Sleep Maintenance Insomnia

Disease and Market Overview

Sleep maintenance insomnia (SMI) is the inability to stay asleep or to resume sleep after waking and is a major unmet medical need. Deep, or slow wave, sleep decreases with age, which leads to superficial sleep and difficulty staying asleep. There is also an increased incidence of SMI in medical, neurological and psychiatric conditions. Patients with SMI complain of frequent awakenings and difficulty staying asleep after falling asleep. Patients with these symptoms also frequently report impairments of daytime functioning. Most available sleep agents are sedatives that are ineffective in treating the symptoms of SMI.

We believe there is a large unmet medical need for a novel treatment of sleep maintenance insomnia that improves the patient's ability to stay asleep without impairing daytime functioning and creating addiction.

Our Sleep Maintenance Insomnia Program

We are developing pimavanserin, a proprietary small molecule discovered by ACADIA, as a next-generation treatment for sleep maintenance insomnia. As a potent and selective 5-HT_2A inverse agonist, pimavanserin provides the opportunity to effectively treat the symptoms of sleep maintenance insomnia without causing sedation.

In April 2006, we announced positive results from a proof-of-concept clinical study that was designed to assess the effect of pimavanserin on deep, or slow wave, sleep in healthy older volunteers. The clinical trial was a double-blind, placebo-controlled study involving 45 healthy volunteers ranging in age from 40 to 64. The subjects were randomized to one of five treatment arms, including placebo and four different doses of pimavanserin. Each group was administered placebo or the specified dose of pimavanserin once-daily for 14 consecutive days.

Results of the study demonstrated that pimavanserin induced a robust and statistically significant increase in slow wave sleep that was dose-related. In addition, pimavanserin treatment had a positive impact on measures for sleep maintenance, including decreases in the number of awakenings after sleep onset and in the time awake after sleep onset. Pimavanserin also did not alter latency to sleep onset and did not impair daytime functioning. Pimavanserin was safe and well tolerated in the study subjects.

In 2003, we completed two Phase I clinical trials that assessed the safety, tolerability and blood drug levels of pimavanserin following oral administration in a total of 57 healthy volunteers. The results showed that pimavanserin was well tolerated at plasma levels of 229 nanograms per milliliter and below. No serious adverse events were reported at any plasma level of pimavanserin. In addition to our Phase I clinical trials with pimavanserin, we conducted drug receptor occupancy studies in healthy volunteers using positron emission tomography, or PET, with various single doses of pimavanserin. This study demonstrated that even low acute doses of this drug candidate produced significant occupancy of 5-HT_2A receptors in the human brain.

ACADIA is also developing pimavanserin for treatment of Parkinson's disease psychosis and as a co-therapy for schizophrenia. For more information about these programs, please click here.

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