Cocaine was later added to the formulation to increase its potency through the multiplicative effects of drug interaction and to reinforce its use by individuals .
Cocaine 's effects substantially overlap with those of amphetamine but feature greater euphoria .
Cocaine , whose effects substantially overlap with those of amphetamine but feature greater euphoria , was later added to the formulation to increase its potency through the multiplicative effects of drug interaction and to reinforce its use by individuals .