Dangerous Drug: Phenylephrine Hydrochloride(fen ill ef’ rin)
Parenteral: Neo-Synephrine
Oral: AH-chew D, Sudafed PE
Oral drops: Little Colds, Decongestant for Infants & Children, PediaCare Children’s Decongestant
Topical OTC nasal decongestants: Little Noses Gentle Formula, Neo-Synephrine, Rhinall, Vicks Sinex Ultra Fine Mist
Strips: Sudafed PE Quick-Dissolve, Thin Strips Decongestant, Triaminic Thin Strips Cold
Ophthalmic preparations (0.12% solutions are OTC): AK-Dilate, Mydfrin, Neo-Synephrine
PREGNANCY CATEGORY C
Drug Classes
Alpha-adrenergic agonist
Nasal decongestant
Ophthalmic vasoconstrictor or mydriatic
Sympathomimetic amine
Vasopressor
Therapeutic Actions
Powerful postsynaptic alpha-adrenergic receptor stimulant that causes vasoconstriction and increased systolic and diastolic BP with little effect on the beta receptors of the heart. Topical application causes vasoconstriction of the mucous membranes, which in turn relieves pressure and promotes drainage of the nasal passages. Topical ophthalmic application causes contraction of the dilator muscles of the pupil (mydriasis), vasoconstriction, and increased outflow of aqueous humor.
Indications
Parenteral
Treatment of vascular failure in shock, shocklike states, drug-induced hypotension, or hypersensitivity
To overcome paroxysmal supraventricular tachycardia
To prolong spinal anesthesia
Vasoconstrictor in regional anesthesia
To maintain an adequate level of BP during spinal and inhalation anesthesia
Nasal solution and oral
Symptomatic relief of nasal and nasopharyngeal mucosal congestion due to the common cold, sinusitis, hay fever, or other respiratory allergies
Adjunctive therapy of middle ear infections by decreasing congestion around the eustachian ostia
Ophthalmic solution
10% solution: Decongestant and vasoconstrictor and for pupil dilation in uveitis, wide-angle glaucoma, and surgery
2.5% solution: Decongestant and vasoconstrictor and for pupil dilation in uveitis, open-angle glaucoma in conjunction with miotics, refraction, ophthalmoscopic examination, diagnostic procedures, and before intraocular surgery
0.12% solution: Decongestant to provide temporary relief of minor eye irritations caused by hay fever, colds, dust, wind, smog, or hard contact lenses
Contraindications and Cautions
Contraindicated with hypersensitivity to phenylephrine or sulfites; severe hypertension, ventricular tachycardia; narrow-angle glaucoma.
Use cautiously with thyrotoxicosis, diabetes, hypertension, CV disorders; prostatic hypertrophy, unstable vasomotor syndrome, bronchial asthma, lactation, pregnancy.
Available Forms
Chewable tablets—10 mg; tablets—10 mg; oral drops—2.5 mg/mL, 7.5 mg/5 mL; strips—1.25, 2.5, 10 mg; nasal solution—0.125%, 0.25%, 0.5%, 1%; ophthalmic solution—0.12%, 2.5%, 10%; injection—10 mg/mL
Dosages
Parenteral preparations may be given IM, subcutaneously, by slow IV injection, or as a continuous IV infusion of dilute solutions; for supraventricular tachycardia and emergency use, give by direct IV injection.
Adults
Parenteral
Mild to moderate hypotension (adjust dosage on basis of BP response): 1–10 mg subcutaneously or IM; do not exceed an initial dose of 5 mg. A 5-mg IM dose should raise BP for 1–2 hr. Or, for IV use, 0.1–0.5 mg IV. Initial dose should not exceed 0.5 mg. Do not repeat more often than every 10–15 min. 0.5 mg IV should raise the pressure for 15 min.
Severe hypotension and shock: For continuous IV infusion, add 10 mg to 500 mL of dextrose injection or sodium chloride injection. Start infusion at 100–180 mcg/min (based on a drop factor of 20 drops/mL; this would be 100–180 drops/min). When BP is stabilized, maintain at 40–60 mcg/min. If prompt vasopressor response is not obtained, add 10-mg increments to infusion bottle.
Spinal anesthesia: 2–3 mg subcutaneously or IM 3–4 min before injection of spinal anesthetic.
Hypotensive emergencies during anesthesia: Give 0.2 mg IV. Do not exceed 0.5 mg/dose.
Prolongation of spinal anesthesia: Addition of 2–5 mg to the anesthetic solution increases the duration of motor block by as much as 50%.
Vasoconstrictor for regional anesthesia: 1:20,000 concentration (add 1 mg of phenylephrine to every 20 mL of local anesthetic solution).
Paroxysmal supraventricular tachycardia: Rapid IV injection (within 20–30 sec) is recommended. Do not exceed an initial dose of 0.5 mg. Subsequent doses should not exceed the preceding dose by more than 0.1–0.2 mg and should never exceed 1 mg. Use only after other treatments have failed.
Nasal solution
Nasal congestion: 2–3 sprays or drops of the 0.25% or 0.5% solution in each nostril every 3–4 hr. In severe cases, the 0.5% or 1% solution may be needed; 10 mg PO bid–qid.
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