Attention deficit hyperactivity disorder management
There are two major medications derived from methylphenidate's isomers: a racemic mixture of half d-threo-methylphenidate and half l-threo-methylphenidate called methylphenidate (Ritalin, Concerta), and an enantiopure formulation containing just d-threo-methylphenidate called dexmethylphenidate (Focalin).
Synephrine
Experiments conducted by Hibino and co-workers also showed that synephrine (stereochemistry unspecified) produced a dose-dependent constriction of isolated rat aorta strips, in the concentration range 10–3 × 10 M. This constriction was found to be competitively antagonized by prazosin (a standard α antagonist) and ketanserin, with prazosin being the more potent antagonist (pA = 9.38, vs pA = 8.23 for ketanserin). Synephrine constrictions were also antagonized by BRL-15,572, but not by SB-216,641 (used here as a selective 5-HT antagonist), or by propranolol (a common β antagonist).