Neo-Synephrine

General Injectables & Vaccines, Inc

Neo-Synephrine HCL (Phenylephrine Hydrochloride) 10 mg/mL Injection, USP 1 mL Single Dose Ampule

FULL PRESCRIBING INFORMATION: CONTENTS*

• Boxed Warning
• Description
• Clinical Pharmacology
• Neo-Synephrine Indications and Usage
• Contraindications
• Warnings
• Precautions
• Side Effects
• Overdosage
• Dosage and Administration
• How Supplied
• Sample Outer Label

FULL PRESCRIBING INFORMATION

Description

NEO-SYNEPHRINE hydrochloride, brand of phenylephrine hydrochloride injectino, is a vasoconstrictor and pressor drug chemically related to epinephrine and ephedrine. 

NEO-SYNEPHRINE hydrochloride is a synthetic sympathomimetic agent in sterile form for parenteral injection.  Chemically, phenylephrine hydrochloride is (-)-m-Hydroxy-a-[(methylamino)methyl]benzyl alcohol hydrochloride, and has the following structural formula:

Clinical Pharmacology

NEO-SYNEPHRINE hydrochloride produces vasoconstriction that lasts longer than that of epinephrine and ephedrine. Responses are more sustained than those to epinephrine, lasting 20 minutes after intravenous and as long as 50 minutes after subcutaneous injection. Its action on the heart contrasts sharply with that of epinephrine and ephedrine, in that it slows the heart rate and increases the stroke output, producing no disturbance in the rhythm of the pulse.

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.

The predominant actions of phenylephrine are on the cardiovascular system. Parenteral administration causes a rise in systolic and diastolic pressures in man and other species. Accompanying the pressor response to phenylephrine is a marked reflex bradycardia that can be blocked by atropine; after atropine, large doses of the drug increase the heart rate only slightly. In man, cardiac output is slightly decreased and peripheral resistance is considerably increased. Circulation time is slightly prolonged, and venous pressure is slightly increased; venous constriction is not marked. Most vascular beds are constricted; renal splanchnic, cutaneous and limb blood flows are reduced but coronary blood flow is increased. Pulmonary vessels are constricted, and pulmonary arterial pressure is raised.

The drug is a powerful vasoconstrictor with properties very similar to those of norepinephrine but almost completely lacking the chronotropic and inotropic actions on the heart. Cardiac irregularities are seen only very rarely even with large doses.

Neo-Synephrine Indications and Usage

NEO-SYNEPHRINE is intended for the maintenance of an adequate level of blood pressure during spinal and inhalation anesthesia and for the treatment of vascular failure in shock, shock-like states and drug induced hypotension or hypersensitivity. It is also employed to overcome paroxysmal supraventricular tachycardia, to prolong spinal anesthesia and as a vasoconstrictor in regional analgesia.

Contraindications

NEO-SYNEPHRINE hydrochloride should not be used in patients with severe hypertension, ventricular tachycardia or in patients who are hypersensitive to it or to any of the components.

Warnings

If used in conjunction with oxytocic drugs, the pressor effect of sympathomimetic pressor amines is potentiated (see Drug Interactions). The obstetrician should be warned that some oxytocic drugs may cause severe persistent hypertension and that even a rupture of a cerebral blood vessel may occur during the postpartum period.

Contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people.

Precautions

NEO-SYNEPHRINE hydrochloride should be employed only with extreme caution in elderly patients or in patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease or severe arteriosclerosis.

Drug Interactions
Vasopressors, particularly metaraminol, may cause serious cardiac arrhythmias during halothane anesthesia and therefore should be used only with great caution or not at all.

MAO Inhibitors
The pressor effect of sympathomimetic pressor amines is markedly potentiated in patients receiving monoamine oxidase inhibitors (MAOI). Therefore, when initiating pressor therapy in these patients, the initial dose should be small and used with due caution. The pressor response of adrenergic agents may also be potentiated by tricyclic antidepressants.

Carcinogenesis, Mutagenesis, Impairment of Fertility
No long-term animal studies have been done to evaluate the potential of phenylephrine in these areas.

Pregnancy
Teratogenic Effects:
Pregnancy Category C.
Animal reproduction studies have not been conducted with phenylephrine. It is also not known whether phenylephrine can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Phenylephrine should be given to a pregnant woman only if clearly needed.

Labor and Delivery
If vasopressor drugs are either used to correct hypotension or added to the local anesthetic solution, the obstetrician should be cautioned that some oxytocic drugs may cause severe persistent hypertension and that even a rupture of a cerebral blood vessel may occur during the postpartum period (see WARNINGS).

Nursing Mother
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when NEO-SYNEPHRINE hydrochloride is administered to a nursing woman.

Pediatric Use
To combat hypotension during spinal anesthesia in children, a dose of 0.5 mg to 1 mg per 25 pounds of body weight, administered subcutaneously or intramuscularly, is recommended.

Side Effects

Headache, reflex bradycardia, excitability, restlessness and rarely arrhythmias.

Overdosage

Overdosage may induce ventricular extrasystole and short paroxysms of ventricular tachycardia, a sensation of fullness in the head and tingling of the extremities.

Should an excessive elevation of blood pressure occur, it may be immediately relieved by an a-adrenergic blocking agent (e.g. phentolamine).

The oral LD50 in the rat is 350 mg/kg, in the mouse 120 mg/kg.

Dosage and Administration

NEO-SYNEPHRINE is generally injected subcutaneously, intramuscularly, slowly intravenously or in dilute solution as a continuous intravenous infusion. In patients with paroxysmal supraventricular tachycardia and, if indicated, in case of emergency, Phenylephrine Hydrochloride Injection is administered directly intravenously. The dose should be adjusted according to the pressor response.

How Supplied

Solution 1 percent

Each mL contains 10 mg of NEO-SYNEPHRINE hydrochloride, 3.5 mg of sodium chloride, 4 mg of sodium citrate, 1 mg of citric acid monohydrate, and not more than 2 mg of sodium metabisulfite.

Uni-Amp unit dose pak of 1 mL, box of 25, List 1800.
Single-dose pak of 1 mL, box of 25, List 1800.

The air in all ampuls and Cartridge Units has been displaced by nitrogen gas.

Protect from light if removed from carton or dispensing bin. 

Store at 20°-25°C (68°-77°F), excursions permitted to 15°-30°C (59°-86°F) [see USP Controlled Room Temperature].

Revised: November, 2005

Hospira, Inc
Lake Forest, IL 60045, USA

Sample Outer Label