Exhibit 10.2

AMENDMENT NO. 4

TO THE TOLL MANUFACTURING AGREEMENT

This Amendment No. 4 (the “Amendment”), effective as of January 1, 2011, 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.

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. Sections 6.2(ii) and (iii) are amended and restated in their entirety as
follows:

“(ii) The Sales Prices charged to SIEGFRIED, on a stock keeping unit
(hereinafter “SKU”) by SKU basis for each Product, shall be agreed upon in
writing from time to time by the Parties. The Parties are aware that the prices
in years subsequent to 2011 may decrease as a result of e.g. improved cost
structures, or increase as a result of increased direct costs. Not later than
November 30, 2011 (and November 30 of subsequent years, if applicable),
SIEGFRIED will propose Sales Prices for the following calendar year, on a SKU by
SKU basis, for consideration by ARENA. The Parties shall discuss and agree upon
pricing for the following year not later than December 31, 2011 (and December 31
of subsequent years, if applicable).

(iii) With respect to this Section 6.2(iii), the term “Main Products” shall
refer to Felodipine, Fluoxetine, Doxazosine, Nifedipine, Selegilin and Rhefluin.
Notwithstanding anything to the contrary herein, for Main Products manufactured
during the period beginning January 1, 2011 and ending on June 30, 2012, the
prices charged by ARENA shall be equal to the Sales Price for the Product,
reduced by (1) 20% for bulk Products and (2) 40% for packaged Products (price
without bulk part, whereby bulk part carries discount of 20%). The Parties may
mutually agree to extend such discounted pricing after June 30, 2012, and/or
that additional Products be included as Main Products hereunder; any such
agreement must be in writing by amendment to this Agreement.”

2. A new part (v) to Section 6.2 is hereby added as follows:

“(v) An adjustment to the Sales Price for each Product in packaged form that is
ordered (one SKU, in one order, for delivery on one date) shall be applied to
invoices for such Product where the volumes are less than 1,500 packages of the
Product or greater than 9,000 packages of the Product. For such orders of less
than 1,500 packages of a Product, the Sales Price will be increased by 30%
(after reduction under Section 6.2(iii), if applicable). For such orders of
greater than 9,000 packages of a Product, the Sales Price will be decreased by
10% (after reduction under Section 6.2(iii), if applicable). This Section 6.2(v)
does not apply to orders for bulk Products.”

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3. Unless otherwise specifically amended herein, all of the terms and conditions
of the Agreement shall remain in full force and effect.

4. 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.

5. This Amendment shall be governed by 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/ Daniel Müller

Name:  

Hans-Rudolf Kern

    Name:  

Daniel Müller

Date:  

May 19, 2011

    Date:  

May 19, 2011

By:  

/s/ Hubert Stückler

    By:  

/s/ Bernhard Brecht

Name:  

Hubert Stückler

    Name:  

Bernhard Brecht

Date:  

May 25, 2011

    Date:  

May 18, 2011