American Journal of Respiratory and Critical Care Medicine Publishes Study On Adjunct Use of Unique Wake-Promoting Agent in Obstructive Sleep Apnea

West Chester, PA - November 2, 2001

Cephalon, Inc. announced that a study published today in the American Journal of Respiratory and Critical Care Medicine shows that its unique wake-promoting drug, PROVIGIL® (modafinil) Tablets [C-IV], increased daytime wakefulness in patients suffering from excessive sleepiness associated with obstructive sleep apnea (OSA), who regularly use nasal continuous positive airway pressure (nCPAP).

In this investigational randomized, double-blind, placebo-controlled, parallel group study, patients were treated with nCPAP plus placebo or nCPAP plus PROVIGIL® for four weeks. Forty-five percent of the 157 patients entering the study were classified as severely sleepy, with a score of 15 or greater on the Epworth Sleepiness Scale (ESS). Data show that patients receiving PROVIGIL® and nCPAP achieved greater improvements in wakefulness; 51 percent achieved a normalized ESS score of less than 10, compared to 27 percent of patients receiving nCPAP and placebo (p< .01). Patients administered PROVIGIL® plus nCPAP also showed significant reduction in their tendency to fall asleep, as measured by the Multiple Sleep Latency Test (MSLT).

In this four-week study, nCPAP use did not differ between the two treatment groups. Adverse events reported were predominantly mild to moderate. The most commonly observed side effects in patients receiving PROVIGIL® plus nCPAP were headache, nervousness and rhinitis.

"Some individuals with OSA continue to experience significant sleepiness, although they are well treated by current criteria," said Allan Pack, M.D. Ph.D., Professor of Medicine and Director of the Center for Sleep and Respiratory Neurobiology, University of Pennsylvania, lead author on the paper. "This investigational study indicates that PROVIGIL® may be a useful adjunctive treatment for patients continuing to experience excessive daytime sleepiness despite consistent use of their nCPAP treatment."

PROVIGIL®

PROVIGIL® is a unique wake-promoting agent launched in the United States. in February 1999, indicated for the treatment of excessive daytime sleepiness (EDS) associated with narcolepsy. Since its launch, more than one million prescriptions have been written and the American Academy of Sleep Medicine regards PROVIGIL® as a standard for the treatment of EDS associated with narcolepsy. Cephalon is studying PROVIGIL® in a number of sleep-related conditions, including sleep apnea, as part of the company's strategy to expand the labeled indication.

In controlled clinical trials, PROVIGIL® has been found to be generally well-tolerated, with an incidence of adverse events mostly comparable to placebo. The most commonly observed adverse events were headache, infection, nausea, nervousness, anxiety, and insomnia.

Obstructive Sleep Apnea

According to the American Sleep Apnea Association, obstructive sleep apnea is a serious and potentially life-threatening sleep disorder that afflicts as many as 12 million Americans. Research indicates that more than 90 percent of women and 80 percent of men with moderate to severe sleep apnea have not been diagnosed.

Individuals with obstructive sleep apnea experience frequent awakenings, sometimes occurring numerous times during 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 whether at their jobs or at home. The standard treatment for obstructive sleep apnea is CPAP, which is designed to prevent the closure of the airway by delivering air into the breathing pathway. Despite regular use of CPAP, some patients still suffer from residual daytime sleepiness.

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.