Presentation on Nitrates

Overview

• Purpose: Understand nitrates' usage, effects, and implications for practice and patient cardiac care.
• Nitrates: A class of vasodilator drugs, primarily act as veno-dilators, providing an external source of nitric oxide.

Mechanism of Action

• Primary Action: On venous beds, causing coronary vasodilation by relaxing vascular smooth muscle.
• Effects:
  • Dilation of veins → Reduced preload, ventricular wall stress, myocardial oxygen consumption and demand.
  • Modest dilation of coronary arteries → Increased coronary blood flow and oxygen supply.
  • Minimal arterial dilation → Minor reduction in afterload.

Anti-Anginals and Vasodilators

• Anti-Anginals:
  • Treat acute angina and ischemic attacks by increasing oxygen supply and decreasing demand.
• Vasodilators:
  • Decrease vascular tone, afterload, preload, and myocardial oxygen demand.

Nitrates Effects

• Coronary Vasodilators:
  • Dilate large coronary arteries and redistribute blood flow.
  • Effective for acute angina and ischemic attacks.
• Peripheral Vasodilators:
  • Decrease preload and afterload, thus decreasing oxygen demand.

Comparison with Other Vasodilators

• Beta Blockers & Calcium Channel Blockers:
  • Act more distally, not effective for angina due to potential coronary steal.

Oxygen Supply and Demand

• Nitrates:
  • Decrease oxygen demand by dilating veins and arteries, reducing workload and consumption.
  • Increase oxygen supply by improving coronary artery perfusion.

Nitrate Types and Administration

• Common Nitrates: Nitroglycerin, Isosorbide.
• Routes:
  • Sublingual spray, tablets, patches, IV, ointments.
• Half-life: Varies by administration method.

Adverse Effects

• Common Effects:
  • Syncope, hypotension, tachycardia, bradycardia, headaches.
  • Tolerance with continuous high-dose therapy, requiring a nitrate-free interval.

Contraindications

• Conditions: Hypertrophic cardiomyopathy, severe aortic stenosis, certain myocardial infarctions, and others.
• Drug Interactions: Viagra and similar agents.

Clinical Application

• Treatment: Unstable angina, myocardial infarction types.
• Procedure:
  • Administer nitroglycerin for angina; monitor pain and blood pressure.
  • Emergency protocol if pain persists beyond 15 minutes.
  • Use of ECG and blood work to assess.

Nitrate Tolerance

• Management:
  • Implement nitrate-free intervals, typically at night, to prevent tolerance.

Conclusion

• Summary: Nitrates decrease oxygen demand and increase supply, playing a crucial role in managing cardiac conditions.