Filed by Enzon Pharmaceuticals, Inc.

                                    Pursuant to Rule 425 under the
                                    Securities Act of 1933 and deemed filed
                                    pursuant to Rule 14a-12 of the
                                    Securities Exchange Act of 1934

                                    Commission File No. 000-12957

                                    Subject Company: Enzon Pharmaceuticals, Inc.
                                                     NPS Pharmaceuticals, Inc.

The following letter was sent to employees of Enzon Pharmaceuticals, Inc.
("Enzon") on February 20, 2003 in connection with the announcement of the
proposed business combination between NPS Pharmaceuticals, Inc. and Enzon.


                                                                Interoffice Memo
================================================================================

TO:      Enzon Employees

FROM:    Arthur Higgins

DATE:    February 20, 2003

RE:      Enzon's Merger with NPS Pharmaceuticals

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

Earlier this morning, Enzon and NPS Pharmaceuticals, announced a merger of
equals. Together, the two companies will become one new entity, a biotechnology
leader that blends science, pipeline, and products. The new executive management
team of the combined company will include myself, Ken Zuerblis, Uli Grau, as
well as additional individuals from both Enzon's and NPS's top management. Over
the course of the next few weeks, the new management will spend time
communicating the transaction and the benefits of our new company to various
constituencies.

As has always been the case with Enzon, our combined company will continue to
place our employees as our most valued asset; it is all of you who bring such
promise to this merger. This morning at 10:00 am EST, NPS's Chairman, Hunter
Jackson and myself will be hosting a webcast. I invite all of you listen to this
discussion which can be accessed at WWW.VIDEONEWSWIRE.COM/NEWCO/022003 or via
phone by dialing 1-800-231-5571 or (973)- 582- 2703. We will also be setting up
the meeting/board rooms at our New Jersey and Indianapolis facilities to
broadcast this webcast, and members of our senior management team will be
available for questions following the webcast. My apologies for being unable to
attend, however, I will personally share the potential bringing these two
companies together has for you, our partners, and the biotechnology industry, at
a future date. Meanwhile, Ralph del Campo will hold an employee forum today in
Indianapolis immediately following the webcast. Uli Grau, Paul Davit, Clarke
Atwell and Eric Liebler will hold an employee forum in the cafeteria at the
Piscataway facility at 10:30 am EST, on Friday February 21st, for the associates
at 20 P, 300 C and Bridgewater. Friday's presentation will also be webcast to
provide the sales force the opportunity to listen to the presentation via the
internet at www.videonewswire.com/newco/022103 or via phone by dialing
1-888-277-8636 or (973)- 582- 2729.

In advance of these meetings I wanted to point out some of the key highlights of
this merger and answer some of the more immediate questions that might come to
mind:

         o        We are now positioned to be a biotechnology leader with a
                  deep, diversified pipeline of discovery and clinical stage
                  products, with a clearly defined path to clinical and
                  commercial success

         o        We boast a commercial infrastructure that will allow us to
                  extract maximum value from our R&D efforts

         o        We are a financially strong and fully funded biotech company
                  with a commitment to profitability, a strong balance sheet and
                  the resources to independently capitalize on, and create,
                  opportunity for our employees, our partners and our
                  shareholders



         o        We are a biotech company with a seasoned management team and a
                  talented team of employees totaling about 500 people, that
                  combines extensive pharmaceutical and business experience with
                  a wealth of drug discovery and development expertise giving us
                  a competitive advantage in the marketplace

Questions you may have:

         o        Could this affect my job? In most cases, your job will not
                  change. Importantly, the merger logic is about growth and the
                  coming together of two strong organizations to create an
                  exciting future.

         o        What is the new management structure? For the vast majority of
                  you, there will not be any change in reporting structure. I
                  will be the CEO of the new company and Hunter Jackson,
                  currently the CEO of NPS, will be the Executive Chairman. We
                  will both report to the Board of Directors. Uli Grau will
                  continue as the Head of R&D and Ken Zuerblis will remain CFO
                  for the combined company. The rest of the senior management
                  positions will be announced in the next few months.

         o        What about my compensation, benefits and stock options? The
                  Enzon option plan calls for the acceleration and termination
                  of any outstanding stock options. For most of us, since our
                  options are out of the money, this will have no impact. For
                  those who have options that remain valuable, you will have to
                  exercise those options prior to the closing of the merger. HR
                  will be in touch to assist you with this process. All
                  employees will receive a new grant of options in the new
                  entity so that we can participate in the growth and success of
                  our new company. With regards to benefits, they will stay the
                  same for the remainder of 2003 and a new plan will be rolled
                  out in 2004.

         o        What if I have questions about the merger? Please direct any
                  inquiries you may have about the merger to any member of our
                  Corporate Management Committee. We are working hard to
                  communicate with all of our valued employees and will continue
                  to respond to your questions. You can also refer to the press
                  release, which is attached to this email, and any other public
                  documents we have disclosed that are associated with this
                  transaction.

Recently I've said, "our employees will continue to be the force driving our
strategy forward - a united front that is committed to excellence, focused on
results, and looking confidently ahead - eager to build one of the most
successful and fastest growing biotechnology companies." That statement is still
accurate - today's announcement only brings us one step closer to making this
vision a reality.

The Board of Directors, your management team and I, all believe that the
formation of our new company, which will bear a new name, will allow all of us
at Enzon to be a part of something truly remarkable and special. Together we are
a strong force, poised to become one of the true leaders of biotechnology over
the next decade, and I look forward to us all working together with our new
colleagues to make this opportunity a reality.

Cheers!




      Cautionary Statement For The Purpose Of The "Safe Harbor" Provisions
            Of The Private Securities Litigation Reform Act Of 1995

         This letter contains forward-looking statements within the meaning of
the "safe harbor" provisions of the Private Securities Litigation Reform Act of
1995. These statements are based on management's current expectations and
beliefs and are subject to a number of factors and uncertainties that could
cause actual results to differ materially from those described in the
forward-looking statements. The forward-looking statements contained in this
presentation include statements about future financial and operating results and
the proposed NPS/Enzon merger. These statements are not guarantees of future
performance, involve certain risks, uncertainties and assumptions that are
difficult to predict, and are based upon assumptions as to future events that
may not prove accurate. Therefore, actual outcomes and results may differ
materially from what is expressed herein. For example, if either of the
companies do not receive required stockholder or governmental approvals or fail
to satisfy other conditions to closing, the transaction will not be consummated.
In any forward-looking statement in which NPS or Enzon expresses an expectation
or belief as to future results, such expectation or belief is expressed in good
faith and believed to have a reasonable basis, but there can be no assurance
that the statement or expectation or belief will result or be achieved or
accomplished. The following factors, among others, could cause actual results to
differ materially from those described in the forward-looking statements: the
risk that the NPS and Enzon businesses will not be integrated successfully;
costs related to the proposed merger, failure of the NPS or Enzon stockholders
to approve the proposed merger; and other economic, business, competitive and/or
regulatory factors affecting NPS' and Enzon's businesses generally as set forth
in NPS' and Enzon's filings with the SEC, including their Annual Reports on Form
10-K for their respective most recent fiscal years, especially in the
Management's Discussion and Analysis section, their most recent Quarterly
Reports on Form 10-Q and their Current Reports on Form 8-K. NPS and Enzon are
under no obligation to (and expressly disclaim any such obligation to) update or
alter their forward-looking statements whether as a result of new information,
future events or otherwise.

                                      ***



                   Additional Information And Where To Find It
                   -------------------------------------------

         In connection with the proposed NPS/Enzon merger, NPS, Enzon and
Momentum Merger Corporation (which will be renamed by NPS and Enzon in
connection with the proposed merger) intend to file a joint proxy
statement/prospectus with the Securities and Exchange Commission (the "SEC") in
connection with the transaction described herein. INVESTORS AND SECURITY HOLDERS
ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS WHEN IT BECOMES AVAILABLE
BECAUSE IT WILL CONTAIN IMPORTANT INFORMATION ABOUT THE TRANSACTION DESCRIBED
HEREIN. Investors and security holders may obtain a free copy of the joint proxy
statement/prospectus (when it is available) and other documents filed by NPS and
Enzon with the SEC at the SEC's web site at WWW.SEC.GOV or by contacting NPS at
801-583-4939 and through NPS' website at WWW.NPSP.COM, or by contacting Enzon at
908-541-8678 and through Enzon's website at www.enzon.com.

         NPS and its directors and executive officers may be deemed to be
participants in the solicitation of proxies from the stockholders of NPS and
Enzon in connection with the transaction described herein. Information regarding
the special interests of these directors and executive officers in the
transaction described herein will be included in the joint proxy
statement/prospectus described above. Additional information regarding these
directors and executive officers is also included in NPS' proxy statement for
its 2002 Annual Meeting of Stockholders, which was filed with the SEC on or
about April 19, 2002. This document is available free of charge at the SEC's web
site at www.sec.gov or by contacting NPS at 801-583-4939 and through NPS'
website at [WWW.NPSP.COM]

         Enzon and its directors and executive officers also may be deemed to be
participants in the solicitation of proxies from the stockholders of Enzon and
NPS in connection with the transaction described herein. Information regarding
the special interests of these directors and executive officers in the
transaction described herein will be included in the joint proxy
statement/prospectus described above. Additional information regarding these
directors and executive officers is also included in Enzon's proxy statement for
its 2002 Annual Meeting of Stockholders, which was filed with the SEC on or
about October 28, 2002. This document is available free of charge at the SEC's
web site at www.sec.gov or by contacting Enzon at 908-541-8678 and through
Enzon's website at www.enzon.com.