News Release

Shire investigational drug (SPD465) designed to reduce ADHD symptoms for up to 16 hours

Data on an investigational drug presented at a Major Child and Adolescent Psychiatry Meeting

Peer-Reviewed Publication

Porter Novelli

Philadelphia – Oct. 31, 2006 -- Shire plc (LSE: SHP, NASDAQ: SHPGY, TSX: SHQ) announced the results of two phase II trials in adults (studies 201 and 203) of the investigational amphetamine compound SPD465 (triple-bead mixed amphetamine salts [MAS]) at a major medical meeting of child and adolescent psychiatrists in San Diego, Calif. These results demonstrated that SPD465 improved Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms in adults for up to 16 hours post-dose and had a generally well tolerated safety profile consistent with currently marketed amphetamine products.

"If approved, triple-bead MAS may be useful for maintaining adult ADHD symptom control throughout the day and during the evening hours, at work or at home, due to its long duration of action," said Timothy Wigal, Ph.D., lead investigator for both studies and associate clinical professor of pediatrics and deputy director of the Child Development Center at the University of California, Irvine.

On July 21, 2006, Shire submitted a New Drug Application for triple-bead MAS, which is now under FDA review. If approved, triple-bead MAS would be the first and only ADHD stimulant product designed to control inattention, hyperactivity and impulsivity in adults for up to 16 hours with one daily dose. More than 9 million American adults currently exhibit symptoms of ADHD.

Study 203: Single Morning Dose of Triple-bead MAS 25 mg In this study of 73 adult subjects, those taking the 25 mg dose had significantly higher scores than subjects taking placebo as measured by the Permanent Product Measure of Performance (PERMP), the primary endpoint, at 16-hours post-dose (P < .0001). This test is a 10-minute, written, age-adjusted collection of 80 math problems that provides an accurate measure of a person's ability to pay attention and stay on task. Subanalyses of the number of problems attempted and the number answered correctly showed similar results.

In addition, subjects treated with triple-bead MAS had significantly improved average ADHD Rating Scale (ADHD-SRS) total scores than those taking placebo (P < .0001) at all test times (5.5, 11 and 16.5 hours) post-dose.

Study 201: This study evaluated 77 adult subjects with ADHD during three seven-day treatment periods at doses of 50 mg or 75 mg of triple-bead MAS compared to placebo, and used an active control for test sensitivity. The study results demonstrated that triple-bead MAS provided significant improvement in ADHD symptom control based on PERMP and ADHD-RS scores.

With both triple-bead MAS doses, the average PERMP total, attempted and correct scores were significantly better than with placebo at all times measured after dosing. Average ADHD-SRS total scores were significantly better for participants receiving triple-bead MAS than those taking placebo (P < .0001) at all three test times (5.5, 11.0 and 16.5 hours) post-dose.

Triple-bead MAS was generally well tolerated in both studies, although two serious adverse events, chest pain with no sequelae and hypertension with no sequelae, were reported in subjects treated with 75 mg. The most frequently reported adverse events in both studies were insomnia, decreased appetite, dry mouth, headache and anorexia and were consistent with amphetamine use.

Shire Development Inc. supported these studies.

About ADHD Approximately 7.8 percent of all school-age children, or about 4.4 million U.S. children aged 4 to 17 years, have been diagnosed with ADHD at some point in their lives, according to the U.S. Centers for Disease Control and Prevention (CDC). ADHD is one of the most common psychiatric disorders in children and adolescents. ADHD is a neurobiological psychiatric 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 level of development. A diagnosis of Attention-Deficit/Hyperactivity Disorder in adults (ADHD; DSM-IV) implies the presence of hyperactive-impulsive and/or inattentive symptoms that cause impairment and were present before the age of 7 years. The symptoms must cause clinically significant impairment, e.g., in social, academic, or occupational functioning, and be present in two or more settings, e.g., school (or work) and at home. The symptoms must not be better accounted for by another mental disorder.

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.

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Shire plc
725 Chesterbrook Boulevard
Wayne, PA 19087-5637
Tel (484) 595-8110
Fax (484) 595-8151
www.shire.com

For further information please contact:
Marion E. Glick (Porter Novelli), 212-601-8273, marion.glick@porternovelli.com

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

Notes to editors

About SPD465
SPD465, a mixed amphetamine salt formulation designed to provide sustained release of medication with symptom control for up to 16 hours, is being studied for the treatment of ADHD in adults. The most common adverse events reported in SPD465 phase II studies were insomnia, decreased appetite, dry mouth, headache and anorexia.

Shire 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, gastrointestinal, general products and human genetic therapies. 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 ad market products for specialty physicians. Shire's in-licensing, 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 forwarding-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 plc's ADHD franchise; government regulation and approval, including but not limited to the expected product approval dates of SPD503 (guanfacine extended release) (ADHD), SPD465 (extended release of mixed amphetamine salts) (ADHD), MESAVANCE (mesalamine) with MMX technology (SPD 476) (ulcerative colitis), ELAPRASE (idursulfase) (Hunter Syndrome) and NRP104 (lisdexamfetamine dimesylate) (ADHD), including its scheduling classification by the Drug Enforcement Administration in the United States; 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 and its predecessor registrant Shire Pharmaceuticals Group plc's filings with the Securities and Exchange Commission, particularly Shire plc's Annual Report on Form 10-K for the year ended December 31, 2005.


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