Diltiazem hydrochloride is a benzothiazepine class calcium channel blocker indicated for the management of hypertension, chronic stable angina, and atrial arrhythmias. It functions by inhibiting the influx of calcium ions during cardiac and vascular smooth muscle depolarization, leading to reduced peripheral vascular resistance and decreased myocardial oxygen demand. This comprehensive profile details its pharmacological characteristics, clinical applications, and essential safety information for healthcare professionals.

Features

• Active Ingredient: Diltiazem hydrochloride
• Pharmacological Class: Benzothiazepine calcium channel blocker
• Available Formulations: Immediate-release tablets, extended-release capsules and tablets, intravenous solution
• Mechanism of Action: Selective inhibition of transmembrane calcium influx in vascular smooth muscle and cardiac cells
• Bioavailability: Approximately 40% (subject to extensive first-pass metabolism)
• Protein Binding: 70–80%
• Elimination Half-Life: 3–4.5 hours (immediate-release); 5–8 hours (extended-release formulations)
• Metabolism: Hepatic via CYP3A4 isoenzyme system
• Excretion: Primarily renal (35%) and fecal (65%)

Benefits

• Provides effective blood pressure reduction through arteriolar vasodilation, decreasing systemic vascular resistance
• Reduces frequency and severity of angina pectoris episodes by improving myocardial oxygen supply/demand ratio
• Controls ventricular rate in atrial fibrillation and flutter through depression of atrioventricular node conduction
• Offers multiple formulation options allowing for tailored dosing regimens across cardiovascular indications
• Demonstrates favorable safety profile compared to other antiarrhythmic agents with minimal proarrhythmic potential
• May provide cardioprotective effects through reduction of left ventricular hypertrophy in hypertensive patients

Common use

Diltiazem is primarily prescribed for the management of essential hypertension, either as monotherapy or in combination with other antihypertensive agents. It is equally effective in treating chronic stable angina pectoris when beta-blockers are contraindicated or poorly tolerated. The intravenous formulation is specifically indicated for rapid control of ventricular response in atrial fibrillation or flutter, as well as for termination of paroxysmal supraventricular tachycardia. Off-label uses include Raynaud’s phenomenon, esophageal spasm, and migraine prophylaxis in selected cases.

Dosage and direction

Hypertension: Extended-release formulations typically initiated at 180–240 mg once daily, titrated to maximum of 540 mg daily based on therapeutic response. Angina: Immediate-release tablets 30 mg four times daily, increased gradually to 180–360 mg daily in divided doses; extended-release formulations 120–480 mg once daily. Atrial Arrhythmias: Intravenous bolus of 0.25 mg/kg over 2 minutes, followed by second bolus of 0.35 mg/kg if needed; maintenance infusion of 5–15 mg/hour. Oral maintenance for rate control typically 120–360 mg daily in divided doses. Administration with food minimizes gastrointestinal upset; extended-release formulations must be swallowed whole without crushing or chewing.

Precautions

Monitor blood pressure and heart rate regularly during initiation and titration. Use cautiously in patients with hepatic impairment (reduce dosage) or renal impairment (monitor renal function). May prolong PR interval; monitor for signs of heart block. Use with caution in patients with heart failure with reduced ejection fraction. Abrupt withdrawal may cause rebound angina; taper gradually. Geriatric patients may require lower doses due to decreased clearance. Regular liver function tests recommended during prolonged therapy.

Contraindications

Patients with sick sinus syndrome or second- or third-degree AV block (except with functioning pacemaker), severe hypotension (systolic <90 mmHg), acute myocardial infarction with pulmonary congestion, hypersensitivity to diltiazem or any component of the formulation, and concurrent intravenous beta-blocker therapy. The intravenous formulation is contraindicated in patients with atrial fibrillation/flutter associated with accessory pathways (e.g., WPW syndrome).

Possible side effect

Common (>10%): Headache, dizziness, edema, asthenia, flushing, nausea. Less common (1–10%): Bradycardia, AV block, hypotension, palpitations, constipation, rash. Rare (<1%): Hepatotoxicity, gingival hyperplasia, leukopenia, thrombocytopenia, photosensitivity, Stevens-Johnson syndrome. Most adverse effects are dose-dependent and often diminish with continued therapy. Peripheral edema typically responds to diuretic therapy or combination with ACE inhibitors.

Drug interaction

Potent CYP3A4 inhibitors (ketoconazole, clarithromycin, ritonavir) may significantly increase diltiazem concentrations. Beta-blockers may potentiate bradycardia and AV conduction disturbances. May increase digoxin levels by 20–50% (monitor serum concentrations). May potentiate effects of other antihypertensives. Carbamazepine, phenytoin, and rifampin may decrease diltiazem efficacy. Use with simvastatin and lovastatin requires dosage limitation due to increased statin exposure. Cyclosporine levels may increase necessitating monitoring.

Missed dose

If a dose is missed, take as soon as remembered unless close to next scheduled dose. Do not double the dose to make up for missed administration. For once-daily formulations, if missed and remembered the next day, skip missed dose and resume regular schedule. For multiple daily dosing regimens, if within 4 hours of next dose, skip missed dose. Maintain consistent timing to ensure stable therapeutic levels.

Overdose

Manifests as severe bradycardia, hypotension, heart failure, and AV conduction disturbances. Administer activated charcoal if recent ingestion. Cardiovascular support with IV fluids and vasopressors may be necessary. Bradycardia responds to atropine (0.6–1 mg IV), isoproterenol, or cardiac pacing. Calcium gluconate (1 g IV) may reverse hemodynamic effects but not conduction abnormalities. Hemodialysis not effective due to extensive protein binding. Contact poison control center for latest management recommendations.

Storage

Store at controlled room temperature (20–25°C/68–77°F); excursions permitted to 15–30°C (59–86°F). Protect from light and moisture. Keep in original container with tight closure. Do not store in bathroom or near sink. Keep all medications out of reach of children and pets. Properly dispose of expired or unused medication through take-back programs.

Disclaimer

This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult qualified healthcare providers regarding medical conditions and before starting any new therapy. Dosage and indications may vary based on individual patient factors and latest clinical guidelines. Never disregard professional medical advice or delay seeking it based on information contained herein.

Reviews

Clinical studies demonstrate diltiazem’s efficacy in reducing systolic and diastolic blood pressure by 10-15 mmHg and 8-10 mmHg respectively at standard doses. Angina frequency reduction of 40-60% reported in controlled trials. For rate control in atrial fibrillation, achieves ventricular rate <100 bpm in 70-80% of patients. Generally well-tolerated with discontinuation rates of 5-8% in clinical trials, primarily due to edema and headache. Long-term studies show maintained efficacy with minimal tolerance development.