Verapamil (Intravenous)

Verapamil is sold under many different names and it is used to treat a variety of conditions.

Overview

Verapamil blocks calcium channels. It is a first generation calcium channel blocker. The molecular formula is C27H38N2O4. This makes it classify as a hydrochloride. It is water soluble.

Verapamil is a hydrochloride. It works by relaxing the heart muscles and arteries. Its uses include control of the heart rate in patients with supraventricular tachycardia. Verapamil is also prescribed to prevent migraine headaches. The price range varies. In developing countries it costs from 2 to 5 dollars. A monthly dose in the United States costs from 25 to 50. Other uses include cluster heaches and for cerebral vasospasm.

The muscle action and heart rate is reduced when the calcium uptake is blocked. The smooth muscle lining of the heart nodes help to control calcium uptake. These are affected and are used to lower the frequency of impulse. The ventricles of the heart then are less likely to have increased spasms and heart rates.

The smooth muscles that line the heart absorb calcium. By relaxing these muscles, the blood vessels are dialated. The pain in angina is caused by lack of oxygen, so it facilitates oxygen flow and absorption.

Lowering the blood pressure has different uses and applications. For example, lowering the blood pressure can reduce the risk of stroke. It also affects the kidneys and works to heal the kidneys because of the lowered blood pressure and increased blood flow.

By lowering the risk of angina, it increases the ability for you to exercise and reduces the frequency of angina. Verapamil lowers the rate of atrial fibrillation and helps you to regulate your heart rate. When the heart rate is reduced, it makes exercise easier and reduces the frequency of angina. It affects the movement of calcium to the cells of the heart.

The muscles relax and the blood flow is relaxed. It reduces the strain on the heart. This flow makes the blood supply increase as well as the oxygen supply to the heart.Verapamil works when used regularly. However, Verapamil doesn't stop chest pain when it's already occurring. Another more powerful vasodialator might be needed once pain starts. Another use for Verapamil is for mania as a weaker alternative to lithium.

When it is combined with magnesium oxide it is useful for mania, and it is used in pregnant women. Verapamil has veterinary uses as well. Rabbits commonly develop intraabdominal adhesions after surgery. This drug given post operatively helps prevent adhesions from forming in abdominal organs.

Condition(s) treated?

Conditions that verapamil treats includes:

  • heart conditions like arrhythmia
  • hypertension (also known as high blood pressure)
  • angina (chest pain)
  • cerebral vasopasm
  • heart rhythm disorders
  • being tested for use in diabetes.
  • mania

Type of medicine

  • Verapamil is a class-IV antiarrhythmic

Side Effects

The most common side effect from Verapamil is constipation. About 7% of patients reported encountering this side effect. Another side effect is dizziness. Other related side effects are nausea. One of the less common side effect is edema, or swelling.

Congestive heart failure is also listed as a potential side effect. In particular, pulmonary edema is another potential side effect. Some patients might experience fatigue. Some patients display elevated liver enzymes. Another side effect is shortness of breath. Other patients might experience hypotension, which is blood pressure that is so low that it causes fatigue or other effects. It's shown to effect the liver enzymes and cautioned against use in patients with liver disease or cirrhosis.

Some patients might display low heart rate. Another side effect is atrioventricular block. Patients might display rash and flushing. Another potential side effect is sleep disturbance. Other patients might experience ankle swelling. Also, a possible side effect is myalgia and dyspepsia.

Effects to the gastrointestinal system include diarrhea, dry mouth, gastrointestinal distress and gingival hyperplasia. Cardiovascular effects include angina pectoris, atrioventricular dissociation, caludication, myocardial infarction, palpitations, vasculitis and syncope.

Effects on the lymphatic system include bruising.

There are also documented side effects to the nervous system.These include confusion, extrapyramidal symptoms, cerebrovascular accident, psychotic symptoms, shakiness, somnolence, muscle cramps, equilibrium disorders and muscle cramps. There is a possibility for cardiac arrest.

There are indications that Verapamil can effect the immune system. Different infections are reported as well as influenza. Certain patients have jaundice symptoms.

Effects on the respiratory system include labored breathing and dyspnea. Skin side effects include arthralgia, hair loss, exanthema, hyperkeratosis, sweating, maculae, urticaria, Stevens-Johnson syndrome and erthema multiforme. Another reported side effect is vertigo.

Some effects are noted on the extra senses. These include blurred vision and tinnitus. Different complications seeing have been reported.Another possible side effect is muscle weakness, discomfort, distress and sinus arrest. Some patients might report feeling coldness.

Finally, there are urogenital effects. These include gynecomastia, impotence, increased urination and spotty menstruation.

Adverse cardiovascular reactions that require therapy are rare. Because of this, experience with their treatment is limited. When complete AV block occurs or severe hypotension following oral administration of verapamil, there are emergency procedures that have to be applied immediately.The appropriate emergency application is intravenously administered isoproterenol HCI, atropine, levarteronol bitartrate, or calcium gluconate.

When patients have hypertrophic cardiomyopathy, certain alpha-adrenergic agents like metaraminol bitartrate, phenylephrine or methoxamine. This helps to maintain blood pressure. If more support is needed, inotropic agents like dobutamine or dopamine might be administered. Depending on the situation, different treatments and dosages might be required. It depends on the experience and judgment of the attending physician.

Dosage

Doctors originally start patients off on a very low dosage and are monitored. Different patients are administered different dosages depending on a variety of factors. For chest pain, the typical dosage for adults is 80 to 120 milligrams (mg) three times a day.  Children's dosage will be modified. For the oral dosage form of extended-release tablets that work over a period of 24 hours. This is one 180 milligram tablet administered at bedtime.

For heart rhythm problems, adults receive 240 to 480 milligrams  administered three or four times a day. The dosage for high blood pressure is 80 milligrams three or four times a day. The extended release capsules are recommended at a one time dosage of 200 milligrams at bedtime. The extended release tablets dosage for adults is recommended at 180 milligrams.

The 24 extended release tablets start at 180 milligrams once daily at bedtime. The maximum dosage for the extended release capsules is 400 mg a day. The maximum dose is 480 mg a day for the extended release tablets. The immediate release tables are administed in 80 mg tablets or 40 mg tablets 3 times a day. The smaller doses are recommended for people who respond to lower doses such as the elderly or people of smaller stature. The maximum dose is 480 mgs a day.

Daily dosages of 360 or 480 have been documented but there is no evidence that shows these high dosages have any additional effect. When assessing whether or not to upwardly titrate it should be assessed weekly and immediately assessed about 24 hours after the initial dose.If the desired effects are not obtained with the initial dose, it is possible to titrate upwards If you miss a dose, it is recommended to take it as soon as you remember unless it is almost time for your next dose.

The usual dosage for angina pectoris is 180 mg orally once a day and can be titrated upwards to 480 mg. Then, skip the missed dose and continue regularly taking the medication. Do not double dose.

Intravenous dosage for Supraventricular Tachycardia

Initial dose for this condition is 5 to 10 mg (0.075 to 0.15 mg/kg) IV bolus over at least 2 minutes. Precautions are that this medication should be administered over 2 minutes with continuous EKG and blood pressure monitoring.

Interactions

Over 700 medications are known to interact with Verapamil. These include drugs like aspirin and drugs that effect liver enzymes. Inhibitors of CYP3A4 (such as erythromycin and ritonavir) are known to raise the levels of Verapamil in the bloodstream.

When Verapamil is taken with aspirin, it's known to increase bleeding times. Verapamil interacts with blood pressure medications such as beta-adrenergic blockers like Toprol or Inderal. This further affects the heart.

When Verapamil is used with Digitalis, blood digoxin levels can raise up to 75%. It also interacts with irregular heartbeat medications and patients using both should be closely monitored. Another medication that is known to interact with verapamil is lithium. Others include medications for seizures like carbamazepine and phenobaribital.

Grapefruit juice is shown to significantly increase the levels of verapamil. Other medications that interact include quinidine, flecainide and disopyramide. Also medications like clonidine, telithromycin, theophylline, cyclosporine and rifampin are known to interact. Verapamil is known to interact with immune system medications.

Warnings

Patients' blood pressure needs to be closely monitored especially if they have heart conditions. The product might contain inactive ingredients that cause allergies. You need to tell your doctor about any heart surgeries, liver failure or devices such as pacemakers. Because the drug may cause dizziness, it's important not to drive or operate heavy machinery while taking it. Nursing mothers need to be careful as it's possible the drug can be passed on in the breast milk. Patients are told to limit their alcohol consumption because Verapamil increases the blood alcohol level.

Storage

It is recommended to store this medicine in a closed container at room temperature. Keep it from freezing. Also, make sure to keep it away from heat, moisture and direct light. Keep the medication out of reach of children. Do not keep outdated medication or medication no longer needed. When disposing of Verapamil, ask your healthcare professional what to do with the discarded medication.

Summary

Verapamil is a calcium channel blocker that is used to treat high blood pressure and other conditions. Other uses are to regularly take it to prevent chest pains. It might help patients exercise. It's also used as an alternative to lithium. It is administered orally three or four times a day or once at bedtime and also intravenously. It lowers the heart rate and helps patients feel more comfortable.

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Last Reviewed:
December 22, 2017
Last Updated:
April 05, 2018
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