- Allergy to any of the medications to be used in the study (i.e., IL2, PEG-IFN/RBV), or other components of the study products. Peg Intron: benzyl alcohol, NaCl, Na-phosphate, EDTA, polysorbate 80, m-cresol, IL2; phosphate buffer, SDS, mannitol. RBV: cellulose, lactose, croscarmellose, magnesium stearate, Blue pharmaceutical ink: shellac, anhydrous ethyl alcohol, isopropyl alcohol, n-butyl alcohol, propylene glycol, ammonium hydroxide, Blue # 2 aluminum lake.