Medication: Propranolol

Your cat has been prescribed the active ingredient propranolol for the management of cardiac arrhythmias (abnormal heart rhythm) or right-to-left shunts that can cause clinical signs during exercise.

Key points
• Beta-blocker.
• Prescribed off-label by veterinarians.
• May interact with other medications.
• Dosage: two to three times daily.

This information sheet is designed to help answer commonly asked questions and help you give the medication safely and effectively to your pet. It does not contain all available information for this medication. If you have other questions or need more information, contact your veterinarian or pharmacist. Always follow the dosing instructions provided by your veterinarian.

Name

• Propranolol (pro-pran-o-lol).

Brand name

• No veterinary formulations.
• Human formulations; Syprol®, Inderal®, Detensol®, Hemangeol®, Innopran®.

Class of drug

• Beta-1 and beta-2 adrenoceptor antagonist (beta-blocker).

Storage

• Store in sealed container at room temperature (15°-30°C (59°-86°F)).
• Protect from light.

Your veterinarian has prescribed propranolol for the management of cardiac arrythmias (sinus tachycardia, atrial fibrillation, supraventricular tachycardia, premature ventricular depolarization or obstructive heart disease). It may also used as an anti-hypertensive drug to lower blood pressure and can be used to control the pulse rate in patients with phaeochromocytoma. It can be used in patients with right-to-left shunts where they may show collapse or similar signs during exercise.

Propranolol may also be given to reverse the clinical features of thyrotoxicosis prior to surgery in patients with hyperthyroidism and used to reduce signs of anxiety and to modify behavioral problems.

Injectable and oral preparations, as tablets or extended-release capsules or an oral solution, are available. It may be given on an empty stomach or with food.

The following side-effects may be seen:

• Bradycardia (slowing of heart rate).
• Impaired AV conduction.
• Myocardial depression.
• Heart failure.
• Syncope (fainting).
• Glucose intolerance.
• Bronchospasm.
• Diarrhea.
• Peripheral vasoconstriction.
• Depression and lethargy (the result of propranolol's high lipid-solubility and its penetration into the CNS).
• May reduce glomerular filtration rate and therefore exacerbate any pre-existing renal impairment.

Drug interactions

The hypotensive effect of propranolol is enhanced by:

• Anesthetic agents (those that depress myocardial activity).
• Anti-hypertensive drugs, eg hydralazine, prazosin.
• Diazepam.
• Diuretics.
• Other arrhythmic drugs.

Other drug interactions:

• Calcium channel blockers, eg diltiazem, verapamil (increased risk of bradycardia, severe hypotension, heart failure and AV block).
• Thyroid hormones (increases metabolism of propranolol).
• Carbimazole (dose of propranolol may need to be lowered).
• Cimetidine (may decrease the metabolism of propranolol).
• Muscle relaxants (enhanced effect).
• Lidocaine (increased risk of lidocaine toxicity).
• Oral aluminium hydroxide preparations (reduces propranolol absorption).
• Theophylline (bronchodilatory effects may be blocked).
• May enhance the hypoglycemic effect on insulin in cats with diabetes mellitus.

Propranolol should only be given according to your veterinarian's instructions.

Dispose of any unused propranolol safely – do not flush down the toilet or sink. Ask your veterinary team if they take back medication for disposal. Do not save propranolol for future use or give to other pets.

If you miss a dose, give the dose as soon as possible but do not double up a dose. Make sure the dose given doesn’t exceed the total recommended amount in any 24-hour period.

If your pet is unwell, contact your veterinarian for advice and stop the administration of propranolol.

Propranolol should only be given to the cat that it has been prescribed for:

• Do not use in cats with bradyarrhythmias, acute or decompensated congestive heart failure.
• Do not use in cats with asthma.
• Although the use of propranolol is not contraindicated in patients with diabetes mellitus, insulin requirements should be monitored as propranolol may enhance the hypoglycemic effect of insulin.
• Adverse effects are most frequently seen in geriatric patients with chronic heart disease or in patients with rapidly decompensating cardiac failure.
• If accidentally given to other pets, contact your veterinarian for advice.

If accidentally eaten by a human, speak to your primary care physician or poison control center.

Your veterinarian will want to monitor your cat's cardiac and kidney function and blood sugar levels while on propranolol.

Further information

If you have any concerns, further information on propranolol can be found on the package insert.

Always follow the recommended dosage and contact your veterinary team or pharmacist if you have any questions regarding your cat’s medication.