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Home > Drug Category > Blood Pressure Medications (Calcium & Beta Blockers) > Calan SR and Equivalent

Calan SR Information

Calan SR (verapamil hydrochloride) is a calcium channel blocker used to treat hypertension (high blood pressure), angina pectoris (chest pain), and certain heart rhythm disorders such as supraventricular tachycardia and atrial fibrillation. It works by blocking the entry of calcium into the muscle cells of the heart and blood vessels. This action leads to a relaxation of the blood vessels, which lowers blood pressure, and a slowing of the heart rate, which reduces the heart's workload and oxygen demand, thereby relieving angina. In heart rhythm disorders, verapamil helps regulate the heart's electrical activity, restoring a more normal rhythm. Calan SR is a sustained-release formulation designed to release the medication gradually over an extended period, allowing for less frequent dosing, typically once or twice daily. Calcium channel blockers like verapamil exert their effects by binding to voltage-gated calcium channels, which are crucial for the contraction of cardiac and smooth muscle cells. By blocking these channels, verapamil reduces the force of heart muscle contraction, slows the rate at which electrical impulses are conducted through the heart, and dilates arteries. These combined effects make it effective in managing various cardiovascular conditions.

Calan SR Side Effects

Common side effects of Calan SR may include constipation, dizziness, headache, fatigue, nausea, and swelling of the ankles or feet. These side effects are usually mild and may decrease as your body gets used to the medication. Call your doctor immediately if you experience any serious side effects, such as:
• Allergic reactions (rash, hives, itching, swelling of the face, lips, tongue, or throat, difficulty breathing)
• Blurred vision
• Chest pain
• Confusion
• Fainting or lightheadedness
• Irregular or slow heartbeat
• Low blood pressure (hypotension)
• Palpitations (fast or pounding heartbeat)
• Severe dizziness
• Shortness of breath or difficulty breathing
• Significant swelling in the legs or ankles
• Symptoms of liver problems (such as persistent nausea or vomiting, severe stomach pain, yellowing of the skin or eyes, dark urine, pale stools)
• Unusual tiredness or weakness

Calan SR Precautions

Do not use Calan SR if you are allergic to verapamil or its ingredients. Also, do not use this medication if you have certain serious heart conditions, including severe left ventricular dysfunction, sick sinus syndrome or second- or third-degree AV block (unless you have a functioning pacemaker), or if you are in cardiogenic shock. Before taking Calan SR, inform your doctor about your complete medical history, particularly if you have heart failure, kidney disease, liver disease, certain heart rhythm disorders of the atrium with a coexisting accessory AV pathway (e.g., Wolff-Parkinson-White or Lown-Ganong-Levine syndromes), low blood pressure, or a neuromuscular disease such as Duchenne's muscular dystrophy or myasthenia gravis. Tell your doctor if you are pregnant or planning to become pregnant, or if you are breastfeeding or planning to breastfeed. Verapamil can pass into breast milk, and its effects on a nursing infant are not fully known. It is essential to discuss the risks and benefits with your doctor. Inform your doctor about all the medications you are currently taking, including prescription drugs, over-the-counter medications, vitamins, and herbal supplements, as Calan SR can interact with other medicines. Significant interactions can occur with other heart medications (such as digoxin, beta-blockers, amiodarone, and antiarrhythmics), certain antibiotics (like erythromycin and clarithromycin), antifungals (like ketoconazole and itraconazole), cimetidine, lithium, muscle relaxants, certain cholesterol-lowering drugs (statins, including lovastatin and simvastatin), rifampin, theophylline, and cyclosporine. Grapefruit juice can also interact with verapamil, increasing its levels in the blood and potentially increasing side effects; avoid consuming large amounts of grapefruit juice while taking Calan SR. Avoid drinking alcohol, as it may lower your blood pressure. If you are scheduled for any surgery, including dental procedures, inform your healthcare provider that you are taking Calan SR.

Take Calan SR exactly as your doctor prescribed. The sustained-release tablets are usually taken once or twice daily. Swallow the tablets whole and do not crush, chew, or break them. The dosage will depend on your condition and how you respond to the treatment. You can take Calan SR with or without food, but it is essential to be consistent with how you take it daily. Take Calan SR at the same time(s) every day to help you remember. Your doctor may need to adjust your dose over time to achieve the best results. Continue taking Calan SR as your doctor directs, even if you feel better. It is part of a comprehensive treatment plan for your condition, which may also include lifestyle modifications such as diet and exercise. Regular follow-up appointments with your doctor are essential to monitor your progress and adjust your treatment. Store Calan SR at room temperature, away from moisture and heat. Keep all medications safely out of the reach of children.

Do I need a prescription to order Calan SR?

Yes, a prescription is required from your physician to order Calan SR.