Cardizem SR (Diltiazem SR)

Description

Cardizem SR is a brand name for a medicine called Diltiazem, which works as a calcium channel blocker. It helps relax the heart muscles and blood vessels, making it easier for the heart to pump blood and lowering blood pressure. It is mainly used to treat high blood pressure and chest pain (angina). Cardizem SR comes in a special formulation that releases the medicine slowly over time. It is meant for adults and should always be prescribed by a doctor.

Directions

Cardizem SR is taken by mouth once per day in the morning. The typical maintenance dosage ranges from 120 to 360 mg per day, divided into two equal doses. This dosage may be adjusted based on a person’s response to the medication. It is important to swallow the capsules whole and not crush, chew, or split them, as this can affect how the medication is released and absorbed in the body. Cardizem SR can be taken with or without food, but maintaining consistency in the timing of the dose helps keep steady drug levels in the bloodstream.

Ingredients

The active ingredient in Cardizem SR is Diltiazem.

Contraindications

Avoid taking or using this medication if any of the following apply:

• Known hypersensitivity to Diltiazem or any of the components in the product
• Acute myocardial infarction and pulmonary congestion documented by X-ray on admission
• Pregnancy
• Second or third-degree AV block (except in patients with a functioning ventricular pacemaker)
• Sick sinus syndrome (except in patients with a functioning ventricular pacemaker)
• Hypotension (systolic blood pressure less than 90 mm Hg)

Cautions

• Before taking Cardizem SR, you may want to consult a healthcare provider about the following:
• Any existing health conditions
• Any allergies
• A list of all medications you are currently taking
• Whether you are pregnant or breastfeeding

• Cardizem SR can affect how electrical signals travel through your heart, especially in people with existing heart rhythm problems. It may cause your heart to beat too slowly or lead to more serious rhythm issues like heart block. The risk is higher if you're also taking other medications that affect the heart, such as beta-blockers, digoxin, or amiodarone. Your doctor may monitor your heart with tests like an ECG, especially when starting or adjusting the dose.
• Cardizem can weaken the heart’s ability to pump blood, so it should be used carefully in people with heart failure. If you have reduced heart function and are also on beta-blockers, this combination should only be used with close medical supervision.
• Because Cardizem lowers blood pressure, it may sometimes cause it to drop too low, especially if you're already on other medications for high blood pressure or heart problems. Let your doctor know if you feel dizzy, lightheaded, or faint.
• Cardizem is processed by the liver and eliminated through the kidneys and bile. If you have liver or kidney problems, your doctor may adjust your dose and will likely monitor blood tests to check your organ function during treatment.
• Some people may develop rashes or other skin problems while taking Cardizem. These reactions are usually mild and go away on their own, but in rare cases, they can be serious. Let your doctor know if you develop a rash that doesn’t improve.
• If you’re also taking a beta-blocker, it’s important not to stop it suddenly while on Cardizem. Doing so can cause heart-related problems. Your doctor will help you taper off slowly if needed.
• In rare cases, Cardizem has been linked to signs of liver injury, like elevated liver enzymes or jaundice (yellowing of the skin or eyes). These issues usually go away after stopping the medication. Let your doctor know if you experience symptoms like fatigue, dark urine, or abdominal pain.
• People over 65 may be more likely to experience side effects such as slow heart rate, swelling, or dizziness. Your doctor may start you on a lower dose and monitor your response closely.
• Cardizem may pass into breast milk. Because safety in infants hasn’t been established, it’s generally not recommended while breastfeeding.
• Cardizem is broken down in the body by liver enzymes and may affect how other medications are processed. This includes drugs for anxiety, epilepsy, blood pressure, cholesterol, and blood thinning. Always tell your doctor about all medications you take, including over-the-counter drugs and supplements.
• Cardizem may cause dizziness, especially when standing up quickly. It can also affect blood sugar levels, so people with diabetes should monitor their blood glucose regularly when starting or adjusting this medication.

Side Effects

The most common side effects of Cardizem SR include headache, dizziness, swelling (edema), fatigue, and nausea. Some patients may also experience rash, constipation, or flushing. In clinical trials, adverse effects led to treatment discontinuation in about 7% of patients. Most reactions were mild to moderate and occurred more frequently with sustained-release forms of the drug.

Less common but potentially serious effects include bradycardia, first-degree AV block, and worsening heart failure. Rare reactions such as elevated liver enzymes, allergic skin reactions, or blood disorders (e.g., leukopenia, thrombocytopenia) have also been reported. Postmarketing experience has included rare events like angioedema, sinus arrest, and hepatitis. If you notice unusual symptoms such as chest pain, difficulty breathing, severe skin reactions, or mood changes, contact your healthcare provider right away.

References

1. Cardizem SR (Diltiazem SR) Product Monograph. Toronto, Ontario: Apotex, Inc.; 2018.
2. Cardizem SR (Diltiazem SR) Drug Label Information. Steinbach, MB: Bausch Health Companies Inc.; 2019.

About Dr. Gerardo Sison (Page Author)

An honors graduate of the University of Florida, Dr. Sison started his pharmacy career in a community setting, extending his services to hospitals and clinics over time. He has also worked in medication therapy management, advising patients on proper medication use for their chronic health conditions. Read More....