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  • Generic Name: (verapamil hydrochloride)
    Other Brands: Calan
  • Last Revised: 10/2013
    • What is this medication and its most common uses?

      Calan is in a class of medicines known as a calcium channel blockers and is used to treat angina (chest pain), arrhythmias (life-threatening irregular heartbeat), and high blood pressure.

    • What should I know when beginning and continuing on this medication?

      How does this medication work?

      Calan lowers blood pressure by relaxing your blood vessels, which allows your blood to flow through with less resistance. Calan helps to reduce chest pain by increasing the supply of oxygen delivered to your heart and reducing the workload of your heart. Calan also helps control heart rate by slowing down the heart's electrical activity.

      What are the beneficial effects of this medication and when should I begin to have results?


      High Blood Pressure: By lowering your blood pressure, Calan may lower your risk of a stroke or a heart attack.

      Chest Pain: Calan may help manage your symptoms of chest pain.

      Irregular Heartbeat: Calan may help your heart beat normally.


      High Blood Pressure: Calan may lower your blood pressure within 1 week.

      Irregular Heartbeat: Calan may start controlling your irregular heartbeat within 2 days.

      Though you may not feel an improvement or change in the way you feel, it is very important to keep taking your medicine as prescribed to keep your condition under control.

      How do I know it is working?

      Check your blood pressure regularly. Your healthcare provider may also check your blood pressure, heart rate, and your symptoms at every visit. Your healthcare provider may order tests to check how well this medication is working. Following an appropriate diet and exercise plan will also affect your blood pressure results.

    • What are the possible side effects of this medication?

      The following is not a full list of side effects. Side effects cannot be anticipated. If any develop or change in intensity, tell your healthcare provider as soon as possible. Only your healthcare provider can determine if it is safe for you to continue taking this medication.

      More common side effects may include: constipation, dizziness.

      Less common side effects may include:

      Risk of having a very slow heart rate, congestive heart failure (a condition in which your heart cannot pump enough blood throughout your body), low blood pressure, or liver injury.

    • Who should not take this medication?

      Do not take Calan if you are allergic to it or any of its ingredients.

      Do not take Calan if you have severe left ventricular dysfunction (impairment of a section of your heart that is responsible for pumping blood to the rest of your body).

      Do not take Calan if you have low blood pressure.

      Do not take Calan if you have sick sinus syndrome (abnormal heart rhythm) or a heart block, unless you have a pacemaker.

      Do not take Calan if you have atrial fibrillation or flutter (an irregular, fast heartbeat) and certain heart conduction problems (such as Wolff-Parkinson-White or Lown-Ganong-Levine syndrome).

    • What should I tell my healthcare provider before I take the first dose of this medication?

      Tell your healthcare provider about all prescription, over-the-counter, and herbal medications you are taking before beginning treatment with Calan. Also, talk to your healthcare provider about your complete medical history, especially if you have heart problems (such as heart failure or abnormal heart rhythms); kidney or liver disease; low blood pressure; certain conditions that cause muscle weakness (such as myasthenia gravis or Duchenne's muscular dystrophy); or if you are pregnant, plan to become pregnant, or are breastfeeding.

      Also, talk to your healthcare provider about any planned surgeries or procedures.

    • What is the usual dosage?

      The information below is based on the dosage guidelines your healthcare provider uses. Depending on your condition and medical history, your healthcare provider may prescribe a different regimen. Do not change the dosage or stop taking your medication without your healthcare provider's approval.

      Chest Pain

      Adults: The usual starting dose is 80-120 milligrams (mg) three times a day.

      Irregular Heartbeat

      Adults: The recommended dose is 240-480 mg three or four times a day. Your healthcare provider will prescribe the appropriate dose for you based on your condition.

      High Blood Pressure

      Adults: The usual starting dose is 80 mg three times a day.

      Your healthcare provider may increase your dose as needed, until the desired effect is achieved.

      If you are elderly or have small stature or liver impairment, your healthcare provider may adjust your dose appropriately.

    • How should I take this medication?

      Take Calan exactly as prescribed by your healthcare provider.

    • What should I avoid while taking this medication?

      Do not change your dose or stop taking Calan without first talking to your healthcare provider.

    • What are the possible food and drug interactions associated with this medication?

      If Calan is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your healthcare provider before combining Calan with the following: alcohol, aspirin, blood pressure/heart medications (such as furosemide, prazosin, or atenolol), carbamazepine, cholesterol-lowering medications known as statins (such as lovastatin or simvastatin), cimetidine, clonidine, cyclosporine, digoxin, disopyramide, erythromycin, flecainide, grapefruit juice, lithium, phenobarbital, quinidine, rifampin, ritonavir, telithromycin, or theophylline.

    • May I receive this medication if I am pregnant or breastfeeding?

      The effects of Calan during pregnancy are unknown. Calan can be found in your breast milk if you take it while breastfeeding. Do not breastfeed while you are taking Calan. Tell your healthcare provider immediately if you are pregnant, plan to become pregnant, or are breastfeeding.

    • What should I do if I miss a dose of this medication?

      If you miss a dose of Calan, take it as soon as you remember. However, if it is almost time for your next dose, skip the one you missed and return to your regular dosing schedule. Do not take two doses at once.

    • How should I store this medication?

      Store at room temperature. Protect from light.

    • Who should I contact in case of emergency or overdose?
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      In the event of a medical emergency call your doctor or 9-1-1 immediately. In the event of overdose, call your doctor or poison control for further instructions.
      National Poison Control#: Call 1-800-222-1222

      This PDR+ drug information has been developed by the Physicians’ Desk Reference Network (PDRN), a source of medication information trusted by doctors for over 65 years.

      This monograph summarizes the most important information about your medication and does not cover all the information you may need. If you have any questions or concerns or want to learn more about your medication, ask your healthcare provider; he/she will be able to provide answers to your questions. This medication should only be used by the patient for whom it was prescribed and should not be shared with other people.
    • Additional patient resources.
      back to top Use your PDR® Pharmacy Discount Card when you or a family member fills a prescription and ask for your PDR® Discount every
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