phenylephrine hydrochloride (NeoSynephrine, Neofrin) (cont.)



  • Mild to moderate hypotension, hypotension during spinal anesthesia: 0.1 to 0.5 mg intravenously every 10 to 15 minutes or 1 to 5 mg subcutaneously or by intramuscular injection.
  • Severe Hypotension, shock: 100 to 180 mcg/minute continuous intravenous infusion until blood pressure is stable; decrease rate to 40 to 60 mcg/minute to maintain blood pressure.
  • Paroxysmal supraventricular tachycardia: 0.5 mg intravenous injection rapidly given within 20 to 30 seconds. Additional dose should not exceed 0.1 to 0.2 mg more than preceding dose, based on the initial blood pressure response; maximum dose is 1 mg.

DRUG INTERACTIONS: Phenylephrine should be used cautiously with MAO inhibitors like selegiline (Eldepryl, Zelapar), phenelzine (Nardil), isocarboxazid (Marplan), because they can also increase blood pressure and can cause a serious hypertensive episode. A similar reaction occurs when phenylephrine is combined with amphetamine and related drugs.

Phenylephrine should be used with caution with antidepressants like amitriptyline (Elavil, Endep), nortriptyline (Pamelor, Aventyl), doxepin (Sinequan, Adapin), and trazodone (Deyrel). Such anti-depressants may increase blood pressure if used together with phenylephrine.

Medically Reviewed by a Doctor on 7/30/2014

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