This has been a very helpful post for me, timely too. I was going to try to worm out of the 1000mg of riba and ask my NP for 600mg daily instead. Changed my mind. I'll continue with the current dose as my RBC is 11.3 for now. Not really any need to decrease. I just wanted less chemicals in my body, that's all. Shot 19/24 this Wednesday. sigh......

Hi Matt,

This has been discussed since 2005, and numerous papers have been written. All agree that it would be useful to know the plasma concentration of Riba when it reaches steady state. Once reached, this appears to remain fairly stable throughout Rx if the same dose is taken.  All agree there is an optimal plasma concentration that will give increased chance of SVR. The only problem is that there are so many variables in the plasma concentration value as to make this unrealistic. My doc used this argument when he was convincing me to stay on 1,200mgms of Riba, despite my anaemia.  Given a normal renal function, and if Riba is taken with food (particularly with some fat), he suggested the recommended dose was required to give me the best chance of 'optimal' plasma concentration. For cirrhotics in particular, this is important. I asked whether the decreased RCC would decrease the Riba availability. The answer was that the increase in MCV made up for this. Remember that it's not just the plasma Riba that's important. Riba is concentrated in the RBC's, and is found in the extracellular fluids as well.

It seems each patient has a different thresh-hold for Riba. It's a bit like interferon- either you are interferon sensitive or you're not. Finding a specific plasma level that gives the best chance of SVR is well and good, but achieving that level seems impossible to predict.

All this is great in theory, but difficult in practice. I've always been concerned about the massive dose reductions (of Riba) for very mild anaemia in the USA. I wonder how often doses are increased again when the Hb rises above 10? To my simple mind, the best way to get a good plasma concentration is to take as high a dose as possible.  No magic solution I fear. Cheers.

Hey Kellie 

The article indicated that the dose did not factor in the conclusion, but there focus was on the EOT level regardless of the dose. So I guess absorption and retention would be the important area. I would assume that the next study would have them moderate the Ribavirin  based on the saturation level and then see the body responses.

Matt 

Thanks Matt for the link -I've been on 1000 mg a day since beginning treatment. When I was talking to my NP last week about reducing my riba, she was hesitant saying she was concerned about relapses. I know there are other studies saying riba reduction doesn't make a difference. Question: Does the concentration depend on the dose or how well a person absorbs and retains it?

Moved post.

Hey Friends

Check out this article from France, that appears to correlate the level of Ribavirin in the blood plasma at the EOT with SVR. 

This could lead to better SVR % in all treatments that Incorparate Ribavirin in their protocol. If they take a reading of the Ribavirin level during the treatment they might be able to adjust the Tx to achieve the correct saturation level of Ribavirin.  This could be another advancement in the guided therapy approach that seems to be the way things are moving.

Copy this link - http://www.ncbi.nlm.nih.gov/pubmed/23942546#

or read it at - http://hepatitiscnewdrugs.blogspot.com/

(sorry about link I don't know how to do a hyperlink)

Matt