Disclosed herein are solid dispersion comprising VX-950 (telaprevir) and a polymer, particularly hydroxyproplymethylcellulose (HPMC) or hydroxypropylmethylcellulose acetate succinate (HPMCAS), wherein the solid dispersion is obtained by spray drying and a polymer is present in an amount from about 10% by weight to about 80% by weight. Said forms and formulations disclosed herein have improved bioavailability relative to crystalline VX-950 and are useful for treating HCV infection.