Pfizer Inc. on Friday said two small clinical trials showed heart bypass surgery patients taking Bextra, an anti-inflammatory in the same class as the recently withdrawn drug Vioxx, had a higher risk of stroke and heart attack.

The company also updated its warning that Bextra can cause a rare, but sometimes fatal, skin disorder called Stevens-Johnson syndrome to note that cases of the condition are being seen more often with Bextra than with other drugs in the same class.

Pfizer’s shares fell nearly 4 percent on the New York Stock Exchange.

Bextra is approved to treat pain from arthritis and, like Merck & Co.‘s Vioxx, is a COX-2 inhibitor. A recent trial showed Vioxx doubled the risk of heart attack and stroke in arthritis patients who took the drug for more than 18 months.

The Vioxx withdrawal has cast a cloud over the entire class of COX-2 inhibitors, which includes Bextra, Celebrex and an experimental drug from Novartis AG called Prexige.

However, Pfizer said that following the Vioxx withdrawal it re-examined its clinical data base of 8,000 patients with rheumatoid arthritis and osteoarthritis and found no increased risk of dangerous heart events in patients taking Bextra for up to a year. The company also found no increased risk in a trial of patients taking Bextra in a general surgery setting.

Doctors said it is too early to quantify the potential risk of Bextra or of Pfizer’s other COX-2 inhibitor Celebrex as neither have tested for long enough. Pfizer said it is conducting longer term trials in arthritis patients.

The coronary bypass trials are ones that Dr. Eric Topol of the Cleveland Clinic Foundation and an early and outspoken critic of Vioxx, said he finds concerning as they show a cluster of heart attacks and strokes. But he said the danger signal does not appear to be as strong as it was with Vioxx.

“Celebrex and Bextra do appear safer than Vioxx but whether they are really safe, especially in patients with heart risk, that’s an open question,” Topol said.

Pfizer has updated the label on several occasions since it was approved in 2001 to reflect the risk of Stevens Johnson syndrome, a form of allergic reaction often caused by certain types of drug. Symptoms usually begin as a blistering of the mouth and lips, spreading to the throat, tongue and other parts of the body. The blisters sometimes become so extensive as to be fatal. The company also updated its warning that Bextra can cause a rare, but sometimes fatal, skin disorder called Stevens-Johnson syndrome to note that cases of the condition are being seen more often with Bextra than with other drugs in the same class.

Pfizer’s shares fell nearly 4 percent on the New York Stock Exchange.

Bextra is approved to treat pain from arthritis and, like Merck & Co.‘s Vioxx, is a COX-2 inhibitor. A recent trial showed Vioxx doubled the risk of heart attack and stroke in arthritis patients who took the drug for more than 18 months.

The Vioxx withdrawal has cast a cloud over the entire class of COX-2 inhibitors, which includes Bextra, Celebrex and an experimental drug from Novartis AG called Prexige.

However, Pfizer said that following the Vioxx withdrawal it re-examined its clinical data base of 8,000 patients with rheumatoid arthritis and osteoarthritis and found no increased risk of dangerous heart events in patients taking Bextra for up to a year. The company also found no increased risk in a trial of patients taking Bextra in a general surgery setting.

Doctors said it is too early to quantify the potential risk of Bextra or of Pfizer’s other COX-2 inhibitor Celebrex as neither have tested for long enough. Pfizer said it is conducting longer term trials in arthritis patients.

The coronary bypass trials are ones that Dr. Eric Topol of the Cleveland Clinic Foundation and an early and outspoken critic of Vioxx, said he finds concerning as they show a cluster of heart attacks and strokes. But he said the danger signal does not appear to be as strong as it was with Vioxx.

“Celebrex  and Bextra do appear safer than Vioxx but whether they are really safe, especially in patients with heart risk, that’s an open question,” Topol said.

Pfizer has updated the label on several occasions since it was approved in 2001 to reflect the risk of Stevens Johnson syndrome, a form of allergic reaction often caused by certain types of drug. Symptoms usually begin as a blistering of the mouth and lips, spreading to the throat, tongue and other parts of the body. The blisters sometimes become so extensive as to be fatal. The company also updated its warning that Bextra can cause a rare, but sometimes fatal, skin disorder called Stevens-Johnson syndrome to note that cases of the condition are being seen more often with Bextra than with other drugs in the same class.

Pfizer’s shares fell nearly 4 percent on the New York Stock Exchange.

Bextra is approved to treat pain from arthritis and, like Merck & Co.‘s Vioxx, is a COX-2 inhibitor. A recent trial showed Vioxx doubled the risk of heart attack and stroke in arthritis patients who took the drug for more than 18 months.

The Vioxx withdrawal has cast a cloud over the entire class of COX-2 inhibitors, which includes Bextra, Celebrex and an experimental drug from Novartis AG called Prexige.

However, Pfizer said that following the Vioxx withdrawal it re-examined its clinical data base of 8,000 patients with rheumatoid arthritis and osteoarthritis and found no increased risk of dangerous heart events in patients taking Bextra for up to a year. The company also found no increased risk in a trial of patients taking Bextra in a general surgery setting.

Doctors said it is too early to quantify the potential risk of Bextra or of Pfizer’s other COX-2 inhibitor Celebrex  as neither have tested for long enough. Pfizer said it is conducting longer term trials in arthritis patients.

The coronary bypass trials are ones that Dr. Eric Topol of the Cleveland Clinic Foundation and an early and outspoken critic of Vioxx, said he finds concerning as they show a cluster of heart attacks and strokes. But he said the danger signal does not appear to be as strong as it was with Vioxx.

“Celebrex and Bextra do appear safer than Vioxx but whether they are really safe, especially in patients with heart risk, that’s an open question,” Topol said.

Pfizer has updated the label on several occasions since it was approved in 2001 to reflect the risk of Stevens Johnson syndrome, a form of allergic reaction often caused by certain types of drug. Symptoms usually begin as a blistering of the mouth and lips, spreading to the throat, tongue and other parts of the body. The blisters sometimes become so extensive as to be fatal. The company also updated its warning that Bextra can cause a rare, but sometimes fatal, skin disorder called Stevens-Johnson syndrome to note that cases of the condition are being seen more often with Bextra than with other drugs in the same class.

Pfizer’s shares fell nearly 4 percent on the New York Stock Exchange.

Bextra is approved to treat pain from arthritis and, like Merck & Co.‘s Vioxx, is a COX-2 inhibitor. A recent trial showed Vioxx doubled the risk of heart attack and stroke in arthritis patients who took the drug for more than 18 months.

The Vioxx withdrawal has cast a cloud over the entire class of COX-2 inhibitors, which includes Bextra, Celebrex and an experimental drug from Novartis AG called Prexige.

However, Pfizer said that following the Vioxx withdrawal it re-examined its clinical data base of 8,000 patients with rheumatoid arthritis and osteoarthritis and found no increased risk of dangerous heart events in patients taking Bextra for up to a year. The company also found no increased risk in a trial of patients taking Bextra in a general surgery setting.

Doctors said it is too early to quantify the potential risk of Bextra or of Pfizer’s other COX-2 inhibitor Celebrex as neither have tested for long enough. Pfizer said it is conducting longer term trials in arthritis patients.

The coronary bypass trials are ones that Dr. Eric Topol of the Cleveland Clinic Foundation and an early and outspoken critic of Vioxx, said he finds concerning as they show a cluster of heart attacks and strokes. But he said the danger signal does not appear to be as strong as it was with Vioxx.

“Celebrex and Bextra do appear safer than Vioxx but whether they are really safe, especially in patients with heart risk, that’s an open question,” Topol said.

Pfizer has updated the label on several occasions since it was approved in 2001 to reflect the risk of Stevens Johnson syndrome, a form of allergic reaction often caused by certain types of drug. Symptoms usually begin as a blistering of the mouth and lips, spreading to the throat, tongue and other parts of the body. The blisters sometimes become so extensive as to be fatal.

Shares of Pfizer fell $1.08, or 3.7 percent, to $28.00 in early afternoon trading on the New York Stock Exchange.