NITROGLYCERIN

Nitroglycerin is 1,2,3-propanetriol trinitrate, an organic nitrate whose structural formula is: whose empiric formula is C 3 H 5 N 3 O 9 , and whose molecular weight is 227.09. The organic nitrates are vasodilators, active on both arteries and veins. Nitroglycerin Injection, USP is a clear, practically colorless additive solution for intravenous infusion after dilution. Each mL contains: Nitroglycerin 5 mg, Alcohol 30% (v/v), Propylene Glycol 30%, and Water for Injection q.s. pH (range 3.0 to 6.5) may have been adjusted with Sodium Hydroxide and/or Hydrochloric Acid. The solution is sterile, non-pyrogenic, and nonexplosive. structural formula

Nitroglycerin Injection is indicated for treatment of peri-operative hypertension; for control of congestive heart failure in the setting of acute myocardial infarction; for treatment of angina pectoris in patients who have not responded to sublingual nitroglycerin and β -blockers; and for induction of intraoperative hypotension.

NOT FOR DIRECT INTRAVENOUS INJECTION NITROGLYCERIN INJECTION IS A CONCENTRATED, POTENT DRUG WHICH MUST BE DILUTED IN DEXTROSE (5%) INJECTION OR SODIUM CHLORIDE (0.9%) INJECTION PRIOR TO ITS INFUSION. NITROGLYCERIN INJECTION SHOULD NOT BE MIXED WITH OTHER DRUGS. Initial Dilution: Aseptically transfer the contents of one nitroglycerin vial (50 mg of nitroglycerin) into a 500 mL glass bottle of either Dextrose (5%) Injection or Sodium Chloride Injection (0.9%). This yields a final concentration of 100 mcg/mL. Diluting 5 mg nitroglycerin into 100 mL will yield a final concentration of 50 mcg/mL. Maintenance Dilution: It is important to consider the fluid requirements of the patient as well as the expected duration of infusion in selecting the appropriate dilution of Nitroglycerin Injection. After the initial dosage titration, the concentration of the solution may be increased, if necessary, to limit fluids given to the patient. The nitroglycerin concentration should not exceed 400 mcg/mL. See chart. Note: If the concentration is adjusted, it is imperative to flush or replace the infusion set before a new concentration is utilized. If the set were not flushed or replaced, it could take minutes to hours, depending upon the flow rate and the dead space of the set, for the new concentration to reach the patient. Invert the glass parenteral bottle several times to assure uniform dilution of the nitroglycerin. Dosage is affected by the type of container and administration set used. See WARNINGS . Although the usual starting adult dose range reported in clinical studies was 25 mcg/min or more, these studies used PVC administration sets. THE USE OF NON-ABSORBING TUBING WILL RESULT IN THE NEED FOR REDUCED DOSES. If a peristaltic action infusion pump is used, an appropriate administration set should be selected with a drip chamber that delivers approximately 60 microdrops/mL. Table 1 and the Nitroglycerin Injection Dilution Table below may be used to calculate the nitroglycerin dilution and flow rate in microdrops/minute to achieve the desired Nitroglycerin Injection administration rate. If a volumetric infusion pump is used, an appropriate volumetric infusion pump connector set should be selected. Table 1 below may still be used; however, flow rate will be determined directly by the infusion pump, independent of the drop size of the appropriate set drip chambers. Thus, the reference to ``microdrops/min′′ is not applicable, and the corresponding flow rate in mL/hr should be used to determine pump settings. When using a non-absorbing infusion set, the initial dosage should be 5 mcg/min delivered through an infusion pump capable of exact and constant delivery of the drug. Subsequent titration must be adjusted to the clinical situation, with dose increments becoming more cautious as partial response is seen. Initial titration should be in 5 mcg/min increments, with increases every 3-5 minutes until some response is noted. If no response is seen at 20 mcg/min, increments of 10 and later 20 mcg/min can be used. Once a partial blood pressure response is observed, the dose increase should be reduced and the interval between increases should be lengthened. Some patients with normal or low left ventricular filling pressures or pulmonary capillary wedge pressure (e.g., angina patients without other complications) may be hypersensitive to the effects of nitroglycerin and may respond fully to doses as small as 5 mcg/min. These patients require especially careful titration and monitoring. There is no fixed optimum dose of nitroglycerin. Due to variations in the responsiveness of individual patients to the drug, each patient must be titrated to the desired level of hemodynamic function. Therefore, continuous monitoring of physiologic parameters (i.e., blood pressure and heart rate in all patients, other measurements such as pulmonary capillary wedge pressure, as appropriate) MUST be performed to achieve the correct dose. Adequate systemic blood pressure and coronary perfusion pressure must be maintained. Dilution: Nitroglycerin Injection is supplied in 5 mg/mL solution. A dilution and administration scheme for Nitroglycerin Injection is shown in Table 1 below. TABLE 1 60 MICRODROPS = 1 mL Solution Concentration (mcg/mL) 100 200 400 Dose (mcg/min) FLOW RATE (microdrops/min = mL/hr) 5 3 — — 10 6 3 — 15 9 — — 20 12 6 3 30 18 9 — 40 24 12 6 60 36 18 9 80 48 24 12 120 72 36 18 160 96 48 24 240 — 72 36 320 — 96 48 480 — — 72 640 — — 96 NITROGLYCERIN INJECTION DILUTION TABLE (Diluent: Dextrose 5% Injection or Sodium Chloride Injection (0.9%)) Each mL of Nitroglycerin Injection contains 5 mg of nitroglycerin. Total Contents: Each 10 mL vial contains 50 mg of nitroglycerin. mL of Nitroglycerin Injection mg Final Concentration 100 mcg/mL 200 mcg/mL 400 mcg/mL Volume q.s. to q.s. to q.s. to 5 mL 25 mg 250 mL 125 mL - - - 10 mL 50 mg 500 mL 250 mL 125 mL 20 mL 100 mg 1000 mL 500 mL 250 mL 40 mL 200 mg - - - 1000 mL 500 mL NOTE: Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.

Allergic reactions to organic nitrates are extremely rare, but they do occur. Nitroglycerin Injection is contraindicated in patients who are allergic to it. In patients with pericardial tamponade, restrictive cardiomyopathy, or constrictive pericarditis, cardiac output is dependent upon venous return. Intravenous nitroglycerin is contraindicated in patients with these conditions.

Adverse reactions to nitroglycerin are generally dose-related and almost all of these reactions are the result of nitroglycerin's activity as a vasodilator. Headache, which may be severe, is the most commonly reported side effect. Headache may be recurrent with each daily dose, especially at higher doses. Transient episodes of lightheadedness, occasionally related to blood pressure changes, may also occur. Hypotension occurs infrequently, but in some patients it may be severe enough to warrant discontinuation of therapy. Syncope, crescendo angina, and rebound hypertension have been reported but are uncommon. Extremely rarely, ordinary doses of organic nitrates have caused methemoglobinemia in normal-seeming patients. Methemoglobinemia is so infrequent at these doses that further discussion of its diagnosis and treatment is deferred (see OVERDOSAGE ).

The vasodilating effects of nitroglycerin may be additive with those of other vasodilators. Administration of nitroglycerin infusions through the same infusion set as blood can result in pseudoagglutination and hemolysis. More generally, nitroglycerin in 5% dextrose or sodium chloride 0.9% should not be mixed with any other medication of any kind. Intravenous nitroglycerin interferes, at least in some patients, with the anticoagulant effect of heparin. In patients receiving intravenous nitroglycerin, concomitant heparin therapy should be guided by frequent measurement of the activated partial thromboplastin time.