• Management of hypotension associated with shock that may persist after adequate fluid replacement.
• Management of hypotension associated with anesthesia.

Anesthesia adjunct:

• • Prolongation of the duration of spinal anesthesia.
  • Localization of the effect of regional anesthesia.

Contraindicated in:

• Hypersensitivity to bisulfites.

Use Cautiously in:

• HF, coronary artery disease, or peripheral arterial disease
• OB: Has been used safely during Caesarean section procedure; safety of use during first or second trimester of pregnancy not established
• Lactation: Use while breastfeeding only if potential maternal benefit justifies potential risk to infant
• Pedi: Safety and effectiveness not established in children.

CV: ARRHYTHMIAS, bradycardia, chest pain, hypertension, ischemia, tachycardia.

Derm: pruritus.

GI: epigastric pain, nausea, vomiting.

Local: phlebitis, sloughing at IV sites.

Neuro: blurred vision, headache, insomnia, nervousness, tremor.

Resp: dyspnea.

Drug-Drug:

• Use with general anesthetics may result in myocardial irritability; use with extreme caution.
• Use with MAO inhibitors, ergot alkaloids (methylergonovine), oxytocics, tricyclic antidepressants, atropine, corticosteroids, or atomoxetine results in severe hypertension.
• Alpha-adrenergic blockers, PDE-5 inhibitors, calcium channel blockers, benzodiazepines, ACE inhibitors, or guanfacine may antagonize vasopressor effects.

(Generic available)

• Solution for injection: 0.1 mg/mL; 10 mg/mL;
• Premixed infusion: 20 mg/250 mL 0.9% NaCl; 25 mg/250 mL 0.9% NaCl; 40 mg/250 mL 0.9% NaCl; 50 mg/250 mL 0.9% NaCl;

Hypotension

• SC, IM (Adults): 2–5 mg.
• SC, IM (Children): 0.1 mg/kg/dose every 1–2 hr as needed, maximum dose 5 mg.
• IV (Adults): 0.2 mg (range 0.1–0.5 mg), may be repeated every 10–15 min or as an infusion at 100–180 mcg/min initially, 40–60 mcg/min maintenance.
• IV (Children): 5–20 mcg/kg/dose every 10–15 min as needed or 0.1–0.5 mcg/kg/min infusion, titrate to effect.

Hypotension During Anesthesia

• SC, IM (Adults): 2–3 mg has been used 3–4 min before spinal anesthesia to prevent hypotension.
• IM, SC (Children): 0.5–1 mg/25 lb body weight.
• IV (Adults): 40–100 mcg; may repeat every 1–2 min as needed (not to exceed total dose of 200 mcg); if BP remains low, initiate continuous infusion at 10–35 mcg/min (not to exceed 200 mcg/min).

Vasoconstrictor for Regional Anesthesia

• Local (Adults): Add 1 mg to every 20 mL of local anesthetic (yields a 1:20,000 solution).

Prolongation of Spinal Anesthesia

• Spinal (Adults): 2–5 mg added to anesthetic solution.

Biorphen, Vazculep

• Constricts blood vessels by stimulating alpha-adrenergic receptors.

• Increased BP.

Therapeutic Classification: vasopressors

Pharmacologic Classification: adrenergics, vasopressors

Absorption: Well absorbed from IM sites. IV administration results in complete bioavailability.

Distribution: Widely distributed to tissues.

Metabolism/Excretion: Metabolized by the liver into inactive metabolites.

Half-life: 2.5 hr.

Neo-Synephrine

(vasopressor effects)

• Explain purpose of phenylephrine to patient.
• IV: Instruct patient to report headache, dizziness, dyspnea, or pain at IV infusion site promptly.
• Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

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