Felis ISSN 2398-2950

Propranolol

Contributor(s): Mark Rishniw

Introduction

Name

  • Propranolol.

Class of drug

  • Beta-1 and beta-2 adrenoceptor antagonist.

Description

Chemical name

  • 1-(isopropylamino)-3-(1-naphthyloxy)-2-propanol HCl.

Molecular weight

  • 295.8.

Physical properties

  • Bitter-tasting, white powder.

Storage requirements

  • Room temperature.

Uses

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Indications

  • Management of cardiac arrhythmias   Heart: dysrhythmia  (sinus tachycardia, atrial fibrillation or flutter, supraventricular tachycardia, premature ventricular depolarization), hypertrophic cardiomyopathy or obstructive heart disease.
  • Control of the cardiac features of thyrotoxicosis prior to surgery in patients with hyperthyroidism   Hyperthyroidism  .
  • May be used to control the pulse rate in patients with phaeochromocytoma   Pheochromocytomas  ; always use with phenoxybenzamine   Phenoxybenzamine  for this indication, as beta-blockade without concurrent alpha-blockade may lead to a hypertensive crisis.

Administration

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Pharmocokinetics

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Precautions

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Interactions

with other drugs

Sympathomimetics (eg epinephrine, phenylpropanolamine, terbutaline)
  • The beta-effects may be blocked by propranolol.
  • The unopposed alpha effects of epinephrine and norepinephrine may result in severe hypertension and a decreased heart rate.

Drugs enhancing the hypotensive effect of propranolol

  • Anesthetic agents (those that depress myocardial activity).
  • Antihypertensive drugs (eg hydralazine, prazosin).
  • Diazepam.
  • Diuretics.
  • Other anti-arrhythmics.

Calcium channel blockers (eg diltiazem, verapamil)

  • There is an increased risk of bradycardia, severe hypotension, heart failure and AV block.

Thyroid hormones

  • The metabolism of propranolol is decreased in hyperthyroid cats, so duration of effect may be prolonged.

Methimazole

  • The dose of propranolol may need to be decreased when initiating methimazole therapy.

Muscle relaxants (eg suxamethonium, tubocurarine)

  • Propranolol enhances the effects.

Phenobarbitone, phenytoin or rifampin

  • Hepatic enzyme induction by these drugs may increase the metabolism of propranolol.

Theophylline

  • The bronchodilatory effects may be blocked by propranolol.

Adverse Reactions

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Further Reading

Publications

Refereed papers

  • Jacobs Get al(1997)Pharmacokinetics of propanolol in healthy cats during euthyroid and hyperthyroid states.Am J Vet Res,58(4), 398-403.
  • Bright J Met al(1991)Evaluation of the calcium channel-blocking agents dilatiazem and verapamil for treatment of feline hypertrophic cardiomyopathy.JVIM5(5), 272-282.

Other sources of information

  • Based onSmall Animal Formulary.Tennant, Bryn (1999) 3rd edn. Cheltenham: BSAVA.
  • Plumb D C (1999)Veterinary Drug Handbook.3rd edn, Iowa State University Press.

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