FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * Ridgeback Capital Investments Ltd.   2. Issuer Name and Ticker or Trading Symbol PIPEX PHARMACEUTICALS, INC. [PP] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 430 PARK AVENUE, 12TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 11/09/2007 (Street) NEW YOR,, NY 10022 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 11/09/2007   X   618,855 A $ 0.74 1,856,565 (1) D

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Warrants (right to buy)

$ 0.74

11/09/2007

X

618,855

11/22/2006

11/22/2011

Common Stock

618,855

$ 0

0

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Ridgeback Capital Investments Ltd. 430 PARK AVENUE 12TH FLOOR NEW YOR,, NY 10022		X
Ridgeback Capital Management LLC 430 PARK AVENUE 12TH FLOOR NEW YORK, NY 10022		X
Holman Wayne George 430 PARK AVENUE 12TH FLOOR NEW YORK, NY 10022		X

Signatures

/s/ Bud Holman, as Attorney-in-Fact		11/13/2007
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Wayne Holman and Ridgeback Capital Management LLC ("RCM") do not own any securities directly. Pursuant to an investment management agreement, RCM maintains investment and voting power with respect to the securities held by Ridgeback Capital Investments Ltd. ("RCI"). Wayne Holman controls RCM. Both Wayne Holman and RCM disclaim beneficial ownership of any of the securities covered by this statement except to the extent of any pecuniary interest therein. The Issuer was formerly known as Sheffield Pharmaceuticals Inc. The share information reported herein reflects a 1-for-3 reverse stock split.

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