Description

Diltiazem HCl is a medication classified as a non-dihydropyridine calcium channel blocker. Unlike its dihydropyridine counterparts (like amlodipine), diltiazem has a significant effect on both vascular smooth muscle and cardiac muscle. The “HCl” in its name stands for hydrochloride, which is a salt form used to improve the drug’s stability and solubility for administration.

Indications

Diltiazem HCl is used to treat a variety of cardiovascular conditions. Its primary indications include:

• Hypertension (High Blood Pressure): It is effective in lowering blood pressure by dilating blood vessels, which reduces the heart’s workload.

• Angina Pectoris (Chest Pain):
  • Chronic Stable Angina: It helps prevent and manage chest pain by increasing oxygen supply to the heart.

  • Vasospastic Angina (Prinzmetal’s Angina): It is highly effective in treating this form of angina, which is caused by coronary artery spasms.

• Supraventricular Tachycardia (SVT): It is used to control the ventricular rate in patients with atrial fibrillation or atrial flutter, and to terminate episodes of paroxysmal supraventricular tachycardia.

Mechanism of Action

Diltiazem’s mechanism of action involves the inhibition of calcium ion flow into muscle cells, but it affects both the heart and blood vessels.

1. Calcium Channel Blockade: Diltiazem specifically blocks the entry of calcium ions through L-type voltage-gated calcium channels on the membranes of both vascular smooth muscle cells and cardiac muscle cells.

2. Effects on Cardiac Muscle:

   • Decreased Myocardial Contractility: By reducing calcium influx into heart muscle cells, diltiazem weakens the force of heart muscle contractions (a negative inotropic effect).
   • Slowed Heart Rate: It also slows down the electrical conduction through the sinoatrial (SA) and atrioventricular (AV) nodes of the heart. This leads to a slower heart rate (a negative chronotropic effect).

3. Effects on Vascular Smooth Muscle:

   • Vasodilation: By blocking calcium in the smooth muscle cells of the arteries, diltiazem causes these muscles to relax. This leads to the widening of both coronary arteries (which supply blood to the heart) and peripheral arteries throughout the body.
   • Combined Effect:The combined action of diltiazem provides multiple therapeutic benefits:

• Lowered Blood Pressure: The dilation of peripheral arteries reduces the resistance the heart has to pump against, lowering blood pressure.
• Reduced Cardiac Workload: The reduced heart rate and force of contraction decrease the heart’s oxygen demand, which is beneficial for managing angina.
• Improved Oxygen Supply: The dilation of coronary arteries increases blood flow and oxygen supply to the heart muscle, directly helping to relieve chest pain.

• Rate Control: The effect on the heart’s electrical conduction system helps to control and normalize abnormal heart rhythms.