Exhibit 24.1

                                POWER OF ATTORNEY

                  KNOW ALL MEN BY THESE PRESENTS,  that the  undersigned  hereby
constitutes and appoints, as of the date hereof, Bud Holman, his true and lawful
attorney-in-fact with full power of substitution, resubstitution and revocation,
for the undersigned and in the  undersigned's  name, place and stead, in any and
all  capacities,  including,  but not limited to, the  undersigned's  individual
capacity and the undersigned's capacity as a member of each of Ridgeback Capital
Investments  Ltd.,  a Cayman  limited  company  ("RCI")  and  Ridgeback  Capital
Management LLC, a Delaware limited  liability  company  ("RCM"),  to execute all
agreements,  certificates,  forms, instruments,  or other documents, and to take
any action, necessary to file: (i) beneficial ownership reports on Schedules 13D
and 13G and Forms 3, 4 and 5 (including  any amendments  thereto,  and including
any  beneficial  ownership  reports  which may in the future be  required by the
Securities  and Exchange  Commission  to be filed  provided that the purpose and
form of such reports is substantially similar to Schedules 13D or 13G or Form 3,
4 or 5) under  the  Securities  Exchange  Act of 1934  with the  Securities  and
Exchange  Commission or any stock exchange or similar  authority,  in connection
with any equity  investments  in  Sheffield  Pharmaceuticals,  Inc. and (ii) all
filings under or pursuant to the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended, and the regulations promulgated thereunder,  including but not
limited to the filing of any  Notification  and Report Form required to be filed
thereunder  and any  affidavits  and notices or other  documents  required to be
delivered in connection therewith, by the undersigned in his individual capacity
and by each of RCI and RCM.

                  In connection with the  appointment of such  attorney-in-fact,
the  undersigned  hereby  grants  unto  said  attorney-in-fact  full  power  and
authority to do and perform  each and every act and thing which,  in the opinion
of such attorney-in-fact,  may be requisite,  necessary, proper or of benefit to
be done in and about the  premises,  as fully to all intents and purposes as the
undersigned  might or could do in person,  thereby  ratifying and confirming all
that said  attorney-in-fact (or  attorney-in-fact's  substitute or substitutes),
may lawfully do or cause to be done by virtue hereof,  it being  understood that
the documents  executed by such  attorney-in-fact  on behalf of the  undersigned
pursuant to this Power of Attorney  shall be in such form and shall contain such
terms and conditions as such attorney-in-fact may approve in his own discretion.
The undersigned acknowledges that the foregoing attorney-in-fact,  in serving in
such  capacity at the request of the  undersigned,  is not  assuming  any of the
undersigned's  or RCI's or RCM's  responsibilities  to comply with Section 13 or
Section 16 of the Securities Exchange Act of 1934.



Dated as of: November 29, 2006                     /s/ Wayne Holman
                                                   -----------------------------
                                                   Wayne Holman