Izopamil - Use | Dosage | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on Thu, 27 Dec 2018. To read more about an author, click here.

Izopamil is a medicine that contains an active substance called verapamil. It is a drug that belongs to a group of medicines called calcium channel blockers. This medicine works by reducing the amount of calcium that goes into smooth muscle cells, which cause smooth muscle cells to relax. The result of these effects is reducing your heart's need for oxygen, facilitating blood flow through the blood vessels and slowing down your heart rate. Because all of these effects, it is used to treat high blood pressure, angina and tachycardia (rapid heartbeat).


It cannot be used or can be used only with great caution in the following conditions:

  • Atrioventricular block (AV block) I, II or III level. Izopamil can further slow heartbeat in these patients and cause cardiac arrest.
  • Patients who have ever had cardiogenic shock!
  • In patients with slow heart rate (bradycardia)
  • Hypotension (low blood pressure)
  • It can be used only with great caution in patients with liver disorders. This drug is excreted by the liver and patients with liver disorders can use Izopamil only in a low dose.
  • Patients with myasthenia gravis (muscle disorder).
  • It cannot be used in patients with heart failure
  • Izopamil can be used only with great caution in patients with kidney disorders
  • In patients with Wolff-Parkinson-White syndrome
  • It cannot be used in patients with pacemaker

It cannot be used concomitant with drugs called beta blockers, used to treat high blood pressure, such as:

  • propranolol,
  • bisoprolol,
  • metoprolol,
  • nebivolol,
  • atenolol (Prinorm) and others. Beta blockers can slow the heart rate so as Izopamil, therefore the combination of these drugs can lead to cardiac arrest!

Do not get up too quickly from a seated or lying position, because it orthostatic hypotension may occur. Orthostatic hypotension is characterized by a sudden fall in blood pressure when you get up too quickly from a seated or lying position, which cause dizziness and feeling lightheadedness. If patient has fainted, you should place him on the bed and raise his arms and legs. If fainting occur, contact your doctor immediately.

Izopamil cannot be used concomitant with grapefruit or grapefruit juice, because this fruit can increase the effect of this drug and cause side effects.

Izopamil also cannot be used concomitant with the alcoholic beverages, because alcohol may increase the effect of this medicament and cause side effects.

If you experience a slow heart rate (bradycardia), immediately contact your doctor!

Use during pregnancy and breastfeeding

According to the US Agency for Food and Drug Administration, Izopamil belongs to the group C (FDA: Group C). This means that animal studies have shown that it is harmful to the fetus, but there are no studies in humans! It can be used during pregnancy only if the benefit to the mother outweighs the risk to the child.

Izopamil passes into breast milk and may harm your baby. Avoid breastfeeding your baby while using Izopamil.

How to use

Condition (Indication) Dose
High blood pressure (hypertension) Izopamil 40-120 mg, 3-4 times a day
Prinzmetal angina pectoris Izopamil 120 mg, 3 times per day
Tachycardia (rapid heartbeat) 40-120 mg, 3-4 times a day

Dose should not exceed 480 mg per day!

Dose of Izopamil pills need to be reduced in patients older than 65 years of age as well as in the patients with liver disorders.

It must to be taken with food or after meals, with a little water (150ml). Swallow the tablet whole. Do not crush or chew the tablet, because it may reduce the effect of Izopamil.

As we have already mentioned, it cannot be used concomitant with grapefruit or alcoholic beverages because these foods increase the effect of Izopamil tablets.

Get up slowly from the seated or a lying position. If you feel lightheaded or dizzy, do not drive a car while using Izopamil.


Symptoms of an overdose include:

  1. dizziness,
  2. headache,
  3. flushing,
  4. drowsiness and bradycardia (slow heart rate).

Treatment of Izopamil overdose include the use of calcium gluconate 10% (20 ml of infusion). Bradycardia should be treated with atropine. Contact your doctor immediately if you have taken more tablets than your doctor recommended.

Use with other medicines (Interactions)

Izopamil cannot be used concomitant with the following medications:

  • Beta-blockers such as:
    • bisoprolol,
    • propranolol,
    • nebivolol,
    • metoprolol,
    • atenolol (Prinorm) and others. Concomitant use of these drugs with Izopamil can slow your heart rate and cause heart failure.
  • It increases the effect of colchicine tablets used to treat gout, therefore these medicines should not be used simultaneously.
  • Izopamil increases the effect of medicines used to treat high cholesterol (so-called statins) such as:
    • rosuvastatin,
    • simvastatin (Cholipam),
    • fluvastatin,
    • lovastatin,
    • atorvastatin and others.
  • Antibiotics, such as:
    • erythromycin,
    • clarithromycin,
    • telithromycin,
    • itraconazole,
    • ketoconazole and others. These medicines increase the effect of Izopamil and can cause side effects.
  • Medicines used in the treatment of AIDS (HIV) such as:
    • saquinavir,
    • ritonavir,
    • indinavir,
    • efavirenz,
    • lopinavir and others.
  • Drugs used in the treatment of heart failure such as:
    • digoxin,
    • digitoxin.
  • Medicines used to treat tuberculosis, such as:
    • isoniazid,
    • rifampicin.
  • Medicines used to treat epilepsy such as:
    • carbamazepine,
    • phenytoin,
    • phenobarbital.
  • Other calcium channel blockers such as:
    • diltiazem,
    • nifedipine,
    • felodipine,
    • nimodipine,
    • nicardipine,
    • amlodipine and others.
  • St. John's Wort.

Side effects

Izopamil may cause the following side effects:

  1. dizziness,
  2. fainting,
  3. headache,
  4. flushing,
  5. tremor (shaking),
  6. slow heart rate (bradycardia),
  7. low blood pressure (hypotension),
  8. nausea,
  9. vomiting,
  10. constipation,
  11. Stevens-Johnson syndrome (a life threatening skin disorders),
  12. breast enlargement in men (gynecomastia),
  13. mood changes,
  14. flu-like symptoms (sore throat, cough),
  15. allergy and others.

Tell your doctor if you experience any of abovementioned side effects.

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.