Analogization, Optimization, and Isosterism

Analogs falling within the scope of a generic formula are equivalents in the sense of patent law. This is the consequence of the existence of structure-activity relationships. Equivalents do not have to be taken into account for novelty but for the assessment of the inventive step [46]. 

When a well-known drug interacts with a new target, there is a risk that several hundreds or thousands of analogs of the original drug molecule have already been synthesized by the original inventors and/or their competitors. These molecules are usually protected by patents or belong to the public domain. 

The aim is to modify the structure sufficiently such that it avoids patent restrictions, retains activity, and ideally has improved therapeutic properties. 

At first glance, a high risk of interference thus appears probable. 

However, when optimizing a therapeutic profile other than that of the original inventors during the SOSA approach, the medicinal chemist will rapidly prepare analogs with distinct chemical structures, thus avoiding overlap from the original hit in the sense of patent terms. 

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