Pharmacists Act Article 17

Pharmacists shall dispense according to the prescriptions without any mistakes; in the case that pharmaceuticals are not available or in short supply, pharmacists shall inform the prescribing physician for change, and shall not omit or substitute pharmaceuticals at will.
中文原文 藥師法第17條
藥師調劑,應按照處方,不得錯誤,如藥品未備或缺乏時,應通知原處方醫師,請其更換,不得任意省略或代以他藥。

English translation for reference only; the Chinese text prevails. Not legal advice.