What is the typical dosing for Diltiazem (calcium channel blocker) in adults with hypertension or angina?

Diltiazem Dosing for Hypertension and Angina

For hypertension, start diltiazem at 120-180 mg daily and titrate up to 240-360 mg daily (maximum 360-420 mg daily with extended-release formulations), while angina typically requires lower doses of 180-240 mg daily. 1

Initial Dosing Strategy

For Hypertension

• Start with 120-180 mg once daily using extended-release formulations (Cardizem CD) 1
• The 120 mg dose is essentially a "no-effect dose" for hypertension and should be viewed as a starting point only 2
• Titrate cautiously and progressively over several weeks to reach effective blood pressure control 1
• Most patients require 240-360 mg daily for adequate hypertension control, with evidence supporting doses up to 480-540 mg daily showing clear linear dose-response relationships 2, 3

For Angina

• Start with immediate-release formulation at 30 mg four times daily (before meals and at bedtime) 4
• Increase gradually at 1-2 day intervals until optimum response is obtained 4
• The average optimum dosage range for angina is 180-240 mg daily, which is notably lower than hypertension dosing 1, 2

Maximum Dosing

• Maximum maintenance dose is 360 mg daily in divided doses or as a single dose with long-acting formulations 1
• Extended-release formulations (Cardizem CD) can be dosed up to 420 mg once daily 1
• Research evidence supports efficacy and safety up to 540 mg daily for resistant hypertension, though this exceeds typical guideline recommendations 3

Formulation-Specific Considerations

Extended-Release (Once-Daily)

• Cardizem CD provides controlled delivery over 24 hours with consistent blood levels 1
• Dosing range: 180-420 mg once daily 1
• Cannot be split, crushed, or chewed—must be swallowed whole 5

Immediate-Release

• Available in 30-90 mg tablets 1
• Can be swallowed whole, crushed, or chewed (do not split) 4
• Requires 3-4 times daily dosing 4

Critical Contraindications

Absolute contraindications include: 1, 6

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

Important Drug Interactions

• Diltiazem is both a CYP3A4 substrate (major) and moderate CYP3A4 inhibitor 1
• Use extreme caution with: apixaban, itraconazole, bosutinib, ceritinib, cilostazol, cyclosporine, everolimus, ibrutinib, idelalisib, ivabradine, lomitapide, olaparib, ranolazole, rifampin, and simeprevir 1
• Exercise caution when combining with beta-blockers due to risk of significant bradyarrhythmias and heart failure 1

Monitoring Requirements

Essential monitoring parameters include: 1

• Blood pressure and heart rate regularly during dose titration
• Signs and symptoms of heart failure in at-risk patients
• Liver function tests if clinically indicated
• ECG monitoring in patients with conduction system disease

Common Adverse Effects

• Hypotension is the most common adverse effect 1, 6
• Bradycardia (may be dose-limiting) 1
• Peripheral edema (consider adding diuretics for management) 1
• Constipation (particularly problematic in elderly patients) 7
• Worsening heart failure in patients with pre-existing ventricular dysfunction 1

Special Population Considerations

Hepatic or Renal Dysfunction

• Titrate with particular caution as diltiazem is metabolized by the liver 1, 4
• Dose adjustment may be required in renal dysfunction 1

Elderly Patients

• Consider starting at 180 mg daily as optimal dose for elderly patients with angina 7
• Higher doses (270-360 mg daily) in elderly patients significantly increase adverse effects, particularly constipation 7

Common Prescribing Pitfall

Diltiazem is frequently underdosed for hypertension. Studies show that 70% of prescriptions are for 180-240 mg doses, when most patients actually require 240-360 mg daily for adequate blood pressure control 2. This underdosing stems from physicians' familiarity with lower antianginal doses that were used for 7 years before the hypertension indication was approved 2.

Discontinuation

• Unlike beta-blockers, diltiazem does not require gradual tapering 5
• Can simply stop the medication without intermediate steps 5
• Monitor blood pressure and heart rate for 1-2 weeks after stopping to assess for return of underlying condition 5
• Watch for return of symptoms (elevated blood pressure, angina, or rapid heart rate) rather than withdrawal effects 5