This may only be coincidence...but

[dick0236]

Those of us on Warfarin try to manage our diets, activities, etc. in order to keep our INRs within a safe range and make dosing adjustments as needed......assuming that our diets or habits are to blame if we get out of range. My recent experience indicates that the real culprit MAY be the Rx bottle in my medicine cabinet.

The majority of my time on the drug has been without incident....except for the stroke, which was due to my mismanagement. I have taken Coumadin thru two owners, Dupont Chemicals and Bristol, Myers, Squibb and generic warfarin thru Barr Labs and Taro Lab without incident.....or significant INR change, until early 2012. For a year or so, prior to 2012, I had been taking Barr Lab when my druggist switched me to a new lab, Zydus which made me uncomfortable and I asked to be switched back to either Barr or Taro upon my next refill. In March,2012 I started taking Taro and my INRs immediately took a nose dive to the low end, or below, my range of 2.5. I have learned, thru my doc, Bill B, and others that the variance between labs can be as much a +25% or -20%.....that's a LOT.....and means a 5mg tablet can vary from 4mg to 6.25mg between labs.

After 4 of 5 months on Taro, with INRs hovering around 2.5, I went back to Barr, one week ago, and my INR yesterday was 3.4(where I am much more comfortable). Coincidence?.....perhaps. I will test again in two weeks to confirm that the lab change was, or was not, the reason for my sudden INR drop.....I'll let you know. If my "hunch" is correct, I will no longer accept that it is OK, for me, to move between warfarin labs and expect little, or no, INR change. Any of the reputable labs may be OK, but it may be more sensible to stay with the lab that you have adusted to.

 

[Protimenow]

Unfortunately, although all are supposed to be bioequivalent, this is not always the case. When I change from one manufacturer to another, I test a few days after making the change, to see if there are any surprises.

That's one of the nice things about having your own meter. (Of course, OTOH, you have to be confident that the METER is also giving an accurate INR. With mine, I'm not entirely sure....)

 

[dick0236]

Unfortunately, although all are supposed to be bioequivalent, this is not always the case. When I change from one manufacturer to another, I test a few days after making the change, to see if there are any surprises.

That's one of the nice things about having your own meter. (Of course, OTOH, you have to be confident that the METER is also giving an accurate INR. With mine, I'm not entirely sure....)

My pharmacy...uh, X-pharmacy, carries several brands of generic warfarin, but pushes the one with the best "deal"....without regard to any patient inconvenience(testing inconsistency, etc)....and I could ask for a "specific lab brand" if it was important to me. My NEW pharmacy does the same thing....and has noted, in my file, to use only Barr Lab without my instructions to the contrary.

BTW, my doc tells me that they use a daily(chemical?) test to verify to accuracy of their Coaguchek XS. You may want to see if such a test is available for a home tester.

 

[Protimenow]

I'm using an InRatio meter - and am planning on getting cuvettes for my old ProTime meter (which I am beginning to think is more accurate). All three meters (CoaguChek XS, InRatio, ProTime) have quality controls built into the strips - in theory, this is all the testing that they need.

OTOH -- the ProTime also has an available set of test solutions, with a specific INR, that can be used to verify the accuracy of the meter. The CoaguChek also used chemical (and electronic) QC, and I am not surprised to hear that the CoaguChek XS also has some standard chemicals that can be used to verify the meter accuracy.

(These 'standards' are designed to give a SPECIFIC INR -- if the target values are off, it's an indication that the meter is inaccurate. For a lab or doctor who is doing a lot of tests, a daily test can help to indicate the accuracy of the meter, but for most home testers - although it would be a great thing to be able to confirm a meter's accuracy - such a test would either be too expensive, or just plain unavailable)

FWIW -- my InRatio and InRatio 2 often have very similar results -- which could indicate accuracy, or could confirm that they are BOTH nearly equally inaccurate.

 

[scott.eitman]

Thanks for sharing this. I bet this may help a lot of people.

 

[dick0236]

.....I'll let you know. If my "hunch" is correct, I will no longer accept that it is OK, for me, to move between warfarin labs and expect little, or no, INR change. Any of the reputable labs may be OK, but it may be more sensible to stay with the lab that you have adusted to.

I have a "hunch" that my initial "hunch" was correct. In March,2012 I switched my Warfarin Rx to Taro Labs and my INR dropped immediately to the low/mid 2's from the low/mid 3's, even as I increased my dosage by about 15% (from 35 to 40mg/wk). My diet, habits and activities are pretty consistant and I suspected the Warfarin. In mid July, 2012 I switched my Rx back to Barr Lab and my INR's reacted immediately and rose to the mid 3's. My INR on 7/25 was 3.4 and today, 8/8 was 3.5, even as I decreased my dose back to 35mg/wk. I had switched back and forth between the Taro and Barr brands several times in the past several years without affecting my INRs.....but this has taught me to stay with one brand.

 

[Bina]

I have a "hunch" that my initial "hunch" was correct. In March,2012 I switched my Warfarin Rx to Taro Labs and my INR dropped immediately to the low/mid 2's from the low/mid 3's, even as I increased my dosage by about 15% (from 35 to 40mg/wk). My diet, habits and activities are pretty consistant and I suspected the Warfarin. In mid July, 2012 I switched my Rx back to Barr Lab and my INR's reacted immediately and rose to the mid 3's. My INR on 7/25 was 3.4 and today, 8/8 was 3.5, even as I decreased my dose back to 35mg/wk. I had switched back and forth between the Taro and Barr brands several times in the past several years without affecting my INRs.....but this has taught me to stay with one brand.

Yes, I think that is the key here: Take what you want but stick with it.
My own doctor pointed out that since I have insurance I may as well take the name brand Coumadin, which I feel safe with.

 

[njean]

Throughout my life, my cardiologists have all insisted that I stick to the brand name, 'coumadin' and never allow the insurance or pharmacy to make the decision for me and push the generic on me. So whenever the drs write out the Rx, they make sure to write in "Brand Name Only". My co-pay is indeed higher but I too feel safe and confident taking coumadin and I have no intentions of ever changing.