INN stands for International Non-proprietary names. As the name suggests, these are names which cannot be appropriated or owned by any person. INNs are common terms used in respect of a drug/pharmaceutical substance that is commonly used in the medical field. Hence the INNs are not permitted to be owned or applied for by any specific entity and no term deceptively similar to the INN can be owned by any entity either.

In light of the above, while applying for a trademark, especially in relating to pharmaceutical industry, it is better to first conduct a search in the list of INNs to ensure that there is no conflict. The list of INNs is available in the TMO website here.