    Sentence’ I: With Claritin ’s decline. , Schering-Plough ‘s  best-selling products now are'Iwo drugs used fogether  10 treat hepatitis C, the antiviral: pill ribavirin and. an  interferon medicine called Peg-Intron .    Sentefice 2: With Claritin ‘s decline , Schering-Plough ‘s  best-selling ‘products are: now: aniiviral drug ‘ribavirin  and an. interferon medicine called Peg-Infron -- wo  drugs used together to treat hepatitis C: