Effect of Phosphorus Binders

[Restorer]

I haven't been able to find specific information on phosphorus binders, specifically the Renvela I'm taking. What I'm wondering is how much phosphorus one pill (800 mg) can bind. My understanding of how it works is that, given plenty of phosphorus to bind to, one dose of a binder will bind a certain amount of phosphorus, potentially reducing the absorbed phosphorus from a meal by several hundred milligrams.

I know that the end effects of the binders on serum phosphorus vary from person to person, based on all kinds of things like residual kidney function with respect to phosphorus, dietary intake, and plenty of other things. But chemically, it makes sense to me that a maximum absolute value could be derived, e.g. 800 mg of Renvela can bind 200 mg of phosphorus (just an example - this is the number I'm looking for).

Anyone have any idea where I can look to find this info?

[jbeany]

I don't know if that's possible.  When I was taking Renegels, I kept taking more and more, and nothing helped.  The dietitian finally admitted that they don't work at all for some people, because of the pH of their stomach acid.  (And a big fat raspberry to her, for making me half starve myself of everything with phos in it to prove that they weren't working for me...)  I don't know enough about the chemistry.  Does Renevela work the same way?
I was switched from Renegels to Fosrenol, which worked really well for me at the 1000 mg dose with every meal and snack.  Then I had PTH surgery, and now I barely need 1000 mg a day, when I was taking 4000 or 5000 a day before the surgery.  It doesn't seem logical to me that they could give a consistent binder/phos ratio when individual body chemistry can change the dosing that much.

[Zach]

jbeany,

You know me, I've tested this out on myself.

Here are my findings:

One-800 mg of Renagel (and I'm testing Renevela as we speak) seems to work on about 90-100 mg of phosphorus, to keep my serum PO₄ at about 4.8 mg/dl.

One-667 mg of PhosLo seems to work on about 100-120 mg of phosphorus.

Both these numbers also include the 4.5 hours of hemodialysis which remove some, too.
To be little more accurate, one would need a post-dialysis phosphorus on Monday and a pre-dialysis phosphorus the next treatment.

And Restorer, jb is correct. Renagel did in fact have a pH factor when binding.  Not sure if Renevela has the same issue, since it is a carbonate base and not a hydrochloride base.

While there are some differences in people, more data should be provided to patients.  What may happen now is that for some meals, we may be taking too many pills, while others (such as dinner) we may be taking too few.  A typical prescription reads: take three tablets with meals, or worse, take three tablets 3 x a day.

Information=Knowledge=Empowerment



PS:  I think this is a chart of how Renagel works:

[jbeany]

Restorer - Zach keeps better track of how much phos he's eating than anyone else I know.  His numbers would be a good start.

What do the docs base an initial prescription dose of binders on?  Anyone know if it's anything more than a random guess based on weight, or do they just "one size fits all" an initial dose and then adjust it only if it doesn't work?  All I've ever heard from my doc is "Try this amount. . ."  He never gives any reason for how he computes dosages.  My endo has a Blackberry where he keeps a dosage calculator, and when ever he starts me on something new, he's busy with his stylus, entering in weight, ht, etc. to get a good starting dose.

I was prescribed 1000 mg per meal, but when my phos dropped to low after surgery, I started adjusting it myself, by chewing only partial tablets with meals that I knew had high phos, and skipping them entirely with meals with very low phos.  The orders from my nurse were actually to only take binders with breakfast and dinner, not lunch or snacks, but that made no sense to me at all.

[Zach]

The orders from my nurse were actually to only take binders with breakfast and dinner, not lunch or snacks, but that made no sense to me at all.

Perhaps because, "While lanthanum has been shown to accumulate in the GI tract, liver, and bone in animals, the clinical significance in humans is unknown." 

The above sentence comes from the "Important Safety Information" section of the Shire product web site.
http://www.fosrenol.com/Default.aspx
 

[RightSide]

Here's a list of some commonly prescribed phosphorus binders and how much phosphorus each one binds.  It comes from the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI):

http://tinyurl.com/5us6jf

Unfortunately, Renvela (sevelamer carbonate) is not included among them, though Renagel (sevelamer hydrochloride) is.  I would imagine their phosphorus-binding power is similar though.  In animal testing, 1 gm Renagel bound to 80 mg phosphorus.  No data on human testing is available yet though.

BTW, for those of us taking calcium carbonate (Tums, etc.) as a phosphorus binder, note how little phosphorus it really binds.  To bind all the phosphorus in just one three-ounce serving of cooked chicken would require at least FIVE Tums tablets. 

[Bajanne]

BTW, for those of us taking calcium carbonate (Tums, etc.) as a phosphorus binder, note how little phosphorus it really binds.  To bind all the phosphorus in just one three-ounce serving of cooked chicken would require at least FIVE Tums tablets. 

Oh my goodness!!!  Thanks for telling me that!  Does that apply to Ultra Strength Tums?  Seems I am going to have to go back to PhosLo!!!

[Quickfeet]

Is there any info about revela the list posted by right side is up to date any more?

Here's a list of some commonly prescribed phosphorus binders and how much phosphorus each one binds.  It comes from the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI):

http://tinyurl.com/5us6jf

Unfortunately, Renvela (sevelamer carbonate) is not included among them, though Renagel (sevelamer hydrochloride) is.  I would imagine their phosphorus-binding power is similar though.  In animal testing, 1 gm Renagel bound to 80 mg phosphorus.  No data on human testing is available yet though.

BTW, for those of us taking calcium carbonate (Tums, etc.) as a phosphorus binder, note how little phosphorus it really binds.  To bind all the phosphorus in just one three-ounce serving of cooked chicken would require at least FIVE Tums tablets.

[pagandialysis]

i still blame Renvela for my frequent diarrhea though I have no evidence other then my own observation.

[Jean]

There is nowhere I the world where I can go and feel dumber than I do here. Thanks so much to those of you who know of what you speak. ( oh, and, yes, I know, listen to you Dr. first, right?)

[BattleScars]

This is some interesting info. I've been struggling with phosphorus control and I take my binders religiously with every meal or snack. I also have really bad acid reflux. I wonder if that's why they are not working for me? I admit I was eating pizza often, and cheese, and ice cream, and nuts so my diet wasn't good. I was also reading today about some things I had no idea had a lot of phosphorus like brown rice and corn tortilla chips. I pretty much have to adjust my entire diet and really limit these things to get this under control.   

[Quickfeet]

Based on the study linked below an 800 mg tablet will bind about 21 mg of phosphate.

http://wcct.com/wp-content/uploads/2011/03/128-full-publication.pdf