Can Cardizem (diltiazem) lower blood pressure?

Can Cardizem (Diltiazem) Lower Blood Pressure?

Yes, Cardizem (diltiazem) effectively lowers blood pressure and is an established antihypertensive medication, particularly at doses of 240-360 mg daily. 1

Mechanism of Action

Diltiazem is a non-dihydropyridine calcium channel blocker (CCB) that works by:

• Inhibiting calcium influx during membrane depolarization in vascular smooth muscle
• Causing relaxation of coronary and peripheral vascular smooth muscle
• Decreasing peripheral vascular resistance, which leads to blood pressure reduction 1

Dosing for Hypertension

• Starting dose: Typically 120-240 mg daily of extended-release formulation
• Usual maintenance dose: 240-360 mg daily
• Maximum dose: 480 mg daily 2

Important note: Research shows diltiazem is often underdosed for hypertension. While angina treatment typically requires 240 mg/day, hypertension management often requires 360 mg/day for optimal blood pressure control 2.

Efficacy in Blood Pressure Control

Diltiazem demonstrates clear dose-dependent blood pressure lowering effects:

• Studies show a linear dose-response relationship through the 480-540 mg/day range 2
• In clinical trials, diltiazem significantly reduced both systolic and diastolic blood pressure over a 24-hour period 3
• Once-daily extended-release formulations (Cardizem CD, Cardizem LA) provide effective 24-hour blood pressure control 3, 4

A multicenter, randomized, placebo-controlled trial showed:

• Average supine blood pressure fell from 156/100 mmHg at baseline to 145/90 mmHg after 12 weeks of treatment
• Standing blood pressure fell from 152/101 mmHg to 143/91 mmHg 5

Clinical Applications and Guidelines

According to guidelines, diltiazem may be used in hypertension management in specific scenarios:

• As a substitute for β-blockers when they are contraindicated or produce intolerable side effects, but not if left ventricular dysfunction is present 6
• As part of combination therapy when angina or hypertension remains uncontrolled on first-line agents 6

Important Precautions and Contraindications

Diltiazem should be avoided in:

1. Patients with heart failure or left ventricular dysfunction (LVEF <40%) 6, 7
2. Patients with significant bradyarrhythmias, sick sinus syndrome, or high-degree AV block 1
3. Combination with β-blockers requires caution due to increased risk of bradyarrhythmias and heart failure 6, 7

Side Effects to Monitor

• Hypotension
• Bradycardia
• Edema
• Dizziness
• Flushing 7, 1

Practical Considerations

• Extended-release formulations allow for once-daily dosing, improving adherence 3, 4
• Diltiazem tends to be more effective in older patients 5
• Blood pressure monitoring should be performed to assess response and titrate dosing appropriately
• When properly dosed, diltiazem can be a potent antihypertensive agent 2

In summary, Cardizem (diltiazem) is an effective antihypertensive medication that works by reducing peripheral vascular resistance. While it's not typically a first-line agent for uncomplicated hypertension, it has established efficacy and may be particularly useful in patients with coexisting conditions like angina when β-blockers are contraindicated.