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FDA Approves Dose Adjustments of PegIntron and Rebetol for Certain Patients with Chronic Hepatitis C

The U.S. Food and Drug Administration (FDA) last week announced approval of a new dosing regimens for certain patients taking pegylated interferon alfa-2b (PegIntron) plus ribavirin (Rebetol brand) for the treatment of chronic hepatitis C virus (HCV) infection.

The package insert now specifies revised reduced doses of pegylated interferon and ribavirin to manage side effects such as blood cell deficiencies. These changes reflect findings from the IDEAL study, which indicated that lower doses of pegylated interferon could still be effective, but an adequate dose of ribavirin was needed to prevent relapse.

Below is the FDA's announcement of the label change.

FDA Hepatitis Update -- Dose adjustments of PegIntron and
Rebetol for certain patients with chronic hepatitis C

On May 8, 2009, FDA approved updates to the package insert for PegIntron (peginterferon alfa-2b), a polyethylene glycol-conjugated formulation of interferon alfa-2b, currently approved for the treatment of chronic hepatitis C (HCV) in patients 3 years of age and older with compensated liver disease, to reflect the results of the IDEAL study, P03471, which includes adding a two-step dose reduction scheme for PegIntron and increasing the dose of Rebetol to 1200 mg/day for patients who weigh between 81 and 85 kilograms.

The package insert for PegIntron has been revised to provide changes in the DOSAGE AND ADMINISTRATION section regarding the new two-step dose reduction for PegIntron in the event of poor tolerability or toxicity. Dose reduction recommendations include decreasing from PegInton 1.5 mcg/kg/week to 1.0 mcg/kg/week, then to 0.5 mcg/kg/week if a second dose reduction is needed. In addition, dose recommendations for the accompanying dose of Rebetol in patients > 80 to 85 kg have been revised to 1200 mg daily rather than 1000 mg daily. Study P03471 is described in the CLINICAL STUDIES section of the label.

The IDEAL study compared PegIntron 1.5 mcg/kg/week and PegIntron 1.0 mcg/kg/week both in combination with Rebetol and Pegasys [pegylated interferon alfa-2a] 180 mcg/week in combination with Copegus [ribavirin] in 3070 treatment-naive subjects with genotype 1 HCV infection. Overall, sustained viral response (SVR) rates were similar in all three treatment arms, however, the PegIntron 1.5 mcg dose appeared to provide numerically higher sustained viral response (SVR) rates than the PegIntron 1.0 mcg dose in many hard-to-treat subgroups including African Americans, patients > 40 years of age, and patients with high viral load.

The two-step approach to dose reduction appears to provide optimal efficacy in the greatest number of patients while preserving demonstrated efficacy of PegIntron 1.0 mcg/kg in those patients who require dose reduction because of intolerance or toxicity. A second dose reduction was required in a relatively small proportion of study subjects (2%-7% across the arms).

The revised label will be available soon on the FDA web site at Drugs@FDA.

Complete prescribing for PegIntron is available online at


R Klein and K Struble (Food and Drug Administration). FDA Hepatitis Update -- Dose adjustments of PegIntron and Rebetol for certain patients with chronic hepatitis C. May 12, 2009.