Nitromak Retard Dosage
NOT FOR DIRECT INTRAVENOUS INJECTION
Nitromak Retard Injection IS A CONCENTRATED, POTENT DRUG WHICH MUST BE DILUTED IN DEXTROSE (5%) INJECTION OR SODIUM CHLORIDE (0.9%) INJECTION PRIOR TO ITS INFUSION. Nitromak Retard Injection SHOULD NOT BE MIXED WITH OTHER DRUGS.
Aseptically transfer the contents of one Nitromak Retard vial (50 mg of Nitromak Retard) 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 Nitromak Retard into 100 mL will yield a final concentration of 50 mcg/mL.
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 Nitromak Retard Injection.
After the initial dosage titration, the concentration of the solution may be increased, if necessary, to limit fluids given to the patient. The Nitromak Retard 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 Nitromak Retard.
Dosage is affected by the type of container and administration set used. See.
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 Nitromak Retard Injection Dilution Table below may be used to calculate the Nitromak Retard dilution and flow rate in microdrops/minute to achieve the desired Nitromak Retard 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 Nitromak Retard 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 Nitromak Retard. 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.
Nitromak Retard Injection is supplied in 5 mg/mL solution. A dilution and administration scheme for Nitromak Retard Injection is shown in Table 1 below.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.
Many drugs can interact with Nitromak Retard. Below is just a partial list. Tell your doctor if you are using:
This list is not complete and there are many other drugs that can interact with Nitromak Retard. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.
Phosphodiesterase type 5 (PDE5) inhibitors such as sildenafil, vardenafil, and tadalafil have been shown to potentiate the hypotensive effects of organic nitrates.
The time course of the interaction appears to be related to the half-life of the PDE5 inhibitor, however, the dose dependence of this interaction has not been studied. Use of Nitromak Retard within a few days of PDE5 inhibitors is contraindicated.
Patients receiving antihypertensive drugs, beta-adrenergic blockers, and other nitrates should be observed for possible additive hypotensive effects when using Nitromak Retard. Marked orthostatic hypotension has been reported when calcium channel blockers and organic nitrates were used concomitantly.
Beta-blockers blunt the reflex tachycardia produced by Nitromak Retard without preventing its hypotensive effects. If beta-blockers are used with Nitromak Retard in patients with angina pectoris, additional hypotensive effects may occur.
Coadministration of aspirin (at doses between 500 mg and 1000 mg) and Nitromak Retard has been reported to result in increased Nitromak Retard maximum concentrations by as much as 67% and AUC by 73% when administered as a single dose. The pharmacological effects of Nitromak Retard may be enhanced by concomitant administration of aspirin.
Intravenous administration of Nitromak Retard decreases the thrombolytic effect of tissue-type plasminogen activator (t-PA). Plasma levels of t-PA are reduced when coadministered with Nitromak Retard. Therefore, caution should be observed in patients receiving Nitromak Retard during t-PA therapy.
Although an interaction has been reported between intravenous heparin and intravenous Nitromak Retard (resulting in a decrease in the anticoagulant effect of heparin), the data are not consistent. If patients are to receive intravenous heparin and Nitromak Retard concurrently, the anticoagulation status of the patient must be checked.
Oral administration of Nitromak Retard markedly decreases the first-pass metabolism of dihydroergotamine and consequently increases its oral bioavailability. Ergotamine is known to precipitate angina pectoris. Therefore the possibility of ergotism in patients receiving Nitromak Retard should be considered.
The vasodilating effects of Nitromak Retard have been shown to be additive to the effects observed with alcohol.
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Information checked by Dr. Sachin Kumar, MD Pharmacology