Drugmaker Pfizer Inc. (PFE) is in talks with regulators over a likely change to arthritis drug Bextra's (search) label to carry a strict warning alerting doctors of the risk of a potentially deadly skin reaction, the company said in a regulatory filing.

Pfizer, whose shares fell nearly 3 percent Monday morning, also said in the filing it is under investigation by New York and Connecticut in connection with potentially improper promotion of drugs for uses other than those approved by U.S. regulators.

Pfizer also said it has initiated an internal probe relating to its sales operations in Croatia.

A Pfizer spokesman declined to comment on the investigation or its talks with the Food and Drug Administration (search) over Bextra.

Prudential Securities analyst Tim Anderson said the warning on Bextra, which is in the same class of drugs as Pfizer's Celebrex and Merck & Co.'s (MRK) withdrawn arthritis drug Vioxx (search), suggests the commercial future of Bextra is at risk.

Pfizer said it is talking to regulators about carrying a "black box" warning that it might result in a rare, but sometimes fatal skin disorder called Stevens-Johnson syndrome.

Launched in 2001, Bextra had sales last year of $687 million.

In the New York investigation, Pfizer said it has received a letter from Attorney General Eliot Spitzer's (search) office requesting documents and information on clinical trials of certain drugs for uses other than those approved by the U.S. Food and Drug Administration. Pfizer said the probe involved the possible promotion of products for unapproved uses.

Pfizer said it received a letter from the Office of the Attorney General of the State of Connecticut requesting similar materials concerning its antidepressant Zoloft.

Pfizer spokesman Paul Fitzhenry said both investigations were new, but declined to specify which drugs the New York attorney general was investigating. A spokesman for Spitzer's office declined to comment.

Pfizer also said it has voluntarily provided the Department of Justice and the Securities and Exchange Commission (search) with information regarding an internal probe of certain potentially improper payments made in connection with foreign sales activities in Croatia.

Pfizer's shares fell 79 cents to $28.00 Monday on the New York Stock Exchange.