Study Demonstrates Provigil Significantly Improves Wakefulness in Patients with Obstructive Sleep Apnea

West Chester, PA - October 9, 2001

Cephalon, Inc. today announced results from a 327-patient, multi-center clinical study that indicate PROVIGIL® (modafinil) Tablets [C-IV] increased daytime wakefulness in patients suffering from excessive daytime sleepiness (EDS) associated with obstructive sleep apnea.

In this randomized, double-blind, placebo-controlled, parallel-group study, obstructive sleep apnea patients who use continuous positive airway pressure (CPAP) received a once-daily dose of PROVIGIL® (200 mg or 400 mg) or placebo for 12 weeks. Primary endpoint measures were the Maintenance of Wakefulness Test (MWT) and the Clinical Global Impression of Change (CGI-C).

The MWT is an objective test of wakefulness and the CGI-C is a subjective assessment of improvement in a patient's overall clinical condition from a physician's perspective. Statistically significant improvements in wakefulness and overall clinical condition were found at 12 weeks on the MWT (p<0.0001) and CGI-C (p<0.001) in patients treated with either PROVIGIL® dose compared to placebo.

Secondary results were measured using a number of endpoints that assess patients' wakefulness and quality of life, including the Epworth Sleepiness Scale, the Functional Outcome of Sleep Questionnaire and the SF36 Health Quality of Life Survey. The results of the secondary measures also were statistically significant in patients treated with either PROVIGIL® dose compared to placebo.

The most commonly reported side effects in this study were headache, nausea and anxiety.

"Data from this study are consistent with results from other clinical trials of PROVIGIL® in patients who suffer from excessive daytime sleepiness," said Dr. Paul Blake, Senior Vice President of Clinical and Regulatory Affairs at Cephalon. "This study is the latest in a series -- including earlier sleep apnea studies -- that have demonstrated PROVIGIL® improves wakefulness and overall functioning in patients who have disorders where excessive sleepiness is a major symptom."

The study is a key component in Cephalon's regulatory efforts to expand the label for PROVIGIL® in the United States and United Kingdom.

PROVIGIL®

PROVIGIL® is a unique, wake-promoting agent launched in the U.S. in February 1999. The American Academy of Sleep Medicine regards PROVIGIL® as a standard for the treatment of EDS associated with narcolepsy. In controlled clinical trials, PROVIGIL® has been found to be generally well tolerated with a low incidence of adverse events relative to placebo. The most commonly observed adverse events associated with the use of PROVIGIL® were headache, infection, nausea, nervousness, anxiety and insomnia.

Obstructive Sleep Apnea

According to the American Sleep Apnea Association and the National Institutes of Health, obstructive sleep apnea is a serious and potentially life-threatening sleep disorder that afflicts as many as 18 million Americans. Individuals with obstructive sleep apnea experience frequent awakenings throughout the night as a result of blockage of the airway during sleep. This disruption of sleep leads to excessive daytime sleepiness causing many people to doze off repeatedly throughout the day -- at their jobs and at home.

The primary treatment for obstructive sleep apnea is continuous positive airway pressure (CPAP). A nasal CPAP device can prevent airway closure while in use, but despite this treatment, many patients continue to experience significant daytime sleepiness. The results of this and other studies indicate that PROVIGIL® may be a useful adjunctive treatment for excessive daytime sleepiness in patients with obstructive sleep apnea who use CPAP.

Cephalon, Inc.

Cephalon, Inc., headquartered in West Chester, Pennsylvania, is an international biopharmaceutical company that discovers, develops and markets products to treat sleep and neurological disorders, cancer and pain. The company currently markets its three proprietary products in the United States and nine products internationally. Cephalon develops innovative products for the treatment of neurological diseases and cancer through identification of novel compounds that affect both cell survival and death. Copies of press releases and additional information about Cephalon can be obtained by visiting the company's website at www.cephalon.com.