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Diltiazem

Calcium Channel Blockerprescriptionoral · predicted

Nondihydropyridine calcium channel blocker used for hypertension, angina, and rate control in atrial fibrillation. Unlike dihydropyridines, produces meaningful AV-nodal slowing and negative inotropy. Extended-release formulations (120-360 mg/day) are standard outpatient therapy. Extensive CYP3A4 metabolism results in many drug interactions.

Projected serum levels — 240 mg, once daily

Diltiazem
Diltiazem modeled serum levels, 240 mg once daily over 15 days Population-based pharmacokinetic estimate. Steady state reached after approximately 1 days. 0 25 50 75 100 Day 0 Day 4 Day 8 Day 11 Day 15 Time on a regular schedule ≈ steady state · day 1

Maintenance schedule: 240 mg once daily (oral).

Modeled steady state after ~1 days: peak ≈ 67.3 mg, trough ≈ 3.1 mg body load. Population-based estimate over 15 days for a 240 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
Calcium Channel Blocker
Route modeled
Oral
Model confidence
predicted
Half-life
5 h
Common dose
240 mg
Suggested maximum
360 mg/day
Reference dose range
120–360 mg (single dose)
Suggested cadence
once daily
Validated against
120 mg oral — Cmax 0.085 mg/L at 4 h

Documented interactions

  • contraindicated
    Alfuzosin (Uroxatral) + Diltiazem CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Alfuzosin (Uroxatral) AUC by ~10.00x

  • contraindicated
    Alprazolam (Xanax) + Diltiazem CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Alprazolam (Xanax) AUC by ~10.00x

  • contraindicated
    Amlodipine (Norvasc) + Diltiazem CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Amlodipine (Norvasc) AUC by ~10.00x

  • contraindicated
    Anastrozole (Arimidex) + Diltiazem CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Anastrozole (Arimidex) AUC by ~5.14x

  • contraindicated
    Astaxanthin + Diltiazem CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Astaxanthin AUC by ~10.00x

  • contraindicated
    Atogepant (Qulipta) + Diltiazem CYP inhibition

    Diltiazem mechanism_based of CYP3A4 predicted to change Atogepant (Qulipta) AUC by ~10.00x

Serum checks 303 modeled interaction pairings for diltiazem across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. The effect of diltiazem on mortality and reinfarction after myocardial infarction Multicenter Diltiazem Postinfarction Trial Research Group (Moss AJ et al.) · New England Journal of Medicine, 1988 DOI

    MDPIT trial of 2466 post-MI patients showed diltiazem had no overall mortality benefit but significantly reduced reinfarction in the non-Q-wave subgroup without pulmonary congestion.

  2. Clinical pharmacokinetics of diltiazem Chaffman M, Brogden RN · Clinical Pharmacokinetics, 1985 DOI

    Foundational PK review establishing diltiazem's ~40% bioavailability due to first-pass CYP3A4 metabolism, 3-5 hour half-life for IR and longer apparent half-life for ER formulations.

  3. A Calcium Antagonist vs a Non-Calcium Antagonist Hypertension Treatment Strategy for Patients With Coronary Artery Disease (INVEST) Pepine CJ et al. · JAMA, 2003 DOI

    INVEST trial of 22576 HTN patients with CAD showed a verapamil-based strategy (comparator to diltiazem-class agents) was non-inferior to a beta-blocker strategy for cardiovascular outcomes.

3 published studies referenced in the app, each with a plain-language summary.