Ribavirin weight based dosing
Common Questions and Answers about Ribavirin weight based dosing
rebetol
Summary of Key Conclusions
* Dosing according to glomerular filtration rate (GFR) may be preferable to weight-based ribavirin among ribavirin-treated HCV genotype 1/4 patients with poor renal function
* Poor renal function (low GFR) associated with
o Lower sustained virologic response (SVR) rates
o More adverse events
o Possibly due to nonoptimal ribavirin dosing
* GFR varied according to sex, age, and genotype but not according to weight or body mass i
If every person absorbs ribavirin at different levels based on many more factors then their weight (kidney function for example) then weight based dosing doesn't make a lot of sense. If anemia is more then a crude indicator of riba absorption then why do a good amount of people still svr without becoming anemic, and why not just reduce riba when a person becomes anemic rather then give them procrit to keep the dose up.
In the present study, the investigators conducted an exploratory pharmacokinetic-pharmacodynamic analysis of 28 genotype 1 chronic hepatitis C patients treated with pegylated interferon alfa-2a (Pegasys) plus weight-based ribavirin for 12 weeks, with amantadine (an influenza drug once studied as an experimental anti-HCV therapy) added for an additional 36 weeks; 24 participants completed the study.
Recently, data from the Individualized Dosing Efficacy vs Flat Dosing to Assess Optimal Pegylated Interferon Therapy (IDEAL) study has provided a within-trial comparison of these 2 peginterferon regimens when used together with weight-based ribavirin dosing and demonstrated that SVR rates and tolerability were equivalent (Capsule Summary).
Of note, within the weight-based ribavirin group, SVR rates were consistent across all weight categories, whereas SVR significantly decreased with increasing weight in the fixed-dose group (Figure 5). Weight-based ribavirin dosing could be considered for those patients that may be more difficult to treat due to underlying host characteristics such as obesity or advanced fibrosis.
They suggest that the larger question of whether true weight-based dosing of ribavirin is superior to the currently approved standard dosing schemes still awaits head-to-head studies to answer. "At the minimum," they conclude, "the traditional notion that ribavirin dosage should be fixed has now been sidelined by the idea that we should tailor ribavirin dosing to our patients.
Yes... Riba dosing is weight based and given your current weight of 135 lb or 61.4 kg then according to the chart below 800 would be the correct amount.
Having said that if you weighed 7 or 8 lbs. more then your recommended dose of Riba would have been 1000.
Something you may want to take up with your doctor as you are right on the edge of the recommended amount ,given current weight.
Tolerability is always important.
Will
http://www.rxlist.com/copegus-drug.
75 kg 1000 mg dosage is the current recommendation for copegus with pegasys and the weight based dosing you are referring to is the recommendation by merck for rebetol and pegintron.
http://www.rxlist.com/copegus-drug.htm
It seems odd to call it old school when there are people in current trials well under your weight taking 1000 mgs. Victrelis and Incivek still depend heavily on soc to eliminate the stragglers and prevent relapse.
(48kg) when treatment started your doctor did well by you to start you on 1000mg,which would actually have been quite high given the guidelines for weight based dosing. However it is most important to get the maximum amount of benefit from Ribavirin early on(especially in the first 12 weeks ) and secondly until UND.
Because you were undetected at week 4 and still at week 12 given your weight and how much time has lapsed it would seem your dose is fine.
Your are currently taking 800 (16.
Finally, in the SPRINT-1 study of boceprevir for genotype 1, treatment-naive patients, those receiving low-dose RBV achieved an SVR rate of only 36% vs 50% with standard weight-based RBV dosing, each combined with boceprevir and pegIFN
http://www.clinicaloptions.com/Hepatitis/Annual%20Updates/2011%20Annual%20Update/Modules/DAA%20Naive/Pages/Page%204.
While statistically less anemia was observed in patients treated with TBV compared to RBV, the primary efficacy endpoint of these studies, a non-inferior SVR between the TBV and RBV, was not achieved. Detailed subgroup analyses of the data suggest fixed dosing as opposed to weight-based dosing, and the selection of an inadequate dose, are to blame.
These results suggest that weight-based dosing of taribavirin at higher doses may be an alternative to ribavirin for the treatment of hepatitis C with an advantage for anemia."
If I recall, it didn’t receive FDA approval because it didn’t have *superior* efficacy over ribavirin, despite its better tox profile… go figure.
If I were going to pre-dose ribavirin, I'd do it for 4 weeks. Many of the articles I read show steady-state concentration at 3-4 weeks. So I would go for the 4 weeks to get maximum effect. Perhaps that's why the study coeric has posted chose a 4 week lead-in? Just a pondering thought.
Definitely take the riba with fat content foods, however I have a feeling your friend knows that.
The current standard of care for G3, is usually for 6 months or more, with peginterferon and weight based Ribavirin (800 - 1400 mg per day in two doses, within 10 hours with food)
Hope this helps, some basics:
http://www.hepmag.com/articles/2512_18756.shtml
What treatments are available?
The goal of HCV treatment is to cure the virus, which can be done by using a combination of drugs.
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