News Release

FDA expands indication for ADDERALL XR® (CII) confirming safety and efficacy in adolescents

Business Announcement

Porter Novelli

Philadelphia, US – July 22, 2005 – Shire Pharmaceuticals Group plc (LSE: SHP, NASDAQ: SHPGY, TSX: SHQ) announced today that the US Food and Drug Administration (FDA) has approved ADDERALL XR® (mixed salts of a single-entity amphetamine product) as a once-daily treatment for adolescents aged 13 to 17 with attention deficit hyperactivity disorder (ADHD). Since October 2001, ADDERALL XR has been approved in the U.S. for treatment in children aged 6 to 12 years and since August 2004 in adults 18 years and older. ADDERALL XR is currently the most commonly prescribed brand of ADHD medication in the United States.

"There has long been an unmet need for ADHD research and treatment among the adolescent population despite an increasing awareness of ADHD's potential impact on quality of life. Therefore, approval of an ADHD treatment for this underidentified age group is an important milestone," explained Dr. Timothy Wilens of Massachusetts General Hospital. "The symptoms of ADHD often continue past childhood into adolescence and adulthood, where they can have a significant impact on an individual's family, academic performance, and overall quality of life. Stimulant therapies are effective and generally well tolerated, and have been used medically in patients for more than 60 years."

ADHD affects approximately 3 to 7 percent of all school-age children, or approximately two million U.S. children, and is considered the most commonly diagnosed psychiatric disorder in children and adolescents. ADHD is a neurological brain disorder that manifests as a persistent pattern of inattention and/or hyperactivity-impulsivity that is more frequent and severe than is typically observed in individuals at a comparable age and maturity. ADHD can have a profound effect on a child's quality of life and can be serious enough to interfere beyond academics, leading to problems maintaining friendships, difficulties focusing on sports or other after-school activities, and challenges in relating well with other family members. Untreated ADHD has long-term adverse effects on academic performance, vocational success and social-emotional development. Evidence also suggests that many with untreated ADHD may be at risk for other problems, such as drug abuse, anti-social behavior and poor self-esteem. As they age, up to 65 percent of adolescents with ADHD may still exhibit symptoms into adulthood.

"The new adolescent labeling for ADDERALL XR offers health care providers, parents and patients continuity in the management of ADHD symptoms as children become older," said Greg Flexter, Executive Vice President and General Manager, Shire North America. " We are pleased that a thorough review by the FDA once again confirms the safety and efficacy of Adderall XR in another age group."

The FDA based its approval on data that Shire provided in a supplement to its New Drug Application (sNDA). These data included the results of a pharmacokinetic study and a placebo-controlled, fixed-dose clinical trial of a range of doses of once-daily ADDERALL XR in adolescents with ADHD.

In a randomized, double-blind, placebo-controlled clinical trial, ADDERALL XR was proven to be significantly more effective than placebo in the treatment of ADHD symptoms in adolescents. ADDERALL XR was generally safe and well tolerated with adverse events similar to those seen in other populations. The most common adverse events were loss of appetite, insomnia, abdominal pain, and weight loss. The results of this study show that ADDERALL XR produces a positive clinical response in adolescents diagnosed with ADHD. The study showed ADDERALL XR at doses between 10 mg and 40 mg daily were statistically significantly superior to placebo (p<0.0001) on the ADHD-RS-IV (investigator-rated with the parent and adolescent). Furthermore, 63 percent of investigators considered their subjects' ADHD symptoms to be much improved or very much improved with ADDERALL XR compared to 27 percent for placebo (p<0.0001).

About ADDERALL XR

ADDERALL XR may not be right for everyone. ADDERALL XR was generally well tolerated in clinical studies. The most common adverse events in pediatric trials included loss of appetite, insomnia, abdominal pain, and emotional lability. The most common side effects in the adolescent trial included loss of appetite, insomnia, abdominal pain, and weight loss. The most common adverse events in the adult trial included dry mouth, loss of appetite, insomnia, headache, and weight loss.

The effectiveness of ADDERALL XR for long-term use has not been systematically evaluated in controlled trials. As with other psychostimulants indicated for ADHD, there is a potential for exacerbating motor and phonic tics and Tourette's syndrome. A side effect seen with the amphetamine class is psychosis. Caution also should be exercised in patients with a history of psychosis.

Abuse of amphetamines may lead to dependence. Misuse of amphetamine may cause sudden death and serious cardiovascular adverse events. ADDERALL XR generally should not be used in children or adults with structural cardiac abnormalities. ADDERALL XR is contraindicated in patients with symptomatic cardiovascular disease, moderate to severe hypertension, hyperthyroidism and glaucoma, known hypersensitivity to this class of compounds, agitated states, history of drug abuse, or current or recent use of MAO inhibitors. ADDERALL XR should be prescribed with close physician supervision.

About ADHD

ADHD is a neurobiological disorder that manifests as a persistent pattern of inattention and/or hyperactivity-impulsivity more frequent and severe than typically observed in individuals at a comparable level of development. To be properly diagnosed with ADHD, a child needs to demonstrate at least six of nine symptoms of inattention; at least six of nine symptoms of hyperactivity/impulsivity; the onset of such symptoms before age 7 years; that some impairment from the symptoms is present in two or more settings (e.g., at school and home); and that the symptoms continue for at least six months.

Although there is no "cure" for ADHD, there are accepted treatments that specifically target its symptoms. The most common standard treatments include educational approaches, psychological or behavioral modification, and medication.

For further information please contact: Media
Marion Glick (Porter Novelli), 212-601-8273
Janice Miller (Porter Novelli), 212-601-8176

Notes to editors

Shire Pharmaceuticals Group plc

Shire Pharmaceuticals Group plc (Shire) is a global specialty pharmaceutical company with a strategic focus on meeting the needs of the specialist physician and currently focuses on developing projects and marketing products in the areas of central nervous system (CNS), gastrointestinal (GI), and renal diseases. Shire has operations in the world's key pharmaceutical markets (US, Canada, UK, France, Italy, Spain and Germany) as well as a specialist drug delivery unit in the US.

For further information on ADDERALL XR, please visit the ADDERALL XR website at http://www.AdderallXR.com.

"SAFE HARBOR" STATEMENT UNDER THE PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995

Statements included herein that are not historical facts are forward-looking statements. Such forward-looking statements involve a number of risks and uncertainties and are subject to change at any time. In the event such risks or uncertainties materialize, Shire's results could be materially affected. The risks and uncertainties include, but are not limited to, risks associated with the inherent uncertainty of pharmaceutical research, product development, manufacturing and commercialization, the impact of competitive products, including, but not limited to, the impact of those on Shire's ADHD franchise, patents, including but not limited to, legal challenges relating to Shire's ADHD franchise, government regulation and approval, including but not limited to Health Canada's suspension of ADDERALL XR® sales in Canada and the expected product approval dates of MTS (METHYPATCH) (ADHD), SPD503 (ADHD), SPD465 (ADHD), SPD476 (ulcerative colitis), and NRP104 (ADHD), including its scheduling classification by the Drug Enforcement Agency in the United States, Shire's ability to consummate and benefit from its proposed acquisition of Transkaryotic Therapies, Inc., Shire's ability to secure new products for commercialization and/or development and other risks and uncertainties detailed from time to time in Shire's filings with the Securities and Exchange Commission, including its Annual Report on Form 10-K for the year to December 31, 2004.

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