Bristol-Myers Squibb has recalled some of its samples of Coumadin, a popular blood thinner, because of a variation in an ingredient that stabilizes the active drug.

A spokeswoman for the company said 8 lots, or 144,700 samples, each of which contained 10 tablets, have been recalled. The affected lots were distributed only as samples, she said.In a letter to doctors, the drugmaker said it was recalling the 1 mg tablets of blister-packed samples of Coumadin — the name brand for warfarin — that doctors to give to patients.

The letter noted a variation in isopropanol, which helps to stabilize the active ingredient in Coumadin.

“We monitor our patients on Coumadin closely, and if the stabilizer is not consistent, it can be very dangerous. Coumadin is prescribed to treat or prevent blood clots. So if there’s too little, then there’s a risk of clots, which could lead to heart attack or stroke, and if there’s too much, there’s an increased risk of bleeding,” said Dr. Micah Eimer, a cardiologist in suburban Chicago.

“There are serious life-threatening consequences if (isopropanol) is too high or too low,” he added.