Generic Name

Phenylephrine Hydrochloride

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Classification

FDA Approved Indications

• Hypotension (especially in the setting of anesthesia-induced hypotension)
• Congestion relief (nasal decongestion, though not FDA-approved specifically for this)

Mechanism of Action

Phenylephrine is an alpha-1 adrenergic receptor agonist, causing vasoconstriction of blood vessels, which increases blood pressure and decreases nasal congestion when used topically.

Dosage and Administration

Adult: Dose varies; for hypotension, 100-180 mcg/min IV infusion titrated to response.

Pediatric: Doses are weight-based; typically, 1-10 mcg/kg/min IV infusion, titrated to effect.

Geriatric: Start at lower doses and titrate carefully due to increased sensitivity and risk of cardiovascular events.

Renal Impairment: Use with caution; monitor blood pressure closely as dose adjustments are primarily clinical.

Hepatic Impairment: Limited data; use cautiously with close monitoring.

Pharmacokinetics

Absorption: Not applicable (administration is typically IV, IM, or topical)

Distribution: Widely distributed; crosses some barrier membranes

Metabolism: Metabolized minimally; primarily excreted unchanged

Excretion: Renal excretion

Half Life: Approximately 2-3 hours

Contraindications

• Use in patients with severe hypertension
• Use with caution in patients with ischemic heart disease, peripheral vascular disease, or cerebrovascular disease

Precautions

• Monitor blood pressure closely during infusion
• Use with caution in patients with tachyarrhythmias
• Pregnancy category C; use only if clearly needed

Adverse Reactions - Common

• Elevated blood pressure (Common)
• Reflex bradycardia (Common)
• Headache (Common)
• Nausea (Common)

Adverse Reactions - Serious

• Cardiac arrhythmias (Less common)
• Myocardial ischemia (Rare)
• Extravasation leading to tissue necrosis (Very rare)

Drug-Drug Interactions

• Monoamine oxidase inhibitors (MAOIs)
• Other vasopressors
• Beta-blockers

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Report chest pain, dizziness, or excessive hypertension.
• Understand that this medication is administered in a clinical setting.
• Report any vision changes or signs of tissue damage at infusion site.

Special Considerations

Black Box Warnings:

• Extravasation may cause tissue necrosis; use caution and infusion techniques.

Genetic Factors: No specific genetic considerations reported.

Lab Test Interference: May interfere with blood pressure readings if not measured appropriately.

Overdose Management

Signs/Symptoms: Severe hypertension, bradycardia, arrhythmias.

Treatment: Stop infusion immediately, administer antihypertensives if needed, provide supportive care, and manage tissue necrosis if extravasation occurs.

Storage and Handling

Storage: Store at controlled room temperature, protect from light.

Stability: Stable for up to 24 months when stored properly.