Cardiology · Non-dihydropyridine calcium channel blocker
Diltiazem
Dose
IV 0.25 mg/kg over 2 min (may repeat 0.35 mg/kg), infusion 5–15 mg/h. PO 60–120 mg TDS (IR) or 180–360 mg OD (SR).
Mechanism
L-type Ca channel block → AV node slowing, negative inotropy, coronary + peripheral vasodilation.
Indications
- • Rate control AF/flutter
- • SVT termination
- • Angina (variant and effort)
- • Hypertension
Contraindications
- • LVEF <40%
- • 2°/3° AV block
- • SBP <90
- • Concurrent IV β-blocker (risk asystole)
- • WPW with AF
Dose adjustment
Hepatic impairment: start low; CYP3A4 substrate
Use
Rate control in AF when β-blocker contraindicated or ineffective.
Monitoring
HR, BP, ECG (PR interval), LFTs.
Side effects
- • Bradycardia
- • AV block
- • Ankle oedema
- • Constipation
- • Flushing
- • Headache
Always confirm dose against your local formulary / BNF before prescribing.
