This is from a 2007 Clinical Care Option article. See: http://tiny.cc/KWKAw
CCO Independent Conference Coverage of the 2007 Annual Meeting of the European Association for the Study of the Liver*
Week 4 Plasma Ribavirin Concentration Independent Predictor of SVR in HCV-Infected Patients—Optimal Cutoff Suggested
Posting Date: April 14, 2007
* Nonrandomized study
Summary of Key Conclusions
* Week 4 plasma ribavirin concentration > 2 mg/L strongly predictive of achieving sustained virologic response (SVR) in patients receiving peginterferon plus weight-based ribavirin for HCV infection
o SVR rate: 86%
* Achieving SVR at ribavirin plasma concentration > 2 mg/L likely due to early HCV clearance in these patients
o Early virologic response (EVR) in this group: 100%
* For patients with Week 4 plasma ribavirin 1.89 mg/L: 70% SVR
o Sensitivity of 70% and specificity of 75%
* At Week 4, achieving ribavirin plasma concentration of > 2 mg/L by Week 4 further increased SVR rate to 86%
* In multivariate analysis, plasma ribavirin concentration of > 2 mg/L at Week 4 significantly associated with SVR
o Independent of genotype, baseline HCV RNA, and patient status (ie, treatment naive vs nonresponder)
o Odds ratio: 31 (95% confidence interval: 1.32-7.50; P = .033)
Would have been interesting if they had revealed if the 'high absorbers' had a corresponingly increased drop in Hgb as treatment progressed.
Measuring riba serum (presumably the high definition liquid chromatography method) is devilishly hard to get done-I tried but couldn't find a lab with the facility.
Conceptually, I've advocated pre-dosing riba for some time here -- perhaps the first person here to do so (tooting Jenna's horn :) ) and would do it myself if I had to treat again. That said, as Willing somewhat suggests, this paper really doesn't support pre-dosing and there could be other reasons why the cohort did so well. Indeed, they simply may be better riba absorbers which is consistent with the Lindahl work.
interesting paper; thanks for posting. Agreed that it makes a good case for pre-dosing rbv for a couple of weeks before starting ifn. Up to this, the importance of having rbv plasma concentration at full levels before the ifn kicked in was, as far as I know, complete speculation. It seemed a reasonable thing to do, but there was no evidence in support. The difference in the SVR prospects of those with elevated RBV during the first 12 hours, as reported here, is pretty impressive.
From the abstract it doesn't appear any pre-dosing was involved, so the higher D0 levels were presumably a consequence of dose/clearance-rate, factors that would have stayed with the patients throughout tx. Nevertheless, the fact that they reported D0 levels, rather than W12,W12+1 or W24, as most significantly predictive, suggests there's something critical about that first knockout punch - a theme that also appears in the Alinia and boceprevir pre-dosing.
Incredibly interesting!!!
Makes me really consider to predose, especially since my VL has gone up to 2.2 mio .
I for one am glad that I titered up the Riba for a month. Also, glad that I was able to tolerate a higher dose. 1600. Still at the level at 8 weeks.
Amen sister now you're preaching!!!!!!!!! ;)
So many many variables that it's just mind boggling but at least they are learning and getting some of them down! That's just gotta help the odds a bit!
Debby
Studies like this and the weight-based dosage ones may make ribavirin LESS of a crapshoot and wouldn't THAT be nice. :)
Trish
I hope people keep in mind that adequate ribavirin is what's required, not as much as you can shove into your system and not keel over. The absorption / concentration factor is a very interesting one that I'd like to see and read more studies on. Just as weight-based and "true" weight-based dosage attitudes have come onstream to improve outcomes of treatment by determining effective ribavirin dosages, perhaps there will be more attention to concentration factors down the road as well, with further studies.
What all this means to ME is that it's not ONLY getting the dosage amount right, it's being aware that absorption / concentration also plays a part in the effectiveness of ribavirin and paying attention to that, whether it's taking the ribavirin with high-fat meals or, perhaps down the road, testing the absorption levels to determine the effectiveness factor of the dosage one is getting and using that to help determine appropriate dosage amounts. It might even allow for LESS ribavirin, imagine that, in the sense that if someone thinks MORE is required, their absorption factor may tell them that they're doing just fine.
I read excerpts on the Lindahl study. While the results were 9/10 people achieved SVR by taking much higher dosages of ribavirin, they managed those higher dosages by making use of blood transfusions and rescue drugs. Like, I'm a big Riba fan but that's over the top to me, like using a hammer to take the door off it's hinges when the right screwdrivers would have done the same job with less damage and with more finesse.
The cautions are duly noted. While I'm convinced of the importance of getting ENOUGH ribavirin, I'm not one for loading up just for the sake of it. That's reckless and as Jim said, it's a serious drug. Monitoring of blood levels and responding accordingly is definitely required.
And I agree with you, Jim. It's certainly not conclusive by any means that pre-dosing can help with SVR. For me, it simply backs up other studies that have found that appropriate dosage and effectiveness of ribavirin is vitally important in the beginning of treatment (other studies have been more specific to say the first 12 weeks in particular) and if pre-dosing can raise the effectiveness of ribavirin from a superior concentration standpoint in those early stages, it does make pre-dosing at least worth some consideration. Personally, I'd implement it if doing SOC, but that's me.
Interesting stuff, for sure.
Trish
I think what this study is about is the metabolic variability among individuals in terms of their ability to sustain Ribavirin levels in their system.
My treating physician has a study underway hypothesizing that the reason that African Americans respond at a lower rate to treatment is specifically because of this variability in maintaining Ribavirin levels. In order to get this information, you have to be plugged into a machine for a number of hours after you take the Rivavirin, so it's not exactly a picnic.
I don't see the study as saying anything about adjusting dosages of Ribavirin to compensate for the variability. I have no idea whether it would work. If your body doesn't hold onto the Ribavirin, it doesn't necessarily stand to reason that giving it more would make the situation better. You might just fail to process that much more.
Well pretty much we all already knew this - but I want to point out that Andromadaes statement of
"This does NOT mean to anyone taking an s-load of ribavirin their first day will necessarily have a higher chance of SVR"
Should be well heeded. As I've freely admitted I went bonkers with riba way over my weight based dosage - almost had to stop treatment because of the drastic anemia in the 2/3 week mark and STILL had to extend treatment.
But we all know how crucial getting and keeping the dose of riba up is - I just don't want anyone to think taking 2,000 a day of the junk will help...mostly all it did for me was get my hemo to drop 6 points in one week. That was NOT good.
This article does make me think that pre-loading riba IS a good idea though to get that serum level up however we don't know for sure if because you've already gotten it inside of you whether or not that might be a negative in the long run.
Still a big crapshoot.
Ja gotta love a study that throws amantadine into the mix at this late date. I wonder if any of the patients got colloidial silver or leeches on top of everything else.
While certainly not conclusive that pre-dosing ribavirin can help with SVR, the study certainly makes pre-dosing a more reasonable option. As to serum riba levels, the Lindahl Swedish research group has been on this train for some time now highlighted by their pilot high dose riba (HDR) study. For a number of years, Lindahl's thesis has been that body weight is a poor gauge of riba dosing, do to individual variances in how riba is metabolized. Lindahl mesured riba absorption through HPLC (high performance liquid chromatography) testing which is not available in this country, unless perhaps in some research labs. Unfortuantely, very little work here in this area which could potentially have salvaged many, many SVRs, but resources (money and white coats) are elsewhere, mostly with the PI's. I expect we will see some pre-dosing studies soon and maybe some enlightened clinicians will start demanding HPLC testing for their patients.
As a word of caution before people start getting overly enthusiastic about upping their ribavitin, its not a drug to play around with. Two or Three of Lindahl's small pilot study (10 participants) required two blood tranfusions each, not to mention increased side effects (and epo) for the rest. On a personal note, I tried to emulate the Lindahl study when I started tx and ended up in the ER, resulting in having to go off riba for close to a week which could have cost me my eventual SVR. It also terminated any HDR plans, including a planned trip to Sweden for HPLC testing. That said, for the right highly motivated patient, with the right medical team, focusing more on the riba is something worth exploring, especially if prior treatments failed, PI's are not available, and if riba absorption from prior treatments is suspect. As to pre-dosing, I think it's a reasonable concept that anyone starting tx should discuss with their doctor. FWIW Dr. Dieterich in the professional forum, made a favorable mention of the concept recently.
-- Jim
-- Jim
Correction...the article you quoted doesn't mention the importance of adequate ribavirin in the first 12 weeks, other articles I've read mention that first 12 weeks as being important but not to the exclusion of the next 12 weeks or the ones after that,...just that the first 12 weeks is most important.
As well...I'm not suggesting that everyone should have their concentration levels tested and dosage adjusted accordingly...it's simply interesting food for thought in my mind at the moment when reading such things and definitely warrants more consideration IMHO. I wonder where such studies will lead to down the road in determining appropriate ribavirin levels.
Trish
What it's saying in essence is that it's not only important to get the right dosage amount, the amount of ribavirin concentration / absorption achieved is also an important factor in the effectiveness of ribavirin, particularly in the first 12 weeks of treatment.
It's also suggesting that the higher the ribavirin concentration in the first stage of treatment, the better chance at SVR ... one can potentially make a case for pre-dosing with ribavirin to achieve maximum concentration of ribavirin at start of treatment.
One of the best ways to increase concentration of ribavirin is to take it with a high-fat meal. To take your riba with no meal or a regular meal has the equivalent absorption factor, while taking riba with a high-fat meal of some kind increases the absorption factor by a whopping 46%
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1804105
I can tell you that I've increased my intake of ice cream eaten with my riba after reading that with alot less guilt. ;->
There are ways of measuring how well your body is "concentrating" the ribavirin, though I'm not well-versed in that. I'm thinking it's what Willy50 referred to as "trough" levels of ribavirin. I'm thinking that if it's able to be measured, then dosage can be adjusted according to how well the body is absorbing / concentrating it and titer the dosage upwards if necessary. I did read and thought I had bookmarked an article on that and I guess it will depend which part of the article I found significant at the time as to where I filed it. There was some mention in the article on measuring effective absorption of ribavirin by measuring the CL, or Creatinin clearance levels. I'll look for it.
That's my take on it.
Perhaps others have some insight on this as well.
Trish
As I understand it the article is prosing that patients with higher blood plasma ribavirin levels on day 0 is a predictor of success at attaining SVR.
This does NOT mean to anyone taking an s-load of ribavirin their first day will necessarily have a higher chance of SVR It MAY mean that some people's metabolism create, for some unknown reason, higher blood levels of Riba during treatment. For THOSE people their chances of SVR may be higher - although the authors do seem to be implying that higher Riba dosing on day 0 may be a good thing.
***** for me as my treating P.A. had me start the Riba 12 hours AFTER my first shot. Veterans Administration . Yeah.