What is the typical starting dose of diltiazem (calcium channel blocker) for hypertension (high blood pressure)?

Diltiazem Dosing for Hypertension

The typical starting dose of diltiazem for hypertension is 120-180 mg once daily, with titration up to a maximum of 360 mg daily to achieve blood pressure control. 1

Initial Dosing Strategy

• Start with 120 mg daily using either divided doses or a single dose with long-acting formulations 1
• The American College of Cardiology supports initiating at 120-180 mg once daily for the extended-release formulations 1
• Doses below 120 mg/day are generally ineffective for hypertension, as the 90-120 mg/day range represents a "no-effect dose" for blood pressure reduction 2

Dose Titration and Target

• Titrate cautiously and progressively over several weeks to reach effective blood pressure control 1
• The maximum maintenance dose is 360 mg daily, administered either in divided doses or as a single dose with long-acting formulations 1
• Hypertension typically requires higher doses (up to 360 mg daily) compared to angina (typically 240 mg daily) 1
• Research demonstrates a clear linear dose-response relationship between diltiazem dose and blood pressure lowering through the 480-540 mg/day range, though 360 mg is the FDA-approved maximum 2

Common Dosing Pitfall

Most physicians significantly underdose diltiazem for hypertension. Recent prescribing data show that 180-240 mg capsule strengths constitute over 70% of diltiazem prescriptions for hypertension, despite evidence that 360 mg/day is often required for optimal blood pressure control 2. This underdosing stems from physicians becoming accustomed to lower antianginal doses (240 mg) before the hypertension indication was approved 2.

Formulation Considerations

• Extended-release once-daily formulations (Cardizem CD) are preferred for controlled delivery over 24 hours, with dosing ranging from 180-420 mg 1
• The once-daily CD formulation maintains consistent blood levels over 24 hours, starting at 120-180 mg once daily, titrated to a maximum of 360-420 mg daily 1
• Immediate-release tablets are available in 30-90 mg doses but require multiple daily dosing 1

Monitoring During Titration

• Monitor blood pressure and heart rate regularly during dose titration 1
• Watch for common adverse effects including hypotension (most common), bradycardia, peripheral edema, and constipation 1
• Use caution in patients with bradycardia, as this may be dose-limiting 1
• Monitor for signs and symptoms of heart failure in at-risk patients 1
• Check liver function tests if clinically indicated 1
• Perform ECG monitoring in patients with conduction system disease 1

Absolute Contraindications

• Second or third-degree AV block without a functioning ventricular pacemaker 1
• Sick sinus syndrome or SA node dysfunction without a pacemaker 1, 3
• Decompensated systolic heart failure or severe LV dysfunction 1
• Cardiogenic shock 1
• Wolff-Parkinson-White (WPW) syndrome with atrial fibrillation/flutter 1
• Hypotension 1, 3

Relative Contraindications and Cautions

• Use with caution when combined with beta-blockers, due to risk of significant bradyarrhythmias and heart failure 1
• Exercise caution in patients with hepatic dysfunction, as diltiazem is metabolized by the liver 1
• Use caution in patients with renal dysfunction, as dose adjustment may be required 1
• Avoid in patients taking medications with SA/AV nodal-blocking properties due to increased risk of conduction abnormalities 1

Drug Interactions

• Diltiazem is a substrate of CYP3A4 (major) and a moderate CYP3A4 inhibitor 1
• Use caution with: apixaban, itraconazole, bosutinib, ceritinib, cilostazol, cyclosporine, everolimus, ibrutinib, idelalisib, ivabradine, lomitapide, olaparib, ranolazine, rifampin, and simeprevir 1

Clinical Pearls

• For patients with relative tachycardia, diltiazem may be preferred over other calcium channel blockers like nifedipine 1
• Adding diuretics may help manage peripheral edema side effects 1
• For hypertension in patients with coronary artery disease, if beta-blockers are contraindicated, diltiazem may be substituted, but not if there is LV dysfunction 1
• When used for hypertension with stable angina, diltiazem can be combined with an ACE inhibitor/ARB and thiazide diuretic if needed for BP control 1

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