From the Guidelines
Nitroglycerin (GTN) infusion should be initiated at a rate of 10 mcg per min and titrated up by 10 mcg per min every 3 to 5 min until symptom relief or blood pressure response is noted, with a maximum recommended dose of 200 mcg/min, which corresponds to 120 mL/hr for a standard concentration of 100 mcg/mL 1.
Key Considerations for GTN Infusion
- The initial dose of 10 mcg/min is equivalent to 6 mL/hr for a standard concentration of 100 mcg/mL.
- As the dose increases, the corresponding flow rate in mL/hr also increases proportionally - for example, 20 mcg/min equals 12 mL/hr, and so on.
- GTN works by releasing nitric oxide, causing vascular smooth muscle relaxation and vasodilation, particularly in the venous system at lower doses and in both venous and arterial systems at higher doses.
- This reduces preload and afterload, decreasing myocardial oxygen demand and improving coronary blood flow.
Monitoring and Adjustments
- Continuous monitoring of blood pressure is essential during administration as hypotension is a common side effect.
- Tolerance may develop with prolonged use, requiring dose adjustments.
- The dosage increase should be reduced and the interval between increments lengthened once a partial blood pressure response is observed.
- Systolic blood pressure generally should not be titrated to less than 110 mm Hg in previously normotensive patients or to greater than 25% below the starting mean arterial blood pressure if hypertension was present.
Additional Guidance
- Nitroglycerin should be avoided in patients with initial systolic blood pressure less than 90 mm Hg or 30 mm Hg or more below baseline or with marked bradycardia or tachycardia.
- Although recommendations for a maximal dose are not available, a ceiling of 200 mcg per min is commonly used, as supported by the 2012 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines 1.
From the FDA Drug Label
DOSAGE & ADMINISTRATION ... 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 ... 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.
- The initial dose of glycerol trinitrate (GTN) is 5 mcg/min when using a non-absorbing infusion set.
- To convert mcg/min to mL/hr, we need to know the concentration of the solution.
- A concentration of 100 mcg/mL can be achieved by diluting 50 mg of nitroglycerin in 500 mL of solution.
- Using this concentration, a dose of 5 mcg/min is equivalent to 0.05 mL/min or 3 mL/hr.
- The dose may need to be adjusted based on the patient's response, with increments of 5 mcg/min every 3-5 minutes until some response is noted 2.
From the Research
GTN Dose Information
- The provided studies do not directly mention the dose of GTN (glyceryl trinitrate) in ml/hr and mcg.
- However, one study 3 mentions the use of glyceryl trinitrate (GTN) in evaluating its effect on platelet function in healthy volunteers.
- Another study 4 discusses the role of triple therapy, including nitrates, in patients with chronic stable angina pectoris, but does not provide specific dosage information for GTN.
Relevant Studies
- Study 3 used whole-blood flow cytometry to evaluate the effect of GTN on platelet function, but does not provide dosage information.
- Study 4 mentions the use of nitrates in combination with beta-blockers and calcium-channel blockers, but does not specify the dose of GTN.
Dosage Information
- Unfortunately, the provided studies do not offer specific information on the dose of GTN in ml/hr and mcg.
- It is recommended to consult other medical resources or studies that specifically focus on GTN dosage for more accurate information.