What is the dose of Diltiazem (Cardizem)?

From the Guidelines

Diltiazem dosing for supraventricular tachycardia (SVT) should start with an initial dose of 15 mg to 20 mg (0.25 mg/kg) IV over 2 minutes, followed by an additional dose of 20 mg to 25 mg (0.35 mg/kg) if needed, and a maintenance infusion of 5 mg/hour to 15 mg/hour, titrated to heart rate 1. The dosing of diltiazem can vary depending on the specific indication and patient population.

• For SVT, the initial dose is typically 15 mg to 20 mg (0.25 mg/kg) IV over 2 minutes, with a second dose of 20 mg to 25 mg (0.35 mg/kg) if needed, and a maintenance infusion of 5 mg/hour to 15 mg/hour, titrated to heart rate 1.
• It is essential to note that diltiazem should only be given to patients with narrow-complex tachycardias (regular or irregular) and avoided in patients with heart failure and pre-excited AF or flutter or rhythms consistent with VT 1. Some key considerations when using diltiazem include:
• Monitoring blood pressure, heart rate, and ECG, especially when initiating therapy or adjusting doses.
• Adjusting doses for elderly patients and those with liver or kidney impairment.
• Being aware of potential side effects, such as hypotension, bradycardia, and precipitation of heart failure. Diltiazem works by blocking calcium channels in cardiac and vascular smooth muscle, reducing heart rate, contractility, and blood pressure 1. Regular monitoring and dose adjustments are crucial to minimize adverse effects and optimize therapeutic outcomes.

From the FDA Drug Label

Diltiazem Hydrochloride Tablets: Diltiazem is absorbed from the tablet formulation to about 98% of a reference solution Single oral doses of 30 to 120 mg of diltiazem hydrochloride tablets result in detectable plasma levels within 30 to 60 minutes and peak plasma levels 2 to 4 hours after drug administration. As the dose of diltiazem hydrochloride tablets is increased from a daily dose of 120 mg (30 mg qid) to 240 mg (60 mg qid) daily, there is an increase in area-under-the-curve of 2. 3 times. When the dose is increased from 240 mg to 360 mg daily, there is an increase in area-under-the-curve of 1.8 times. The recommended dose of diltiazem is between 30 mg and 360 mg daily, given in divided doses.

• The dose can be increased from 120 mg (30 mg qid) to 240 mg (60 mg qid) daily.
• Further increase from 240 mg to 360 mg daily can be made. 2

From the Research

Diltiazem Dosing Information

• The dose of diltiazem can vary depending on the condition being treated and the formulation of the medication 3.
• For the treatment of angina pectoris and hypertension, sustained-release diltiazem (D-SR) can be given at a dose of 120 to 180 mg twice a day 3.
• In the management of atrial fibrillation or flutter with rapid ventricular rate, diltiazem can be administered intravenously, with the dose not specified in the provided studies 4, 5, 6.
• The effectiveness of diltiazem in achieving rate control in atrial fibrillation or flutter has been compared to other medications, such as metoprolol and verapamil, with diltiazem showing faster and more substantial decreases in heart rate 4, 5.

Considerations for Diltiazem Administration

• Diltiazem can cause hypotension, and pretreatment with intravenous calcium may help prevent this adverse effect 6.
• The choice of diltiazem dose and formulation should be individualized based on the patient's specific condition and response to treatment 3, 7.
• Diltiazem has been shown to be effective in terminating paroxysmal supraventricular tachycardia and slowing the ventricular response in atrial flutter and fibrillation, with its antiarrhythmic effects correlated with its electrophysiological properties 7.