Phenidates

Methylphenidate and its analogues: a piperidine ring bearing a phenyl group and an ester side chain. They block the dopamine and noradrenaline transporters rather than reversing them, so they amplify what is already being released instead of forcing release — a real mechanistic difference from the amphetamines, and not a safety margin. Stereochemistry does much of the work, dexmethylphenidate being the active enantiomer of a racemate that is half inert.

The ester is the other half of the family's behaviour. It is hydrolysed to an inactive acid, and in the presence of ethanol it is transesterified in the body to ethylphenidate, so drinking alongside methylphenidate produces a second drug. The research-chemical members — ethylphenidate, isopropylphenidate, 4F-MPH, HDMP-28 — run longer or stronger than the medicine and are associated with compulsive redosing, vasoconstriction and the cardiovascular strain common to the subject.