To provide a novel injectable agent having an excellent medicinal agent sustained release property. The injectable agent comprises, for example, a medicinal agent of 0.0001 to 50.00% (w/v), trehalose of 0.1 to 50.0% (w/v) and gellan gum of 0.01 to 3.00% (w/v). The injectable agent can form a depot upon contact with a phosphate buffer solution, a body fluid (tear fluid, vitreous fluid, etc.) or a pseudo body fluid.本發明之目的在於提供一種藥物之緩釋性優異之新穎注射劑。本發明之注射劑含有藥物、海藻糖、及結冷膠(gellan gum)。相對於注射劑之總體積，較佳為藥物之含量為0.0001~50.00%(w/v)，海藻糖之含量為0.1~50.0%(w/v)，結冷膠之含量為0.01~3.00%(w/v)。較佳為注射劑係與磷酸緩衝液、體液(淚液、玻璃體液等)接觸而形成緩釋者。
