The Effects of Nitroglycerin:
Nitroglycerin, a nitrate, causes smooth muscle relaxation. This produces systemic venous pooling of blood through the action of vasodilation. This, in turn, decreases venous blood flow return to the heart and reduces preload as well as venous afterload.
This should be watched closely so as to not cause detrimental hypotension.
Nitroglycerin Indications for Use:
Nitroglycerin is indicated to relieve chest discomfort suspected to be the result of an acute myocardial infarction (AMI). It can also relieve cardiogenic pulmonary edema related to left-side heart failure.
Nitroglycerin Precautions & Contraindications:
Nitroglycerin is not indicated or may even be contraindicated if the patient is suffering from:
- Low systolic blood pressure of less than 90 mm/Hg
- Right-sided ventricular infarction
- Use of tadalafil (sometimes better known as brand names Cialis or Adcirca) within the past 48 hours
- Severe bradycardia of less than 50 bpm
- Tachycardia greater than 100 bpm in the absence of heart failure
When the patient is taking a phosphodiesterase type 5 inhibitor (a class of medications including Sildenafil) within the past 24 hours, nitroglycerin could cause severe hypotensive side effects. It is important to gather a thorough medication list from the patient to avoid these serious contraindications.
Adult Dosage for Nitroglycerin:
- Nitroglycerin administered sublingually in the dose of .4 mg, which is usually 1 tablet. This can be repeated in 5 minute intervals to a maximum of three tablets
- Nitroglycerin via a sublingual spray, which is given with 1 spray equivalent to .4 mg in metered doses. This, too, can be repeated in 5 minute intervals to a maximum of three sprays
- Nitroglycerin can be administered via IV and may increase to 10 mcg/min every 3 to 5 minutes until desired effect is reached
Serial blood pressure should be monitored and hypotension treated accordingly.