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                                                                  Exhibit 10.12


                           JOINT DEVELOPMENT AGREEMENT


                  JOINT DEVELOPMENT AGREEMENT, dated as of March 20, 2002
(this "AGREEMENT"), by and between HEXAL A.G., a German company ("HEXAL"),
and EON LABS, INC., a Delaware corporation ("EON").

                              W I T N E S S E T H :

                  WHEREAS, Hexal and its Affiliates and Eon are currently
developing Technology jointly and desire to continue to cooperate jointly to
develop such Technology.

                  WHEREAS, Hexal and its Affiliates and Eon desire to set
forth each other's right, title and interest in and to the Technology.

                  NOW, THEREFORE, for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties agree
as follows:

SECTION 1. DEFINITIONS

                  "Affiliate" with respect to any Person, shall mean any
Person or entity, directly or indirectly controlling, controlled by or under
common control with such Person.

                  "Confidential Information" shall mean any confidential
technical data, trade secrets, know-how or other confidential information
disclosed by any party hereunder in writing, orally, or by drawing or other
form.

                  "Exploitation Rights" shall mean the right to manufacture,
distribute, market, sell, license, sublicense, use or otherwise exploit the
Technology.

                  "Person" shall mean an individual, partnership, joint-stock
company, corporation, limited liability company, trust or unincorporated
organization, and a government or agency or political subdivision thereof.

                  "Products" shall mean the three (3) generic transdermal
patch delivery products.

                  "Proprietary Rights" shall mean any and all technical
information, including, without limitation, all inventions, all improvements
thereto, research, computer software, data, formulas, compositions,
specifications, know-how, drawings, details, blue prints, technical
descriptions, dimensions, part lists, supplier lists, processes, methods, and
procedures.

                  "Technology" shall mean the Products and any Proprietary
Rights now or in the future conceived, created, made or developed jointly by
Hexal and Eon in the course of the development of the Products.

                  "Territory" shall mean the United States.

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SECTION 2. OWNERSHIP RIGHTS

         2.1.     All Confidential Information of either party which has been
provided to the other party in the course of the development of the Products
shall continue to belong to such providing party.

         2.2.     All Proprietary Rights owned solely by Hexal or its
Affiliates and provided to Eon in the course of the development of the
Products shall belong exclusively to Hexal. All Proprietary Rights owned
solely by Eon and provided to Hexal in the course of the development of the
Products shall belong exclusively to Eon.

SECTION 3. EXPLOITATION RIGHTS

         3.1.     The Parties agree that, subject to securing approval of an
Abbreviated New Drug Application for each of the Products from the United
States Food and Drug Administration (the "FDA"), Eon shall have exclusive
Exploitation Rights for each Product throughout the Territory, and the
Parties shall negotiate in good faith to reach an agreement as soon as
practicable, and in any case no later than promptly following the receipt of
approval from the FDA for each Product, regarding any payments to be made by
Eon to Hexal with respect to Eon's exercise of its Exploitation Rights with
respect to that Product.

         3.2.     The Parties agree that Hexal shall have exclusive
Exploitation Rights with respect to each Product outside the Territory.

SECTION 4. RESTRICTIVE COVENANTS

         4.1.     ASSIGNMENT. Neither party may assign its rights in and to
the Technology or its rights granted hereunder without the prior written
consent of the other party which may not be unreasonably withheld.

SECTION 5. DISCLOSURE OF TECHNOLOGY

         5.1.     Hexal shall communicate promptly and disclose to Eon the
Technology, including all supporting information, details and data, and Hexal
shall execute and deliver to Eon such formal transfers and assignments and
such other papers and documents as may be necessary or required of Hexal to
vest joint ownership of the Technology in Eon.

         5.2.     Eon shall communicate promptly and disclose to Hexal the
Technology, including all supporting information, details and data, and Eon
shall execute and deliver to Hexal such formal transfers and assignments and
such other papers and documents as may be necessary or required of Hexal to
vest joint ownership of the Technology in Hexal.

SECTION 6. CONFIDENTIALITY.

         6.1.     NONDISCLOSURE. The receiving party agrees that it will not
disclose any Confidential Information to any third party, except that Hexal may
disclose Confidential Information to its Affiliates for purposes relating to
this Agreement provided that they shall hold such information in confidence, and
will not use Confidential Information of the disclosing party for any purpose

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other than for the performance of the rights and obligations hereunder during
the term of this Agreement and for a period of five (5) years thereafter,
without the prior written consent of the disclosing party. The receiving
party further agrees that Confidential Information shall remain the sole
property of the disclosing party and that it will take all reasonable
precautions to prevent any unauthorized disclosure of Confidential
Information by its employees. No license shall be granted by the disclosing
party to the receiving party with respect to Confidential Information
disclosed hereunder unless otherwise expressly provided herein.

         6.2.     RETURN OF CONFIDENTIAL INFORMATION. Upon the request of the
disclosing party, the receiving party will promptly return all Confidential
Information furnished hereunder and all copies thereof.

SECTION 7. MISCELLANEOUS

         7.1.     AGENCY; JOINT VENTURE. The Parties agree that this
Agreement is not intended to create any employment, agency or subcontractor
relationships of any kind between the Parties. Nothing contained in this
Agreement shall constitute or be construed to be or create a partnership or
joint venture between the Parties hereto.

         7.2.     FURTHER ASSURANCES. In case at any time after the date
hereof any further action is necessary to carry out the purposes of this
Agreement, each of the Parties will take such further action (including the
execution and delivery of such further instruments and documents) as the
other party reasonably may request.

         7.3.     THIRD-PARTY BENEFICIARIES. This Agreement shall not confer
any rights or remedies upon any person other than the Parties and their
respective successors and permitted assigns.

         7.4.     TERMINATION. This Agreement shall terminate five (5) years
upon execution unless otherwise terminated beforehand upon the mutual written
consent of the Parties.

         7.5.     PARAGRAPHS AND SECTION HEADINGS. The headings of the
sections and subsections of this Agreement are inserted for convenience only
and shall not be deemed to constitute a part thereof.

         7.6.     NOTICES

                  (a)      All communications under this Agreement shall be
in writing and shall be delivered by hand or facsimile or mailed by overnight
courier or by registered or certified mail, postage prepaid:

                  (i)      if to Hexal, at Industriestrasse 25, 83607
                           Holzkirchen, Germany, marked for the attention of
                           Thomas Strungmann, facsimile +49 8024 908 116, or at
                           such other address as Hexal may have furnished Eon in
                           writing; and

                  (ii)     if to Eon, at 227-15 North Conduit Avenue, Laurelton,
                           New York, 11413, marked for the attention of
                           President, (facsimile: (718) 276-1735), or at such
                           other address as Eon may have furnished Hexal in
                           writing.

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                  (b)      Any notice so addressed shall be deemed to be
given: if delivered by hand or facsimile, on the date of such delivery; if
mailed by courier, on the first business day following the date of such
mailing; and if mailed by registered or certified mail, on the third business
day after the date of such mailing; except in case of common proof of late
arrival of such notice.

         7.7.     GOVERNING LAW; VENUE. This Agreement shall be governed by
and construed in accordance with the laws of Germany. Jurisdiction for
disputes brought under this Agreement shall be Landgericht Muenchen II.

         7.8.     SUCCESSORS AND ASSIGNS. This Agreement shall inure to the
benefit of and be binding upon the successors and assigns of each of the
Parties.

         7.9.     ENTIRE AGREEMENT; AMENDMENT AND WAIVER. This Agreement
constitutes the entire understandings of the Parties hereto and supersedes
all prior agreements, understandings, or representations with respect to the
subject matter hereof among such Parties. This Agreement may be amended, and
the observance of any term of this Agreement may be waived, with (and only
with) the written consent of Hexal and Eon.

         7.10.    SEVERABILITY. In the event that any part or parts of this
Agreement shall be held illegal or unenforceable by any court or
administrative body of competent jurisdiction or otherwise by law, such
determination shall not effect the remaining provision of this Agreement
which shall remain in full force and effect.

         7.11.    COUNTERPARTS. This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original all of which together
shall be considered one and the same Agreement.

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                  IN WITNESS WHEREOF, Hexal and Eon have caused this
Technology Agreement to be duly executed and delivered as of the date first
above written.

                              HEXAL A.G.


                              By: /s/ Thomas Strungmann
                                 -----------------------------------------------
                                   Name:  Thomas Strungmann
                                   Title: Co-President and Co-Chief Executive
                                          Officer


                              EON LABS, INC.


                              By: /s/ Bernhard Hampl, Ph.D.
                                 -----------------------------------------------
                                   Name:  Bernhard Hampl, Ph.D.
                                   Title: President and Chief Executive Officer

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