Felis ISSN 2398-2950

Verapamil

Contributor(s): Mark Rishniw

Introduction

Name

  • Verapamil.

Class of drug

  • Calcium channel blocker.
  • Class IV antidysrhythmic agent.

Description

Chemical name

  • Benzenacetonitrile, alpha-[3-[[2-(3,4-dimethoxyphenyl)ethy]methylamino]propyl]-3,4-dimethoxy-alpha-(1-methylethyl)monohydrochloride.

Molecular formula

  • C27H38N2O4.HCl.

Molecular weight

  • 491.

Physical properties

  • Crystalline powder with bitter taste.

Uses

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Indications

  • Primarily used to control supraventricular tachycardias, sustained and paroxysmal ventricular tachycardias particularly in cases of hypertrophic cardiomyopathy , and the heart rate in dogs with atrial fibrillation as an adjunct to digoxin .

Administration

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Pharmocokinetics

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Precautions

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Interactions

with other drugs

Beta-adrenergic blockers, eg propranolol
  • Propranolol   Propranolol  may be additive negative inotropic and chronotropic effects.

Calcium salts or vitamin D

  • The activity of verapamil may be adversely affected.

Cardiac glycosides

  • Digoxin   Digoxin  and digitoxin   Digitoxin  plasma concentrations are increased by verapamil   Verapamil  .
  • Monitor serum levels if used with verapamil.

Non-depolarizing muscle relaxants

  • Effects enhanced by verapamil.

Cimetidine

  • Cimetidine   Cimetidine  inhibits the metabolism of verapamil increasing plasma concentrations.

Theophylline

  • Verapamil enhances the effect of theophylline   Theophylline  possibly leading to toxicity.

Protein bound agents, eg warfarin

  • Verapamil may displace these   Warfarin  from plasma proteins.

Vincristine

  • Verapamil may increase intracellular vincristine   Vincristine  levels by inhibiting the drugs outflow from the cell.

with diagnostic tests

  • Raised liver enzymes (in humans).

Further Reading

Publications

Other sources of information

  • Based onSmall Animal Formulary.Tennant, Bryn (1999) 3rd edn. Cheltenham: BSAVA.

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