Filed by Pfizer Inc.
                           pursuant to Rule 425 under the Securities Act of 1933
                                           and deemed filed pursuant Rule 14a-12
                                          of the Securities Exchange Act of 1934
                                                   Commission File No: 001-02516
                                                Subject Company: Pharmacia Corp.


The following press release was issued today:

For immediate release                                    Contact: Andy McCormick
October 22, 2002                                         (212) 573-1226


                   PFIZER JOINT PROXY STATEMENT/PROSPECTUS FOR
           PHARMACIA ACQUISITION DECLARED EFFECTIVE BY SECURITIES AND
                              EXCHANGE COMMISSION

NEW YORK, Oct. 22 -- Pfizer Inc said yesterday that the Securities and Exchange
Commission declared effective Pfizer's Registration Statement on Form S-4 in
connection with its proposed acquisition of Pharmacia Corporation. This
Registration Statement includes a joint proxy statement/prospectus that will be
sent to the shareholders of both companies.

Pfizer has scheduled a shareholder meeting December 6 to vote to increase the
number of authorized shares and to issue Pfizer common stock in connection with
the proposed acquisition. Pharmacia has announced a meeting for its shareholders
to take place December 9 to vote on the proposed acquisition. Each meeting will
take place in Wilmington, Delaware.

                                  # # # # #

We urge investors to read the proxy statement/prospectus and any other relevant
documents that Pfizer Inc and Pharmacia Corporation have filed and will file
with the Securities and Exchange Commission because they contain important
information.

Pfizer and Pharmacia have filed a proxy statement/prospectus and other relevant
documents concerning the proposed merger transaction with the SEC. Investors are
urged to read the proxy statement/prospectus when it becomes available and any
other relevant documents filed with the SEC because they will contain important
information. You will be able to obtain the documents free of charge at the
website maintained by the

SEC at www.sec.gov. In addition, you may obtain documents filed with the SEC by
Pfizer free of charge by requesting them in writing from Pfizer Inc, 235 East
42nd Street, New York, New York 10017, Attention: Investor Relations, telephone:
(212) 573-2668. You may obtain documents filed with the SEC by Pharmacia free of
charge by requesting them in writing from Pharmacia Investor Relations, Route
206 North, Peapack, New Jersey 07977, or by telephone at (908) 901-8000.

Pfizer and Pharmacia, and their respective directors and executive officers and
other members of their management and employees, may be deemed to be
participants in the solicitation of proxies from the stockholders of Pfizer and
Pharmacia in connection with the merger. Information about the directors and
executive officers of Pfizer and their ownership of Pfizer shares is set forth
in the proxy statement for Pfizer's 2002 annual meeting of shareholders.
Information about the directors and executive officers of Pharmacia and their
ownership of Pharmacia stock is set forth in the proxy statement for Pharmacia's
2002 annual meeting of stockholders. Investors may obtain additional information
regarding the interests of such participants by reading the proxy
statement/prospectus when its becomes available.

                                      * * *

Article from Pfizer newsletter disseminated to Pfizer employees through its
internal intranet:

TRANSITION TEAM LEADERS MEET AS COMPANIES CONTINUE TO WORK TOWARD CLOSE

OCTOBER 21, 2002

THE TIMING OF DAY ONE. DECISIONS ABOUT ORGANIZATIONAL STRUCTURES. THE STATUS OF
FACILITIES PLANNING. COMPENSATION AND BENEFITS. ORGANIZATIONAL HEALTH. ALL THIS
AND MORE WAS ON THE AGENDA OF THE LATEST TRANSITION TEAM LEADER MEETING. HERE'S
A FULL REPORT.

HEADQUARTERS - Transition team leaders from Pfizer and Pharmacia gathered in New
York on October 17 for their third meeting since the acquisition was announced
in July.

Pfizer's Chief Financial Officer David Shedlarz, who is leading the company's
transition planning efforts, opened the meeting by thanking participants for the
"exemplary job" they have been doing thus far in getting "a heck of a lot of
work done." Shedlarz then turned his attention to an area of great interest for
transition team leaders and just about everyone else at both companies: the
timing of Day One.

"We have an aggressive target of closing the acquisition by the end of the year
- not by November 15th," he said. "As we've said from the outset, November 15th
is an internal target date by which we will have completed the first phase of
transition planning. The time between November 15th and the end of the year is a
terrific opportunity for us to

make further refinements to our transition plans and also to craft plans for the
first 100 days that we operate as a combined company."

Shedlarz said he believed that the U.S. Securities and Exchange Commission (SEC)
would soon "declare effective" the companies' Form S-4 - a 350-page document
containing information relating to the acquisition that will be mailed to all
Pfizer and Pharmacia shareholders. On Monday, October 21, the SEC did, indeed,
declare effective our Form S-4. This is a significant step toward securing the
shareholder approvals needed to complete the acquisition.

Shedlarz also provided some insight into the request for additional information
received on October 4 from the U.S. Federal Trade Commission (FTC), one of the
regulatory agencies that needs to approve the acquisition before it can be
completed. He said there was "nothing remarkable" about the request and that the
items of interest identified by the FTC mostly related to anticipated areas or
to "minor product lines." Shedlarz said he remained hopeful that all issues
would be resolved with the FTC by the end of the year, but that "the holiday
season is tricky." He added that gaining approval from the European Commission
(EC) might be less of an issue from a timing perspective, since, unlike the FTC,
the EC allows companies to contract for required divestitures after a deal is
closed.

Shedlarz's counterpart at Pharmacia, Chris Coughlin, shared his observations on
the transition planning process, saying that he'd been through numerous mergers
and acquisitions in his career and that "this one is the best I've ever seen."
Coughlin said that the spirit of cooperation that has existed from the beginning
among transition team leaders "has rippled right down into the rest of the
organization" as more and more colleagues have become involved. He also added a
cautionary note, saying that many of the most difficult decisions are still to
come, and he encouraged transition team leaders to focus on "keeping their
relationships strong" as we move closer to Day One.

Rick Hoddeson, vice president, Operations Planning & Analysis, Corporate
Finance, and a member of Pfizer's Program Office, told attendees that the
mapping process - comparing Pfizer's organizational structures with those of
Pharmacia in order to determine which groups and colleagues belong where - was
nearly complete. This is an essential step toward determining the organizational
structure of the combined company.

Hoddeson said that high-level organizational structures will be reviewed on
October 31 by the Pfizer Management Council (PMC) - which consists of
approximately 25 of the company's senior-most leaders. This will include three
levels of each organization - the head of the business, his or her direct
reports, and that person's direct reports - but will not include people's names
at that point. On November 5, the Pfizer Leadership Team (PLT) - which is led by
Hank McKinnell and consists of the company's top eight leaders - will have a
similar discussion, but names will be put forward for approval. What this means
is that colleagues should not expect to hear any general announcements about the
organizational structure of the combined company until sometime after November
5.

Martha Newton, senior director, Corporate Affairs, who is also a member of
Pfizer's Program Office, spoke more about creating a "100 Day Plan" that will
guide the combined company's efforts immediately following the completion of the
deal. The plan is designed to ensure that the combined company quickly delivers
results, maintains business momentum, and transfers knowledge for all products
and processes. Each business is expected to have its own plan, and all plans
will be reviewed by the PLT and PMC on December 17-18. The PLT will regularly
monitor the progress made against these plans after the close.

Program Office member Dan O'Shea, vice president, Operations and Public Affairs,
Pfizer Global Research and Development (PGRD), discussed efforts around
facilities integration. He said that a number of regions around the world have
been identified as posing issues on a cross-divisional basis. For example, the
Midwestern United States is home to about 14,000 Pfizer and Pharmacia colleagues
at seven locations: Ann Arbor, Kalamazoo, and Holland, Michigan; St. Louis,
Missouri; Skokie, Illinois; Terre Haute, Indiana; and Lincoln, Nebraska. The
vast majority of these colleagues work for PGRD or for Pfizer Global
Manufacturing (PGM), but some work for other businesses and divisions. O'Shea
said that a team has been formed to coordinate site selection, HR processes, and
other key internal activity in the Midwest, as well as to ensure that Pfizer
speaks with "one voice" publicly about its plans. Teams have also been
established to deal with cross-divisional issues in California, Sweden, Italy,
France, Japan, and Pakistan.

Greg Vahle, who leads human resources for Corporate Finance, spoke about the
issue of office space in the New York/New Jersey area. A team that he leads has
been compiling demographic data about the colleague populations in both states,
as well as cost data about our facilities. Vahle said his team expects to make
some initial recommendations to the PLT in mid-December.

Don Nelson, senior vice president, Human Resources, PPG, shared guidelines that
have been established around selection and job posting, saying that the overall
objective is to "staff the right person in the right job at the right time." A
Pharmacia colleague said his sense was that some of the company's top 1,000
people were actively pursuing job opportunities elsewhere, and questioned
whether Pfizer needed to accelerate its outreach efforts to those people it is
interested in retaining. Nelson agreed, saying that while the turnover rate at
Pharmacia thus far is not troublesome, Pfizer's experience with Warner-Lambert
showed that more and more people decided to leave as Day One drew closer.

Kelli Watson, vice president, HR Planning, Corporate Human Resources, discussed
the separation process, stressing that it would be conducted in full accordance
with the values of both companies. One important guiding principle is that
Pharmacia managers and HR professionals will communicate separation details to
Pharmacia colleagues, since they are most familiar with that company's
separation packages. Watson said that the process will be clear, simple, and
tailored to the individual. This is especially important for Pharmacia
colleagues whose career path includes legacy companies like Monsanto, Searle,
and Upjohn.

Watson also said that a pool of administrative assistants was being established
in the New York/New Jersey area, with a goal of retaining top administrative
talent and reducing Pfizer's use of temporary labor.

Barry Westgate, vice president, Corporate Compensation, Benefits, and HR
Information Technology, Corporate Human Resources, presented on compensation,
benefits, and policies. He said that, in general, Pfizer's "footprint" would be
used - largely because the company has spent the past two and a half years
revising its compensation, benefits, and policies as a result of the
Warner-Lambert merger - but noted that the company was committed to providing
"substantial equivalence" to Pharmacia colleagues. Westgate said that Pfizer was
also looking closely at how merit increases, incentive payments, and stock
options for Pharmacia colleagues may be affected by the timing of the close of
the deal.

Joe Bonito, vice president, Worldwide Organizational Effectiveness, PPG, and a
member of the Program Office, spoke about the challenges of maintaining
"organizational health" during this deal, compared to the Warner-Lambert merger.
At the time of the Warner-Lambert deal, for example, the economy was relatively
strong and the job market was hot - factors which made it fairly easy for many
colleagues to take their packages and find work elsewhere. Today, the economy is
weaker and the job market has cooled down. For Pfizer colleagues, Bonito said
that the Warner-Lambert integration was a new challenge that many found
intellectually exciting and rewarding. This time around, some are feeling
"integration fatigue" at a time when the organization was already stretched
thin.

What all this means, Bonito said, is that businesses and divisions need to be
particularly attuned to their organization's health. He noted that a wide
variety of tracking mechanisms are already being deployed throughout the company
- including one-on-one meetings, informal lunches, town halls, focus groups, and
surveys.

A Pharmacia colleague asked Bonito if Pfizer's culture had actually changed as a
result of the Warner-Lambert merger. Bonito said that Pfizer in recent years has
formally articulated a set of Leader Behaviors - such as encouraging open and
honest communications and debate - and has been using these behaviors to manage
performance and drive change in its culture. He said that this effort came about
not only as a result of the Warner-Lambert integration, but also of the changes
in Pfizer's top leadership and in the company's governance structure that were
taking place at virtually the same time.

Jonathan White, integration team leader, Corporate Information Technology,
discussed how increased scale resulting from infrastructure integration has
lowered the unit costs of IT services at Pfizer by over 40 percent this year - a
trend that will continue with the addition of Pharmacia's volume. The challenge,
he said, is that demand for services is rising almost as fast as costs are
declining. White said that Pharmacia's IT operations are well managed and that
we have very compatible systems, both of which are making Day One planning more
manageable. It is also allowing the companies to take an intelligent approach to
building a new IT organization that will meet the needs of the combined company,
while continuing to drive costs down.

At the close of the meeting, David Shedlarz again thanked transition team
leaders for their continued focus and cooperation, and urged them to keep up the
good work. "This is an awesome responsibility," he said. "More than 130,000
colleagues in both companies are counting on us. I know we will deliver."

                                      * * *

Safe Harbor Statement

This release contains certain "forward-looking" statements within the meaning of
the Private Securities Litigation Reform Act of 1995. These statements are based
on management's current expectation and are naturally subject to uncertainty and
changes in circumstances. Actual results may vary materially from the
expectations contained herein. The forward-looking statements contained herein
include statements about future financial operating results and benefits of the
pending merger between Pfizer Inc. and Pharmacia Corp. Factors that could cause
actual results to differ materially from those described herein include: the
inability to obtain shareholder or regulatory approvals; actions of the U.S.,
foreign and local governments; the inability to successfully integrate the
businesses of Pfizer Inc. and Pharmacia Corp.; costs related to the merger; the
inability to achieve cost-cutting synergies resulting from the merger; changing
consumer or marketplace trends: and the general economic environment. Neither
Pfizer Inc. nor Pharmacia Corp. is under any obligation to (and expressly
disclaims any such obligation to) update or alter its forward-looking
statements, whether as a result of new information, future events, or otherwise.

We urge investors to read the proxy statement/prospectus and any other relevant
documents that Pfizer Inc. and Pharmacia Corp. have filed and will file with the
Securities and Exchange Commission because they contain important information.

Pfizer and Pharmacia have filed a proxy statement/prospectus and other relevant
documents concerning the proposed merger transaction with the SEC. INVESTORS ARE
URGED TO READ THE PROXY STATEMENT/PROSPECTUS WHEN IT BECOMES AVAILABLE AND ANY
OTHER RELEVANT DOCUMENTS FILED WITH THE SEC BECAUSE THEY WILL CONTAIN IMPORTANT
INFORMATION. You will be able to obtain the documents free of charge at the
website maintained by the SEC at www.sec.gov. In addition, you may obtain
documents filed with the SEC by Pfizer free of charge by requesting them in
writing from Pfizer Inc., 235 East 42nd Street, New York, New York 10017,
Attention: Investor Relations, telephone: (212) 573-2668. You may obtain
documents filed with the SEC by Pharmacia free of charge by requesting them in
writing from Pharmacia Investor Relations, Route 206 North, Peapack, New Jersey
07977, or by telephone at (908) 901-8000.

Pfizer and Pharmacia, and their respective directors and executive officers and
other members of their management and employees, may be deemed to be
participants in the solicitation of proxies from the stockholders of Pfizer and
Pharmacia in connection with the merger. Information about the directors and
executive officers of Pfizer and their

ownership of Pfizer shares is set forth in the proxy statement for Pfizer's 2002
annual meeting of shareholders. Information about the directors and executive
officers of Pharmacia and their ownership of Pharmacia stock is set forth in the
proxy statement for Pharmacia's 2002 annual meeting of stockholders. Investors
may obtain additional information regarding the interests of such participants
by reading the proxy statement/prospectus when its becomes available.