Norepinephrine Bitartrate Injection is a concentrated, potent drug which must be diluted in dextrose-containing solutions prior to infusion. An infusion of N-EPI should be given into a large vein (see Precautions).
Restoration of Blood Pressure in the Acute Hypotensive States: Blood volume depletion should always be corrected as fully as possible before any vasopressor is administered. When, as an emergency measure, intraaortic pressures must be maintained to prevent cerebral or coronary artery ischemia, N-EPI can be administered before and concurrently with blood volume replacement.
Diluent: N-EPI should be diluted in 5% glucose injection or 5% dextrose and sodium chloride injections. These dextrose containing fluids are protection against significant loss of potency due to oxidation. Administration in saline solution alone is not recommended. Whole blood or plasma, if indicated to increase blood volume, should be administered separately (for example, by use of a Y-tube and individual containers if given simultaneously).
Average Dosage: Add the content of the vial (4 mg/4 mL) of N-EPI to 1,000 mL of a 5 percent dextrose containing solution. Each mL of this dilution contains 4 mcg of the base of N-EPI.
Give the solution by intravenous infusion. Insert a plastic intravenous catheter through a suitable bore needle well advanced centrally into the vein and securely fixed with adhesive tape, avoiding, if possible, a catheter tie-in technique as this promotes stasis. An intravenous drip chamber or other suitable metering device is essential to permit an accurate estimation of the rate of flow in drops per minute. After observing the response to an initial dose of 2 mL to 3 mL (from 8 mcg to 12 mcg of base) per minute, adjust the rate of flow to establish and maintain a low normal blood pressure (usually 80 mm Hg to 100 mm Hg systolic) sufficient to maintain the circulation to vital organs. In previously hypertensive patients, it is recommended that the blood pressure should be raised no higher than 40 mm Hg below the pre-existing systolic pressure. The average maintenance dose ranges from 0.5 mL to 1 mL per min (from 2 mcg to 4 mcg of base).
High Dosage: Great individual variation occurs in the dose required to attain and maintain adequate blood pressure. In all cases, the dosage of N-EPI should be titrated according to the response of the patient. Occasionally much larger or even enormous daily doses (as high as 68 mg base or 17 vials) may be necessary if the patient remains hypotensive, but occult blood volume depletion should always be suspected and corrected when present. Central venous pressure monitoring is usually helpful in detecting and treating this situation.
Fluid Intake: The degree of dilution depends on clinical fluid volume requirements. If large volumes of fluid (dextrose) are needed at a flow rate that would involve an excessive dose of the pressor agent per unit of time, a solution more dilute than 4 mcg per mL should be used. On the other hand, when large volumes of fluid are clinically undesirable, a concentration greater than 4 mcg per mL may be necessary.
Duration of Therapy: The infusion should be continued until adequate blood pressure and tissue perfusion are maintained without therapy. Infusions of N-EPI should be reduced gradually, avoiding abrupt withdrawal. In some of the reported cases of vascular collapse due to acute myocardial infarction, treatment was required for up to six days.
Adjunctive Treatment in Cardiac Arrest: Infusions of N-EPI are usually administered intravenously during cardiac resuscitation to restore and maintain adequate blood pressure after an effective heartbeat and ventilation have been established by other means. [N-EPI's powerful beta-adrenergic stimulating action is also thought to increase the strength and effectiveness of systolic contractions once they occur].
Average Dosage: To maintain systemic blood pressure during the management of cardiac arrest, N-EPI is used in the same manner as described under Restoration of Blood Pressure in Acute Hypotensive States.
Parenteral drug products should be inspected visually for particulate matter and discolouration prior to use, whenever solution and container permit.
Do not use the solution if its colour is pinkish or darker than slightly yellow or if it contains a precipitate. Avoid contact with iron salts, alkali or oxidizing agents.
Route of Administration: Intravenous (IV).