Non-dihydropyridine calcium channel blocker

Diltiazem hydrochloride

Brand names: Tildiem, Adizem, Slozem, Zemtard

Diltiazem is a rate-limiting (non-dihydropyridine) calcium-channel blocker used for angina and hypertension.

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 cardiac and vascular smooth muscle, slowing the heart rate, reducing myocardial contractility and causing coronary and peripheral vasodilatation.

Prescribing in practice

Avoid combining with a beta-blocker, and use caution with other rate-limiting drugs, because of the risk of bradycardia and heart block.
Avoid in significant left ventricular dysfunction or heart failure owing to its negative inotropic effect.
It is a CYP3A4 inhibitor with many interactions, and modified-release products are brand-specific so prescribe and dispense by brand.

Monitoring

Monitor heart rate, blood pressure and for signs of heart failure, particularly after dose changes or when other cardiac drugs are added.

Counselling the patient

Report a slow pulse, dizziness, fainting, breathlessness or ankle swelling.
Do not switch between different brands of modified-release product without medical advice.

Evidence & guidelines

An established option for angina and hypertension in UK guidance (NICE), particularly where rate control is also desirable.

Reference: NICE NG136; NICE NG196; ESC AF/HT guidelines; MHRA brand-prescribing notice; 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).

Curated clinical cross-links plus same-class fallbacks.

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