See above, box 1. Finding a new, more efficient or less invasive way of administering a known drug is also a case of new use. It is important to emphasize that a new use by definition results from the same chemical entity, i.e., a known pre-existing substance. The new drug prescribed for the new use thus makes no change to the chemical structure of the existing product (as would be the case of derivatives, which are discussed later in this Guide). This is particularly true in countries where knowledge of traditional medicines exists, and new indications might be found through targeted research.