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Non-Dihydropyridine Calcium Channel Blocker

Diltiazem

Brand names: Tildiem, Dilzem

Used in: Atrial Fibrillation

Diltiazem is a rate-limiting (non-dihydropyridine) calcium-channel blocker used for angina, hypertension and rate control in certain arrhythmias.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION Patients controlled on diltiazem alone or in combination with other medications may be switched to diltiazem hydrochloride extended-release capsules, USP at the nearest equivalent total daily dose. Higher doses of diltiazem hydrochloride extended-release capsules, USP may be needed in some patients. Monitor patients closely. Subsequent titration to higher or lower doses may be necessary. There is limited general clinical experience with doses above 360 mg, but doses to 540 mg have been studied in clinical trials. The incidence of side effects increases as the dose increases with first-degree AV block, dizziness, and sinus bradycardia bearing the strongest …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-08-20. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It blocks L-type calcium channels in the heart and blood vessels, slowing AV-node conduction and heart rate and causing vasodilatation.

Prescribing in practice

  • Avoid combining it with a beta-blocker in most cases (risk of bradycardia and heart block), and avoid in significant left-ventricular systolic dysfunction.
  • Modified-release preparations are not interchangeable — prescribe and dispense by brand.
  • It inhibits CYP3A4, increasing levels of several interacting drugs.

Monitoring

Monitor heart rate, blood pressure and (where relevant) heart-failure status.

Counselling the patient

  • Stay on the same brand of your modified-release product.
  • Report a very slow pulse, dizziness or ankle swelling.

Evidence & guidelines

An option for angina and rate control; avoided with beta-blockers and in heart failure with reduced ejection fraction.

Reference: ESC AF Guidelines 2020; NICE NG196 AF guideline; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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