Exhibit 10.36

AMENDMENT NO. 2

TO THE TOLL MANUFACTURING AGREEMENT

This Amendment No. 2 (the “Amendment”), effective September 17, 2009, is by and
between Arena Pharmaceuticals GmbH (“Arena”) and Siegfried Ltd. (“Siegfried”),
and modifies the Toll Manufacturing Agreement, dated January 7, 2008, as
amended, by and between Arena and Siegfried (the “Agreement”). All capitalized
terms used herein and not otherwise defined shall have the meanings set forth in
the Agreement.

WHEREAS, subject to the concurrent amendment of the Technical Services Agreement
between Arena and Siegfried, dated January 7, 2008, the Parties wish to amend
the Agreement as stated in this Amendment.

NOW, THEREFORE, in consideration of the promises and the mutual covenants set
forth herein, the receipt and sufficiency of which are hereby acknowledged, the
Parties agree as follows:

1. The last sentence of Section 2.1 paragraph 1 shall be replaced with the
following sentence:

“Until December 31, 2010, SIEGFRIED shall use its reasonable commercial effort
to order from ARENA such quantity of products as is necessary for ARENA’s
personnel to maintain its manufacturing skills.”

2. Section 2.6 shall be replaced with the following text:

“Term. This Agreement is entered into for indefinite period of time. This entire
Agreement may be terminated by either Party upon giving 18 months prior notice
at any time after the Effective Date, in a Party’s discretion and for any reason
or for no reason, with an effective termination date no earlier than
December 31, 2010. As from December 31, 2010, either Party may terminate this
Agreement upon giving six (6) months prior notice at any time, in a Party’s
discretion and for any reason or for no reason, with an effective termination
date no earlier than June 30, 2011. In addition, upon giving the number of
months notice as specified in Appendix A, ARENA shall be entitled to terminate
its obligations with regard to certain Products effective on or after
December 31, 2010; with regard to Gabitril, however, effective on or after
August 11, 2012 only, and with regard to Idebenon effective on or after
December 31, 2012 only (provided the foregoing obligation is subject to the last
sentence of the first paragraph of Section 3.1). In the event ARENA’s
obligations are terminated with regard to certain Product(s) and not with regard
to the entire Agreement, the maximum quantities of remaining Products that
SIEGFRIED may order per Appendix B shall be reduced based on the most recent 12
months forecast issued before the termination is communicated to SIEGFRIED.
SIEGFRIED’s continued performance under the Technical Services Agreement between
ARENA and SIEGFRIED dated January 7, 2008, as amended (the “TSA”), if so
requested by ARENA, is a condition precedent to ARENA’s continued performance
under this Agreement after December 31, 2010. If ARENA is asked to manufacture
validation lots of Product(s) under this Agreement, the standard cost and any
additional costs for relevant Services of Arena for such lots must be agreed in
advance between the parties.”

3. With effect as of January 1, 2011:

(i) the last column in Appendix A (“Termination period / months”) shall mention
a period of six (6) months only; and

(ii) Section 3.7 and Appendix B1 shall be deleted in their entirety;

(iii) the following language is hereby added to the end of Appendix B: For each
year after 2011, unless otherwise agreed by the Parties in advance, the maximum
quantities of Products shall match twice the preceding year’s quantity.

4. With effect as of January 1, 2011, Appendix F shall be deleted and paragraphs
2 though 4 of Section 6.2 shall be replaced by the following text:

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“The Standard Prices charged to Siegfried shall be the actual costs generated in
SAP, as agreed upon by the parties, subject to increase as a result of
inflation. For the years following 2011, the Swiss consumer price index shall
govern the inflation rate applied to the Standard Prices, with Standard Prices
increased by the inflation from (i) November of the penultimate year prior to
the year for which the Standard Prices are to be computed, to (ii) November of
the year before the year for which the Standard Prices are to be computed. For
example, to calculate any increase to the Standard Prices for 2012, inflation
would be measured between November 2010 through November 2011. Such adjustments
to Standard Prices due to inflation shall be performed within the SAP system by
Siegfried, provided Arena shall be consulted in advance as to the calculations
and provided written support for the calculations. For clarity, any increases in
ARENA’s costs pursuant to the terms of the TSA will be reflected in the
calculation of the Standard Prices.”

5. The following sentence shall be added to the end of the first paragraph of
Section 5.3:

“The Product forecast of July 2010 shall cover the entire year 2011, whereby the
forecast for the second half of 2011 shall as well be for planning purposes
only.”

6. Unless otherwise specifically amended herein, all of the terms and conditions
of the Agreement shall remain in full force and effect. The Agreement, as
amended hereby, constitutes and contains the entire agreement of the Parties and
supersedes any and all prior negotiations, correspondence, understandings,
letters of intent and agreements between the Parties respecting the subject
matter hereof. The Agreement may be amended or modified, or one or more
provisions hereof may be waived, only by written instrument signed by the
authorized representatives of the Parties.

7. This Amendment may be executed in multiple counterparts, each of which shall
be considered and shall have the same force and effect of an original.

8. This Amendment shall in all respects be construed and enforced in accordance
with the laws of Switzerland under the exclusion of the UN Convention on
Agreements for the International Sale of Goods (the so-called Vienna
Convention).

IN WITNESS WHEREOF, the undersigned, intending to be legally bound, have
executed, or caused to be duly executed, this Amendment.

 

Siegfried Ltd.     Arena Pharmaceuticals GmbH

By:

  

/s/    Hans–Rudolf Kern

    By:   

/s/    Bernhard Brecht

Name:

   Hans–Rudolf Kern    

Name:

   Bernhard Brecht

Date:

   September 17, 2009    

Date:

   September 17, 2009

By:

  

/s/    A. Richard Bruce

   

By:

  

/s/    Sabine Plaas

Name:

   A. Richard Bruce    

Name:

   Sabine Plaas

Date:

   September 17, 2009    

Date:

   September 17, 2009