Addex ADX48621 Positive Primate Parkinson's Data

Geneva, Switzerland, 24 November 2009 - Addex Pharmaceuticals
(SWX:ADXN), the allosteric modulation company, announced today that
in a non-human primate model of Parkinson's disease (PD) levodopa
induced dyskinesia (LID), ADX48621 statistically and significantly
inhibited LID. More specifically, the compound inhibited dose
dependently both chorea and dystonia, the two major components of
LID, without affecting the beneficial effects of levodopa. There is
currently no approved treatment available for PD-LID. ADX48621 is a
metabotropic glutamate receptor 5 (mGluR5) negative allosteric
modulator (NAM) that has completed Phase I testing and is scheduled
to start Phase IIa testing in Parkinson's disease next year.

In the non-human primate MPTP model of PD-LID, the highest dose of
ADX48621 (30mg/kg) abolished LID over the course of the experiment
and a dose response was observed during the first two hours, reaching
statistical significance for the highest dose tested. Importantly,
statistically significant reductions were seen for both chorea and
dystonia in a dose dependent fashion.

Addex reported earlier this year that when tested in a rat model,
oral administration of ADX48621 dose-dependently reversed the
catalepsy induced by haloperidol in three independent experiments.
These data indicate that ADX48621 has potential as a treatment for
Parkinsonian symptoms as well as LID symptoms.

Although other drug candidates have shown some efficacy on chorea,
similar effects on dystonia have not previously been reported in this
model with drug-like molecules either in development or on the
market, (except with ADX10059, another mGluR5 NAM from Addex).
ADX48621 is a next-stage mGluR5 NAM, which was generated from a
separate chemical scaffold than ADX10059; both mGluR5 NAM have
similar selectivity and activity at the target receptor. Addex' lead
product ADX10059 is in Phase IIb development for gastroesophageal
reflux disease (GERD) and migraine prevention. Addex plans to move
ADX48621 forward in PD-LID, PD and dystonia.

PD is a degenerative disease of the brain that often impairs motor
skills, speech, and other functions. It is estimated that 60,000 new
cases are diagnosed each year in the U.S., where more than 1.5
million people currently have PD. While the condition usually
develops after the age of 65, 15% of those diagnosed are under 50. PD
affects both men and women in almost equal numbers.

PD-LID develops in most PD patients after receiving levodopa for
several years. It is a complication caused by dopamine replacement
therapy (i.e. levodopa). The two main components of LID are chorea
and dystonia. Chorea is manifest as abnormal involuntary movements.
Dystonia is a neurologic movement disorder characterized by sustained
muscle contractions that frequently cause twisting or repetitive
movements and abnormal, sometimes painful, postures or positions.
Currently there are an estimated 1.2 million patients with PD-LID in
the U.S.
mGluR5 inhibition reduces signaling activity of the neurotransmitter
glutamate. Marketed blockbuster drugs treat multiple indications by
targeting other types of neurotransmitter signaling, including
selecitive serotonin reuptake inhibitors (SSRIs) used to treat
depression and dopamine receptor inhibitors used to treat
schizophrenia. The rationale for using mGluR5 inhibition in PD is
that the loss of dopamine producing cells leads to excess
glutamatergic stimulation in the brain's "striatopallidal pathway".
mGluR5 are found abundantly in the striatum and are implicated in the
excess glutamate activity in Parkinson's Disease. Research shows that
inhibition of glutamate stimulation in this pathway has generated
anti-Parkinsonian effects in animal models of PD and PD-LID and in
humans with PD-LID.

Addex Pharmaceuticals (www.addexpharma.com) discovers and develops
allosteric modulators for human health. Allosteric modulators are a
different kind of orally available small molecule therapeutic agent,
which we believe will offer a competitive advantage over classical
drugs. Our lead allosteric modulator product, ADX10059, has achieved
clinical proof of concept and is in Phase IIb testing for the
treatment of GERD and, separately, migraine headache. ADX10059 is a
first-in-class mGluR5 inhibitor, a therapeutic strategy that also is
being pursued in multiple indications by large pharma competitors.
Our products and technology already have proven their value through
our relationships with four of the top 10 pharmaceutical companies in
the world. Specifically, under an agreement with Ortho-McNeil-Janssen
Inc., a Johnson & Johnson company, ADX71149, a positive allosteric
modulator (PAM) of mGluR2, is undergoing Phase I clinical testing and
has potential for treatment of schizophrenia and anxiety. Under two
separate agreements with Merck & Co., Inc., we are developing PAMs of
mGluR4 and mGluR5 as drugs to treat Parkinson's disease and
schizophrenia, respectively. In addition, GlaxoSmithKline and Roche
have made equity investments in Addex.

Chris Maggos
Investor Relations & Communications
Addex Pharmaceuticals
+41 22 884 15 11
chris.maggos@addexpharma.com

Disclaimer: The foregoing release contains 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, and involve
known and unknown risks, uncertainties and other factors that may
cause actual results with allosteric modulators of mGluR4, mGluR2,
mGluR5 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 mGluR4, mGluR2 or mGluR5 will be approved for sale in
any market or by any regulatory authority. Nor can there be any
guarantee that allosteric modulators of mGluR4, mGluR2, mGluR5 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 mGluR4, mGluR2,
mGluR5 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 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.

This announcement was originally distributed by Hugin. The issuer is
solely responsible for the content of this announcement.

SOURCE: Addex Pharmaceuticals

For full details on (ADDXF) ADDXF. (ADDXF) has Short Term PowerRatings at TradingMarkets. Details on (ADDXF) Short Term PowerRatings is available at This Link.