A solid pharmaceutical composition comprising a solid composition, wherein the solid com- position comprises sofosbuvir and at least one pharmaceutically acceptable matrix compound, wherein at least 99 weight-% of the sofosbuvir comprised in the solid composition are present in amorphous form, at least 99 weight-% of the solid composition consist of the sofosbuvir and the at least one matrix compound, wherein the solid composition contains the sofosbuvir in an amount of at least 25 weight-%, or at least 30 weight-%, or at least 35 weight-%, or at least 40 weight-% or at least 50 weight-% or at least 55 weight-% or preferably at least 5 weight-% based on the combined weight of the sofosbuvir and the at least one matrix com- pound, wherein in the adsorption-desorption isotherm of the at least one pharmaceutically acceptable matrix compound, the desorption mass difference minus the adsorption mass dif- ference at 75 % relative humidity and 25 °C is less than 0.
