PEG-Intron.

(peginterferon alfa-2b, Schering-Plough Corp.)

A long-acting formulation of Intron A (interferon alfa-2b) for once-weekly monotherapy in patients with chronic hepatitis C who were not previously treated with alpha-interferon, have compensated liver disease, and are at least age 18 years. This is the first pegylated interferon formulation to be approved.

* Recommended Dosage: Administered subcutaneously once a week for 1 year.

* Special Considerations: In the trial that led to approval, the most common side effects were flulike symptoms (about half of subjects), injection site irritation or inflammation (49%), and psychiatric adverse events (57%, including depression in 29%). Other potential side effects include reduced neutrophil and platelet counts.

* Comment: Pegylation entails attaching polyethylene glycol to interferon, which increases the drug's mean half-life by five, thereby facilitating convenient dosing. Approval was based on a study of 1,219 adults with chronic hepatitis C infection who had not received alpha-interferon. Treatment responses--defined as undetectable HCV RNA and normalization of alanine transaminase after 24 weeks--were 17% and 24% in those on the 1- and the 1.5-[micro]g doses of PEG-Intron, respectively, vs. 12% in those on Intron alone.

"By going from regular Intron to [the 1.5-[micro]g dose of] pegylated interferon, you've doubled the sustained response rate," ...