British drug regulators said on Tuesday that patients should stop taking COX-2 inhibitors if they have heart disease.

“Patients treated with any COX-2 inhibitor who have established ischaemic heart disease or cerebrovascular disease should be switched to alternative (non-COX-2 selective) treatments as soon as is convenient,” they said in a “Dear Doctor” letter.

The letter was issued by the Medicines and Healthcare Products Regulatory Agency (MHRA) following concern over a study last week that found an increased risk of heart attacks and strokes in patients taking high doses of Pfizer’s Celebrex (celecoxib).

Professor Gordon Duff, Chairman of the Committee on Safety of Medicines, the author of the letter, advised that all patients taking Celebrex or other selective COX-2 inhibitors should make a non-urgent appointment to have their treatment reviewed.

“For all patients, alternative treatments should be considered in light of an individual assessment of risks and benefits of COX-2 inhibitors, in particular cardiovascular, gastrointestinal and other risk factors,” he said.

The letter also reminds doctors that all nonsteroidal anti-inflammatory drugs, including COX-2 inhibitors, should be prescribed at the lowest effective dose for the shortest duration necessary.

It notes that a recent letter to healthcare professionals from Pfizer, which highlighted the cardiovascular safety of Celebrex was “not authorised by the MHRA”.

The latest Celebrex study, conducted by the US National Cancer Institute, found that the risk of heart attacks and strokes was 2.5 times higher in patients taking the 400-mg dose of the drug and 3.4 times higher with the 800-mg dose.