Phenylpropanolamine

Phenylpropanolamine (PPA), sold under many brand names, is a sympathomimetic agent used as a decongestant and appetite suppressant.^{[7][8][9][10]} It was once common in prescription and over-the-counter cough and cold preparations. The medication is taken orally.^[2][11]

Side effects of phenylpropanolamine include increased heart rate and blood pressure.^{[12][13][14][11]} Rarely, PPA has been associated with hemorrhagic stroke.^[10][15][12] PPA acts as a norepinephrine releasing agent, indirectly activating adrenergic receptors.^[16][17][18] As such, it is an indirectly acting sympathomimetic.^{[16][17][18][9]} It was once thought to act as a sympathomimetic with additional direct agonist action on adrenergic receptors, but this proved wrong.^[16][17][18] Chemically, phenylpropanolamine is a substituted amphetamine and is closely related to ephedrine, pseudoephedrine, amphetamine, and cathinone.^{[19][20][21][10]} It is usually a racemic mixture of the (1R,2S)- and (1S,2R)-enantiomers of β-hydroxyamphetamine and is also known as dl-norephedrine.^[20][7][8]

Phenylpropanolamine was first synthesized around 1910 and its effects on blood pressure were characterized around 1930.^[20][10] It was introduced as medicine by the 1930s.^[22][10] It was withdrawn from many markets starting in 2000 after learning that it was associated with increased risk of hemorrhagic stroke.^[22][10] It was previously available both over-the-counter and by prescription.^{[22][23][24][25]} Phenylpropanolamine is available for both human and/or veterinary use in some countries.^[23]