There was a small study done in Argentina a few years ago comparing the two, but I can't find it right now. Bottom line is, Pegasys stays in your system longer and PegIntron may do some things during the early part of treatment better for a net result of equal statistical efficacy. Some people do respond better to one or the other, but we can't tell ahead of time who will respod better to which. I weigh about what you do and SVRd with PegIntron.
J Viral Hepat. 2007 Oct;14(10):721-9
Di Bisceglie AM, Ghalib RH, Hamzeh FM, Rustgi VK.
Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St Louis, MO 63110, USA. ***@****
Patients infected with hepatitis C virus (HCV) genotype 1 and with serum HCV RNA concentrations over 800 000 IU/mL have relatively low rates of virologic response to pegylated interferons. The 2 forms of pegylated interferon have different pharmacokinetic profiles, and pilot studies comparing them have yielded varying results. We compared the virologic response to 12 weeks of treatment with peginterferon alpha-2a plus ribavirin vs peginterferon alpha-2b plus ribavirin in 380 patients who were infected with HCV genotype 1 and had high viral loads. We observed no between-group differences in viral load reduction over time and no differences in the percentage of patients treated with peginterferon alpha-2a or peginterferon alpha-2b plus ribavirin who achieved early virologic response (EVR), defined as >/=2-log reduction in HCV RNA concentration or undetectable HCV RNA at 12 weeks (66%vs 63%). Serum levels of interferon were more frequently below the level of quantitation in patients treated with peginterferon alpha-2b plus ribavirin (58-68%) than in those treated with peginterferon alpha-2a plus ribavirin (1-2%). Patients treated with peginterferon alpha-2b plus ribavirin had higher rates of discontinuation for safety reasons (6%vs 1%). In conclusion, a substantial percentage of patients infected with HCV genotype 1 and high viral load can achieve EVR when treated with peginterferon and ribavirin. The 2 pegylated interferons showed comparable anti-HCV activity during the first 12 weeks of treatment when combined with the same doses of ribavirin (1000-1200 mg/day), but discontinuations for safety reasons were higher in the patients treated with peginterferon alpha-2b plus ribavirin.
PMID: 17875007 [PubMed - indexed for MEDLINE]
Here is an article which attempts to compare the two drugs. The study concludes that the efficacy of both drugs are quite similar though it appears that more patients discontinued treatment for safety issues with alpha 2b. I believe that you'll find the article worth reading. Mike
Early Virologic Response After Peginterferon Alpha-2a Plus Ribavirin or Peginterferon Alpha-2b Plus Ribavirin Treatment in Patients With Chronic Hepatitis C
"The safety profiles of both regimens were generally typical of those observed during treatment with pegylated interferon and ribavirin.[5,24] We found, however, that a greater percentage of patients treated with peginterferon alpha-2b plus ribavirin discontinued for safety reasons than did patients treated with peginterferon alpha-2a plus ribavirin. Discontinuations because of nonsafety reasons were comparable. We also observed that the peginterferon alpha-2b plus ribavirin group had a > 25% greater relative frequency of chills, fever and influenza-like symptoms, which may be related to fluctuations in interferon concentration over time. The relative frequencies of influenza-like adverse events may be related to the peak interferon concentration after each dose following very low or undetectable trough concentrations.[12,15-17] The frequency of other adverse events was about the same, suggesting that influenza-like illness is related to the peak concentration relative to the end of each dosing period, at which peginterferon alpha-2b was frequently undetectable.
In conclusion, the results presented here show that a substantial percentage of patients infected with HCV genotype 1 and a high viral load can achieve EVR when treated with peginterferon and ribavirin. The 2 pegylated interferons showed comparable anti-HCV activity during the first 12 weeks of therapy when combined with the same doses of ribavirin (1000 or 1200 mg/day), and there was no evidence that RVR or EVR differed when either peginterferon was combined with ribavirin."
Thanks for posting these I found them very helpful in deciding on my husbands third attempt at treating. He has used Pegintron and responded too slow (2 log drop at 13 weeks but too late for Ideal trial) next was Infergen but they had to keep lowering riba and he had a breakthrough. Joe has cirrhosis and his labs are low enough that this is likely our last chance to treat so I sure don't want to blow our last bullet. He was sicker on Peg intron than he was Infergen but he hasn't tried Pegasys. His Doctor prefers Peg-intron but I'm sure he never had to take it! I think our plan is to try Pegasys /Riba and Alinia. Hopefully the Alinia will keep him covered when they have to reduce Riba. He is also taking PPC which could help this time.