Similarity between (+)-amphetamine and amfonelic acid

Rats, trained to discriminate the CNS stimulant (+)-amphetamine (1.0 mg/kg) from saline in a two-lever drug administration task, were challenged with various doses of the structurally dissimilar CNS stimulant amfonelic acid. Amfonelic acid was found to substitute for the amphetamine stimulus and was found to be 1.5 times more potent than amphetamine.