Cephalon Announces Positive Results from a Study of PROVIGIL in Children with Attention Deficit Hyperactivity Disorder (ADHD)

West Chester, PA - September 16, 2002

Cephalon, Inc. (Nasdaq: CEPH) today announced results from an investigational, multi-center clinical study in 248 children between the ages of six and 13. The results of the study show that PROVIGIL® (modafinil) Tablets [C-IV] significantly improves symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in children.

In the four-week, randomized, double-blind, placebo-controlled, parallel design study, children and adolescents with ADHD were assigned to one of four dose regimens of PROVIGIL daily or placebo. The primary efficacy endpoint measure was the teacher-completed school version of the ADHD Rating Scale IV. All of the PROVIGIL treated groups showed a reduction in symptoms of ADHD, with certain groups reaching statistical significance compared to placebo (p<0.05). The greatest significance was achieved in the group assigned to 300 mg of PROVIGIL once a day (p<0.01). PROVIGIL was generally well tolerated and the side effects seen in this study were consistent with those described in the product label, with insomnia being the most frequent. The complete study data are expected to be presented at a major medical meeting in 2003.

"This was a well-controlled study that provided us with a rich data set into the potential benefits that PROVIGIL may offer in treating children with ADHD," said Paul Blake, M.D., Senior Vice President of Clinical Research and Regulatory Affairs at Cephalon. "We are excited about the results and look forward to discussing these data with experts in the field and regulators to determine the best path for further development in the area of ADHD."

PROVIGIL

PROVIGIL is the first in a new class of wake-promoting agents. Launched in the U.S. in February 1999, the drug is currently approved in more than 20 countries for the treatment of excessive daytime sleepiness 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.

Attention Deficit Hyperactivity Disorder

According to the National Institutes of Mental Health, ADHD is one of the most common psychiatric disorders among children, affecting 3 to 5 percent of American children. Boys are two to three times more likely than girls to have ADHD.

The most common ADHD behaviors fall into three categories: inattention, hyperactivity, and impulsivity. A diagnosis of ADHD is generally made when these behaviors become excessive, long-term, and pervasive.

Cephalon, Inc.

Founded in 1987, Cephalon, Inc. is an international biopharmaceutical company dedicated to the discovery, development and marketing of innovative products to treat sleep and neurological disorders, cancer and pain.

Cephalon currently employs approximately 1,200 people in the United States and Europe. U.S. sites include the company's headquarters in West Chester, Pennsylvania, and offices and manufacturing facilities in Salt Lake City, Utah. Cephalon's major European offices are located in Guilford, England, and at Laboratoire L. Lafon in Maisons-Alfort, France.

The company currently markets three proprietary products in the United States: PROVIGIL® (modafinil) Tablets [C-IV], GABITRIL® (tiagabine hydrochloride) and ACTIQ® (oral transmucosal fentanyl citrate) [C-II] and more than 20 products internationally. Further information about Cephalon and full prescribing information on its U.S. products is available at www.cephalon.com or by calling 1-800-896-5855.

In addition to historical facts or statements of current condition, this press release may contain forward-looking statements. Forward-looking statements provide Cephalon's current expectations or forecasts of future events. These may include statements regarding anticipated scientific progress on its research programs, development of potential pharmaceutical products, interpretation of clinical results, prospects for regulatory approval, manufacturing development and capabilities, market prospects for its products, sales and earnings guidance, and other statements regarding matters that are not historical facts.

You may identify some of these forward-looking statements by the use of words in the statements such as "anticipate," "estimate," "expect," "project," "intend," "plan," "believe" or other words and terms of similar meaning. Cephalon's performance and financial results could differ materially from those reflected in these forward-looking statements due to general financial, economic, regulatory and political conditions affecting the biotechnology and pharmaceutical industries as well as more specific risks and uncertainties facing Cephalon such as those set forth in its reports on Form 8-K, 10-Q and 10-K filed with the U.S. Securities and Exchange Commission.

Given these risks and uncertainties, any or all of these forward-looking statements may prove to be incorrect. Therefore, you should not rely on any such factors or forward-looking statements. Furthermore, Cephalon does not intend to update publicly any forward-looking statement, except as required by law. The Private Securities Litigation Reform Act of 1995 permits this discussion.

Source: Cephalon, Inc.