From the Guidelines
Cardizem (diltiazem) causes significant vasodilation, which is its primary mechanism of action in lowering blood pressure, by blocking calcium channels in blood vessels, leading to a reduction in peripheral resistance. The effects of Cardizem on blood pressure are well-documented, and it is commonly used in the treatment of hypertension. According to the seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure 1, the usual dose range for diltiazem extended release (Cardizem CD, Dilacor XR, Tiazac) is 180–420 mg/d, taken once daily.
For hypertension, the typical starting dose is 120-240 mg once daily using extended-release formulations, with dosage adjustments made every 7-14 days based on response. The maximum daily dose is generally 360-480 mg. For immediate-release formulations, the usual dosing is 30 mg three to four times daily, which can be increased gradually to 180-360 mg total daily dose. Elderly patients or those with liver or kidney impairment should start at lower doses.
It's also important to note that Cardizem can be used in the management of certain cardiac conditions, such as atrial fibrillation or angina, alongside hypertension. The 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1 provide dosing information for diltiazem in the context of tachycardia, with an initial dose of 15 to 20 mg (0.25 mg/kg) IV over 2 minutes, and additional doses as needed.
Common side effects of Cardizem include headache, dizziness, and constipation. Blood pressure monitoring is essential when starting therapy or adjusting doses. Overall, Cardizem is a effective medication for the treatment of hypertension, and its vasodilatory effects make it a useful option for patients with certain cardiac conditions.
From the FDA Drug Label
Decreases in blood pressure associated with diltiazem hydrochloride therapy may occasionally result in symptomatic hypotension. The amount of vasodilation caused by Cardizem (Diltiazem) is not explicitly quantified in the provided drug labels. However, it is mentioned that decreases in blood pressure may occur, which can occasionally result in symptomatic hypotension 2. Recommended dosing guidelines are not provided in the given text, but it is stated that caution should be exercised when using the drug in patients with impaired ventricular function 2. Key points to consider:
- Hypotension is a potential effect of Diltiazem therapy
- Caution is advised when using Diltiazem in patients with impaired ventricular function
- Diltiazem is contraindicated in patients with hypotension (less than 90 mm Hg systolic) 2
From the Research
Effects of Cardizem (Diltiazem) on Blood Pressure
- Cardizem (Diltiazem) is a calcium antagonist that has arterial vasodilator properties, which can lead to a decrease in blood pressure 3.
- The vasodilator properties of diltiazem can be utilized for effective long-term treatment of hypertension, with a significant decrease in blood pressure maintained during open long-term therapy over a mean of 11 months 3.
- Diltiazem produces similar haemodynamic and electrophysiological effects to those of verapamil, but has less potency in inducing arterial dilatation and more of a tendency to slow the heart rate 4.
Recommended Dosing Guidelines
- The clinical efficacy and feasibility of diltiazem monotherapy was evaluated in 40 patients with mild to moderate essential hypertension treated with a slow-release formulation of diltiazem, 90 mg twice daily over 8 weeks, and in a subgroup of 21 patients with two tablets of 90 mg once daily in the morning over a period of 2 weeks 3.
- Blood pressure was lowered significantly and to a similar extent by either twice- or once-daily administration of diltiazem, suggesting that once-daily dosing may be a viable option for long-term treatment of hypertension 3.
Comparison with Other Antihypertensive Agents
- Calcium-blocking drugs, such as diltiazem, are more effective in elderly patients at lowering systolic blood pressure compared to ACE inhibitors, beta-blockers, and diuretics 5.
- ACE inhibitors and ARBs have an equal class of recommendation for first-line treatment for the management of hypertension, but ARBs may have improved tolerability and neuroprotective effects compared to ACE inhibitors 6, 7.