Biogen Idec and Elan Announce Availability of TYSABRI(R) for the Treatment of Relapsing Forms of Multiple Sclerosis

The FDA granted approval for reintroduction based on the review ofTYSABRI clinical trial data; revised labeling with enhanced safetywarnings; and a risk management plan (TOUCH Prescribing Program)designed to inform physicians and patients of the benefits and risksof TYSABRI treatment and minimize potential risk of progressivemultifocal leukoencephalopathy (PML). Because of the increased risk ofPML, TYSABRI is generally recommended for patients who have had aninadequate response to, or are unable to tolerate, alternate MStherapies.

Under the TOUCH Prescribing Program, only prescribers, infusioncenters and pharmacies associated with infusion centers registered inthe TOUCH program are able to prescribe, infuse or distribute TYSABRI.Elan has contracted with a single distributor, ICS, a division ofAmerisourceBergen Specialty Group, and 12 specialty pharmacies:Caremark, CuraScript, PharmaCare, PrecisionRx Specialty Solutions,Medmark, BioScrip, McKesson Specialty, Option Care, Cigna Tel-DrugSpecialty Pharmacy, Aetna Specialty Pharmacy, Prescription Solutions,and Accredo NovaFactor. ICS and the 12 specialty pharmacies have beentrained on the TOUCH Prescribing Program and are obligated to followthe requirements of the program in order to purchase and distributeTYSABRI to authorized infusion sites and central pharmacies.

In addition, following the recent approval by the EuropeanCommission, the companies have introduced TYSABRI in several countriesin Europe.

About TYSABRI

Two-year data from the AFFIRM monotherapy trial showed thattreatment with TYSABRI reduced the risk of disability progression by42% (p<0.001), the primary endpoint of the study, and led to a 67%reduction (p<0.001) in the annualized relapse rate compared toplacebo. TYSABRI treatment also resulted in sustained andstatistically significant reductions in brain lesion activity asmeasured by MRI. The two-year data from the SENTINEL add-on trial alsodemonstrated that treatment with TYSABRI in addition to AVONEX(R)(Interferon beta-1a) had a significant effect on disabilityprogression, relapse rate and brain MRI disease activity compared toAVONEX alone.

TYSABRI increases the risk of PML, an opportunistic viralinfection of the brain that usually leads to death or severedisability. Three cases of PML occurred in clinical trial patients whowere concomitantly exposed to immunomodulators (interferon beta in thepatients with MS) or were immunocompromised due to recent treatmentwith immunosuppressants (e.g., azathioprine in the patient withCrohn's disease). Two of the cases were observed in 1,869 patientswith MS treated for a median of 120 weeks. A third case of PMLoccurred among 1,043 patients with Crohn's disease after the patientreceived eight doses. The number of cases is too few and the number ofpatients treated too small to reliably conclude that the risk of PMLis lower in patients treated with TYSABRI alone than in patients whoare receiving other drugs that decrease immune function or who areotherwise immunocompromised. Healthcare professionals should monitorpatients on TYSABRI for any new signs or symptoms that may besuggestive of PML. TYSABRI dosing should be withheld immediately atthe first sign or symptom suggestive of PML.

TYSABRI is contraindicated in patients who have or have had PML orwith known hypersensitivity to TYSABRI or any of its components. InPhase III placebo-controlled trials of TYSABRI in MS, the overallincidence and rate of other infections were balanced betweenTYSABRI-treated patients and controls. Herpes infections were slightlymore common in patients treated with TYSABRI. Commonly reportedinfections with TYSABRI included urinary tract infections, lowerrespiratory tract infections, gastroenteritis and vaginitis. Seriousopportunistic and other atypical infections have been observed inTYSABRI-treated patients, some of these patients were receivingconcurrent immunosuppressants.

The incidence and rate of other serious and common adverse eventsin clinical trials were similarly balanced between treatment groups.Serious events that occurred in TYSABRI-treated patients includedhypersensitivity reactions (e.g., anaphylaxis), depression andgallstones. Appendicitis was more common in patients receiving TYSABRIwith AVONEX. Common adverse events reported in TYSABRI-treatedpatients include infusion reactions, headache, fatigue, joint and limbpain, abdominal discomfort, diarrhea and rash.

For more information about TYSABRI please visitwww.biogenidec.com, www.elan.com, or www.tysabri.com.

About Biogen Idec

Biogen Idec creates new standards of care in oncology, neurologyand immunology. As a global leader in the development, manufacturing,and commercialization of novel therapies, Biogen Idec transformsscientific discoveries into advances in human healthcare. For productlabeling, press releases and additional information about the company,please visit www.biogenidec.com.

About Elan

Elan Corporation, plc is a neuroscience-based biotechnologycompany committed to making a difference in the lives of patients andtheir families by dedicating itself to bringing innovations in scienceto fill significant unmet medical needs that continue to exist aroundthe world. Elan shares trade on the New York, London and Dublin StockExchanges. For additional information about the company, please visitwww.elan.com.

Safe Harbor/Forward Looking Statements

This press release contains forward-looking statements regardingTYSABRI. These statements are based on the companies' current beliefsand expectations. The commercial potential of TYSABRI is subject to anumber of risks and uncertainties. Factors which could cause actualresults to differ materially from the companies' current expectationsinclude the risk that we may unable to adequately address concerns orquestions raised by FDA or other regulatory authorities, that concernsmay arise from additional data, that the incidence and/or risk of PMLor other opportunistic infections in patients treated with TYSABRI maybe higher than observed in clinical trials, or that the companies mayencounter other unexpected delays or hurdles. There is no assurancethat the companies will be able to market and sell TYSABRI outside ofthe United States. Drug development and commercialization involves ahigh degree of risk. For more detailed information on the risks anduncertainties associated with the companies' drug development andother activities, see the periodic and current reports that BiogenIdec and Elan have filed with the Securities and Exchange Commission.The companies assume no obligation to update any forward-lookingstatements, whether as a result of new information, future events orotherwise.