News Release

Shire announces positive two-year study of ADDERALL XR in the treatment of adult ADHD

Data presented at U.S. Psychiatric & Mental Health Congress

Peer-Reviewed Publication

Porter Novelli

Shire Announces Positive Results of Two-Year Study of ADDERALL XR® in the Treatment of Adult ADHD Data Presented at U.S. Psychiatric & Mental Health Congress

Las Vegas, NV – November 8, 2005 – A study presented today demonstrated that adults with attention-deficit/hyperactivity disorder (ADHD) experienced significant long-term ADHD symptom control when treated with once-daily ADDERALL XR® (mixed salts of a single-entity amphetamine product). The results of a two-year, open-label trial led by Harvard Medical School investigators at Massachusetts General Hospital were presented today at the U.S. Psychiatric & Mental Health Congress in Las Vegas, NV.

"This study shows that this treatment can control the core symptoms of ADHD for longer periods of time," said lead investigator Joseph Biederman, M.D., Professor of Psychiatry at Harvard Medical School.

Two hundred fifty-five adult patients participated in an initial four-week, multi-center, double-blind, placebo-controlled, parallel-group, forced-dose-escalation trial with ADDERALL XR. Two hundred twenty-one of these patients entered into a 24-month open-label extension study. Funding for this study was provided by Shire.

Investigators measured patients' symptoms using a validated ADHD Rating Scale (ADHD-RS). Results revealed that all patients maintained a significant average reduction in their ADHD symptoms when treated with ADDERALL XR, as measured by a change from baseline in mean ADHD-RS total scores (–7.2; P<.001). Patients taking ADDERALL XR for the first time as part of the open-label extension study showed the most improvement (–11.6; P<.001; n=56) after 24 months in comparison to patients who continuously received ADDERALL XR treatment (–5.7; P<.001; n=144) and those whose treatment was interrupted between the initial study and the open-label extension (–6.0; P=.12; n=21). Investigators found similar significantly improved results in patients using the ADHD-RS hyperactivity/impulsivity and inattentive subscales.

ADDERALL XR exhibited a good tolerability profile during the trial at all doses. The approved dose for adult patients is 20 mg per day. The majority of side effects occurred in the first month of the trial, diminished over time and were generally mild or moderate in nature. The most frequently reported drug-related adverse events included dry mouth, insomnia, loss of appetite, headache and nervousness.

Additional Study Information The average age of participants was 40 and all had a history of ADHD before age 7. Of the participants, about 60 percent were men and 90 percent were Caucasian. Many of the participants were not diagnosed until they were adults and reported that their symptoms had negatively impacted their lives prior to treatment. At the end of the trial, an evaluation of the validated Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q) Medication Satisfaction test revealed that patients were significantly satisfied with their treatment.

About ADHD

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 typically observed in individuals at a comparable age and maturity level. Because everyone shows signs of these behaviors at times, the behaviors must appear early in life (before age 7 years) and continue for at least six months, according to the ADHD diagnosis criteria as defined in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TRÒ). Up to 65 percent of children with ADHD may still exhibit symptoms into adulthood. In fact, approximately eight million American adults currently struggle with the inattention, impulsivity and hyperactivity symptoms of ADHD.

Without an effective treatment program, the symptoms of ADHD may lead to potentially serious consequences. A survey has shown that when compared to adults without ADHD symptoms, adults with untreated ADHD were more than twice as likely to have been arrested, 47 percent more likely to have received more than one speeding ticket in the last year, twice as likely to have been divorced and twice as likely to have held six or more jobs in the past decade. Further, evidence suggests that many adults with untreated ADHD may be at risk for other problems, including poor performance in the workplace and poor self-image.

Although there is no cure for ADHD, physicians and advocates are finding ways to help people with the condition learn to adapt to their school, home, social and work settings. ADHD usually can be successfully managed with behavioral therapy, structured coping techniques and medication. Psychostimulant medications are thought to stimulate areas of the brain that control attention, impulses, and self-regulation of behavior, remain among the most successful treatments for people with ADHD. Up to 70 percent of children with ADHD respond positively to psychostimulants. Medication should be considered part of an overall multi-modal treatment plan for ADHD.

For further information on ADHD please visit www.adhdsupport.com, www.CHADD.org or www.NMHA.org.

About ADDERALL XR

ADDERALL XR (R) was generally well tolerated in clinical studies. The most common side effects in studies included: children - decreased appetite, difficulty falling asleep, stomachache, and emotional lability; adolescents - loss of appetite, difficulty falling asleep, stomachache, and weight loss; adults - dry mouth, loss of appetite, difficulty falling asleep, headache, and weight loss.

Adderall XR may not be right for everyone. Patients should speak with their doctor if they have a history of high blood pressure or any heart conditions, glaucoma, thyroid problems, emotional instability, mental illness, or a known allergy to this type of medication. Abuse of amphetamines may lead to dependence. Misuse of amphetamine may cause sudden death and serious cardiovascular adverse events. These events have also been reported rarely with amphetamine use.

If you are currently taking or have recently taken a type of antidepressant called a MAO inhibitor or have a pre-existing structural heart abnormality, you should not take Adderall XR. There is a potential for worsening of motion or verbal tics and Tourette's syndrome. A patient should report any new psychological symptoms to his or her physician.

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Notes to editors

Shire Pharmaceuticals Inc.

Shire Pharmaceuticals Inc. is a US subsidiary of Shire Pharmaceuticals Group plc. Shire's strategic goal is to become the leading specialty pharmaceutical company that focuses on meeting the needs of the specialist physician. Shire focuses its business on central nervous system (CNS), gastrointestinal (GI), general products (GP) and human genetic therapies (HGT) - all being areas in which Shire has a commercial presence. The structure is sufficiently flexible to allow Shire to target new therapeutic areas to the extent opportunities arise through acquisitions. Shire believes that a carefully selected portfolio of products with a strategically aligned and relatively small-scale sales force will deliver strong results.

Shire's focused strategy is to develop and market products for specialty physicians. This approach aims to deliver increased returns and lower risks. Shire's in-licensing and merger and acquisition efforts are focused on products in niche markets with strong intellectual property protection either in the US or Europe.

For further information on Shire, please visit the Company's website: www.shire.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 Attention Deficit and Hyperactivity Disorder (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, the expected product approval dates of DAYTRANATM (MTS/METHYPATCHTM) (ADHD), SPD503 (ADHD), SPD465 (ADHD), MESAVANCETM (SPD476) (ulcerative colitis), I2S (iduronate-2-sulfatase) (Hunter syndrome), and NRP104 (ADHD), including its scheduling classification by the Drug Enforcement Administration in the United States; Shire's ability to benefit from its 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.

Tuesday, November 8, 2005, 3:45 PM PST "Long-Term Safety and Effectiveness of Extended-Release Mixed Amphetamine Salts In Adults With ADHD." Biederman, Joseph, M.D.


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