The present invention creates the optically active 4-phenyl thiazole derivatives having thrombopoietin receptor agonist activity and the pharmaceutical composition containing the compound as the active ingredient, and provides the oral administration possible platelet producing modulator. [solution]The pharmaceutical composition contains, as the active ingredient, the optically active compound of the following fomula (I):(wherein, R1is a halogen atom or a C1-C3 alkyloxy R2is a C1-C8 alkyl R3is a C1-C8 alkyl R4and R5 respectively independent a fluorine atoms or a chlorine atoms R6is a C1-C3 alkyl or a C1-C3 alkyloxy * shows that the attached carbon atom is an asymmetric carbon), or the pharmaceutically acceptable salt, or the solvate thereof.創製具有血小板生成素受體激動劑作用之光學活性之4-苯基噻唑衍生物及以該化合物為有效成分含有之醫藥組成物,提供可經口投與之血小板產生調節劑。以如下式光學活性化合物、其製藥容許鹽、或以彼等之溶劑合物為有效成分含有之醫藥組成物:(式中R1為鹵原子或C1-C3烷氧基;R2為C1-C8烷基;R3為C1-C8烷基;R4及R5各自獨立為氟原子或氯原子;R6為C1-C3烷基或C1-C3烷氧基;*乃示所附碳原子為不對稱碳)。
