Final answer:
A drug that intensifies or mimics a neurotransmitter is characterized as an agonist.
Step-by-step explanation:
A drug that has the effect of intensifying or mimicking a particular neurotransmitter can be characterized as an agonist, because it intensifies the effects of a particular neurotransmitter. Agonists bind to neurotransmitter receptors and activate them, resulting in an increased neurotransmitter effect. This can lead to enhanced signaling and increased activity in the central nervous system.
Learn more about neurotransmitters