Cardizem (diltiazem hydrochloride) is a calcium channel blocker prescription medication designed for the management of chronic cardiovascular conditions. It functions by relaxing the blood vessels and reducing the heart’s workload, facilitating improved blood flow and decreased myocardial oxygen demand. This medication is a cornerstone in therapeutic regimens for hypertension and chronic stable angina, offering a well-established efficacy and safety profile when used under appropriate medical supervision. It is available in multiple formulations, including immediate-release and extended-release options, to suit individualized treatment protocols and patient-specific needs.

Features

• Active ingredient: Diltiazem hydrochloride
• Available in immediate-release tablets, extended-release capsules, and intravenous formulations
• Dosage strengths ranging from 30 mg to 360 mg to accommodate titration
• FDA-approved for hypertension and chronic stable angina
• May be used off-label for certain arrhythmias
• Compatible with many antihypertensive and antianginal combination therapies

Benefits

• Effectively lowers blood pressure, reducing long-term cardiovascular risk
• Decreases frequency and severity of angina episodes, improving exercise tolerance
• Helps maintain sinus rhythm in certain atrial arrhythmias
• Extended-release formulations support once-daily dosing for improved adherence
• Generally well-tolerated with a predictable side effect profile
• May be used safely in many patients with comorbid conditions like diabetes or asthma

Common use

Cardizem is primarily indicated for the management of hypertension (high blood pressure) and chronic stable angina. In hypertension, it reduces peripheral vascular resistance, thereby lowering blood pressure. For angina, it decreases myocardial oxygen demand by reducing heart rate and contractility while improving coronary blood flow. It is also used in certain supraventricular tachyarrhythmias, such as atrial fibrillation or flutter, for ventricular rate control. Off-label uses may include Raynaud’s phenomenon and esophageal spasm, though these are less common and require careful medical oversight.

Dosage and direction

Dosage must be individualized based on patient response and tolerance. For hypertension, typical starting doses range from 180–240 mg once daily for extended-release formulations, titrated upward at 2-week intervals. For angina, initial doses often start at 120–180 mg daily. Immediate-release tablets are usually administered three to four times daily. The maximum daily dose should not exceed 360 mg without specific cardiology guidance. Tablets should be swallowed whole and not crushed or chewed. Cardizem may be taken with or without food, though consistency in administration relative to meals is advised. Always follow the prescribing physician’s instructions precisely.

Precautions

Patients should be monitored for signs of hypotension, bradycardia, or heart block, especially during dose titration. Liver function should be assessed periodically, as diltiazem is metabolized hepatically. Use with caution in patients with congestive heart failure or impaired renal function. Grapefruit juice should be avoided, as it can increase diltiazem plasma concentrations. Abrupt discontinuation may provoke rebound angina or hypertension. Elderly patients may require lower initial doses due to altered pharmacokinetics. Inform your healthcare provider if you are scheduled for surgery or dental procedures.

Contraindications

Cardizem is contraindicated in patients with known hypersensitivity to diltiazem or any component of the formulation. It should not be used in individuals with sick sinus syndrome or second- or third-degree AV block, except in the presence of a functioning ventricular pacemaker. It is contraindicated in patients with hypotension (systolic pressure <90 mmHg), acute myocardial infarction, and pulmonary congestion documented by x-ray on admission. Concomitant use with strong CYP3A4 inhibitors like ketoconazole or clarithromycin is also contraindicated.

Possible side effects

Common side effects include dizziness, headache, edema, flushing, and nausea. Less frequently, patients may experience bradycardia, hypotension, fatigue, or constipation. Rare but serious adverse effects include heart block, hepatotoxicity, rash, or symptomatic hypotension. Any signs of allergic reaction (e.g., swelling, difficulty breathing, severe dizziness) warrant immediate medical attention. Most side effects are dose-dependent and may diminish with continued use or dose adjustment.

Drug interaction

Diltiazem is a moderate CYP3A4 inhibitor and may increase plasma levels of drugs metabolized by this enzyme, such as simvastatin, lovastatin, and certain benzodiazepines. Concurrent use with beta-blockers or digoxin may potentiate bradycardia or AV conduction disturbances. Avoid combining with other vasodilators or antihypertensives without close monitoring due to additive hypotensive effects. Use caution with cyclosporine, carbamazepine, and lithium, as diltiazem may alter their concentrations. Always inform your prescriber of all medications, including over-the-counter drugs and supplements.

Missed dose

If a dose is missed, take it as soon as remembered unless it is nearly time for the next dose. Do not double the dose to catch up. For once-daily formulations, if missed and remembered the next day, skip the missed dose and resume the regular schedule. Consistent daily use is important for maintaining stable blood levels and therapeutic effect. Setting a daily reminder or using a pill organizer may help improve adherence.

Overdose

Overdose may lead to severe hypotension, bradycardia, heart block, and cardiac arrest. Symptoms can include dizziness, confusion, slurred speech, and profound weakness. In case of suspected overdose, seek emergency medical attention immediately. Treatment is supportive and may include intravenous fluids, vasopressors, atropine, cardiac pacing, or glucagon administration. Gastric lavage or activated charcoal may be considered if ingestion was recent. Hemodialysis is not effective due to high protein binding.

Storage

Store at room temperature (20–25°C or 68–77°F), away from light, moisture, and heat. Keep in the original container with the lid tightly closed. Do not store in bathrooms or damp areas. Keep out of reach of children and pets. Do not use beyond the expiration date printed on the packaging. Properly discard any unused or expired medication through a drug take-back program or as directed by a pharmacist.

Disclaimer

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or medication. Do not disregard professional medical advice or delay in seeking it because of something you have read here. Individual patient responses to medication may vary.

Reviews

Clinical studies and post-marketing surveillance consistently support Cardizem’s efficacy in blood pressure and angina management. Many patients report improved quality of life and reduced symptom frequency. Some note the convenience of once-daily dosing with extended-release formulations. A minority of users report side effects such as ankle swelling or dizziness, though these often resolve with dose adjustment. Overall, it remains a widely trusted option in cardiovascular pharmacotherapy with decades of clinical use supporting its role in evidence-based practice.