Sec Form 4 Filing - CHU MAY @ IMPAX LABORATORIES INC - 2005-03-02

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 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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1. Name and Address of Reporting Person CHU MAY 2. Issuer Name and Ticker or Trading Symbol IMPAX LABORATORIES INC [ IPXL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Sr. VP Quality Affairs (Last) (First) (Middle) C/O IMPAX LABORATORIES, INC., 30831 HUNTWOOD AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 03/02/2005 (Street) HAYWARD, CA94544 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 Purchase common stock through Employee Stock Purchase Plan 03/02/2005 03/02/2005 P 139 A $ 14.3565 55,427 D Common stock 83,027 I Owned by spouse

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Option to buy common stock $ 0.75 09/09/1997( 1 ) 09/09/2006 Common stock 13,373 13,373 D Option to buy common stock $ 0.75 04/02/2000( 2 ) 04/02/2009 Common stock 46,716 46,716 D Option to buy common stock $ 5.25 08/01/2001( 3 ) 08/01/2010 Common stock 16,000 16,000 D Option to buy common stock $ 5.625 12/19/2001( 4 ) 12/19/2010 Common stock 15,000 15,000 D Option to buy common stock $ 6.72 03/08/2003( 5 ) 03/08/2012 Common stock 30,000 30,000 D Option to buy commmon stock $ 3.04 03/10/2004( 6 ) 03/10/2013 Common stock 20,000 20,000 D Option to buy common stock $ 23.05 04/14/2005( 7 ) 04/14/2014 Common stock 25,000 25,000 D Option to buy common stock $ 20.78 06/25/2005( 8 ) 06/25/2014 Common stock 10,000 10,000 D Option to buy common stock $ 5.25 08/01/2001( 9 ) 08/01/2010 Common stock 20,000 20,000 I Spouse's option Option to buy common stock $ 5.625 12/19/2001( 10 ) 12/19/2010 Common stock 20,000 20,000 I Spouse's option Option to buy common stock $ 6.72 03/08/2003( 11 ) 03/08/2012 Common stock 20,000 20,000 I Spouse's option Option to buy common stock $ 3.04 03/10/2004( 12 ) 03/10/2013 Common stock 25,000 25,000 I Spouse's option Option to buy common stock $ 22.15 05/29/2005( 13 ) 05/29/2014 Common stock 6,000 6,000 I Spouse's option

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other CHU MAY C/O IMPAX LABORATORIES, INC. 30831 HUNTWOOD AVENUE HAYWARD, CA94544 Sr. VP Quality Affairs Signatures May Chu 03/02/2005 Signature of Reporting Person Date

Explanation of Responses:

( 1 )100% vested - effective 4 years from date of grant (09/09/1996) ( 2 )100% vested - effective 4 years from date of grant (04/02/1999) ( 3 )100% vested - effective 4 years from date of grant (08/01/2000) ( 4 )100% vested - effective 4 years from date of grant (12/19/2000) ( 5 )Vesting over 4 years from date of grant (03/08/2002) in equal installments of 25% annually ( 6 )Vesting over 4 years from date of grant (03/10/2003) in equal installments of 25% annually ( 7 )Vesting over 4 years from date of grant (04/14/2004) in equal installments of 25% annually ( 8 )Vesting over 4 years from date of grant (06/25/2004) in equal installments of 25% annually ( 9 )100% vested - effective 4 years from date of grant (08/01/2000) ( 10 )100% vested - effective 4 years from date of grant (12/19/2000) ( 11 )Vesting over 4 years from date of grant (03/08/2002) in equal installments of 25% annually ( 12 )Vesting over 4 years from date of grant (03/10/2003) in equal installments of 25% annually ( 13 )Vesting over 4 years from date of grant (05/29/2004) in equal installments of 25% annually

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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).

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