Disclosure of Shareholdings in Accordance with Stock Market Rules

Geneva, Switzerland, 26 September 2008 - Addex Pharmaceuticals
(SWX:ADXN) announced today that on September 25, 2008, S.R. One Ltd,
the investment arm of GlaxoSmithKline plc, has informed of reaching
the threshold of 3.0% in the shareholding of Addex Pharmaceuticals
Ltd., holding a total of 175,951 registered shares, corresponding to
3.0% of the voting rights.

About Addex

Addex Pharmaceuticals discovers and develops allosteric modulators
for human health. Allosteric modulators are an emerging class of
orally available small molecule therapeutic agents that we believe
will offer patients better results than classical drugs. Most
marketed drugs bind receptors where the body's own natural molecular
activators (i.e. endogenous ligands) bind, specifically to a key part
of each receptor's anatomy called the "active site". In short, most
drugs must out-compete endogenous ligands for the active site. By
contrast, allosteric modulators are non-competitive because they bind
receptors and modify their function even if the endogenous ligand
also is binding it. In addition, because of this, allosteric
modulators aren't limited to simply turning a receptor on or off, the
way most drugs are. Instead, they act more like a dimmer switch,
offering control over the degree of activation or deactivation, while
offering the body the ability to maintain control over initiating
receptor activation. Furthermore, the allosteric approach generally
affords freedom to operate - even on well-known, clinically validated
targets - because the intellectual property surrounding allosteric
chemistry and the allosteric sites on receptors is most often
un-exploited.

ADX10059, our most advanced product, is an mGluR5 NAM (metabotropic
glutamate receptor 5 negative allosteric modulator). It has
demonstrated clinically and statistically significant efficacy in
separate Phase IIa clinical trials in gastroesophageal reflux disease
(GERD) patients and migraine headache patients and has potential in
Parkinson's disease and other indications.

The Addex allosteric modulation discovery and development platform
have been additionally validated through three seperatate product
license or collaboration agreements with Merck & Co., Inc. and
Johnson & Johnson as well as an investment by Roche Ventures.

Contact

Chris Maggos
Head of IR & Communications
Addex Pharmaceuticals
+41 22 884 15 11
chris.maggos@addexpharma.com

Disclaimer
The foregoing release may contain forward-looking statements that can
be identified by terminology such as "not approvable", "continue",
"believes", "believe", "will", "remained open to exploring", "would",
"could", or similar expressions, or by express or implied discussions
regarding Addex Pharmaceuticals Ltd, its business, the potential
approval of its products by regulatory authorities, or regarding
potential future revenues from such products. Such forward-looking
statements reflect the current views of Addex Pharmaceuticals Ltd
regarding future events, future economic performance or prospects,
and, by their very nature, involve inherent risks and uncertainties,
both general and specific, whether known or unknown, and/or any other
factor that may materially differ from the plans, objectives,
expectations, estimates and intentions expressed or implied in such
forward-looking statements. Such may in particular cause actual
results with allosteric modulators of mGluR2, mGluR4, mGluR5, mGluR7
or other therapeutic targets to be materially different from any
future results, performance or achievements expressed or implied by
such statements. There can be no guarantee that allosteric modulators
of mGluR2, mGluR4, mGluR5, mGluR7 will be approved for sale in any
market or by any regulatory authority. Nor can there be any guarantee
that allosteric modulators of mGluR2, mGluR4, mGluR5, mGluR7 or other
therapeutic targets will achieve any particular levels of revenue (if
any) in the future. In particular, management's expectations
regarding allosteric modulators of mGluR2, mGluR4, mGluR5, mGluR7 or
other therapeutic targets could be affected by, among other things,
unexpected actions by our partners, unexpected regulatory actions or
delays or government regulation generally; unexpected clinical trial
results, including unexpected new clinical data and unexpected
additional analysis of existing clinical data; competition in
general; government, industry and general public pricing pressures;
the company's ability to obtain or maintain patent or other
proprietary intellectual property protection. Should one or more of
these risks or uncertainties materialize, or should underlying
assumptions prove incorrect, actual results may vary materially from
those anticipated, believed, estimated or expected. Addex
Pharmaceuticals Ltd is providing the information in this press
release as of this date and does not undertake any obligation to
update any forward-looking statements contained in this press release
as a result of new information, future events or otherwise, except as
may be required by applicable laws.
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