Calan is used for treating supraventricular tachycardia, a rhythm disturbance of the heart. It is also used for controlling heart rate response to other rhythm disturbances, specifically atrial fibrillation and atrial flutter. Calan is a calcium channel blocker. It works by slowing the electrical conduction in the heart, slowing heart rate, and/or normalizing heart rhythm.
Use Calan as directed by your doctor.
- Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
- Your doctor may occasionally change your dose to make sure you get the best results.
- Do not crush, chew, break, or open Calan. Swallow it whole. Breaking or opening the pill may cause too much of the drug to be released at one time.
- Do not stop taking this medication without first talking to your doctor. If you stop taking Calan suddenly, your condition may become worse.
- If you miss a dose of Calan, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.
Ask your health care provider any questions you may have about how to use Calan.
Store Calan at room temperature, between 68 and 77 degrees F (20 and 25 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep Calan out of the reach of children and away from pets.
Active Ingredient: Verapamil hydrochloride.
Do NOT use Calan if:
- you are allergic to any ingredient in Calan
- you have certain heart problems (eg, left ventricular dysfunction, sick sinus syndrome, second- or third-degree heart block and do not have a pacemaker), very low blood pressure, or moderate to severe congestive heart failure (CHF)
- you have atrial fibrillation or flutter and a pre-excitation syndrome (extra conduction pathway in the heart), such as Wolff-Parkinson-White (WPW) syndrome or Lown-Ganong-Levine (LGL) syndrome
- you have shock due to serious heart problems
- you are taking dofetilide, or you have taken disopyramide within the past 48 hours.
Contact your doctor or health care provider right away if any of these apply to you.
Some medical conditions may interact with Calan. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you have heart failure or a recent heart attack with lung congestion, low blood pressure, or heart problems (eg, a very slow heart rate, heart block, heart valve disease)
- if you have kidney or liver problems, muscular dystrophy, or a neuromuscular disease
- if you are taking another blood pressure medicine or you are being treated for cancer.
Some medicines may interact with Calan. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Beta-blockers (eg, propranolol), clonidine, disopyramide, ketolides (eg, telithromycin), macrolides (eg, erythromycin), or ritonavir because they may increase the risk of Calan’s side effects
- Phenobarbital, rifampin, or St. John’s wort because they may decrease Calan’s effectiveness
- Aldosterone blockers (eg, eplerenone), aspirin, carbamazepine, colchicine, cyclosporine, digoxin, dofetilide, doxorubicin, dronedarone, eletriptan, erythromycin, everolimus, flecainide, HMG-CoA reductase inhibitors (eg, lovastatin, simvastatin), lithium, narcotic pain relievers (eg, fentanyl), paclitaxel, quinazolines (eg, terazosin), quinidine, ranolazine, theophyllines, or tolvaptan because the risk of their side effects may be increased by Calan.
This may not be a complete list of all interactions that may occur. Ask your health care provider if Calan may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.