Cardizem (diltiazem hydrochloride) is a prescription calcium channel blocker medication specifically formulated for the management of hypertension, chronic stable angina, and atrial arrhythmias. As a cornerstone therapy in cardiovascular medicine, it functions by inhibiting calcium ion influx during cardiac and vascular smooth muscle depolarization, resulting in reduced peripheral vascular resistance and decreased myocardial oxygen demand. Its well-established efficacy and favorable safety profile make it a first-line option for clinicians seeking to optimize cardiovascular outcomes in appropriate patient populations.

Features

• Active pharmaceutical ingredient: Diltiazem hydrochloride
• Available in multiple formulations including immediate-release tablets, extended-release capsules, and intravenous injection
• Dosage strengths ranging from 30 mg to 360 mg to accommodate individualized titration
• Bioavailability of approximately 40% due to first-pass metabolism
• Plasma protein binding: 70-80%
• Elimination half-life: 3-4.5 hours (immediate-release); 5-8 hours (extended-release)
• Primary metabolic pathway: hepatic deacetylation via CYP3A4
• Renal excretion of metabolites (2-4% unchanged drug)

Benefits

• Effectively lowers systolic and diastolic blood pressure through arterial vasodilation
• Reduces frequency and severity of angina episodes by decreasing myocardial oxygen demand
• Controls ventricular rate in atrial fibrillation and atrial flutter through AV node conduction slowing
• Demonstrates negative chronotropic effects without significant negative inotropic action at therapeutic doses
• Offers flexible dosing regimens across multiple formulations for personalized treatment
• Provides 24-hour blood pressure control with extended-release formulations

Common use

Cardizem is primarily indicated for the treatment of essential hypertension, either as monotherapy or in combination with other antihypertensive agents. It is equally effective in managing chronic stable angina pectoris when beta-blockers or nitrates are contraindicated or insufficient. The medication is also routinely employed for ventricular rate control in patients with atrial fibrillation or atrial flutter, particularly when rapid conversion to sinus rhythm is not immediately necessary. Off-label uses may include Raynaud’s phenomenon, esophageal spasm, and migraine prophylaxis, though these applications require careful clinical consideration.

Dosage and direction

Dosage must be individualized based on therapeutic response and tolerance. For hypertension: Initial dose typically ranges from 180-240 mg once daily (extended-release), titrated upward at 2-week intervals to maximum 540 mg daily. For angina: Starting dose 120-180 mg once daily, increased gradually to 480 mg daily if needed. For atrial arrhythmias: Intravenous bolus of 0.25 mg/kg over 2 minutes, followed by continuous infusion of 5-15 mg/hour. Oral maintenance dose ranges from 120-360 mg daily in divided doses. Tablets should be swallowed whole without crushing or chewing, preferably with food to enhance gastrointestinal tolerance. Regular blood pressure monitoring is essential during dosage adjustments.

Precautions

Cardizem requires careful consideration in patients with impaired hepatic function, as reduced clearance may necessitate dosage reduction. Caution is advised in those with left ventricular dysfunction or congestive heart failure, though the drug is generally better tolerated than other calcium channel blockers in this population. Elderly patients may exhibit increased sensitivity and require lower initial doses. Abrupt discontinuation should be avoided due to potential rebound hypertension or angina exacerbation. Regular monitoring of liver enzymes, renal function, and electrocardiograms is recommended during long-term therapy. Patients should be advised about potential dizziness, especially during initial treatment or dosage increases.

Contraindications

Cardizem is contraindicated in patients with known hypersensitivity to diltiazem or any component of the formulation. Additional absolute contraindications include sick sinus syndrome (except with functioning ventricular pacemaker), second- or third-degree AV block, severe hypotension (systolic pressure <90 mmHg), acute myocardial infarction with pulmonary congestion demonstrated by x-ray, and concurrent intravenous beta-blocker administration. The medication is also contraindicated in patients with atrial fibrillation complicating Wolff-Parkinson-White syndrome due to risk of accelerated accessory pathway conduction.

Possible side effect

Common adverse reactions (≥5%) include headache, dizziness, fatigue, edema, flushing, and nausea. Less frequent side effects (1-5%) comprise bradycardia, first-degree AV block, constipation, and rash. Serious but rare adverse events (<1%) include symptomatic hypotension, heart failure exacerbation, hepatotoxicity, and severe skin reactions. Laboratory abnormalities may include transient elevations in liver enzymes, though clinically apparent hepatitis is uncommon. Most side effects are dose-dependent and often diminish with continued therapy or dosage adjustment. Patients should report any persistent or severe symptoms promptly.

Drug interaction

Cardizem undergoes extensive CYP3A4 metabolism and may interact with numerous medications. Significant interactions include increased levels of simvastatin, lovastatin, and cyclosporine (monitoring required). Concurrent use with beta-blockers may produce additive bradycardia or AV conduction disturbances. CYP3A4 inhibitors (ketoconazole, erythromycin) may increase diltiazem concentrations, while inducers (rifampin, phenytoin) may decrease efficacy. Enhanced hypotensive effects may occur with concomitant alpha-blockers, nitrates, or diuretics. Grapefruit juice may increase bioavailability and should be avoided. Comprehensive medication review is essential before initiation.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next scheduled dose. In such cases, the missed dose should be skipped, and the regular dosing schedule resumed. Patients should never double the dose to compensate for a missed administration. Consistency in dosing is particularly important for extended-release formulations to maintain stable plasma concentrations. Healthcare providers should educate patients about the importance of adherence and establish strategies to minimize missed doses, especially in hypertension management where consistency affects long-term outcomes.

Overdose

Cardizem overdose may manifest as profound hypotension, bradycardia, heart failure, or conduction abnormalities. Symptoms can include dizziness, syncope, confusion, and dyspnea. Management involves cardiovascular support with elevation of lower extremities, intravenous fluids, and vasopressors if necessary. Calcium gluconate (1 g IV) may reverse hemodynamic effects, while atropine can address bradycardia. Temporary cardiac pacing may be required for high-grade AV block. Glucagon administration has shown benefit in some cases. Hemodialysis is ineffective due to extensive protein binding. All suspected overdoses require immediate medical attention and continuous cardiac monitoring.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) in the original container, protected from light and moisture. Keep tightly closed and avoid exposure to excessive heat or humidity. Do not transfer capsules or tablets to other containers unless specifically designed for medication storage. Keep out of reach of children and pets. Do not use if the product appears discolored or shows signs of deterioration. Proper disposal of unused medication should follow local regulations, typically through drug take-back programs rather than flushing or household trash.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Cardizem is available by prescription only and should be used under appropriate medical supervision. Individual response to medication may vary, and therapeutic decisions should be based on comprehensive clinical evaluation. Patients should consult qualified healthcare providers for diagnosis, treatment recommendations, and monitoring. The manufacturer’s prescribing information contains the most complete and updated guidance for safe and effective use.

Reviews

Clinical studies consistently demonstrate Cardizem’s efficacy in blood pressure reduction and angina management. Meta-analyses of hypertension trials show mean systolic reductions of 10-15 mmHg and diastolic reductions of 8-10 mmHg at standard doses. Angina studies report significant improvement in exercise tolerance and reduced nitrate requirements. Cardiologists frequently note its favorable side effect profile compared to other antihypertensive classes. Patient satisfaction surveys indicate good tolerability and convenience of once-daily dosing. However, some reviews note the need for careful titration in elderly patients and those with conduction abnormalities. Overall professional assessment considers Cardizem a valuable therapeutic option within comprehensive cardiovascular management.