What drug blocks the effects of certain neurotransmitters on the brain

Explanation:

Cocaine is a highly addictive drug which elevate levels of attention, energy and alertness, it can be seen as an stimulant because of these effects.

This drug blocks certain neurotransmitters like dopamine, serotonin and norepinephrine. What cocaine does is to bind to the transporters that remove the excess of these neurotransmitters, basically, cocaine cause an excess of these neurotransmitters, that's why people feel the effect of more energy and attention. Cocaine prevent the reabsorption of these transporters which causes the "increase". The final result is an amplification of these neurotransmitters, that's why this drug is highly addictive.