<p>There is a relentless effort on gaining information on the reason why some compounds could cause similar effects though they are or not structural similar. That is the chemical similarity that plays an equally important role and we approach it via metric space theory on a set of analgesic drugs and euphoric compounds. The findings of the present study are in agreement to these obtained via traditional structural indices moreover are in accord with clinical findings.</p>

<p>There is a relentless effort on gaining information on the reason why some compounds could cause similar effects though they are or not structural similar. That is the chemical similarity that plays an equally important role and we approach it via metric space theory on a set of analgesic drugs and euphoric compounds. The findings of the present study are in agreement to these obtained via traditional structural indices moreover are in accord with clinical findings.</p>