Phenylephrine

Evidence Level: L4

Predicted Indications: 2

Phenylephrine

Pharmacist Assessment Report

Phenylephrine: From Allergic Rhinitis and the Common Cold to Nasal Cavity Disease

One-Sentence Summary

Phenylephrine is an alpha-1 adrenergic agonist decongestant, originally used for allergic rhinitis, the common cold, pharyngitis, and related upper-airway and eye conditions. The TxGNN model predicts it may be effective for nasal cavity disease, but this is supported by no registered clinical trials and only 5 publications, mostly indirect or combination-product studies.

Quick Overview

Item	Content
Original Indication	Allergic rhinitis, vasomotor rhinitis, pharyngitis, common cold, conjunctivitis (atopic, papillary, vernal), nasopharyngitis, headache disorder, hemorrhoid, proctitis (the label text for Canadian licences is not available)
Predicted New Indication	Nasal cavity disease
TxGNN Prediction Score	0.9997
Evidence Level	L4
Canada Market Status	Marketed (marketed DINs on record: at least 16; dormant: 1; cancelled: 3)
Number of DINs	at least 20
Recommended Decision	Hold

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available in the compiled data. Based on general pharmacology, phenylephrine is an alpha-1 adrenergic agonist. It constricts the blood vessels of the nasal mucosa, which reduces congestion, swelling, and mucosal bleeding.

This is the same mechanism behind its existing use in rhinitis and the common cold. The predicted indication, “nasal cavity disease,” is therefore largely a broader label for uses that already exist, not a truly new therapeutic area. The literature also describes phenylephrine in combination nasal sprays (such as Polydexa with phenylephrine) and as a vasoconstrictor to improve the surgical field in endoscopic sinus surgery.

The available evidence is indirect or based on combination products, not on phenylephrine alone. Absorption into the bloodstream (cardiovascular effects) and a case report of toxicity with topical vasoconstrictors in nasal surgery call for attention to safety.

Clinical Trial Evidence

Currently no related clinical trials registered.

Literature Evidence

PMID	Year	Type	Journal	Key Findings
40899890	2025	Experimental and clinical evaluation	Vestnik otorinolaringologii	Safety and efficacy evaluation of Polydexa spray with phenylephrine in acute rhinosinusitis (combination product)
37184554	2023	Review/Clinical article	Vestnik otorinolaringologii	Nasal mucosa state after local anti-inflammatory and antibacterial therapy with a phenylephrine-containing spray
37970776	2023	Review	Vestnik otorinolaringologii	Pathogenetic approach to treating inflammatory diseases of the nose and paranasal sinuses
25133491	2014	Randomized clinical trial	PloS one	Topical tranexamic acid and bleeding during endoscopic sinus surgery (phenylephrine is not the focus)
7378007	1980	Case report	Archives of ophthalmology	Cocaine toxicity during dacryocystorhinostomy, with an additional reaction to intranasal phenylephrine

Canada Market Information

DIN	Product Name	Dosage Form	Approved Indication
02479281	Phenylephrine Hydrochloride Injection USP 1%	Not available	Not available
02504545	Phenylephrine Hydrochloride Injection USP	Not available	Not available
02148455	Minims Phenylephrine Hydrochloride	Not available	Not available
02238400	Phenylephrine Hydrochloride Injection USP 1%	Not available	Not available
01953583	Phenylephrine Hydrochloride Injection USP	Not available	Not available

The others include over-the-counter cold and sinus products (for example Extra Strength Tylenol Sinus Daytime, Neocitran, Benylin, Dayquil/Nyquil) and Preparation H-PE Gel.

Safety Considerations

Contraindications suggested by the knowledge graph (not label text): hypertension and hypertensive disorder, liver failure and liver disease, kidney disease, epilepsy, insomnia, COPD, peptic and gastric ulcer, porphyria, hypothyroidism, adrenocortical insufficiency (Addison disease), inflammatory bowel disease, pancreatitis, gallbladder disease, thrombocytopenia, and psychotic or other mental disorders.
Drug interactions: 100 interactions were found, and the 20 listed are all of moderate level. The main groups are antidiabetic drugs (acarbose, glimepiride, glipizide, glyburide, insulin, canagliflozin, dapagliflozin, empagliflozin, exenatide, dulaglutide and others) and anticholinergics (atropine ophthalmic, hyoscyamine, clidinium). Diethylpropion is also listed.
Literature signal: a case report describes toxic reactions with topical vasoconstrictors used in nasal surgery.

Conclusion and Next Steps

Decision: Hold

Rationale: The prediction score is very high, but the evidence is model-based plus a small, indirect literature set, with no registered trials. The predicted indication also overlaps closely with phenylephrine’s existing uses in rhinitis and the common cold, so it adds little new therapeutic information.

To proceed, the following is needed:

Health Canada package insert warnings and contraindications (currently missing and blocking safety screening)
Mechanism of action data from DrugBank
Phenylephrine-specific clinical studies in nasal cavity disease, not combination-product studies
Approved indication text and dosage forms for the Canadian licences
A safety assessment of systemic absorption, especially in patients with hypertension or taking antidiabetic drugs

Other Predicted Indications (for reference)

Predicted Indication	TxGNN Score	Evidence Level	Decision	Comment
Trigeminal autonomic cephalalgia	0.9930	L4	Hold	The 12 publications describe phenylephrine only as a diagnostic eye-drop probe in pupillometry (cluster headache, SUNCT, Horner’s syndrome). They do not show treatment benefit, and its pressor effects could be a concern in headache patients.

Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.