In the claims of patent applications relating to chemical compounds having a medical use, not only the compounds per se but also the derivatives such as the pharmaceutically acceptable salts, esters, stereoisomers, solvates, hydrates, and prodrugs of the compounds are usually claimed at the time of filing.

However, the current Patent Examination Guidelines for Pharmaceutical-Related Inventions (as of 2013) only provide examination criteria for compounds, not their derivatives. Consequently, the Taiwan Intellectual Property Office (TIPO) takes a conservative attitude on the examination of derivatives of compounds. Except for pharmaceutically acceptable salts, applicants are generally required during the course of examination to delete derivatives of compounds from the claims as unpatentable for lacking support by working examples in the specification.

According to the amended Patent Examination Guidelines for Pharmaceutical-Related Inventions, which will be effected on 1 January 2020, pharmaceutically acceptable salts, esters, stereoisomers, hydrates and the like of a compound are deemed acceptable derivatives if the specification clearly discloses that there are derivatives of a compound, and the derivatives can be arrived at by persons of ordinary skill in the art based on the disclosure of the specification without undue experimentation. Therefore, after the draft amendment takes effect, it is expected that there will be a significant change in the TIPO's attitude towards the derivatives of compounds. Nevertheless, according to our understanding, the TIPO will still take a conservative approach in examining the solvates and prodrugs of a compound.