Ross
Well-known member
Bill if your INR was 5.0 from taking 10.5 mg per week, just how would you lower it?
Most doctors know very little about Coumadin doseage.
- Thread starter Herb M
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Marty
Well-known member
Ross, I'd been on warfarin about a month, not given any couseling by my busy cardiologist, called in my INR's to his nurse and rarely got a call back so quite confused about the whole warfarin business ( Im a radiologist). Then I lucked out. I was at a medical meeting and had lunch sitting next to a doctor(hematologist) from Vienna Austria. He gave me the 10% rule and I've been using it ever since. My cardiologist prescribed a Coaguchek for me in 1998 so I wouldn't have to bother his office nurse. Self test, self dose I advise everybody. You may get some static from some doctors but if you explain you are doing this to help them they usually say OK. My wifes doctors were a little reluctant at first but then said fine as long as she called in her INR's and told them what dose she is taking. They said this protected them medicolegally.
Ross
Well-known member
I think most professionals over complicate the whole dosing thing by thinking it through too much.
I strongly agree with your comment. Warfarin dosing, for me, is NOT that big of a deal. For well over twenty years, I have been able to successfully manage my INR using a combination of only one strength pill(5mg=0,2.5,5.0,7.5) and testing routinely, as needed, but seldom more often than once per week and usually bi-weekly. I also agree with Marty that self-testing and self-dosing (after you've been on the drug for awhile) is the way to go
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Ross, the question exposes the problem. One value out of nowhere makes the adjustment largely a guess. How people will respond to 10 or 20 or 50% dosing change is individual. To get to the target, someone could require any one of those adjustments. If you do 10% per week, it might work in a week for one or 5 weeks for another. So, that's my point. The existing protocols are too general and only work optimally on some patients. You may feel that's OK because it doesn't cause a problem if it takes 5 weeks, but it well could. So, anyway, I was proposing an idea that we started and used for theophyliine that would involve taking 2 blood samples early on and directly calculating (with a computer) that individual's metabolic rate for warfarin and rate of response in INR, something that could be done but is not done now. That would allow tailored dosing. It surprised me that for as long as anticoag clinics and the such have been around, nobody appears to have studied this. It requires some understanding of pharmacokinetics, a computer, but it could be done and might produce better results in terms of adverse events. About the best people can do now is look back at the individual's history of response to previous adjustments and go from there with some hemming and hawing. In theory, IF things were linear, if someone had an INR of 5 and you wanted it to be, say, 2.5, you would just cut the dose in half.
Anyway, I'm just thinking out loud here. Pharmacokinetics was an area of interest for me when I was in the business, but I left that behind long ago. The paper I published on this idea is not available for download.
http://jcp.sagepub.com/cgi/content/abstract/22/7/326
It certainly could be that people tried this and it didn't work because warfarin dose-response is much more complicated than other drugs due to the mess of clotting factors affected and all the outside influences.
Also, I'm very glad that you and others here have found warfarin to be easy to use and pretty much trouble-free. Maybe I'll feel closer to your way after I get some more experience. I already admitted I've had no problems other than some goofy INRs due to my high sensitivity to small changes in dose.
Bill
Ross
Well-known member
Bill all I'm saying is, I think your method over complicates the dosing. When you first start out, yes, test every 24 to 48 hours and establish just how quickly your metabolizing the drug, but past that point, the 10% up or down rule works for almost everyone. You get into problems when people are on Amiodarone and some other drugs, as you know, which is why in my opinion, testing once a month is not something I'd recommend. 2 weeks tops.
