The objective of the present invention is to provide a technique for increasing the thermal stability of dibutylhydroxytoluene and suppressing a decrease in the content thereof over time in a liquid drug that includes dibutylhydroxytoluene and pranoprofen and/or a salt thereof. By mixing, into the liquid drug that includes dibutylhydroxytoluene and pranoprofen and/or a salt thereof, at least one item selected from the group consisting of a chondroitin sulfate ester, aspartic acid, alginic acid, an alginic acid derivative, pharmaceutically acceptable salts of these, cyanocobalamin, panthenol, a tocopherol, and a tocopherol derivative, and by employing a resin including polybutylene terephthalate as a resin that constitutes an inner wall surface (such as the wall surface of an interior space in a spout portion and/or a lid wall surface facing a spout opening in the spout portion) of an accommodating container, the thermal stability of the dibutylhydroxytoluene in the liquid drug can be increased, adsorption of the dibutylhydroxytoluene to the container can be suppressed, and a decrease in the dibutylhydroxytoluene content over time can be suppressed.
