AVANIR's Investigational Anthrax Antibody Effective in Recognized Animal Model; UTMB Scientists Present Data at ASM Meeting

Data presented today at the 105th General Meeting of the
American Society for Microbiology (ASM) described activity of AVANIR
Pharmaceuticals' (AMEX:AVN) fully human monoclonal antibody treatment
against inhalation anthrax. The data demonstrates that one dose
(lowest dose tested was 1 mg/kg) of AVANIR's antibody, AVP 21D9,
completely protected rabbits challenged with 100xLD50 dose of B.
anthracis administered nasally. All animals, re-challenged three weeks
later with anthrax but without additional antibody treatment, survived
re-challenge as well. The data also showed that AVP 21D9 worked
synergistically with the antibiotic Ciprofloxacin to protect mice and
guinea pigs.
   Johnny W. Peterson, Ph.D. of the University of Texas Medical
Branch (UTMB) presented the results in a poster entitled "Human
Monoclonal Anti-PA Antibody Completely Protects Rabbits and is
Synergistic with Ciprofloxacin in Protecting Mice and Guinea Pigs
Against Inhalation Anthrax" at the ASM meeting being held this week in
Atlanta, Georgia.
   "These data demonstrate that AVANIR's anti-PA human monoclonal
antibody is very effective in protecting rabbits against anthrax spore
challenge." said Dr. Peterson. "The rabbit model is one of the
recognized models for determining efficacy of anti-anthrax antibodies.
These data indicate that AVP 21D9 may provide the necessary immediate
protection following anthrax exposure."
   AVP 21D9 is a human monoclonal antibody to Bacillus anthracis
protective antigen (PA) that was discovered and developed by AVANIR
Pharmaceuticals. AVP 21D9 has demonstrated efficacy in protecting
against anthrax in multiple experimental animal models. One molecule
of the antibody is capable of neutralizing two anthrax toxin molecules
in rat models. AVP 21D9 is the first antibody to demonstrate potency
against a toxin at this "sub-stoichiometric" level.
   "AVANIR's human monoclonal antibodies to PA have high specificity
and very desirable binding properties, and offer considerable promise
for the rapid development of products useful as therapy against the
most lethal form of anthrax, inhalation anthrax," concluded Dr.
Peterson.
   The in vivo tests on passive immunization with AVANIR human
monoclonal antibodies are being conducted in small animal models
established at the University of Texas Medical Branch in Galveston
under contract from the National Institute of Allergy and Infectious
Disease (NIAID), a part of the National Institutes of Health.
   Antibodies that neutralize anthrax toxins may augment existing
treatment options. Currently, a vaccine and antibiotics are the
treatment options available for the prevention or treatment of anthrax
exposure. Both approaches have limitations. The current anthrax
vaccine takes weeks following the first dose before immunity is
established, and requires multiple injections over a period of months,
in addition to annual boosters, to reach and maintain its protective
effect. Antibiotics, the standard treatment of anthrax infection, are
effective in killing anthrax bacteria, but have no effect on the
anthrax toxins and require extended treatment for at least two months
of twice daily dosing.
   AVANIR Pharmaceuticals is a pharmaceutical company focused on
developing and commercializing novel therapeutic products for the
treatment of chronic diseases. AVANIR's product candidates address
therapeutic markets that include central nervous system and
cardiovascular disorders, inflammation, and infectious disease. AVANIR
expects to submit the final module of its rolling new drug application
to the U.S. Food and Drug Administration for its lead product
candidate, Neurodex(TM), in mid-2005. Recently, AVANIR partnered its
preclinical research and development program for inflammatory disease
with Novartis. The Company's first commercialized product, Abreva(R),
is marketed in North America by GlaxoSmithKline Consumer Healthcare
and is the leading over-the-counter product for the treatment of cold
sores. Further information about AVANIR can be found at
www.avanir.com.

   Except for the historical information presented herein, matters
discussed in this press release contain forward-looking statements
that are subject to certain risks and uncertainties that could cause
actual results to differ materially from any future results,
performance or achievements expressed or implied by such statements.
Statements that are not historical facts, including statements that
are preceded by, followed by, or that include such words as
"estimate," "anticipate," "believe," "plan" or "expect" or similar
statements are forward-looking statements. Risks and uncertainties for
AVANIR Pharmaceuticals include risks associated with product discovery
and development, our dependence on government grants to subsidize the
development of our anthrax antibodies, as well as risks shown in
AVANIR's most recent Annual Report on Form 10-K and Quarterly Report
on Form 10-Q and from time-to-time in other publicly available
information regarding the company. Copies of such information are
available from AVANIR upon request. Such publicly available
information sets forth many risks and uncertainties related to
AVANIR's business and technology. Avanir's monoclonal antibody
technology competes with several technologies used by large
pharmaceutical and biotechnology companies and is subject to a number
of uncertainties, including risks associated with the success of
clinical trials, the progress of research and product development
programs, the regulatory approval process, competitive products,
future capital requirements and commercialization risks, particularly
with drug candidates being developed for the U.S. federal government.
There can be no assurance that such development efforts will succeed,
that such products will receive required regulatory clearance, or that
even if such regulatory clearance were received, that such products
would ultimately achieve commercial success. The company disclaims any
intent or obligations to update these forward-looking statements.