Diltiazem is a non-dihydropyridine calcium channel blocker with both cardiac and vascular effects. It works by inhibiting L-type voltage-gated calcium channels in cardiac muscle and vascular smooth muscle, reducing calcium influx during depolarization.
Key pharmacological actions:
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Causes arterial vasodilation by relaxing vascular smooth muscle, leading to decreased peripheral vascular resistance and blood pressure.
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Has negative inotropic effects (reduces myocardial contractility), negative chronotropic effects (lowers heart rate), and negative dromotropic effects (slows atrioventricular nodal conduction).
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Decreases myocardial oxygen demand by lowering heart rate, blood pressure, and contractility, which is beneficial in treating angina.
Clinical indications include hypertension, chronic stable angina, and certain supraventricular arrhythmias (e.g., atrial fibrillation or flutter). It is available in oral (immediate and extended-release) and intravenous formulations.
Clinical pharmacist considerations:
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Monitor heart rate and blood pressure because of the bradycardic and hypotensive potential.
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Be aware of potential drug interactions due to diltiazem’s inhibition of CYP3A4.
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Use cautiously or avoid in patients with severe left ventricular dysfunction, heart block, or sick sinus syndrome unless they have a functioning pacemaker.
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Educate patients on adherence, especially with extended-release forms, and on recognizing symptoms of hypotension or bradycardia.
Diltiazem’s balanced cardiac and vascular effects make it useful for combined control of hypertension, angina, and some arrhythmias with an established efficacy and safety profile