d,l-
Norephedrine (PPA) is available as an over-the-counter
appetite suppressant and
nasal decongestant in the U.S.A. The pseudoisomer d-
norpseudoephedrine, is available as an
appetite suppressant in Europe, and has been isolated as one of the stimulatory components (
cathine) of the Khat plant. Some authors have misidentified
cathine as PPA and this
confusion in the literature has resulted. PPA and d-
norpseudoephedrine possess significantly different pharmacological properties despite having identical structural formulae.
Anorectic activity was determined in a food-deprived rat model. PPA and d-
norpseudoephedrine were approximately one-tenth as potent as
d-amphetamine with all compounds producing a dose-dependent decrease in food intake. Locomotor activity in an open-field apparatus was determined as an index of CNS stimulation. Male Sprague-Dawley rats treated with d-
norpseudoephedrine, in doses between 10 and 50 mg/kg, exhibited significantly increased locomotor scores compared to saline (control) treated animals, an increase similar to that caused by 2 mg/kg
d-amphetamine. PPA (5-50 mg/kg) failed to increase locomotion significantly. These results indicate that although each compound tested decreased food intake in a dose-dependent fashion, significant differences in open-field locomotion do exist between PPA, d-
norpseudoephedrine, and
d-amphetamine. Stereoisomeric compounds, although structurally similar, frequently have different pharmacological effects. Thus extreme care must be taken to properly identify these compounds in the literature.