PROBLEM TO BE SOLVED: To provide a method for reducing one or more side effects of administration of the pharmaceutical composition, the method for inhibiting microbial growth and oxidation in the pharmaceutical composition, and the method for enhancing transport and binding of a pharmaceutical agent to a cell, and to provide the pharmaceutical composition.SOLUTION: There is provided the pharmaceutical composition including a pharmaceutical agent, such as paclitaxel, with human serum albumin in a specific ratio. There are provided the method of reducing the side effects associated with myelosuppression, neurotoxicity, hypersensitivity, inflammation, venous irritation, phlebitis, pain, skin irritation, and the method for enhancing transport of the pharmaceutical agent to the lesion in a human.【課題】医薬組成物の投与の1つ以上の副作用の減少方法、医薬組成物における微生物増殖及び酸化の阻害方法、並びに細胞への医薬の輸送及び結合の増大方法および医薬組成物の提供。【解決手段】パクリタキセルなどの医薬をヒト血清アルブミンと特定比率で含有する医薬組成物であって、骨髄抑制、神経毒性、過敏症、静脈刺激、炎症、静脈炎、疼痛、皮膚刺激などの副作用の低減とヒトにおける疾患部位への医薬の輸送を増大させる方法。【選択図】なし