Definition, Rational, and Concept of the SOSA Approach

In other words, if drugs are able to exert a strong interaction with the main target, they exert also less strong interaction with some other biological targets. 

Most of these targets are imrelated to the primary therapeutic activity of the compound. A drug with poor target specificity can be modified to enhance the side effect and decrease the original effect The objective is then to proceed to a reversal of the affinities the identified side effect is becoming the main effect and vice-versa. By contrast, there is only a limited chemical imiverse of small molecules that can be safely administered to humans. 

In this context [29], it is stated that some 90% of all the new drugs are provided by the modification of already known (lead) compounds. During the last several years, this relationship appears not to have changed considerably [30]. 

The similarity principle, that similar compounds should exert similar biological activities, has always been a most successful approach in drug research, despite many exceptions to this general concept. 

Most drugs used in human therapy possess more than one active principle and display major and/or minor actions, thus delivering one or several pharmacological side effects in addition to their main activity. 

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