vestipitant and Sleep-Initiation-and-Maintenance-Disorders

The difference in location between the receptor occupancy curve of an agonist and its functional response has been described as receptor reserve. This "reserve" for a specific receptor has been found to differ from tissue to tissue and between agonists acting on the same tissue. Recently, two structurally different neurokinin 1 (NK1) receptor antagonists were taken into human and both were tested as antidepressants and for insomnia. Vestipitant and Casopitant both have high affinity for the human NK1 receptor (pKi = 9.4 and 10.2, respectively). In human, at the chosen clinical doses, receptor occupancy was measured in the frontal cortex, at 24 hours post administration, as ∼90% for vestipitant (15 mg) and ∼100% for casopitant (30 mg). In patients with moderate to severe major depression, vestipitant given at 15 mg for 8 weeks showed no statistical significant benefit as measured by change in baseline in HAM-D total score; whereas casopitant at 80 mg achieved statistically significant improvement versus placebo at week 8 (LOCF HAMD17 = -2.7, p = 0.023). A lower dose of 30 mg showed a clear but not significant separation from placebo. However, in acute studies in insomnia, both vestipitant and casopitant at 15 mg and 30 mg, respectively, significantly reduced latency to persistent sleep, wakenings after sleep onset and increased total sleep time by similar amounts. These clinical results suggest that for major depression the receptor occupancy of an NK1 antagonist needs to be very high (almost 100%), whereas, for insomnia a lower occupation is sufficient to give clinical effect.

Topics: Antidepressive Agents; Depressive Disorder, Major; Fluorobenzenes; Humans; Neurokinin-1 Receptor Antagonists; Piperazines; Piperidines; Receptors, Neurokinin-1; Sleep Initiation and Maintenance Disorders; Tissue Distribution

Investigate the hypnotic effects of repeated doses of neurokinin-1 receptor antagonist, vestipitant, in primary insomnia.. Randomized, double-blind, placebo-controlled 28-day parallel-group study.. Eleven sleep centers in Germany.. One hundred sixty-one patients with primary insomnia.. Patients received vestipitant (15 mg) or placebo for 28 days; 2-night polysomnographic assessment occurred on nights 1/2 and 27/28.. Wake after sleep onset (WASO) was improved on nights 1/2 and 27/28 (ratio, vestipitant versus placebo [95% confidence interval]: 0.76 [0.65, 0.90], P = 0.001 and 0.79 [0.65, 0.96], P = 0.02, respectively), demonstrating maintenance of the effect following repeated dosing. Latency to persistent sleep was shorter with vestipitant on nights 1/2 (P = 0.0006 versus placebo), but not on nights 27/28. Total sleep time (TST) improved with vestipitant (nights 1/2: P < 0.0001, nights 27/28: P = 0.02 versus placebo). Next-day cognitive function tests demonstrated no residual effects of vestipitant (P > 0.05 versus placebo). Adverse events (AEs) occurred in 25% of vestipitant patients versus 22% for placebo. Headache was the most common AE (8% of vestipitant patients versus 9% for placebo).. Vestipitant improved sleep maintenance in patients with primary insomnia, with no associated next-day cognitive impairment. The effects on wake after sleep onset and total sleep time were maintained following repeated dosing.

Topics: Adult; Double-Blind Method; Female; Fluorobenzenes; Humans; Male; Middle Aged; Neurokinin-1 Receptor Antagonists; Piperidines; Polysomnography; Sleep Initiation and Maintenance Disorders; Treatment Outcome; Young Adult