Phenylephrine (Neosynephrine ®)
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|NS (preferred) , D5W (less support)|
Standard Dilutions [Amount of drug] [Infusion volume] [Infusion rate]
[Concentration: 0.1 mg/ml - 0.9NS. Stability 14 days at room temperature ] 1:
[25 mg] [250 ml] [Titrate] or [50 mg] [500 ml] [Titrate]OR[Concentration: 0.2 mg/ml -0.9NS. Stability 14 days RT-possibly up to 60 days RT]1,2:
[50 mg] [250 ml] [Titrate] or [100 mg] [500 ml] [Titrate]
[Concentration: 0.4 mg/ml -0.9NS. Stability 60 days RT]2:
[40 mg] [100 ml] [Titrate]
Reference data for updated dilution standards:
3] Product Information (current packaging): PHENYLEPHRINE HYDROCHLORIDE- phenylephrine hydrochloride injection. Baxter Healthcare Corporation, Deerfield, IL 60015; 2014.
Central line required. Peripheral line may be used for short periods (Max concentration: 10mg/250 ml) while preparation for central line is underway.
Stability / Miscellaneous
|Label: Do not Refrigerate.
(Alpha agonist). May be given IM,SC, IV push, or by continuous infusion. Treat mild/moderate hypotension, also PSVT.
IV infusion: usual initial rate: 0.1 to 0.18 mg/min (100 to 180mcg/min) (titrate). Usual maintenance rate: 40-60 mcg/min.
IV bolus therapy: usual dose: 0.5 mg [range: 0.1 to 1 mg (max)] repeat q10-15 min as needed.
PSVT: 0.5 mg rapid IV push, subsequent doses may be increased in increments of 0.1 to 0.2mg.
Phenylephrine is a powerful postsynaptic alpha-receptor stimulant with little effect on the beta receptors of the heart. In therapeutic doses, it produces little if any stimulation of either the spinal cord or cerebrum. A singular advantage of this drug is the fact that repeated injections produce comparable effects.
DOSAGE AND ADMINISTRATION
Mild or Moderate Hypotension
INTRAVENOUSLY: Usual dose, 0.2 mg. Range, from 0.1 mg to 0.5 mg. Initial dose should not exceed 0.5 mg.
Injections should not be repeated more often than every 10 to 15 minutes. A 5 mg intramuscular dose should raise blood pressure for one to two hours. A 0.5 mg intravenous dose should elevate the blood pressure for about 15 minutes.
Severe Hypotension and Shock - Including Drug-Related Hypotension
Hypotension and occasionally severe shock may result from overdosage or idiosyncrasy following the administration of certain drugs, especially adrenergic and ganglionic blocking agents, rauwolfia and veratrum alkaloids and phenothiazines tranquilizers. Patients who receive a phenothiazine derivative as preoperative medication are especially susceptible to these reactions. As an adjunct in the management of such episodes, Phenylephrine Hydrochloride Injection is a suitable agent for restoring blood pressure.
Higher initial and maintenance doses of phenylephrine are required in patients with persistent or untreated severe hypotension or shock. Hypotension produced by powerful peripheral adrenergic blocking agents, chlorpromazine or pheochromocytomectomy may also require more intensive therapy.
If a prompt initial pressor response is not obtained, additional increments of phenylephrine (10 mg or more) are added to the infusion bottle. The rate of flow is then adjusted until the desired blood pressure level is obtained. (In some cases, a more potent vasopressor, such as norepinephrine bitartrate, may be required.) Hypertension should be avoided. The blood pressure should be checked frequently. Headache and/or bradycardia may indicate hypertension. Arrhythmias are rare.
To combat hypotension during spinal anesthesia in children, a dose of 0.5 mg to 1 mg per 25 pounds body weight, administered subcutaneously or intramuscularly, is recommended.
Prolongation of Spinal Anesthesia
Vasoconstrictor for Regional Analgesia
Paroxysmal Supraventricular Tachycardia
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.