When is sublingual nitroglycerin (NTG) contraindicated?

From the Guidelines

Sublingual nitroglycerin (NTG) is contraindicated in patients with severe hypotension, those taking phosphodiester-2 (P-2) inhibitors such as sildenafil within the previous 24 hours or tadalafil within 48 hours, and in cases of known hypersensitivity to nitrates. The primary concern with NTG administration is its potential to cause significant hypotension, particularly when combined with certain medications or in patients with specific medical conditions. According to the guidelines outlined in 1 and further updated in 1, NTG should be avoided in scenarios where its vasodilatory effects could be detrimental, such as in patients with hypotension (systolic blood pressure below 90 mmHg), as it can exacerbate low blood pressure.

Key points to consider regarding the contraindications of sublingual NTG include:

• Severe hypotension (systolic blood pressure < 90 mmHg) as it can lead to further decreases in blood pressure, potentially resulting in inadequate organ perfusion.
• Recent use of phosphodiester-2 (P-2) inhibitors like sildenafil (within 24 hours) or tadalafil (within 48 hours), as the combination can lead to profound and potentially fatal hypotension due to the inhibition of phosphodiester-2 and the resultant vasodilation.
• Known hypersensitivity to nitrates, as it can cause an allergic reaction.
• Other conditions such as hypertrophic obstructive cardiomyopathy and severe aortic stenosis, where the reduction in preload and afterload can be detrimental.

It's crucial to weigh the benefits of NTG against its potential risks, especially in patients with complex medical histories or those taking multiple medications. The most recent guidelines, such as those mentioned in 1, emphasize the importance of careful patient selection and monitoring when administering NTG to minimize adverse effects while maximizing therapeutic benefits.

From the FDA Drug Label

Nitroglycerin sublingual tablets are contraindicated in patients who are allergic to it. Sublingual nitroglycerin therapy is contraindicated in patients with early myocardial infarction, severe anemia, increased intracranial pressure, and those with a known hypersensitivity to nitroglycerin. Administration of nitroglycerin sublingual tablets are contraindicated in patients who are using a phosphodiesterase-5 (PDE-5) inhibitor (e.g., sildenafil citrate, tadalafil, vardenafil hydrochloride) since these compounds have been shown to potentiate the hypotensive effects of organic nitrates. Do not use nitroglycerin sublingual tablets in patients who are taking the soluble guanylate cyclase stimulator riociguat. Concomitant use can cause hypotension.

Sublingual nitroglycerin (NTG) is contraindicated in the following situations:

• Allergy to nitroglycerin
• Early myocardial infarction
• Severe anemia
• Increased intracranial pressure
• Known hypersensitivity to nitroglycerin
• Use of phosphodiesterase-5 (PDE-5) inhibitors (e.g., sildenafil citrate, tadalafil, vardenafil hydrochloride)
• Use of soluble guanylate cyclase stimulator riociguat 2

From the Research

Contraindications for Sublingual Nitroglycerin (NTG)

• Sublingual nitroglycerin is contraindicated in patients with severe aortic stenosis, as it may precipitate profound hypotension 3.
• NTG is also contraindicated in patients who have taken phosphodiesterase 5 (PDE5) inhibitors, such as sildenafil, vardenafil, or tadalafil, due to the risk of synergistic decrease in blood pressure 4, 5.
• However, studies suggest that with close monitoring of blood pressure and heart rate, men with stable coronary artery disease who have taken sildenafil may tolerate intravenous NTG with low starting dosage and gradual upward titration 5.
• Additionally, sublingual application of liquid nitrendipine, a calcium channel blocker, does not result in critical hypotension in healthy volunteers under phosphodiesterase-5 inhibition, but its safety in patients with coronary artery disease needs to be confirmed 6.

Specific Conditions to Avoid

• Severe aortic stenosis 3
• Recent use of PDE5 inhibitors 4, 5
• Increased intracranial pressure, as mentioned in the context of intravenous nitroglycerin 7

Important Considerations

• Patients with coronary artery disease and erectile dysfunction should be cautious when using nitrates after taking PDE5 inhibitors 4, 5, 6.
• Close monitoring of blood pressure and heart rate is necessary when administering NTG to patients who have taken PDE5 inhibitors 5.