phenylpropanolamine

Action and Spectrum

Actions and spectrum: 

Actions: 

• Vasoconstriction: Phenylpropanolamine acts as an alpha-adrenergic agonist, leading to the constriction of blood vessels. This results in reduced blood flow and swelling in nasal tissues, making it effective as a decongestant. 
• Central Nervous System Stimulation: PPA can stimulate the CNS, leading to increased alertness and a potential reduction in appetite. This property has been utilized in the past for weight loss purposes. 

Spectrum: 

• Nasal Decongestant: Phenylpropanolamine has been used to relieve nasal congestion associated with common cold, allergies, or sinusitis. 
• Appetite Suppression: Historically, PPA was included in some over-the-counter weight loss products due to its potential to suppress appetite. However, its use for this purpose has been discontinued due to safety concerns. 

Drug Interaction

Adverse Reaction

Frequency not defined 

Hypertension 

Arrhythmias 

Rhabdomyolysis 

Hallucinations 

Stroke 

Renal failure 

Psychotic disturbances 

Seizures 

Black Box Warning

Black Box Warning: 

There is no specific black box warning associated with phenylpropanolamine. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

• Hypersensitivity or Allergy: Individuals with known hypersensitivity or allergy to phenylpropanolamine or related compounds should avoid its use. 
• Cardiovascular Disease: People with a history of cardiovascular disease, including hypertension or a predisposition to stroke, may have been contraindicated from using products containing phenylpropanolamine. 
• Risk Factors for Stroke: Individuals with stroke, such as a history of cerebrovascular events, may be contraindicated from using phenylpropanolamine due to its association with an increased risk of hemorrhagic stroke. 

Caution: 

• History of Stroke or Cerebrovascular Events: Those with a history of stroke or other cerebrovascular events should avoid PPA, has been associated with an increased risk of hemorrhagic stroke. 
• Pregnancy and Lactation: Pregnant or breastfeeding individuals should exercise caution, as the safety of phenylpropanolamine during pregnancy and lactation has not been well-established. 
• Interactions with Other Medications: Caution should be taken if using other medications that may interact with PPA, including monoamine oxidase inhibitors (MAOIs) and certain antidepressants. Drug interactions can potentially lead to hypertensive crises. 

Comorbidities: 

• Cardiovascular Disease: Individuals with cardiovascular disease or hypertension may have been at an increased risk, as PPA has sympathomimetic properties that can affect blood pressure. 
• Cerebrovascular Disease: Conditions such as a history of stroke or other cerebrovascular events were important considerations, as the use of PPA was associated with an elevated risk of hemorrhagic stroke. 
• Concurrent Medication Use: The use of PPA was cautioned against in individuals taking certain medications, such as monoamine oxidase inhibitors (MAOIs) or certain antidepressants, due to drug interactions and hypertensive crises.

Pregnancy / Lactation

Pregnancy consideration: pregnancy category: C 

Lactation: excreted into human milk: unknown 

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.   
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

Phenylpropanolamine (PPA) is a sympathomimetic amine that was once commonly used in over-the-counter medications as a decongestant and appetite suppressant. Its pharmacology involves stimulating adrenergic receptors, particularly alpha-adrenergic receptors. As an alpha-adrenergic agonist, PPA induces vasoconstriction, leading to reduced blood flow and decreased swelling in nasal tissues, making it effective as a decongestant. Additionally, PPA has central nervous system stimulant properties, potentially contributing to increased alertness and a reduction in appetite, which led to its inclusion in some weight loss products.

However, due to safety concerns, particularly an association with an increased risk of hemorrhagic stroke, regulatory agencies have taken actions to remove products containing PPA from the market. The withdrawal of PPA-containing products underscores the importance of prioritizing patient safety in pharmaceutical use. Individuals should consult with healthcare professionals for the latest information and guidance on medications. 

Pharmacodynamics: 

• Alpha-Adrenergic Agonism: PPA acts on alpha-adrenergic receptors, particularly the alpha-1 receptors. Activation of these receptors induces vasoconstriction, resulting in reduced blood flow and decreased swelling in nasal tissues. This property makes PPA effective as a nasal decongestant. 
• Nasal Decongestant Effects: The vasoconstrictive effects of PPA contribute to its ability to relieve nasal congestion associated with conditions such as the common cold, allergies, or sinusitis. By narrowing blood vessels in nasal tissues, PPA reduces congestion and improves airflow. 
• Appetite Suppression (Historical Use): PPA has historically been included in some weight loss products due to its potential to suppress appetite. This appetite-suppressant effect is believed to be related to its central nervous system stimulant properties. 

Pharmacokinetics: 

• Absorption: Phenylpropanolamine is well-absorbed after oral administration. It is absorbed from gastrointestinal tract into the bloodstream. 
• Distribution: Once absorbed, phenylpropanolamine is distributed throughout the body via the bloodstream. Its effects, particularly as a nasal decongestant, are attributed to its distribution to alpha-adrenergic receptors in nasal tissues. 
• Metabolism: Phenylpropanolamine undergoes hepatic metabolism, primarily through the enzyme cytochrome P450 (CYP). The specific metabolites formed during this process may contribute to its pharmacological effects. 
• Excretion: The elimination of phenylpropanolamine and its metabolites occurs primarily through the kidneys. It is excreted in the urine. The elimination half-life of phenylpropanolamine can vary but is in the range of a few hours. This indicates the time it takes for half of the drug to be eliminated from the body. 

Adminstartion

Administration: 

phenylpropanolamine (PPA) has been discontinued, and its use in medications has been significantly reduced due to safety concerns, particularly an increased risk of hemorrhagic stroke. Regulatory agencies in many countries have taken actions to remove products containing PPA from the market. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: phenylpropanolamine 

Pronounced: (fen-il-proh-puh-NAH-luh-meen) 

Why do we use phenylpropanolamine? 

Phenylpropanolamine (PPA) was historically used in over-the-counter medications for its nasal decongestant properties and appetite suppressant effects. As a nasal decongestant, PPA acted by constricting blood vessels in nasal tissues, reducing swelling and congestion.

Due to its CNS stimulant properties, it was also included in some weight loss products to suppress appetite. However, the use of PPA has significantly declined and, in many regions, products containing PPA have been withdrawn from market due to the safety concerns, particularly an association with an increased risk of hemorrhagic stroke.