What is the Difference Between Phenylephrine and Phenylpropanolamine

The key difference between phenylephrine and phenylpropanolamine is that phenylephrine is useful in relieving nasal discomfort that comes from colds, allergies, and hay fever, whereas phenylpropanolamine is useful as a decongestant and as an appetite suppressant.

Phenylephrine and phenylpropanolamine are two important medications. These drugs are used for different applications and have different routes of administration.

CONTENTS

1. Overview and Key Difference
2. What is Phenylephrine  
3. What is Phenylpropanolamine
4. Phenylephrine vs Phenylpropanolamine in Tabular Form
5. Summary – Phenylephrine vs Phenylpropanolamine

What is Phenylephrine?

Phenylephrine is a type of medication used as a decongestant in dilating the pupil, increasing blood pressure and relieving hemorrhoids. We can take it orally as a decongestant and, it can relieve nasal congestions, which comes due to cold and hay fever. Other routes of administration include a nasal spray and an injection into veins or muscles. Sometimes it is available as a topical treatment where we can apply it on skin.

There are some common side effects related to the phenylephrine medication, which include nausea, headache, and anxiety. In addition, there can be some severe side effects, including slow heart rate, intestinal ischemia, chest pain, kidney failure, and tissue death (at the site where the injection is given).

When considering the biochemical features of this medication, it is about 38% bioavailable through the GI tract, and its protein binding ability is about 95%. Metabolism of this medication occurs at the liver, and the action after administration of the drug is very rapid. The action occurs within 20 minutes when taken orally.

What is Phenylpropanolamine?

Phenylpropanolamine is a medication useful as a decongestant and as an appetite suppressant. It is a type of sympathomimetic agent. This medication is very common as a prescription drug and also as an over-the-counter drug in some countries for cough and cold preparations. Moreover, this medication is useful to control urinary incontinence in dogs.

Phenylpropanolamine is available as an oral medication. Its metabolism occurs in the hepatic mechanism. The elimination half-life of this drug is about 2 to 3 hours. We can abbreviate this drug as PPA. It is a member of the phenethylamine and amphetamine chemical class. Further, this drug is closely related to cathinone.

Originally, scientists thought that this drug acts as a direct antagonist of the adrenergic receptors. Subsequently, it was found to have a weak affinity for these receptors. Instead, it acts by inducing norepinephrine release and activating adrenergic receptors.

What is the Difference Between Phenylephrine and Phenylpropanolamine?

Phenylephrine and phenylpropanolamine are two important medications. The key difference between phenylephrine and phenylpropanolamine is that phenylephrine is useful in relieving nasal discomfort that comes from colds, allergies and hay fever, whereas phenylpropanolamine is useful as a decongestant and as an appetite suppressant. In addition, routes of administration for phenylephrine include oral uptake, nasal spray and injections into veins or muscles while the route of administration for phenylpropanolamine is oral.

The following figure presents the difference between phenylephrine and phenylpropanolamine in tabular form.

Summary – Phenylephrine vs Phenylpropanolamine

Phenylephrine and phenylpropanolamine are two important medications. The key difference between phenylephrine and phenylpropanolamine is that phenylephrine is useful in relieving nasal discomfort that comes from colds, allergies, and hay fever, whereas phenylpropanolamine is useful as a decongestant and as an appetite suppressant.

Reference:

1. “Phenylpropanolamine.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine.

Image Courtesy:

1. “Phenylephrine Structural Formula V1” By Jü – Own work (Public Domain) via Commons Wikimedia
2. Phenylpropanolamine Structure” By Nynyny – PubChem (Public Domain) via Commons Wikimedia