MONTREAL — Patients who have been on the life-saving but notoriously difficult to manage blood thinner warfarin have some new easier-to-use anti-clotting drug options coming.
A new group of oral anticoagulants is slowly starting to enter the market — the first of them, dabigatran, was approved last fall as an alternative to warfarin in cases of atrial fibrillation, a heart rhythm disorder.
This new group of drugs is expected to dramatically change how blood thinner patients are treated by minimizing shortcomings associated with warfarin.
For decades, patients have relied on warfarin, a cheap and heavily used drug sold here under the name Coumadin.
But warfarin interacts with many other medications, just as many natural products and certain foods which can throw off blood levels, so patients require frequent hospital or pharmacy visits to determine the international normalized ratio, or INR, a measure of their blood level.
The new medications, beginning with dabigatran, don’t require testing. And while they bring about certain complications, those are far fewer than with warfarin.
“What’s really exciting is that in the last year we’ve found something that’s easier to use,” says Dr. Stuart Connolly, cardiologist and professor of medicine at McMaster University in Hamilton.
Dabigatran — manufactured by German pharmaceutical giant Boehringer Ingelheim and sold in Canada under the name Pradax — is the first off the block and is considered a gamechanger by cardiologists.
Since last fall, it has started being used as the blood thinner of choice in patients with AF, who make up the majority of patients on thinners. In Canada alone, 250,000 people have atrial fibrillation.
Connolly, who was one of the doctors involved in the massive dabigatran trial involving 18,000 people, says the drug has widespread support from doctors because it’s safer and more effective.
“It turned out to be not just easier to use but more effective than warfarin — something that was not anticipated when this research began was that we could beat warfarin,” Connolly said.
There are big dollars in anti-clotting drugs: $13.6 billion was spent in 2008 worldwide and the demand for options are heavy. Several other drugs are in the pipeline, including a once-a-day drug rivaroxaban (Bayer) and apixaban (Pfizer and Bristol-Myers Squibb).
Warfarin is cheap and the new drugs are likely to be more expensive. Pradax, which has not yet been approved for coverage by provincial plans, will cost between $3 and $4 a day compared to a fraction of that for Coumadin, but that doesn’t take into consideration monthly testing associated with Coumadin.
Doctors agree that there are a lot of AF patients who aren’t getting proper treatment but who can now with the new drugs.
“It’s about value, it’s not about cost,” Connolly said.
“If you can prevent a stroke in a moderate number of people, that reduces the total economic burden of the drug.”
Warfarin was initially developed as a chemical to kill rats by causing them to bleed to death. Since 1954, it began being prescribed as an oral tablet that prevents clotting by blocking vitamin K dependent molecules.
That means certain foods rich in the vitamin — green, leafy vegetables in particular — counteract warfarin and make the blood thicker which predisposes to clotting.
But the new generation of drugs does not have the many warfarin limitations and doesn’t require any followup testing.
At the Montreal Heart Institute, more than 800 patients a week get their blood tested weekly. Dr. Roger Huot, who has run the anti-coagulation clinic at the institute for the past 40 years, says only about three-fifths of warfarin patients come within their target range of thinness.
“So out of 100 patients, between 60 and 65 per cent are within the target zone and the rest are not,” Huot said.
The new drug has not been tested yet on valve patients, who also need to be on blood thinners to prevent clotting, and there is a debate about whether it should be given to patients who, in addition to AF, have coronary disease.
Allen Yarrow, a Montreal man who has been on Coumadin for eight years this August after valve replacement surgery, understands the trials of being on the drug.
“I’ve been at the hospital pretty much every three or four weeks since,” Yarrow, 62, said in an interview.
“I’ve experienced way too dense blood and way too thin blood but I’ve made it a point to familiarize myself (with food) that contains Vitamin K and how it actually affects my density.”
Yarrow is cautious about what he eats, what he does if he gets cut, and how he lives his life, and has learned to find his own balance when it comes to being on blood thinners.
But not all patients are so knowledgeable about blood thinners, even after years of being on them. That’s where the easy-to-use pills could dramatically change things.
“That’s why Pradax will solve a lot of problems,” Huot said. “These people will not be confronted with their lack of literacy, they’ll simply take the drug twice a day and they won’t have to think about other things.”
In a decade from now, the need for most patients to go to a so-called Coumadin clinic will likely be a thing of the past. But Huot notes that also means that patients won’t see doctors regularly. He also suspects some patients who are well served on warfarin will remain on it.
“One of the existing recommendations that for some patients who are well equilibrating with warfarin — who visit after visit are always within their target INR and don’t mind coming to the clinic every five or six weeks — just leave them like this, don’t take the chance to introduce something else,” Huot said.
Yarrow said he doesn’t spend too much time thinking new drugs, happy with being healthy and despite an aversion to needles, OK with getting tested regularly.
“I know that these drugs where you don’t have to care anymore are in the system and that they’re not there yet (for me),” Yarrow said.
“I’d love for medicine to catch up with my situation.”