(At least for now.)
First, the brief background – I’ve had two DVTs in my left leg: one in 2003 and one in 2010. My various physicians don’t have an explanation, but since it has happened twice, I’m now on a blood-thinning regimen for the rest of my life.
Up until now, that blood thinner has been coumadin – a drug that was originally developed as a rodenticide. The nice thing about this drug is that is well understood. It is true that it caused the demise of some unfortunate cattle (sort of), but it has now been on the market for sixty years. And my grandmother always liked to get a rise out of people by telling them that she needed to ingest her daily dose of rat poison.
The problem, however, is that coumadin requires constant monitoring and dosage adjustments. Eating too much or too little of certain foods (specifically, things with vitamin K) will counteract the drug. Would you like a fresh arugula salad on a warm, sunny day in mid-May? I would, but until now it would require a blood test and an increase in my coumadin intake. (In practice, I could get by with blood tests every month or so.)
Rivaroxaban has predictable pharmacokinetics across a wide spectrum of patients (age, gender, weight, race) and has a flat dose response across an eightfold dose range (5–40 mg). Clinical trial data have shown that it allows predictable anticoagulation with no need for dose adjustments and routine coagulation monitoring.
Rivaroxaban is well absorbed from the gut and maximum inhibition of factor Xa occurs four hours after a dose. The effects last 8–12 hours, but factor Xa activity does not return to normal within 24 hours so once-daily dosing is possible.
(Rivaroxaban from Wikipedia)
* Or ‘rivaroxaban’, if you prefer the generic name. Except that you can’t get Xarelto as a generic yet.
The FDA just approved Xarelto for the prevention of the recurrence of DVTs in November, and at my doctor’s appointment in January, my physician suggested I switch from coumadin.
So there you have it. I can eat my salad and not worry about it, since Xarelto works on a different part of the coagulation cascade. No problems! No worries!
Well… maybe one little one. Or two.
It turns out that there isn’t any way to stop the bleeding in an emergency. With coumadin, you can give a dose of vitamin K. With Xarelto, you can only wait until the effect wears off. Which means that if I’m ever in an accident, it would be better if it occurred in the late afternoon (right before my daily dose) and not during the night (when the anticoagulation is greatest).
The other little concern is the price. Brand-name drug with a legal monopoly status, since it’s under patent?
$10 per pill.
But I have insurance and a big-pharma subsidy for at least a year, so I’m paying $10 per month instead of $10 per day. We’ll see what happens after that.
I might just be back on rat poison.