Phenylephrine

GoodRx

Phenylephrine 2.5%, 10% · ophthalmic solution

Mydriatics/Cycloplegics

Approved uses

Mydriasis, age 1 year and older

1 drop of 2.5% or 10% every 3 to 5 minutes, maximum 3 drops per eye, repeated if necessary

FDA label, Clinical Pharmacology and Dosage and Administration; Kazemi A, McLaren JW, Sit AJ. Invest Ophthalmol Vis Sci. 2021;62(13):4, prospective study of 40 eyes of 20 healthy subjects with the fellow eye as control, PMID 34617960

Mydriasis, infants under 1 year

1 drop of 2.5% at 3 to 5 minute intervals, maximum 3 drops per eye

OFF-LABELNot in the FDA label for this product

Horner syndrome, denervation supersensitivity testing

1 drop of a 1% dilution in each eye, pupils measured 1 hour later in bright light; 1% is not a marketed strength and must be diluted

Observational · 71% sensitive

In a standardized series, 71% of sympathetically denervated or decentralized Horner pupils were supersensitive to 1%; a normal 20-year-old dilates by no more than 2.1 mm in bright light at 1 hour, sensitivity rises 0.23 mm per decade, and the interocular difference should not exceed 0.7 mm. The author concluded that supersensitivity is a useful but not invariable feature, so a negative test does not exclude the diagnosis.

Ramsay DA. J Neurol Sci. 1986;73(1):125-134, observational pupil measurement study in normal subjects and in Horner and Holmes-Adie syndromes, PMID 3701366

Episcleritis versus scleritis, vasoconstriction test

Topical instillation over the injected sector, then re-examine those vessels for blanching; no standardized concentration, and 10% was the strength used in the single reported case

Review + case report

A vasculitis review states that episcleritis blanches on instillation of topical phenylephrine while scleritis is painful and does not blanch, without specifying a concentration; in a reported case of nodular anterior scleritis, hyperemia persisted after 10%. No study of diagnostic accuracy and no standardized concentration or reading time was found, so treat the result as supportive rather than definitive.

Garrity JA. Cleve Clin J Med. 2012;79 Suppl 3:S31-S33, review, PMID 23203643; Constancio EG, et al. Arq Bras Oftalmol. 2021;84(1):74-77, case report, PMID 33470345

Contraindications

Hypertension or thyrotoxicosis, for the 10% solution; the 2.5% solution should be used in these patients.
Age less than 1 year, for the 10% solution, due to increased risk of systemic toxicity; the 2.5% solution should be used in these patients.

Available Forms

Ophthalmic solution, 2.5% (10 mL, 15 mL), 10% (5 mL fill in a 10 mL bottle)

Mechanism of Action

Alpha-1 adrenergic receptor agonist that acts locally as a potent vasoconstrictor and mydriatic, constricting ophthalmic blood vessels and contracting the radial muscle of the iris. Maximal mydriasis occurs at 20 to 90 minutes with recovery after 3 to 8 hours, and systemic absorption can raise blood pressure, sometimes with a reflex atropine-sensitive bradycardia.

Warnings & Precautions

Cardiovascular reactions, 10%: Ventricular arrhythmias and myocardial infarction, some fatal, usually in patients with pre-existing cardiovascular disease; the 2.5% solution should be used in these patients.
Blood pressure elevation: Not common but reported after recommended doses of the 10% solution, and less likely with 2.5%; caution with 10% in children under 5 years and in hyperthyroidism or cardiovascular disease, and monitor post-treatment blood pressure in cardiac or endocrine disease and in anyone who develops symptoms.
Rebound miosis: Reported one day after instillation, with a lesser mydriatic effect on re-instillation.
Pressor interactions: Concomitant atropine may enhance the pressor effect and induce tachycardia, and the cardiovascular depressant effects of some inhalation anesthetics may be potentiated.
Sympathomimetic cautions: A review of systemic reactions to ophthalmic drugs associates both 2.5% and 10% with cardiovascular effects and advises caution with monoamine oxidase inhibitors, tricyclic antidepressants, and atropine, and in hypertension, advanced arteriosclerotic change, aneurysm, orthostatic hypotension, long standing insulin dependent diabetes, and low bodyweight children.
Overdose response: Rapid rise in blood pressure, headache, anxiety, nausea, vomiting, and ventricular arrhythmias; prompt injection of a rapidly acting alpha-adrenergic blocking agent such as phentolamine has been recommended.
Route restriction: Topical ophthalmic use only, not for injection.

Common Side Effects

Ocular: Eye pain and stinging on instillation, temporary blurred vision, photophobia, conjunctival sensitization.
Cardiovascular, 10%: Marked blood pressure increase, syncope, myocardial infarction, tachycardia, arrhythmia, and subarachnoid hemorrhage, occurring primarily in hypertensive patients.
Blood pressure, high-risk groups: Marked increase reported particularly, but not limited to, low weight premature neonates, infants, and hypertensive patients.
Frequency: Spontaneous postmarketing reports from a population of uncertain size; rates and causality are not reliably estimable.

Pregnancy & Lactation

Pregnancy: Animal reproduction studies have not been conducted with the topical drug and fetal harm potential is unknown; give only if clearly needed.

Lactation: Excretion in human milk is unknown; exercise caution in a nursing woman.

Pediatric Use

The 10% solution is contraindicated under 1 year of age; use 2.5%.