Disclosed is a preparation which, in an orally fast-disintegrating tablet having as an active ingredient 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazole carboxylic acid, causes basically no irritation in the mouth or throat, retains good dissolvability and oral disintegration even when stored under high temperature or high humidity conditions. The disclosed orally fast-disintegrating tablet is formed to contain particles comprising nuclear particles which contain 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazole carboxylic acid, which are covered by a layer containing a methacrylic acid copolymer, and which are further coated with an outer layer containing water-soluble sugars, such that after two weeks of storage under conditions with the cap open at 40C / 75% RH, a dissolution test performed according to the Japanese Pharmacopoeia Paddle Method at 50 revolutions per minute (test solution: pH6.0McIlvaine buffer) evaluates the dissolution rate of the 2-(3-cyano-4-isobutyloxyphenyl)-4-methyl-5-thiazole carboxylic acid at 70% or greater after 10 minutes.本發明係提供一種以2-(3-氰基-4-異丁氧基苯基)-4-甲基-5-噻唑羧酸為有效成分之口腔內速崩解性錠劑，其係於口腔內及喉頭實質上不會感到刺激感，且即使保存於高溫‧高濕條件下，亦可維持良好的溶出性及口腔內崩解性之製劑。本發明之口腔內速崩解性錠劑係包含將含2-(3-氰基-4-異丁氧基苯基)-4-甲基-5-噻唑羧酸之核粒子，以含甲基丙烯酸聚合物之層進行被覆，及進而以含有於40℃/75%RH之開封條件下保存2星期後，依據日本藥典槳式法以每分鐘旋轉50次(試驗液：pH6.0 McIlvaine緩衝液)進行評價之溶出試驗中，10分鐘後2-(3-氰基-4-異丁氧基苯基)-4-甲基-5-噻唑羧酸之溶出率為70%以上之含水溶性糖類之層進行二次被覆之粒子而成。
