Phenylpropanolamine

Phenylpropanolamine (PPA), sold under many brand names, is a sympathomimetic agent used as a decongestant and appetite suppressant. It was once common in prescription and over-the-counter cough and cold preparations. The medication is taken orally.

Side effects of phenylpropanolamine include increased heart rate and blood pressure. Rarely, PPA has been associated with hemorrhagic stroke. PPA acts as a norepinephrine releasing agent, indirectly activating adrenergic receptors. As such, it is an indirectly acting sympathomimetic. It was once thought to act as a sympathomimetic with additional direct agonist action on adrenergic receptors, but this proved wrong. Chemically, phenylpropanolamine is a substituted amphetamine and is closely related to ephedrine, pseudoephedrine, amphetamine, and cathinone. It is usually a racemic mixture of the (1R,2S)- and (1S,2R)-enantiomers of β-hydroxyamphetamine and is also known as dl-norephedrine.

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 It was withdrawn from many markets starting in 2000 after learning that it was associated with increased risk of hemorrhagic stroke.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