Cardizem (Diltiazem) - Pharmacology Overview

Study Notes

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.

Description

This quiz covers the pharmacology of Cardizem (Diltiazem), focusing on its mechanism of action as a calcium channel blocker. It discusses the pharmacodynamics, including vasodilation and effects on heart rate, as well as pharmacokinetics such as absorption and distribution. Test your knowledge on this important cardiovascular medication.