Diltiazem XC® Extended-Release Capsules

Diltiazem XC® is an extended-release form of diltiazem used to lower high blood pressure and help prevent chronic stable angina episodes. It provides steady 24-hour control in a once-daily capsule. With US delivery from Canada, many patients access consistent therapy alongside transparent Canadian pricing.

What Diltiazem XC® Is and How It Works

Diltiazem is a non-dihydropyridine calcium channel blocker. It relaxes blood vessel walls and slows electrical conduction through the atrioventricular node. The result is reduced vascular resistance, a lower heart rate under exertion, and decreased cardiac oxygen demand, which supports blood pressure control and helps reduce angina frequency. The XC modified-release system spreads absorption across the day to maintain a stable effect between doses.

CanadianInsulin connects patients with licensed Canadian pharmacies. Prescriptions are verified with your clinic before dispensing.

For those paying without insurance, extended-release diltiazem can be a predictable, once-daily option that may align with Canadian pricing compared with typical cash pay at local pharmacies. If exploring broader cardiovascular options, see our Hypertension Cardiovascular category.

Who Diltiazem XC® Is For

Diltiazem XC is used in adults for:

• Hypertension, to lower blood pressure as monotherapy or as part of a combination regimen.
• Chronic stable angina, to reduce episodes and improve exercise tolerance.

Use with caution or avoid in the following situations based on labeling and clinical guidance:

• Known hypersensitivity to diltiazem.
• Severe hypotension, cardiogenic shock, or acute decompensated heart failure.
• Sick sinus syndrome, second- or third-degree AV block without a functioning pacemaker.
• Advanced heart failure with reduced ejection fraction unless a specialist advises otherwise.
• Significant liver impairment, severe kidney impairment, or in older adults who may be more sensitive to heart rate and conduction effects.
• Pregnancy and lactation: discuss risks and alternatives; data are limited.

Diltiazem may be used alongside other agents when clinically indicated. Alternatives within the same class or related classes include options such as Nifedipine XR or beta blockers like Bisoprolol Zebeta and Acebutolol Sectral, selected according to individual goals and tolerability.

Dosage and Usage

Diltiazem XC is taken once daily. Swallow capsules whole with water; do not open, crush, or chew. It may be taken with or without food, but staying consistent with meals can help minimize variability. Clinicians typically start with a low to moderate dose and adjust at intervals based on blood pressure, angina symptoms, and heart rate response. Never change dose or switch between extended-release products without consulting the prescriber, as different technologies may not be interchangeable.

For reference, other modified-release versions exist, such as Diltiazem HCL CD. Your prescriber will indicate the exact product on the prescription so the dispensing pharmacy can match the release profile.

Strengths and Forms

Diltiazem XC is typically supplied as extended-release capsules in multiple strengths to support individualized titration, commonly including 120 mg, 180 mg, 240 mg, 300 mg, and 360 mg. Availability can vary by manufacturer and packaging configuration; the dispensing pharmacy will supply the prescribed strength where available.

Missed Dose and Timing

If a dose is missed, take it when remembered unless it is close to the time of the next scheduled dose. If it is almost time for the next dose, skip the missed capsule and resume the regular schedule. Do not double up. Taking the capsule at the same time each day can support steady blood levels and habit formation.

Storage and Travel Basics

Store at room temperature, away from excess heat and humidity, and keep the container tightly closed. Protect from moisture and avoid storing in bathrooms. For trips, keep capsules in the original labeled container in a carry-on bag. Avoid leaving medicines in hot cars or near windows. Bring enough supply for the full trip plus a small buffer, and carry a copy of the prescription or a recent clinic note if possible.

Benefits

• Once-daily, extended-release delivery that supports 24-hour blood pressure control.
• Helps reduce angina frequency and improve tolerance to physical activity.
• May allow combination therapy with other antihypertensives when needed.
• Non-dihydropyridine CCB mechanism that lowers heart rate response and cardiac workload.
• Multiple strengths to fine-tune the dose for efficacy and tolerability.

Side Effects and Safety

• Common: headache, dizziness, flushing, fatigue, nausea, constipation, or swelling in the ankles or feet.
• Cardiac effects: slower heart rate or palpitations, especially with higher doses or interacting medicines.
• Less common: rash or itching, gastrointestinal discomfort, or mild liver enzyme elevations.

Serious or rare risks can include significant bradycardia, hypotension, conduction abnormalities such as AV block, worsening heart failure in susceptible patients, severe skin reactions, or liver injury. Hypoglycemia is not a typical effect of diltiazem, but blood pressure that drops too low can cause lightheadedness or fainting. Seek urgent care for severe dizziness, fainting, chest pain that worsens, shortness of breath, or signs of an allergic reaction.

Drug Interactions and Cautions

Diltiazem is metabolized by CYP3A4 and can interact with medicines that affect this pathway. Important considerations include:

• CYP3A4 inhibitors or inducers: macrolide antibiotics such as clarithromycin, azole antifungals, HIV protease inhibitors, rifampin, carbamazepine, phenytoin, and others may alter diltiazem levels.
• Beta blockers: combining with agents such as propranolol or bisoprolol can increase the risk of bradycardia or AV block; specialist guidance may be needed.
• Digoxin: diltiazem can increase digoxin concentrations, warranting monitoring.
• Statins: simvastatin and lovastatin exposure may increase; prescribers often limit dose or choose alternative statins.
• Nitrates and other antihypertensives: additive blood pressure lowering can occur.
• Grapefruit or grapefruit juice: can increase diltiazem exposure; avoidance is commonly advised.

Alcohol can enhance blood pressure–lowering and dizziness. Always share a full medication and supplement list with the prescriber and pharmacy so they can screen for interactions.

What to Expect Over Time

Blood pressure response is gradual and depends on baseline readings, dose, other medicines, and diet and lifestyle patterns. Angina frequency may lessen as the dose is optimized. It can take several dose adjustments to balance benefits and tolerability. Regular follow-up, home blood pressure logs, and periodic heart rate checks help guide long-term therapy.

Compare With Alternatives

Other calcium channel blockers include dihydropyridines such as Nifedipine XR, often chosen when added arterial vasodilation is desired, and beta blockers such as Propranolol Hcl when heart rate control or post-MI indications are priorities. Release technologies differ among diltiazem products; some patients are maintained on Diltiazem HCL CD for similar once-daily convenience. Selection depends on clinical goals and individual response.

Pricing and Access

Canadian pharmacy pricing can offer meaningful savings compared with typical cash pay. Orders ship from Canada to the US with prompt, express, cold-chain shipping. Transparent checkout shows product, dispensing pharmacy, and final costs before you place an order. Checkout and customer data are protected by encrypted transfer.

If you are comparing options, browse our broader Heart Health Medications. You can also learn more about related therapies in our article Acebutolol Uses Benefits.

Availability and Substitutions

Availability of specific strengths can vary by manufacturer and by dispensing pharmacy. If a particular strength or release system is unavailable, a prescriber may recommend a therapeutically appropriate alternative or a different extended-release product with comparable daily dosing.

Patient Suitability and Cost-Saving Tips

• Good candidates include adults with hypertension or chronic stable angina who need once-daily therapy and who do not have significant conduction system disease.
• Patients who may not be candidates include those with severe bradycardia, advanced AV block without a pacemaker, or decompensated heart failure.
• Consider multi-month refills to reduce per-capsule costs and minimize pharmacy fees.
• If combined therapy is needed, discuss options like Acebutolol Sectral or Propranolol Hcl, chosen and supervised by your prescriber.
• Set refill reminders so you can order and store your next supply before running low, especially ahead of travel.

Questions to Ask Your Clinician

• What goal blood pressure range is appropriate for my health history?
• How should we monitor heart rate and adjust my dose over time?
• Is Diltiazem XC the right release system for me, or should I use a different brand technology such as CD?
• Which medicines or supplements should I avoid, and do I need lab or ECG monitoring?
• What should I do if I begin to notice ankle swelling, constipation, or dizziness?
• If I also have angina, when should I use a rescue medication such as nitroglycerin?
• Could an alternative like Nifedipine XR be better if I develop side effects?

Authoritative Sources

• DailyMed diltiazem extended-release label
• Health Canada Drug Product Database
• American Heart Association hypertension overview

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Disclaimer: This information is educational and not a substitute for professional medical advice. Always follow your clinician’s directions and the dispensing pharmacy’s label.