This invention provides a non-enteric coated pharmaceutical composition having an enhanced bioavailability comprising an acid-labile active ingredient; and a nanonized biocompatible polymer; , wherein the acid-labile active ingredient is mixed with and trapped by the nanonized biocompatible polymer, and the acid-labile active ingredient is sustained release from the nanonized biocompatible polymer.本發明係提供一種非腸衣塗覆之醫藥組成物,具有強化之生體利用率,係包括:酸不穩定性之活性成分、及奈米化之生物相容性聚合物;其中,該活性成分係與該生物相容性聚合物摻混且被該聚合物所包載;且該活性成分係由該生物相容性聚合物中持續釋出。