VERAPAMIL (Calan): What is used for?

What is Verapamil?

Verapamil is an active ingredient used for the treatment of Supraventricular Tachycardias, Atrial Tachycardia, High Blood Pressure and Angina. The product ingredient is Verapamil hydrochloride (hcl).

The brand names of Verapamil in United States are: Calan, Isoptin, Calan SR and Verelan.

Verapamil’s Mechanism of Action

Inhibits its entry through the membrane of heart and vascular muscle cells.

Therapeutic Indications, Uses and Benefits of Verapamil

Oral forms:

Prophylaxis and treatment of angina, including vasospastic form (Prinzmetal variant) and unstable angina.
HBP (High Blood Pressure).
Prophylaxis of paroxysmal supraventricular tachycardia after treatment.

Intravenous (IV):

Control of patients with flutter and/or chronic atrial fibrillation, except when associated with the existence of accessory conduction pathways (s. de Wolff-Parkinson-White, s. de Lown-Ganong-Levine). Prevention of 2nd postinfarction of myocardium in patients without cardiac insuff. during the acute phase.


Treatment of supraventricular tachycardias, including: paroxysmal supraventricular tachycardia, including that associated with accessory conduction pathways (s. de Wolff-Parkinson-White, s. de Lown-Ganong-Levine).
Atrial flutter or fibrillation, except when associated with the existence of accessory conduction pathways (s. de Wolff-Parkinson-White, s. de Lown-Ganong-Levine).

Dosage of Verapamil

Oral: (Tablets or Capsules of 40 mg, 80 mg, 100 mg, 120 mg, 180 mg, 240 mg, 300 mg, 360 mg)

Adults: individual adjustment, indicative:

– Prevention of second postinfarction of myocardium and angina pectoris: 360 mg/day, optimum dose: 240-480 mg/day.

– High Blood Pressure: 240 mg/day. If necessary, increase after one week to 360 mg/day, up to a maximum of 480 mg/day.

– Prophylaxis of supraventricular tachycardias: 240-480 mg/day (not digitized) and 120-360 mg/day (digitized).

Children: maximum 10 mg/kg/day in several doses.

Injectable: (Injection or Solution 2.5 mg/1mL, 5 mg/1mL)

Adults: initial 5-10 mg (0.075-0.15 mg/kg) in slow injection in no less than 2 minutes (3 minutes in the elderly).
If this is not sufficient, administer 10 mg (0.15 mg/kg) 30 minutes after the first.

Children < 1 year: initial 0.1-0.2 mg/kg (0.75-2 mg) as a single dose (to be administered under electrocardiographic monitoring).
From 1-15 years: initial 0.1-0.3 mg/kg in a single dose for 2 minutes.
In both cases, if necessary, repeat the same dose after 30 minutes.

Contraindications of Verapamil

Hypersensitivity, cardiogenic shock, sinus disease (except if there is an implanted pacemaker), second or third degree AV block (except if there is an implanted pacemaker), flutter or atrial fibrillation that have a conductive accessory AV tract (s. de Wolff-Parkinson-White, s. de Lown-Ganong-Levine).

Also in oral forms: left-sided heart failure, hypotension (systolic < 90 mm Hg).

Also in injectable: severe hypotension, severe CHF, ventricular tachycardia (except verapamil-sensitive), AMI, patients receiving ß-adrenergic blockers.

Warnings and Precautions with Verapamil

  • Liver failure and/or kidney failure should be adjusted dose.
  • Patients with: heart failure or depression of ventricular function (should be compensated before starting treatment).
  • Decreased neuromuscular transmission (affected with Duchenne syndrome).
  • AMI (oral).
  • Monitoring in Duchenne muscular dystrophy and with supratentorial tumors (parenteral route).

Liver failure

Caution with Verapamil. Adjust dose individually.

Kidney failure

Caution with Verapamil. Adjust dose individually.

Interactions with Verapamil

  • Plasma levels increased with: CYP3A4 inhibitors, ritonavir.
  • Decreased plasma levels with CYP3A4 inducers.
  • Mutual potentiation of cardiovascular effects with: antiarrhythmics, ß-blockers.
  • Enhancement of the hypotensive effect with: antihypertensives, diuretics, vasodilators.
  • Additive hypotensive effect with: prazosin, terazosin.
  • Increases toxicity of: lithium.
  • Increase tendency to bleeding with: AAS
  • Increases plasma levels of: ethanol, carbamazepine.
  • Power activity of: neuromuscular blocking agents (curare and depolarizing type).
  • Hypotensive effect decreased by: rifampicin, sulfinpyrazone.
  • Caution with: atorvastatin, simvastatin, lovastatin; with drugs that bind to plasma proteins, with inhalation anesthetics.

Pregnancy and Verapamil

Safety has not been established, its use is not especially recommended in the first trimester.


Avoid Verapamil. It is partly eliminated by milk.

Effects on driving ability

Sometimes there may be a decrease in the capacity to drive dangerous vehicles or machines. This happens even more at the beginning of treatment, when the dose is increased, when changing when another medication was being used, and when alcohol is used.

Adverse reactions and side effects of Verapamil

Dizziness, headache; bradycardia; hypotension.


Source: The content of this active ingredient has been written taking into account the clinical and molecular information of all medicines authorised and marketed in the United States under the Unique Ingredient Identifier (UNII) by the Substance Registration System (SRS) of the Food and Drug Administration (FDA) and the United States Pharmacopeia (USP).

In order to know in detail the information authorized by the FDA for each drug, you should consult the corresponding medication guide authorized by the FDA.


PubChem CID: 2520
NCI Thesaurus: C928

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