Nitroglycerin

Medication Overview

Nitroglycerin is a vasodilator primarily used to treat and prevent acute angina pectoris symptoms and as an emergency medication during myocardial infarction. This drug relaxes vascular smooth muscle, dilates arterial blood vessels, reduces cardiac workload, and increases myocardial blood supply, thereby alleviating chest pain and myocardial hypoxia.

Its mechanism of action involves releasing nitric oxide (NO), which promotes relaxation of vascular smooth muscle, especially significantly dilating the coronary arteries. It is commonly found in emergency rooms, cardiology departments, and home emergency kits, but must be used strictly according to medical instructions to avoid risks such as hypotension due to misuse.

Brand Names and Generic Name

Brand names include Nitrostat®, Minitran®, Nitrodur®, among others. The generic name is Nitroglycerin. Different formulations such as sublingual tablets, transdermal patches, sprays, and intravenous injections all contain the same generic medication.

Drug Classification

Nitroglycerin is classified as a nitrate vasodilator, belonging to the category of coronary vasodilators. These drugs mainly act on arterial vessels, with a notable effect on dilating the coronary arteries, reducing cardiac afterload and myocardial oxygen consumption.

Indications

Primarily used for the prevention of stable angina and relief during acute episodes, as well as emergency treatment for unstable angina. Additionally, during the acute phase of a myocardial infarction, it can be combined with other medications to reduce myocardial oxygen demand.

For long-term use, it is often combined with other cardiovascular drugs such as beta-blockers or calcium channel blockers to enhance efficacy and reduce tolerance development.

Common Side Effects

• Mild side effects: dizziness, headache, facial flushing, mild hypotension.
• Serious side effects: severe hypotension, dizziness, syncope, palpitations. Immediate medical attention is required if these symptoms occur.

Long-term use may lead to nitrate tolerance, reducing drug effectiveness. It is usually recommended to have an 8-hour drug-free interval daily to delay tolerance development.

Warnings and Precautions

Contraindications include hypotension, severe tachycardia, severe aortic stenosis, or hypertrophic cardiomyopathy. Patients who have experienced severe headaches or worsening of glaucoma from nitroglycerin use should use under medical supervision after evaluation.

Pregnancy category C, use only when necessary. During breastfeeding, it may inhibit milk secretion; the benefits and risks should be weighed by a physician.

Drug Interactions

• Contraindicated interactions: concurrent use with phosphodiesterase-5 inhibitors (e.g., Viagra) may cause life-threatening hypotension.
• When combined with other antihypertensive drugs (such as beta-blockers, ACE inhibitors), dosage adjustments are necessary to avoid excessive blood pressure lowering.

Avoid concurrent use with alcohol, which may exacerbate hypotension. Consult a physician before using any herbal medicines or supplements.

Dosage and Administration

Sublingual tablets: 0.3-0.6 mg during acute episodes, repeat within 5 minutes if needed, with a maximum total dose of 1.8 mg.

Transdermal patches: replaced every 24 hours, dosage adjusted according to condition. Sprays should be accurately sprayed onto oral mucosa, avoiding spraying outside the mouth.

Missed Dose Management

If a dose is missed, take it immediately. However, if it is close to the next scheduled dose, skip the missed dose and resume the normal schedule. Do not double doses to make up for missed ones.

Overdose Management

Overdose can cause severe hypotension, tachycardia, or shock. If symptoms such as blurred vision, difficulty breathing, or altered consciousness occur, seek emergency medical attention immediately and inform healthcare providers of the medication use.

Emergency treatment includes lying flat with legs elevated, monitoring vital signs, and administering vasoconstrictors or vasopressors as directed by medical personnel.

 

Frequently Asked Questions

What should I do if chest pain persists after using the sublingual tablet?

If chest pain is not relieved within 5 minutes after using the sublingual tablet, a second tablet can be taken, but the total should not exceed 3 doses. If still ineffective, seek medical attention immediately, as it may be a sign of myocardial infarction. During use, maintain a semi-sitting position to avoid dizziness caused by standing up suddenly.

What are some persistent side effects of long-term nitroglycerin use?

Long-term use may lead to headaches, low blood pressure, or peripheral edema. Headaches usually diminish over time, but if severe or persistent, inform your doctor to adjust the dose. Patients with hypotension should monitor blood pressure changes to prevent fainting from sudden standing.

Which medications can enhance the blood pressure-lowering effect of nitroglycerin?

Combining with beta-blockers or calcium channel blockers may enhance vasodilation, leading to excessively low blood pressure. Always inform your doctor of all medications you are taking, especially other drugs for heart disease, to avoid interactions.

Can I drink alcohol while using nitroglycerin?

Avoid alcohol, as it can increase vasodilation effects, leading to dizziness, headache, or hypotension. Complete abstinence from alcohol and avoiding alcohol-containing medications or supplements during treatment for chest pain is recommended.

What symptoms can occur from overdose, and how should I respond?

Overdose may cause severe hypotension, tachycardia, or collapse. If these occur, lie down with legs elevated to promote blood flow and contact emergency services immediately. Do not adjust the dose yourself; follow your physician's instructions carefully.