The present invention relates to an amorphous solid dispersion with improved stability comprising 9-[2-[[bis[(pivaloyloxy)methyl]phosphono]methoxy]ethyl]adenine as a nucleotide analogue, a pharmaceutical composition comprising the same, and a method for preparing the same.本發明是關於一種具有經改善的穩定性之非晶的固態分散、一種包括此非晶的固態分散之藥的組成物以及一種製備此非晶的固態分散的方法。其中,此非晶的固態分散包括作為核苷酸類似物的9-[2-[[雙[(新戊醯氧基)甲基]膦醯基]甲氧基]乙基]腺嘌呤。