Generic Name: Nitrates, Nitroglycerin.

Trade Name   : Nitromak, Nitronal,Tridil.

Drug Class :  Antianginal Agents, Vasodilators.

Forms of The Drug

  1. Infusion Solution: 25mg/250mL, 50mg/250mL, 100mg/250mL.
  2. Injectable Solution: 5mg/mL.

Mechanism of Action

The mechanism of action of nitrates primarily involves their vasodilatory effects, which means they help widen and relax blood vessels. This results in improved blood flow and reduced workload on the heart. The primary mechanism of action of nitrates involves their conversion into nitric oxide (NO) within the body. Nitric oxide is a signaling molecule that plays a crucial role in regulating various physiological processes, including blood vessel dilation. Here’s how the mechanism of action of nitrates unfolds:

  1. Conversion to Nitric Oxide (NO): Nitrates are administered either orally, sublingually (under the tongue), or topically (as ointments or patches). Once inside the body, nitrates are converted to nitric oxide through a process called biotransformation. This conversion primarily occurs in the smooth muscle cells of blood vessels, especially in the veins. Nitric oxide is a potent vasodilator, which means it causes the smooth muscles lining the blood vessel walls to relax, leading to vessel dilation.
  2. Vasodilation: When nitric oxide is released from the smooth muscle cells of blood vessels, it diffuses into the surrounding muscle layers. Here, it activates an enzyme called guanylate cyclase. Guanylate cyclase converts guanosine triphosphate (GTP) into cyclic guanosine monophosphate (cGMP), a secondary messenger molecule.
  3. cGMP Signaling: The increased levels of cGMP inside the smooth muscle cells trigger a series of intracellular events that lead to relaxation of the smooth muscle. This relaxation causes the blood vessels to widen, resulting in vasodilation. As the blood vessels dilate, the resistance to blood flow decreases, allowing more blood to flow through the vessels.
  4. Improved Blood Flow: By dilating both veins and arteries, nitrates effectively reduce the workload on the heart. In the case of angina, the increased blood flow to the heart muscle relieves the oxygen deficit that often causes chest pain. This is especially important during episodes of angina, as increased blood flow can help restore adequate oxygen supply to the heart and alleviate the associated pain.

Indications:

  1. Angina pectoris.
  2. Acute angina attacks.
  3. Chronic stable angina.
  4. Unstable angina.
  5. Myocardial infarction (Heart Attack).
  6. Heart failure.
  7. Hypertension (High Blood Pressure).
  8. Pulmonary edema.
  9. Raynaud’s disease.
  10. Esophageal spasm.

Contraindications

  1. Hypersensitivity or allergy.
  2. Severe anemia.
  3. Hypotension (Low Blood Pressure).
  4. Increased intracranial pressure.
  5. Phosphodiesterase-5 (PDE-5) inhibitor use.
  6. Glaucoma.
  7. Cardiomyopathy with Obstructive Hypertrophic Subaortic Stenosis.
  8. Constrictive pericarditis.
  9. Use of nitrates beyond prescribed doses.
  10. Pregnancy and breastfeeding.

Side Effects

  1. Headache.
  2. Hypotension.
  3. Tachycardia.
  4. Dyspnea.
  5. Dizziness.
  6. Lightheadedness.
  7. Blurred vision.
  8. Flushing.
  9. N/V.
  10. Nervousness.
  11. Xerostomia.
  12. Serious.
  13. Methemoglobinemia (rare).
  14. Syncope.
  15. Prolonged bleeding time.
  16. Exfoliative dermatitis.
  17. Unstable angina.
  18. Rebound hypertension.
  19. Thrombocytopenia.

Drug Interaction

Drugs that can interact with the drug.

  1. Phosphodiesterase-5 (PDE-5) Inhibitors: Interaction with PDE-5 inhibitors, such as sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis).
  2. Alpha-blockers.
  3. Beta-blockers.
  4. Calcium channel blockers.
  5. Antihypertensive medications.
  6. Alcohol.
  7. Heparin and other anticoagulants.
  8. Antiplatelet medications.
  9. Tricyclic antidepressants.
  10. Potassium channel blockers.
  11. Erectile dysfunction medications.

Precautions

  1. Pregnancy: Category C.
  2. Lactation: Lactation, or breastfeeding, is an important period during which the safety of medications is a primary concern, as substances in the mother’s bloodstream can potentially be transferred to the infant through breast milk.

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