MAIDENHEAD, England and DUBLIN, Ireland, September 10 /PRNewswire/ --     Biogen Idec (NASDAQ: BIIB) and Elan Corporation, plc (NYSE: ELN) welcome
today's announcement by the Scottish Medicines Consortium (SMC) advising the
use of TYSABRI(R) (natalizumab) in people with highly active relapsing
remitting multiple sclerosis (RRMS)(1).

In view of evidence supporting the efficacy, safety and cost
effectiveness of TYSABRI, all NHS Health Boards in Scotland are now obliged
to consider the SMC's advice and ensure that TYSABRI is made available to
meet patient's clinical needs.

Similar positive guidance on TYSABRI was issued in England by the
National Institute for Health and Clinical Excellence (NICE) in August 2007.

"This decision offers real hope of a more active and fulfilled life to MS
patients in Scotland with highly active relapsing remitting multiple
sclerosis," commented Dr. Belinda Weller, Western General Hospital,
Edinburgh. "Access to appropriate therapy is particularly vital in Scotland
as we have the highest number of people with MS per capita in the world. Our
priority now must be to ensure that treatment is made available to those with
the most highly active form of the disease."

Highly active RRMS (defined in the SMC advice as two or more disabling
relapses in one year and an active MRI scan) has a devastating effect on the
lives of the individual and their families. These patients experience more
relapses and will become disabled more quickly than those people with typical
RRMS. Disability often means that these patients are unable to work,
adversely affecting their families as well.

TYSABRI is the first treatment to be specifically licensed for highly
active RRMS. Over two years, treatment with TYSBARI for highly active RRMS
(as defined by the SMC) leads to a 64% reduction in the risk of disability
progression and an 81% reduction in annualised relapse rate compared with
placebo(2).

As of mid-July 2007, approximately 14,000 MS patients worldwide are
currently receiving therapy with TYSABRI, either in the commercial setting or
in clinical trials.

The Scottish Medicines Consortium (SMC) provides advice to NHS Boards and
their Area Drug and Therapeutics Committees (ADTCs) across Scotland about the
status of all newly licensed medicines, all new formulations of existing
medicines and new indications for established products (licenced from January
2002). This advice is made available as soon as practical after the launch of
the product involved.

About TYSABRI (natalizumab)

TYSABRI is a treatment approved for relapsing forms of multiple sclerosis
(MS) in the US and relapsing-remitting MS in the European Union. According to
data that have been published in the New England Journal of Medicine, after
two years, TYSABRI treatment led to a 68% relative reduction (p<0.001) in the
annualised relapse rate compared to placebo and reduced the relative risk of
disability progression by 54% (p<0.001)(3).

TYSABRI use has been associated with an increased risk of progressive
multifocal leukoencephalopathy (PML), an opportunistic viral infection of the
brain that usually leads to death or severe disability. Other serious adverse
events that have occurred in TYSABRI-treated patients included
hypersensitivity reactions (e.g., anaphylaxis) and infections. Serious
opportunistic and other atypical infections have been observed in
TYSABRI-treated patients, some of whom were receiving concurrent
immunosuppressants in MS trials. Herpes infections were slightly more common
in patients treated with TYSABRI. The rate and nature of other infections was
similar to placebo. Common adverse events reported in TYSABRI-treated
patients include headache, fatigue, rash, infusion reactions, urinary tract
infections, joint and limb pain.

In addition to the European Union and the United States, TYSABRI is
approved in Switzerland, Canada, Australia and Israel. TYSABRI was discovered
by Elan and is co-developed with Biogen Idec.

About Biogen Idec

Biogen Idec creates new standards of care in therapeutic areas with high
unmet medical needs. Founded in 1978, Biogen Idec is a global leader in the
discovery, development, manufacturing, and commercialization of innovative
therapies. Patients in more than 90 countries benefit from Biogen Idec's
significant products that address diseases such as lymphoma, multiple
sclerosis, and rheumatoid arthritis. For product labeling, press releases and
additional information about the company, please visit
http://www.biogenidec.com.

About Elan

Elan Corporation, plc is a neuroscience-based biotechnology company
committed to making a difference in the lives of patients and their families
by dedicating itself to bringing innovations in science to fill significant
unmet medical needs that continue to exist around the world. Elan shares
trade on the New York, London and Dublin Stock Exchanges. For additional
information about the company, please visit http://www.elan.com.

Safe Harbor/Forward Looking Statements

This press release contains forward looking statements regarding TYSABRI
that are subject to risks and uncertainties that could cause actual results
to differ materially from that which we expect. Important factors that could
cause our actual results to differ include the possibility that our
competitors may offer treatment options that gain greater acceptance than
TYSABRI, regulatory and safety risks of TYSABRI, and the other risks and
uncertainties that are described in the periodic and current reports that
Biogen Idec and Elan have filed with the Securities and Exchange Commission,
including the "Risk Factors" sections of such filings. These forward looking
statements speak only as of the date of this press release, and the companies
do not undertake any obligation to update any forward looking statements,
whether as a result of new information, future events, or otherwise.

References:

(1). The advice of the Scottish Medicines Consortium reads as follows:

Natalizumab 300mg concentrate for solution for infusion (Tysabri(R))

No. (329/06) Biogen Idec Ltd.

ADVICE: following a resubmission

natalizumab (Tysabri(R)) is accepted for restricted use within
NHS Scotland as single disease modifying therapy in highly active relapsing
remitting multiple sclerosis (RRMS) only in patients with rapidly evolving
severe RRMS defined by two or more disabling relapses in one year and with
one or more gadolinium-enhancing lesions on brain magnetic resonance imaging
(MRI) or a significant increase in T2 lesion load compared with a previous
MRI.

In a post-hoc sub-group analysis of the pivotal trial, which included
patients with rapidly evolving severe RRMS, it was associated with a
significant reduction in the annualised relapse rate and the probability of
sustained progression of disability over two years compared with placebo.

(2). TYSABRI SmPC

(3). Polman, CH et al. N Engl J Med 2006;354:899-910