Exhibit 10.1

March 30, 2008

Michel de Rosen

407 Pugh Road

Wayne, PA 19087

Dear Michel,

In connection with your resignation as Chief Executive Officer and President of
ViroPharma Incorporated (the “Company”), the terms of the option agreements (the
“Option Agreements”) granted to you while an employee of the Company provide
that such Option Agreements shall terminate ninety (90) days following your
termination of employment. As a recognition of your continuing service to the
Company, the Company hereby amends the Option Agreements listed on Schedule A
hereto (the “Amended Options”) to provide that for as long as you continue to
serve as a member of the Board of Directors of the Company or any subsidiary, or
as an advisor or consultant of the Company or any subsidiary (an “Eligible
Person”), other than as a result of death or Disability (as defined in the
Option Agreement), the Amended Options shall remain outstanding and

 

  (i) to the extent the Amended Options are vested, they shall remain
exercisable; and

 

  (ii) to the extent the Amended Options are not vested, they shall continue to
vest pursuant to the terms set forth in each such option agreement;

provided however; that the term set forth in each Amended Option shall remain in
effect and shall not be modified.

In addition, as a result of the amendments, all of the Amended Options shall be
nonstatutory stock options and shall no longer qualify as Incentive Stock
Options within the meaning of section 422 of the Code, or to otherwise qualify
for any special tax benefits to you.

Thank you for your service to the Company as Chief Executive Officer and
President, we look forward to your continued service as Chairman of the Board of
Directors.

--------------------------------------------------------------------------------

Very truly yours,

/s/ Vincent J. Milano

Vincent J. Milano

Agreed and Acknowledged:

 

/s/ Michel de Rosen

Michel de Rosen

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Schedule A

Incentive Stock Options

 

Grant Date

   Options
Granted    Price    Vested    Unvested

8/21/2000

   18,932    $ 21.125    18,932    0

1/1/2001

   5,003    $ 14.125    5,003    0

7/24/2001

   1,000    $ 29.37    1,000    0

1/14/2002

   4,960    $ 20.16    4,960    0

4/16/2002

   1    $ 3.93    1    0

10/10/2002

   3    $ 0.99    3    0

1/21/2005

   30,000    $ 3.14    0    30,000

6/21/2005

   822    $ 7.05    0    822

1/17/2006

   5,068    $ 19.73    0    5,068

1/12/2007

   6,561    $ 15.24    0    6,561

1/11/2008

   7,501    $ 9.96    0    7,501

TOTAL

   79,851       29,899    49,952

Non-qualified Stock Options

 

Grant Date

   Options
Granted    Price    Vested    Unvested

6/1/2000

   20,000    $ 12.00    20,000    0

8/21/2000

   261,068    $ 21.125    261,068    0

1/1/2001

   14,997    $ 14.125    14,997    0

7/24/2001

   15,000    $ 29.37    15,000    0

1/14/2002

   15,040    $ 20.16    15,040    0

4/16/2002

   39,999    $ 3.93    39,999    0

10/10/2002

   59,997    $ 0.99    59,997    0

7/22/2003

   33,747    $ 2.09    33,747    0

2/3/2004

   134,876    $ 2.71    134,876    0

1/21/2005

   90,000    $ 3.14    90,000    0

6/21/2005

   79,178    $ 7.05    40,000    39,178

1/17/2006

   74,932    $ 19.73    40,000    34,932

8/3/2006

   80,000    $ 8.71    20,000    60,000

1/12/2007

   68,439    $ 15.24    18,750    49,689

6/15/2007

   68,000    $ 13.97    0    68,000

1/11/2008

   22,499    $ 9.96    0    22,499

TOTAL

   1,077,772       803,474    274,298