- What is phenylephrine-injection, and how does it work (mechanism of action)?
- What brand names are available for phenylephrine-injection?
- Is phenylephrine-injection available as a generic drug?
- Do I need a prescription for phenylephrine-injection?
- What are the side effects of phenylephrine-injection?
- What is the dosage for phenylephrine-injection?
- Which drugs or supplements interact with phenylephrine-injection?
- Is phenylephrine-injection safe to take if I'm pregnant or breastfeeding?
- What else should I know about phenylephrine-injection?
What is phenylephrine-injection, and how does it work (mechanism of action)?
Phenylephrine is a man-made drug that stimulates receptors (alpha1 receptors) on blood vessels and cause blood vessels to constrict (vasoconstriction). It is a vasoconstrictor medication, structurally similar to epinephrine and ephedrine. Vasoconstriction increases blood pressure. Phenylephrine increases blood pressure and heart rate without affecting heart rhythm.
What are the side effects of phenylephrine-injection?
Side effects of phenylephrine are headache, reflex bradycardia (slow heart beat), excitability, anxiety, restlessness, high blood pressure, and rarely abnormal heart beats.
What is the dosage for phenylephrine-injection?
Injection: 10 mg/mL supplied as a 1 mL single dose vial
Which drugs or supplements interact with phenylephrine-injection?
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.

SLIDESHOW
How to Lower Blood Pressure: Exercise and Tips See SlideshowIs phenylephrine-injection safe to take if I'm pregnant or breastfeeding?
There are no adequate studies done on phenylephrine to determine safe and effective use in pregnant women.
It is not known whether phenylephrine enters breast milk; therefore, it is best to be cautious before using it in nursing mothers.
What else should I know about phenylephrine-injection?
What preparations of phenylephrine-injection are available?
Injection: 10 mg/ml
How should I keep phenylephrine-injection stored?
Store phenylephrine injections between 15 C to 30 C (59 to 86 F).
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Summary
Phenylephrine hydrochloride injection (NeoSynephrine, Neofrin) is a prescription drug used for the maintenance of blood pressure during treatment of vascular failure in shock, drug-induced high blood pressure, and PSVT during anesthesia. Side effects, drug interactions, storage, dosage, and pregnancy safety information should be reviewed prior to taking any medication.
Related Disease Conditions
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High Blood Pressure (Hypertension)
High blood pressure (hypertension) is a disease in which pressure within the arteries of the body is elevated. About 75 million people in the US have hypertension (1 in 3 adults), and only half of them are able to manage it. Many people do not know that they have high blood pressure because it often has no has no warning signs or symptoms. Systolic and diastolic are the two readings in which blood pressure is measured. The American College of Cardiology released new guidelines for high blood pressure in 2017. The guidelines now state that blood normal blood pressure is 120/80 mmHg. If either one of those numbers is higher, you have high blood pressure. The American Academy of Cardiology defines high blood pressure slightly differently. The AAC considers 130/80 mm Hg. or greater (either number) stage 1 hypertension. Stage 2 hypertension is considered 140/90 mm Hg. or greater. If you have high blood pressure you are at risk of developing life threatening diseases like stroke and heart attack.REFERENCE: CDC. High Blood Pressure. Updated: Nov 13, 2017.
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Shock (Medical)
What is shock? A life-threatening condition with symptoms like low blood pressure, weakness, shallow breathing, clammy skin, fainting, anxiety, confusion, and chest pain. Learn about causes, types, and treatment.
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Arrhythmias (Abnormal Heart Rhythms)
Heart rhythm disorders vary from minor palpitations, premature atrial contractions (PACs), premature ventricular contractions (PVCs), sinus tachycardia, and sinus bradycardia, to abnormal heart rhythms such as tachycardia, ventricular fibrillation, ventricular flutter, atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia (PSVT), Wolf-Parkinson-White syndrome, brachycardia, or heart blocks. Treatment is dependent upon the type of heart rhythm disorder.
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Things to Know About High Blood Pressure Treatment
High blood pressure (hypertension) means high pressure (tension) in the arteries. Treatment for high blood pressure include lifestyle modifications (alcohol, smoking, coffee, salt, diet, exercise), drugs and medications such as ACE inhibitors, angiotensin receptor blockers, beta blockers, diuretics, calcium channel blockers (CCBs), alpha blockers, clonidine, minoxidil, and Exforge.
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Paroxysmal Supraventricular Tachycardia (PSVT)
Paroxysmal supraventricular tachycardia (PSVT) is an abnormal conduction of electricity in particular areas of the heart. PSVT was referred to at one time as paroxysmal atrial tachycardia or PAT, however, the term PAT is reserved for as specific heart condition. Symptoms of PSVT include weakness, shortness of breath, chest pressure, lightheadedness, and palpitations. PSVT is treated with medications or procedures that return the heart to its normal electrical pattern.
Treatment & Diagnosis
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