Medication: Atenolol

Your pet may have been prescribed atenolol for an irregular heart rhythm or to treat to aortic or pulmonic stenosis. Atenolol is also sometimes prescribed if cats have hypertrophic obstructive cardiomyopathy (HOCM). It is occasionally used in the management of hyperthyroidism and high blood pressure.

Key points:
• Beta blocker.
• Slows the heart rate.
• Extra monitoring of glucose levels may be needed in diabetic patients.
• Use with care in animals with asthma (more common in cats).
• Do not use in animals with certain conditions that could cause low heart rates (eg AV block).
• Use with care in animals with heart failure.
• Use with care in animals with kidney disease.
• Dosage: once or twice daily in cats.
• Do not stop treatment suddenly always taper dose and withdraw under the advice of your veterinarian.

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

• Atenolol (Aten-A-LOL).

Brand name

• There is no product licensed for use in pets but human drugs can be given with special consent.
• Tenormin® (US and UK).

Class of medication

• Beta-1 adrenoceptor antagonist (beta blocker).

Storage

• Store at room temperature (15-30°C/59-86°F).
• Store away from heat, moisture and sunlight.

Atenolol can be used to treat abnormal heart rhythms (either inappropriately high heart rates or irregular heart beats). It is also used to reduce stress on the heart muscle when there is an abnormality causing obstruction to blood as it leaves the heart (eg aortic stenosis, pulmonic stenosis, hypertrophic cardiomyopathy). Finally, atenolol can be used to reduce blood pressure.

The product is available as tablets or solution which can be given by mouth. The tablets can either be administered directly into your pet’s mouth or along with some food. It is simplest to put the drops onto food for your pet to eat.

The following side-effects have been reported and are more common in older animals:

• Slow heart rate and abnormal heart rhythms.
• Heart failure (particularly in animals with advanced heart disease).
• Diarrhea.
• Loss of appetite.
• Fainting.
• Low blood pressure.
• Bronchospasm (narrowing of the airways), particularly in animals with pre-existing asthma.
• Constriction of blood vessels in extremities.
• Depression and lethargy.

Drug interactions can occur with:

• Some drugs that stimulate the sympathetic nervous system, eg epinephrine; phenylpropanolamine and terbutaline.
• Calcium channel blockers, eg diltiazem, verapamil – may increase risk of slow heart rate, low blood pressure and heart failure.
• Digoxin can potentiate low heart rates when combined with atenolol.
• The metabolism of atenolol can be accelerated if your pet is receiving thyroid hormone supplementation.
• Atenolol increases the effect of muscle relaxants (eg suxamethonium, tubocurarine).
• Phenobarbitone may increase metabolism of atenolol .
• Bronchodilators (eg theophylline) may be blocked by atenolol.
• Cimetidine can reduce the metabolism of atenolol thereby increasing its effect.
• Insulin – atenolol may extend the effects of insulin thereby lowering blood glucose.

Atenolol should be administered according to your veterinarian’s instructions. Treatment may be started at a low dose and then may be gradually increased over time. If treatment is effective the drug may be continued lifelong. If no improvement is seen within a few months, your veterinarian may recommend a different course of therapy. You should never change or stop any treatment without consulting your veterinarian. Remember – do not stop treatment suddenly; always taper dose and withdraw under the advice of your veterinarian.

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

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

If your pet is unwell, contact your veterinarian for advice.

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

• Do not give to other pets in the household.
• Use with care in pregnant or lactating cats and only if advised by your veterinarian.
• If accidentally given to other pets, contact your veterinarian for advice.

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

Your veterinarian will want to make regular checks on your pet if they are receiving any long term therapy to ensure the drugs they are receiving are effective and to adjust the doses if necessary. Regular ECG monitoring will be performed if atenolol is prescribed to manage a heart rhythm abnormality.

Further information 

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

Europe & UK

• There are no products licensed for cats or dogs.

USA

• There are no products licensed for cats or dogs.

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