The autonomic nervous system is divided into primary sympathetic (fight or flight response) and parasympathetic. Sympathetic nerve activity is transmitted to tissues through involuntary (autonomous) nerve impulses and blood.
Inside cells are targets called receptors, which are stimulated by chemicals released by nerves or glands. In the sympathetic system, nerves release a chemical transmitter called norepinephrine. The chemical released by the adrenal glands is called epinephrine. The receptors for these chemicals are alpha-adrenergic receptors and beta-adrenergic receptors.
The effects of adrenergic receptor stimulation include: increased blood sugar, increased heart rate, increased cardiac contraction and increased oxygen consumption, leading to increased blood pressure. In addition, stimulation of the receptors also leads to relaxation of the bronchial tree, resulting in the opening of the airways and dilation of some blood vessels.
Propranolol belongs to a class of drugs known as receptor blockers. Other related drugs include: esmolol, tenormin, and metoprolol.
Receptor blockers have a particularly pronounced effect on the heart, although other organs may also be affected.
Propranolol reduces heart rate, cardiac output, the amount of oxygen needed by the heart muscle, and blood pressure.
Propranolol is a prescription drug that can only be obtained from or by a veterinarian.
This medication is not approved by the Food and Drug Administration for use in animals, but is prescribed by veterinarians as an additional prescription medication.
Formula of Propranolol
This medicine is registered for human use only.
Human formulations: Inderal? (Ayerst), Intensol? (Roxane) and various generic formulations
Veterinary formulations: None available
Use of propranolol in dogs and cats
1. The primary use of beta-adrenergic blockers in animals is to treat (sometimes) is to prevent) arrhythmia. Arrhythmias commonly treated are atrial fibrillation and flutter.
2. Propranolol is also used to treat supraventricular tachycardia and ventricular premature beat complex.
3. Propranolol can reduce cardiac output and reduce high blood pressure (systemic hypertension).
4. Lowering heart rate and myocardial contractility can be beneficial in some cats and dogs with hypertrophic cardiomyopathy, especially when the heart muscle contracts excessively and blocks blood passages.
5. Propranolol can also be used to treat hyperthyroidism in cats.
Precautions and Side Effects
1. Generally, propranolol prescribed by a veterinarian is safe and effective, but this drug can also cause side effects in some animals.
2. Propranolol should not be used in animals known to be allergic to the drug.
3. Propranolol can inhibit myocardial function and heart rate, and reduce cardiac output. This is a problem in animals with congestive heart failure and requires very careful dosing.
4. Propranolol may interact with other medications. You can consult with your veterinarian to determine if other medications your pet is receiving may interact with propranolol. These drugs include: sedatives, cimetidine, incelin, lidocaine, and theophylline.
5. Propranolol may cause weakness in some animals due to slow heart rate or low blood pressure. But pets rarely faint.
Propranolol specifications
1. Propranolol has 10mg, 20mg, 40mg, 60mg , 80mg and 90mg tablets.
2. Propranolol sustained-release capsules are available in 60mg, 80mg, 120mg and 160mg.
3. Propranolol Oral Liquid is available in 4 mg/ml, 8 mg/ml and 80 mg/ml.
4. Propranolol for injection, usually at a concentration of 1 mg/ml.
Dosage of Propranolol
Note: Always consult a veterinarian before administration.
1. Typical doses for dogs are: 0.15 to 0.5 mg per pound of body weight (0.3 to 1.0 mg/kg) three times a day.
2. Typical doses for cats are: 2.5 to 5 mg per cat, two to three times a day.
3. Propranolol is often taken with other medicines, especially in pets who are being treated for heart failure or arrhythmia. In these cases, a lower initial dose may be prescribed.
4. The duration of the medication depends on the condition of the treatment and the response to the medication. Even if your pet appears to be recovering, be sure to complete the entire course of treatment unless specifically directed by your veterinarian.
