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All about: Phenylephrine Hydrochloride

Big Image Pronouncation: (fen-ill-EFF-rin HIGH-droe-KLOR-ide)
Class: Arylalkylamines, Decongestant, Ophthalmic, Vasopressor used in shock

Trade Names:
AH-chew D
- Tablets, chewable 10 mg

Trade Names:
- Solution 2.5%
- Solution 10%

Trade Names:
- Solution 0.5%

Trade Names:
Alconefrin 12
- Solution 0.16%

Trade Names:
Alconefrin 25
- Solution 0.25%

Trade Names:
Children's Nostril
- Solution 0.25%

Trade Names:
- Liquid 7.5 mg per 5 mL

Trade Names:
Mydfrin 2.5%
- Solution 2.5%

Trade Names:
- Tablets, orally disintegrating 10 mg

Trade Names:
- Solution 0.125%
- Solution 0.25%
- Solution 0.5%
- Solution 1%
- Solution 2.5%
- Solution 10%
- Injection 1% (10 mg/mL)

Trade Names:
- Solution 0.5%

Trade Names:
- Solution 2.5%

Trade Names:
- Solution 0.25%

Trade Names:
- Solution 0.5%

Minims Phenylephrine (Canada)
Novahistine Decongestant (Canada)

Mechanism of Action


Stimulates postsynaptic alpha-receptors, resulting in rise in intense arterial peripheral vasoconstriction. Causes marked increase in systolic, diastolic and pulmonary pressures as well as reflex bradycardia. Slightly decreases cardiac output and increases coronary blood flow.







In liver and GI.




Rapid (IV).


20 min (IV); 50 min (subcutaneous).

Indications and Usage

Treatment of vascular failure in shock, shock-like states, drug-induced hypotension or hypersensitivity; correction of paroxysmal supraventricular tachycardia; prolongation of spinal anesthesia; vasoconstriction in regional analgesia; maintenance of adequate level of BP during spinal and inhalation anesthesia; temporary relief of nasal congestion and of minor eye irritations; pupil dilation in uveitis; treatment of open-angle glaucoma; use in diagnostic procedures (funduscopy) and before surgery.


Severe hypertension; ventricular tachycardia; pheochromocytoma; 10% ophthalmic solution contraindicated in infants and patients with aneurysms.

Dosage and Administration

Mild or Moderate Hypotension

Subcutaneous / IM 1 to 10 mg (usually 2 to 5 mg); do not exceed initial dose of 5 mg.

IV 0.1 to 0.5 mg (usually 0.2 mg); do not exceed initial dose of 0.5 mg. Avoid repeat injections more often than every 10 to 15 min.

Severe Hypotension and Shock

IV continuous infusion For initial dose, give 100 to 180 mcg/min of 1:25,000 or 1:50,000 solution (10 mg/250 to 500 mL D5W or sodium chloride); once BP has stabilized to low normal level, decrease to maintenance rate of 40 to 60 mcg/min. If prompt initial vasopressor response is not obtained, increase dosage in increments greater than or equal to 10 mg and add to infusion; adjust rate until desired BP is obtained.

Hypotension of Spinal Anesthesia

Subcutaneous / IM 2 to 3 mg 3 to 4 min before injection of anesthetic. For hypotensive emergencies during spinal anesthesia, inject 0.2 mg, increasing by no more than 0.1 to 0.2 mg/dose (max, 0.5 mg/dose).


Subcutaneous / IM 0.5 to 1 mg/25 lb (55 kg).

Prolongation of Spinal Anesthesia

2 to 5 mg added to anesthetic solution increases duration of motor block by up to 50%.

Vasoconstriction for Regional Analgesia

At least 2 mg added to local anesthetic solution in concentration of 1:20,000 (1 mg per 20 mL).

Paroxysmal Supraventricular Tachycardia


Initial dose

0.5 mg or less via rapid IV push (within 20 to 30 sec); subsequent doses should not exceed preceding dose by more than 0.1 to 0.2 mg (max, 1 mg/dose).

Nasal Congestion
Adults and children 12 yr of age and older

Intranasal 1 to 2 sprays or 3 gtt of 0.25%, 0.5% or 1% solution every 4 h.

Children 6 to 12 yr of age

Intranasal 2 to 3 sprays of 0.25% solution in each nostril every 3 to 4 h.

Children 6 mo to 6 yr of age

Intranasal 1 to 2 gtt of 0.16% solution in each nostril every 3 h.

Vasoconstriction/Pupil Dilation

Ophthalmic Instill 1 gtt 2.5% or 10% on upper limbus. If necessary, repeat after 1 h.

Uveitis/Prevention of Synechiae

Ophthalmic Instill 2.5% or 10% phenylephrine plus atropine.

To Free Recently Formed Posterior Synechiae

Ophthalmic Instill 1 gtt of 2.5% or 10% to upper surface of cornea.

Wide-Angle Glaucoma

Ophthalmic Instill 1 gtt of 10% on upper surface of cornea prn.

Open-Angle Glaucoma

Ophthalmic Instill 2.5% or 10% solution in conjunction with miotics.


Ophthalmic Instill 2.5% or 10% solution 30 to 60 min before operation as short-acting mydriatic.


Ophthalmic Instill 1 gtt 2.5% solution.


Ophthalmic Instill 1 gtt 2.5% solution.

Ophthalmoscopic Examination

Ophthalmic Instill 1 gtt 2.5% solution in each eye.

Diagnostic Procedures/Provocative Test for Angle-block in Glaucoma

Ophthalmic Instill 2.5%.


Ophthalmic Instill 2.5% solution.

Blanching Test

Ophthalmic Instill 1 to 2 gtt of 2.5% solution.

Minor Eye Irritations

Ophthalmic Instill 1 to 2 gtt of 0.12% solution up to 4 times daily.

General Advice

  • For vasopressor use, administer medication via continuous pump infusion. Administer IV through large vein, preferably central vein. Titrate carefully to avoid hypotension.
  • With intranasal administration, do not share container. Instill spray into nose with head upright. Have patient sniff hard for a few minutes after administration. To instill drops, have patient recline on bed, hang head over edge and instill drops. Have patient remain in this position for several minutes after using and turn head from side to side. Do not allow tip of container to touch nasal passage. Discard after medication is no longer needed.
  • To instill ophthalmic solution, tilt patient's head back, hold dropper over eye, drop medication inside lower lid, apply pressure to inside corner of eye for 1 min. Take care not to touch dropper to eye.
  • Prolonged exposure of ophthalmic solution to air or strong light may cause oxidation and discoloration. Do not use if solution is discolored or cloudy or contains precipitate.
  • Store at room temperature and protect from light.

Drug Interactions


Decrease phenylephrine's effect.

General anesthetics



May increase pressor response of phenylephrine; resulting in severe hypertension.

Halogenated hydrocarbon anesthetics

May sensitize myocardium to effects of catecholamines. Use extreme caution to avoid arrhythmias.

MAOIs, furazolidone

May significantly increase pressor response resulting in hypertensive crisis and intracranial hemorrhage.

Oxytocic drugs

May cause severe persistent hypertension.

Tricyclic antidepressants

May decrease or increase response; use with caution.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Reflex bradycardia; hypertension; angina; arrhythmias.


Headache; excitability; restlessness; tremor.


With ophthalmic and intranasal forms: Transitory stinging on initial instillation; blurring of vision; rebound congestion.



Category C .




Ophthalmic use of phenylephrine 10% is contraindicated in infants.

Special Risk Patients

Administer drug with caution to patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease, prostatic hypertrophy, diabetes mellitus, increased IOP or severe arteriosclerosis.

Sulfite Sensitivity

Use drug with caution in sulfite-sensitive individuals; some commercial preparations contain sodium bisulfite.

Corneal effects

If corneal epithelium has been denuded or damaged, corneal clouding may occur if phenylephrine 10% is instilled.


Avoid use in uncorrected hypovolemic states unless used as temporary emergency measure to maintain coronary and cerebral flow and in patients with tachyarrhythmias or ventricular fibrillation.

Narrow-angle glaucoma

Ordinarily any mydriatic is contraindicated in patients with glaucoma. However, when temporary dilation of pupil may free adhesions or when vasoconstriction of intrinsic vessels may lower intraocular tension, these advantages may temporarily outweigh danger from coincident dilation of pupil.

Rebound congestion

May occur with extended use of intranasal or ophthalmic forms.



Severe hypertension, vomiting, ventricular extrasystoles, short paroxysms of ventricular tachycardia, sensation of fullness in head, tingling of extremities, somnolence, sedation, coma, profuse sweating, hypotension, shock.

Patient Information

  • Intranasal
  • Advise patient that intranasal form is for short-term use only and should not be used for more than 3 to 5 days.
  • Inform patient that stinging, burning, or drying of the nose or an increase in nasal discharge may occur with intranasal form.
  • Instruct patient to gradually stop taking intranasal form of this medicine rather than abruptly discontinuing it because rebound congestion can occur with sudden withdrawal. First stop using drug in one nostril and then in both nostrils.
  • Ophthalmic
  • Caution patient that ophthalmic form of drug can cause discoloration of contact lenses and advise patient to wear glasses during therapy.
  • Instruct patient not to use ophthalmic form for greater than 72 h without consulting health care provider.
  • Advise patient to discontinue drug and notify health care provider if severe eye pain, headache, vision changes, floating spots, acute eye redness, pain with light exposure, insomnia, dizziness, weakness, tremor, or irregular heartbeat occurs.
  • Advise patient that drug may cause temporary blurred or unstable vision, and to use caution while driving or performing other tasks requiring mental alertness.

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