Cardizem (Diltiazem) - Pharmacology Overview

Cardizem (Diltiazem) - Pharmacology

• Mechanism of Action: Cardizem is a calcium channel blocker, specifically a non-dihydropyridine type. It inhibits the influx of calcium ions into vascular smooth muscle and cardiac muscle cells, leading to vasodilation and decreased cardiac contractility.

• Pharmacodynamics:

  • Vasodilation: This effect primarily impacts peripheral arterioles, resulting in decreased peripheral vascular resistance and lowering blood pressure.
  • Negative Inotropic Effect: Reduces the force of myocardial contraction, slowing heart rate.
  • Negative Chronotropic Effect: Decreases the heart rate.
  • Negative Dromotropic Effect: Reduces the conduction velocity through the atrioventricular (AV) node.

• Pharmacokinetics:

  • Absorption: Rapidly absorbed from the gastrointestinal tract, but bioavailability can vary depending on the formulation. Food can delay absorption minimally.
  • Distribution: Distributes throughout the body, including the heart and blood vessels.
  • Metabolism: Primarily metabolized by the liver, but significant amounts can be excreted unchanged in the urine.
  • Elimination: Eliminated through both hepatic metabolism and renal excretion.

• Therapeutic Uses:

  • Hypertension: Effective in lowering blood pressure, especially in patients with angina or other conditions where vasodilation is beneficial.
  • Angina Pectoris: Relieves angina symptoms by decreasing myocardial oxygen demand and increasing coronary artery blood flow by vasodilation.
  • Cardiac Arrhythmias: Used to control supraventricular tachycardias (SVTs) by slowing conduction through the AV node and decreasing heart rate.
  • Hypertrophic Cardiomyopathy: Can sometimes be used to help manage symptoms in some patients.

• Adverse Effects:

  • Common: Headache, dizziness, peripheral edema, constipation.
  • Less Common: Bradycardia, AV block, hypotension, flushing, nausea, vomiting.
  • Rare: Severe hypotension, heart failure, hepatic dysfunction.
  • Important Note: Certain adverse effects, especially bradycardia and AV block, are more likely in patients with pre-existing heart conditions.

• Drug Interactions:

  • Other Calcium Channel Blockers: Additive effect on blood pressure lowering, potentially leading to excessive hypotension.
  • Beta-blockers: Additive negative inotropic and chronotropic effects. Increased risk of bradycardia or heart block.
  • CYP3A4 Inhibitors: May increase Cardizem levels, potentially leading to increased adverse effects.
  • CYP3A4 Inducers: May decrease Cardizem levels, reducing its effectiveness.
  • Digoxin: Increased risk of digoxin toxicity (especially if bradycardia occurs).

• Contraindications:

  • Severe Hypotension: Not recommended due to potential for further decreases in blood pressure.
  • Severe Bradycardia or AV Block: Use with extreme caution or contraindicated.
  • Severe Heart Failure: Can worsen symptoms.
  • Hypersensitivity to Diltiazem: Clearly contraindicated.

• Dosage and Administration: Cardizem comes in various formulations (oral tablets, extended-release tablets, intravenous). Dosage depends on the indication and the individual patient's needs. Always follow the physician's prescribed regimen.

• Patient Education:

  • Important to inform patients about potential side effects, including postural hypotension.
  • Instruct patients to monitor for signs of orthostatic hypotension.
  • Educate patients on proper administration techniques and medication compliance.
  • Ensure patients understand the importance of regular follow-up visits.

Important Considerations

• Individualized Therapy: Dosage and administration need to be carefully tailored to each patient based on their specific heart condition, medical history, and response to treatment.
• Monitoring: Regular monitoring of blood pressure, heart rate, and ECG (electrocardiogram) are crucial during treatment.
• Patient Education: Thoroughly explain the potential benefits, risks, and importance of adherence to the prescribed regimen.