PHENYLEPHRINE HYDROCHLORIDE

PHENYLEPHRINE HYDROCHLORIDE
(fen-ill-ef'rin)
AK-Dilate Ophthalmic, Alconefrin, Isopto Frin, Mydfrin, Neo-Synephrine, Nostril, Rhinall, Sinarest Nasal, Sinex
Classifications: eye and nose preparation; alpha-adrenergic agonist; mydriatic; decongestant;
Therapeutic: decongestant; mydriatic; vasoconstrictor

Prototype: Methoxamine
Pregnancy Category: C

Availability

10 mg chewable tablet; 0.125%, 0.16%, 0.5%, 1% nasal solution; 0.12%, 2.5%, 10% ophthalmic solution; 10 mg/mL injection

Action

Potent, synthetic, direct-acting sympathomimetic with strong alpha-adrenergic and weak beta-adrenergic cardiac stimulant actions. Produces little or no CNS stimulation. Elevates systolic and diastolic pressures through arteriolar constriction. Reduces intraocular pressure by increasing outflow and decreasing rate of aqueous humor secretion.

Therapeutic Effect

Topical applications to eye produce vasoconstriction and prompt mydriasis of short duration, usually without causing cycloplegia. Nasal decongestant action qualitatively similar to that of epinephrine but more potent and has longer duration of action.

Uses

Parenterally to maintain BP during anesthesia, to treat vascular failure in shock, and to overcome paroxysmal supraventricular tachycardia. Used topically for rhinitis of common cold, allergic rhinitis, and sinusitis; in selected patients with wide-angle glaucoma; as mydriatic for ophthalmoscopic examination or surgery, and for relief of uveitis.

Contraindications

Severe coronary disease, severe hypertension, atrial fibrillation, atrial flutter, cardiac arrhythmias; cardiac disease, cardiomyopathy; uncontrolled hypertension; ventricular fibrillation or tachycardia; acute MI, angina; cerebral arteriosclerosis, MAOI; narrow-angle glaucoma (ophthalmic preparations); labor, delivery; pregnancy (category C).

Cautious Use

Hyperthyroidism; diabetes mellitus; older adult patients; 21 d before or following termination of MAO inhibitor therapy; lactation. Ophthalmic solution (10%): Cardiovascular disease; diabetes mellitus; hypertension; aneurysms; infants.

Route & Dosage

Hypotension
Adult: IM/SC 1–10 mg (initial dose not to exceed 5 mg) q10–15min as needed IV 0.1–0.18 mg/min until BP stabilizes; then 0.04–0.06 mg/min for maintenance

Ophthalmoscopy

See Appendix A


Supraventricular Tachycardia
Adult: IV 0.25–0.5 mg bolus, then 0.1–0.2 mg doses (total max: 1 mg)

Vasoconstrictor
Adult: Ophthalmic See Appendix A–1 Intranasal Small amount of nasal jelly placed into each nostril q3–4h as needed or 2–3 drops or sprays of 0.25–0.5% solution q3–4h as needed
Child: Intranasal <6 y, 2–3 drops or sprays of 0.125% solution q3–4h as needed; 6–12 y, 2–3 drops or sprays of 0.25% solution q3–4h as needed

Administration

Instillation
  • Nasal preparations: Instruct patient to blow nose gently (with both nostrils open) to clear nasal passages before administration of medication.
  • Instillation (drops): Tilt head back while sitting or standing up, or lie on bed and hang head over side. Stay in position a few minutes to permit medication to spread through nose. (Spray): With head upright, squeeze bottle quickly and firmly to produce 1 or 2 sprays into each nostril; wait 3–5 min, blow nose, and repeat dose. (Jelly): Place in each nostril and sniff it well back into nose.
  • Clean tips and droppers of nasal solution dispensers with hot water after use to prevent contamination of solution. Droppers of ophthalmic solution bottles should not touch any surface including the eye.
  • Ophthalmic preparations: To avoid excessive systemic absorption, apply pressure to lacrimal sac during and for 1–2 min after instillation of drops.
Subcutaneous/Intramuscular
  • Give undiluted.
Intravenous
  • Note: Ensure patency of IV site prior to administration.

PREPARE: Direct: Dilute each 1 mg in 9 mL of sterile water.  IV Infusion: Dilute each 10 mg in 500 mL D5W or NS (concentration: 0.02 mg/mL).  

ADMINISTER: Direct: Give a single dose over 60 sec.  IV Infusion: Titrate to maintain BP.  

INCOMPATIBILITIES Solution/additive: Phenytoin Y-site: Propofol, thiopental.

  • Protect from exposure to air, strong light, or heat, any of which can cause solutions to change color to brown, form a precipitate, and lose potency.

Adverse Effects (≥1%)

Special Senses: Transient stinging, lacrimation, brow ache, headache, blurred vision, allergy (pigmentary deposits on lids, conjunctiva, and cornea with prolonged use), increased sensitivity to light. Rebound nasal congestion (hyperemia and edema of mucosa), nasal burning, stinging, dryness, sneezing. CV: Palpitation, tachycardia, bradycardia (overdosage), extrasystoles, hypertension. Body as a Whole: Trembling, sweating, pallor, sense of fullness in head, tingling of extremities, sleeplessness, dizziness, light-headedness, weakness, restlessness, anxiety, precordial pain, tremor, severe visceral or peripheral vasoconstriction, necrosis if IV infiltrates.

Interactions

Drug: ergot alkaloids, guanethidine, reserpine, tricyclic antidepressants increase pressor effects of phenylephrine; halothane, digoxin increase risk of arrhythmias; mao inhibitors cause hypertensive crisis; oxytocin causes persistent hypertension; alpha blockers, beta blockers antagonize effects of phenylephrine.

Pharmacokinetics

Onset: Immediate IV; 10–15 min IM/SC. Duration: 15–20 min IV; 30–120 min IM/SC; 3–6 h topical. Metabolism: In liver and tissues by monoamine oxidase.

Nursing Implications

Assessment & Drug Effects

  • Monitor infusion site closely as extravasation may cause tissue necrosis and gangrene. If extravasation does occur, area should be immediately injected with 5–10 mg of phentolamine (Regitine) diluted in 10–15 mL of NS.
  • Monitor pulse, BP, and central venous pressure (q2–5min) during IV administration.
  • Control flow rate and dosage to prevent excessive dosage. IV overdoses can induce ventricular dysrhythmias.
  • Observe for congestion or rebound miosis after topical administration to eye.

Patient & Family Education

  • Be aware that instillation of 2.5–10% strength ophthalmic solution can cause burning and stinging.
  • Do not exceed recommended dosage regardless of formulation.
  • Inform the physician if no relief is experienced from preparation in 5 d.
  • Be aware that systemic absorption from nasal and conjunctival membranes can occur, though infrequently (see ADVERSe EFFECTS). Discontinue drug and report to the physician if adverse effects occur.
  • Wear sunglasses in bright light because after instillation of ophthalmic drops, pupils will be large and eyes may be more sensitive to light than usual. Stop medication and notify physician if sensitivity persists beyond 12 h after drug has been discontinued.
  • Be aware that some ophthalmic solutions may stain contact lenses.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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