Generic Name: Diltiazem.

Trade Name    : Diltiazem, Altiazem.

Drug Class      : Antidysrhythmic, Calcium Channel Blockers.

Forms of The Drug

  1. Tablets: 30mg, 60mg, 90mg, 120mg.
  2. Capsule/Tablet, Extended Release: 120mg, 180mg, 240mg, 300mg, 360mg, 420mg.
  3. Injectable Solution: 5mg/mL.
  4. Powder for Injection: 100mg.

Mechanism of Action

Diltiazem is a medication classified as a calcium channel blocker, and its mechanism of action primarily involves its effects on calcium channels in cardiac and smooth muscle cells. How Diltiazem works include:

  1. Inhibition of Calcium Influx: Diltiazem selectively inhibits the influx of calcium ions into cells, particularly into cardiac (heart) and smooth muscle cells. Calcium plays a crucial role in muscle contraction, including the heart, and in regulating blood vessel tone.
  2. Cardiac Effects: In the heart, Diltiazem primarily targets calcium channels in the myocardium (heart muscle). By blocking these channels, it reduces the entry of calcium ions into the cardiac muscle cells. This has several effects on the heart:
    • Reduced Contractility: Diltiazem decreases the force of cardiac muscle contraction. This results in a reduced workload on the heart, reducing oxygen demand and potentially easing the heart’s workload.
    • Slowed Heart Rate: Diltiazem also affects the electrical conduction system of the heart by slowing the conduction of electrical signals through the atrioventricular (AV) node. This can be beneficial in conditions where a slower heart rate is desirable, such as in atrial fibrillation or atrial flutter.
  3. Vasodilation: Diltiazem’s primary effect is on the smooth muscle cells in the walls of blood vessels, particularly arterioles (small arteries). By inhibiting calcium influx in these cells, Diltiazem causes relaxation and dilation of blood vessels. This leads to a decrease in systemic vascular resistance, which reduces blood pressure. Diltiazem is particularly effective at dilating coronary arteries, which supply blood to the heart muscle. This can increase coronary blood flow and is particularly beneficial in the context of angina (chest pain) or other coronary artery diseases.
  4. Antiarrhythmic Properties: In addition to its blood pressure-lowering effects, Diltiazem is also used as an antiarrhythmic medication. It can help control certain abnormal heart rhythms, such as atrial fibrillation and atrial flutter, by slowing electrical conduction in the atria.


  1. Hypertension (High Blood Pressure).
  2. Chronic stable angina.
  3. Atrial Fibrillation and atrial flutter.
  4. Supraventricular Tachycardia (SVT).
  5. Coronary Artery Disease (CAD).
  6. Raynaud’s phenomenon.


  1. Hypersensitivity.
  2. Sick sinus syndrome.
  3. Second- or Third-Degree Atrioventricular (AV) Block (Without a Functioning Pacemaker).
  4. Recent myocardial infarction (Heart Attack).
  5. Severe hypotension (Low Blood Pressure).
  6. Acute pulmonary congestion.
  7. Concomitant use with ivabradine.
  8. Concomitant Use with Strong CYP3A4 Inhibitors: Medications that strongly inhibit the CYP3A4 enzyme, such as ketoconazole, itraconazole, and erythromycin.

Side Effects

  1. Edema (2-15%).
  2. Headache (5-12%).
  3. Dizziness (3-10%).
  4. AV block (2-8%).
  5. Peripheral edema (2-8%).
  6. Bradyarrhythmia (2-6%).
  7. Headache (1-5%).
  8. Hypotension (2-4%).
  9. Nausea (3%).
  10. Vomiting (2%).
  11. Vasodilation (2-3%).
  12. Extrasystoles (2%).
  13. Flushing (1-2%).
  14. Drug-induced gingival hyperplasia (<2%).
  15. Myalgia (2%).
  16. Diarrhea (1-2%).
  17. Constipation (2-4%).
  18. Bronchitis (1-4%).
  19. Sinus congestion (1-2%).
  20. Dyspnea (1-6%).
  21. Congestion (1-2%).

Drug Interaction

Drugs that can interact with the drug.

  1. Beta-Blockers: Combining Diltiazem with beta-blockers (e.g., metoprolol, propranolol).
  2. Digoxin.
  3. Statins (HMG-CoA Reductase Inhibitors): Some statin medications, used to lower cholesterol (e.g., simvastatin, atorvastatin).
  4. Amiodarone.
  5. Antihypertensive Medications: Combining Diltiazem with other antihypertensive medications, such as ACE inhibitors (e.g., enalapril, lisinopril) and ARBs (e.g., losartan, valsartan).
  6. CYP3A4 Inhibitors: Medications that inhibit the CYP3A4 enzyme, such as ketoconazole, itraconazole, and erythromycin.
  7. CYP3A4 Inducers: Medications that strongly induce the CYP3A4 enzyme, such as rifampin or St. John’s Wort.
  8. Grapefruit juice.


  1. Pregnancy: Category C.
  2. Lactation: Diltiazem, a medication primarily used to treat various cardiovascular conditions, including high blood pressure, angina, and certain heart rhythm disorders, can potentially pass into breast milk when taken by lactating mothers. However, the transfer of Diltiazem to breast milk is generally considered to be low.

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