Nitroglycerin

Medication Overview

Nitroglycerin is a vasodilator primarily used to treat and prevent acute angina symptoms and as an emergency medication during myocardial infarction. This drug works by relaxing vascular smooth muscle, dilating arteries, reducing cardiac workload, and increasing myocardial blood supply, thereby alleviating chest pain and myocardial hypoxia.

The mechanism involves releasing nitric oxide (NO), which induces relaxation of vascular smooth muscle, particularly effective in 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.

Brand Names and Generic Name

Brand names include Nitrostat®, Minitran®, Nitrolingual® 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 primarily act on arterial vessels, especially effective in dilating the coronary arteries, reducing afterload and myocardial oxygen consumption.

Indications

Primarily used for the prevention of stable angina and relief during acute episodes, as well as for emergency management of unstable angina. During 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.
• Severe side effects: severe hypotension, dizziness, syncope, palpitations. Immediate medical attention is required if these occur.

Long-term use may lead to nitrate tolerance, resulting in decreased 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 should use it only after medical evaluation.

Pregnancy category C; use only if necessary. During breastfeeding, it may inhibit milk secretion, so use should be carefully considered by a physician.

Drug Interactions

• Contraindicated interactions: combining with phosphodiesterase-5 inhibitors (such as Viagra) may cause life-threatening hypotension.
• When used with other antihypertensives (such as beta-blockers or ACE inhibitors), dose adjustments may be necessary to prevent excessive blood pressure reduction.

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

Dosage and Administration

Sublingual tablets: During acute episodes, place 0.3-0.6 mg under the tongue; repeat once within 5 minutes if needed, with a maximum total dose of 1.8 mg.

Transdermal patches: Replace every 24 hours, with 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 may cause severe hypotension, tachycardia, or shock. If symptoms such as blurred vision, difficulty breathing, or altered consciousness occur, seek emergency medical help immediately and inform healthcare providers of the medication history.

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 sublingual tablet use?

If chest pain is not relieved within 5 minutes after using a sublingual tablet, you may take another tablet, but the total number should not exceed 3 doses. If pain persists, seek medical attention immediately, as it may be a sign of myocardial infarction. When using, sit in a semi-reclined position and avoid standing up suddenly after taking the medication to prevent dizziness.

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

Long-term use may cause headaches, hypotension, or peripheral edema. Headaches often diminish over time, but if severe or persistent, inform your doctor to adjust the dose. Patients with low blood pressure should monitor their blood pressure regularly to avoid fainting from sudden postural changes.

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

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

Can I drink alcohol while using nitroglycerin?

Avoid alcohol, as it can increase vasodilation effects, causing dizziness, headache, or hypotension. During chest pain treatment, complete abstinence from alcohol and avoid alcohol-containing medications or supplements.

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

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