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New blood thinner sought by experts
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Dr. Margaret Kennedy
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Three years ago, when she was 57, Diana Miller-Flanagin of Portersville had a couple of mini-strokes.
"That's when they found my heart goes into atrial fibrillation and that it was the cause of the mini-strokes," she said. A-fib, as it's commonly called, is a condition in which rapid, irregular beating of the muscular wall of the heart causes blood to thicken and clot within the heart chambers.
Her doctors at Allegheny General Hospital put her on an anticoagulant, or blood thinner, which also is used to treat deep vein thrombosis (blood clots deep in the body) and pulmonary embolism (blockage in a lung artery).
Mrs. Miller-Flanagin has taken both Coumadin and, more recently, the generic version, warfarin sodium. Both come in pill form.
"I think the Coumadin regulated [the blood] a little better," she said, adding that she didn't think its higher cost was worth it. Both drugs require monitoring, as you don't want the blood to be too quick to clot, which could cause a blockage in a blood vessel, or too slow to clot, which can lead to excessive bleeding.
"I just take it once a day, but I take different amounts at different times, different doses depending on the thickness or thinness of my blood," Mrs. Miller-Flanagin said. "At the beginning, I had tests done twice a week, then weekly. Now I go every three weeks.
"They've had a very difficult time getting my blood to regulate.
"If my blood is too thin I bruise very easy," Mrs. Miller-Flanagin added. "I have a little lap dog, and I get bruises where his foot goes."
She also noted that with either warfarin or Coumadin, "you have to be very careful on your diet."
The two blood thinners work against vitamin K, which your liver uses to make blood-clotting proteins. That doesn't mean the patient should cut back on foods with vitamin K, but it does mean he or she should maintain a consistent intake of K-rich foods.
For Mrs. Miller-Flanagin that means eating three salads a week.
"It would be nice if they came out with something where I could eat what I want," she said.
The scientists are trying.
At Western Pennsylvania Hospital, for example, hematologist Dr. Margaret Kennedy and other researchers are part of a worldwide clinical trial of a new anticoagulant called rivaroxaban.
The New England Journal of Medicine this month published an article on a clinical study of still another alternative to warfarin called dabigatran.
"There are several different ones," said Dr. Kennedy, medical director of the Anticoagulation Management Center at West Penn and associate director of the hospital's Hemostasis and Thrombosis Laboratory.
But Dr. Kennedy said she doubts that any of the drugs now being tested will ever totally replace Coumadin/warfarin.
"I don't think so, even though I think they will be very good alternatives for some people who are having hard times managing the dosing," she said. The only current trials for new drugs, she said, involve patients with atrial fibrillation or venous thromboembolism, which includes both deep vein and pulmonary conditions.
"There are not trials for patients who use [Coumadin] because of mechanical valves. ... They still will be using warfarin."
And, she said, there are two other groups of patients who might prove unable to use the new anticoagulants: patients with poor kidney function and pregnant women requiring blood thinners. The new blood thinners can accumulate in the body, and patients with kidney problems can't clear them, resulting in bleeding, Dr. Kennedy said. Coumadin/warfarin, meanwhile, can "cause potential changes in a baby, especially early in pregnancy." Heparin is another type of blood thinner that is not harmful to a fetus. An injection, it is often used when a quick-acting thinner is needed.
Dr. Kennedy ticked off other reasons the new drugs will be less attractive than warfarin and Coumadin.
"First of all the cost," she said. "Coumadin is one of the cheapest medications around so anybody who can spend $20 or $30 a month can get it. I can guarantee that will not be the case with the new ones.
"No. 2, what makes clinicians reluctant, is you won't be able to have any blood tests to confirm if the patient is taking the drug ... [because] none of the companies who studied them recommended any testing. ...
"Another reason why physicians might be apprehensive about using them, sometimes they need to take patients to surgery abruptly. They may have had Coumadin the night before and develop a need for surgery in the morning. You have to give them some plasma, bring them back to normal and take them to surgery.
"You can't do that with the new drugs because you don't know what reverses them."
First Published December 30, 2009 12:00 am
