What is the dose of nitroglycerin (Nitro) spray?

From the Guidelines

Nitroglycerin spray should be administered as 0.4 mg as needed, similar to sublingual tablets, for acute angina relief. The dose of nitroglycerin spray is crucial in managing angina symptoms, and according to the ACC/AHA 2007 guidelines 1, the recommended dose is 0.4 mg as needed. This dose is similar to the sublingual tablets, which have a dose range of 0.3 to 0.6 mg up to 1.5 mg. Some key points to consider when using nitroglycerin spray include:

• The duration of effect is similar to sublingual tablets, ranging from 1 to 7 minutes 1
• The medication works by dilating capacitance vessels, increasing venous pooling, and decreasing myocardial preload, thereby reducing ventricular workload 1
• Potential side effects include headache, dizziness, and lightheadedness due to blood pressure lowering, and patients should be advised to sit or lie down when using the spray to prevent falls from potential dizziness. It is essential to follow the recommended dosage and administration guidelines to ensure effective management of angina symptoms while minimizing potential side effects.

From the Research

Nitro Spray Dose

• The ideal dose of nitro spray is not explicitly stated in the provided studies, but it is mentioned that nitroglycerin spray has a rapid onset of action, similar to sublingual nitroglycerin and inhaled amyl nitrate 2.
• The study from 1983 mentions that nitroglycerin spray is one of the preparations that can produce relief of angina in a substantial proportion of patients, with an onset of action within two minutes or less 2.
• However, the other studies do not provide specific information on the dose of nitro spray, but rather discuss the use of nitrates in general, including oral isosorbide dinitrate and sustained release transmucosal nitroglycerin 3, 4, 5, 6.
• It is worth noting that the development of nitrate tolerance is a major drawback to chronic therapy, and carefully designed dosing regimens and/or appropriate use of nitrate formulations can help decrease or eliminate this problem 3, 5, 6.

Nitrate Tolerance

• Nitrate tolerance is a common issue with repeated dosing of nitrates, and it can be prevented by incorporating a nitrate-free period each day 3, 5.
• The study from 1990 suggests that a daily low-nitrate interval is required to prevent tolerance development, and a 12-h patch-free interval should prevent tolerance in most patients 5.
• The study from 2004 found that severe tolerance to isosorbide dinitrate abolishes the anti-ischaemic effects of sublingual nitroglycerin, and appropriate regimens of isosorbide dinitrate have considerable anti-anginal effects during chronic administration 6.

Clinical Use of Nitrates

• Nitrates are highly effective in terminating acute attacks of angina pectoris and in the prophylaxis of symptomatic and asymptomatic myocardial ischemia 5.
• The study from 1996 mentions that nitrates are reliable, safe, familiar to clinicians, inexpensive, and easy to use, with limited side effects 3.
• The study from 2017 notes that angina itself is a predictor of major adverse cardiac events, and treatment should be geared not only to treating the risk factors for atherosclerotic disease and improving survival but also to eliminating or reducing the occurrence of angina and improving the ability of patients to be active 4.