What Is Cartia XR?

Cartia XR is a brand name for Diltiazem Hydrochloride Extended-Release, a prescription medication used to treat high blood pressure (hypertension) and chronic stable angina (chest pain) in adults. It belongs to the calcium channel blocker drug class and is taken once daily as an extended-release capsule.

By lowering blood pressure, Cartia XR helps reduce the risk of heart attack, stroke, and kidney problems. For patients with angina, it helps reduce the frequency and severity of chest pain episodes by improving blood flow to the heart.

Cartia XR is also sold under other brand names including Cardizem CD, Tiazac, and Matzim LA. The generic form, Diltiazem ER, is widely available and typically much more affordable.

How does Cartia XR work?

Cartia XR works by blocking calcium from entering the muscle cells of the heart and blood vessel walls. As a non-dihydropyridine calcium channel blocker, it has two key effects:

• Relaxes blood vessels — By preventing calcium from tightening arterial walls, Cartia XR widens blood vessels, reducing the resistance the heart must pump against and lowering blood pressure.
• Slows heart rate — Diltiazem reduces the electrical activity in the heart's conduction system, causing the heart to beat more slowly and with less force. This decreases the heart's demand for oxygen.

These combined effects make Cartia XR effective for both hypertension and angina. The extended-release formulation releases the medication gradually over 24 hours, allowing for convenient once-daily dosing.

What doses are available for Cartia XR?

Cartia XR (Diltiazem ER) is available in the following extended-release capsule strengths:

• 120 mg — Common starting dose for hypertension
• 180 mg — Frequently prescribed maintenance dose
• 240 mg — Standard dose for blood pressure and angina control
• 300 mg — Higher dose for patients requiring additional blood pressure reduction

All doses are designed to be taken once daily. Do not crush or chew the extended-release capsules.

How hard is it to find Cartia XR in stock?

Cartia XR, also known as generic Diltiazem ER, is generally easy to find at most pharmacies. The brand-name Cartia XT has been discontinued by some manufacturers, but generic diltiazem extended-release capsules (coated beads formulation) are widely stocked and therapeutically equivalent. There is no current FDA drug shortage listed for diltiazem ER. Occasional supply hiccups may occur at individual pharmacies, but alternative generic versions from multiple manufacturers are readily available.

Who Can Prescribe Cartia XR?

Cartia XR can be prescribed by a variety of healthcare providers, including:

• Primary care physicians — Often the first to diagnose and treat high blood pressure
• Cardiologists — Specialists who manage heart conditions and complex blood pressure cases
• Internal medicine doctors — Treat adults with chronic conditions including hypertension
• Nurse practitioners (NPs) — Licensed to prescribe in all 50 states
• Physician assistants (PAs) — Can prescribe under physician supervision or independently depending on the state

If you need help finding a prescriber, Medfinder can help connect you with providers in your area.

Is Cartia XR a controlled substance?

No, Cartia XR is not a controlled substance. It is not classified under any DEA schedule and does not carry a risk of abuse or dependence. Cartia XR is a standard prescription medication — you will need a prescription from a licensed healthcare provider, but there are no special restrictions on refills or how it can be prescribed.

Common Side Effects of Cartia XR

Most people tolerate Cartia XR well, but some side effects may occur:

• Peripheral edema — Swelling in the feet, ankles, or hands, especially early in treatment
• Headache — Usually mild and improves over time
• Dizziness — Particularly when standing up quickly
• Slow heart rate (bradycardia) — A known effect of non-dihydropyridine calcium channel blockers
• Nausea or upset stomach
• Flushing — A warm feeling or redness of the skin
• Fatigue or weakness
• Stuffy nose or sore throat
• Rash

Serious but rare side effects include severe dizziness, fainting, very slow heartbeat, or signs of liver problems (yellowing skin, dark urine). Contact your doctor immediately if you experience any of these. For a complete list of side effects, consult your pharmacist or visit Medfinder.

Alternative Medications to Cartia XR

If Cartia XR isn't available or isn't the right fit, several alternatives may be considered:

• Amlodipine (Norvasc) — A dihydropyridine calcium channel blocker widely used for hypertension; does not slow heart rate like Diltiazem
• Verapamil ER (Calan SR) — Another non-dihydropyridine calcium channel blocker with similar effects on heart rate and blood pressure
• Nifedipine ER (Procardia XL) — Extended-release calcium channel blocker primarily used for blood pressure
• Lisinopril — An ACE inhibitor, a different class of blood pressure medication that is very affordable and widely available
• Losartan (Cozaar) — An ARB (angiotensin receptor blocker) often used when ACE inhibitors cause side effects
• Metoprolol ER (Toprol-XL) — A beta-blocker that also controls heart rate; should not be combined with Diltiazem without careful medical supervision

Always consult your healthcare provider before switching medications.

Drug Interactions with Cartia XR

Diltiazem can interact with several medications. Tell your doctor about all drugs you are taking, including:

• Beta-blockers (Metoprolol, Atenolol, Propranolol) — Combining with Diltiazem increases the risk of dangerously slow heart rate and low blood pressure
• Carbamazepine — Diltiazem can raise carbamazepine levels by 40–72%, potentially causing toxicity
• Statins (Simvastatin, Lovastatin) — Diltiazem increases statin levels, raising the risk of muscle damage (rhabdomyolysis)
• Cyclosporine — Diltiazem increases cyclosporine blood levels, requiring dose monitoring
• Digoxin — May increase digoxin levels and the risk of side effects
• CYP3A4-metabolized drugs — Diltiazem inhibits the CYP3A4 enzyme, which can increase blood levels of many medications

This is not a complete list. Always inform your healthcare provider and pharmacist about all prescription, over-the-counter, and herbal products you take.

Final Thoughts on Cartia XR

Cartia XR (Diltiazem ER) is a well-established, effective medication for managing high blood pressure and angina. While the brand-name Cartia XT may be harder to find at some pharmacies, the generic form — Diltiazem ER — is widely available, affordable, and therapeutically equivalent. With discount cards from services like GoodRx or SingleCare, cash prices can be as low as $6 to $10 for a 30-day supply.

If you're having trouble locating Cartia XR or Diltiazem ER at your local pharmacy, Medfinder can help you find pharmacies near you that have it in stock. Don't hesitate to ask your pharmacist about generic alternatives or different manufacturers if one version is temporarily unavailable.