nasal chemosensory receptors. We hypothesize that afferent signals triggered by activation of these peripheral receptors could reach subgroups of olfactory bulb neurons broadcasting information to gamma-aminobutyric acid (GABAergic) and corticotropin-releasing hormone (CRH) neurons in the limbic amygdala. We propose that chemosensory inputs triggered by pherines project to centrolateral (CeL) and centromedial (CeM) amygdala neurons, with downstream effects mediating behavioral actions. Anxiolytic pherines could activate the forward inhibitory GABAergic neurons that facilitate the release of neuropeptide S (NPS) in the locus coeruleus (LC) and GABA in the bed nucleus of the stria terminalis (BNST) and inhibit catecholamine release in the LC and ventral tegmental area (VTA) leading to rapid anxiolytic effect. Alternatively, antidepressant pherines could facilitate the CRH and GABAergic neurons that inhibit the release of NPS from the LC, increase glutamate release from the BNST, and increase norepinephrine (NE), dopamine (DA), and serotonin release from the LC, VTA, and raphe nucleus, respectively. Activation of these neural circuits leads to rapid antidepressant effect. The information provided is consistent with this model, but it should be noted that some steps on these pathways have not been demonstrated conclusively in the human brain.

Effect of as-needed use of intranasal PH94B on social and performance anxiety in individuals with social anxiety disorder.

BACKGROUND: There are no medications approved for as-needed use for feared situations for individuals with social anxiety disorder (SAD). In the present study, intranasal PH94B was provided for use as needed during stressful events. METHODS: Twenty-two subjects were randomized (double-blind) to 2 weeks of treatment with intranasal PH94B or placebo. Following self-administration of medication prior to a feared event, peak levels of anxiety were recorded using the Subjective Units of Distress Scale (SUDS). After 2 weeks, subjects were crossed over to the opposite treatment for 2 weeks. Average peak SUDS during treatment with PH94B and placebo were compared using a paired t-test. RESULTS: Significant differences in favor of PH94B were found on the primary outcome measure: mean peak SUDS change from baseline for all subjects receiving PH94B was 15.6 points versus 8.3 points for placebo (paired t = 3.09, P = .006, effect size of .658). PH94B showed less superiority over placebo when placebo was given second rather than first, likely due to a carryover effect. Looking between groups at just the first 2 weeks of treatment, PH94B also showed trend superiority to placebo on the Liebowitz Social Anxiety Scale (LSAS) (P = .07) and a significant difference on the Patient Global Impression of Change (P = .024) and the LSAS Avoidance subtotal (P = .02). CONCLUSIONS: While further study is needed, these results, combined with earlier findings, suggest that PH94B could represent a useful as-needed treatment for SAD, and continue to validate the nasal chemosensory system as a novel mechanism for medication delivery.

Effect of an acute intranasal aerosol dose of PH94B on social and performance anxiety in women with social anxiety disorder.

OBJECTIVE: Although social anxiety disorder is a common and sometimes disabling condition, there are no approved treatments that can be used on an as-needed basis. The authors examined the acute use of PH94B, an intranasally administered neurosteroidal aerosol, for the acute management of the symptoms of social anxiety disorder. METHOD: The authors conducted a phase 2, multicenter, randomized, double-blind, placebo-controlled, single-dose study of PH94B. Ninety-one women 19-60 years of age with generalized social anxiety disorder received placebo intranasal spray (single-blind) 15 minutes before laboratory-simulated public speaking and social interaction challenges. Patients who experienced significant distress during at least one challenge returned 1 week later to receive either intranasal PH94B or placebo aerosol spray (double-blind) before repeat challenges. RESULTS: Patients who received PH94B during the second set of challenges had a significantly greater decrease in mean Subjective Units of Distress scores during the public speaking and social interaction challenges compared with the first set of challenges, than did patients who received placebo for both sets of challenges. A significantly greater proportion of the PH94B group were much or very much improved from the first to the second sets of challenges compared with the placebo group (75% and 37%, respectively). The side effects of PH94B were benign. CONCLUSIONS: PH94B may be a novel, effective, and well-tolerated acute treatment for performance and social anxiety in women with social anxiety disorder.