The present invention is to provide a novel substance having in vivo drug dissolution control action, a novel in vivo drug dissolution control agent, a solid preparation controlled drug dissolution, and any one of these production methods.The present invention provides a complex having tannic acid and a drug (optionally, an inert carrier and/or a lower alcohol), a solid preparation having the complex, production methods thereof, and the like. The complex is characterized in that at least one of the peaks due to the functional groups of the drug is not detected in the infrared absorption spectrum obtained when measured with a Fourier transform infrared spectrophotometer.本發明以提供具有在生體內之藥物溶出控制作用的新穎物質、新穎的在生體內之藥物溶出控制劑、藥物的溶出受控制的固形製劑、以及該等的製造方法中的任1種以上為課題。本發明提供含有單寧酸及藥物(視所求,再含有惰性載體及/或低級醇)的複合體、含有該複合體的固形製劑、以及該等的製造方法等。該複合體的特徵為:以傅立葉轉換型紅外分光光度計測定時所得的紅外線吸收光譜中,藥物的官能基的尖峰中至少有1個尖峰不被檢出。本案圖式均為試驗結果數據,故本案無指定代表圖。
