(For veterinary information only)
WARNING
The size of the tablet/medication is NOT an indication of a proper dose. Never administer any drug without your veterinarian's input. Serious side effects or death can occur if you use drugs on your pet without your veterinarian's advice.
It is our policy not to give dosing information over the internet.
Brand Name: Brethine
Available as 2.5 mg tablets, 5 mg tablets, injectable, and as a metered-dose inhaler
Background
Terbutaline works as an airway dilator, making breathing easier when airways have constricted.
Terbutaline is a type of drug called a "beta-2 agonist." Explaining what that means requires some background as there are receptors in the nervous system classified as alpha-1, alpha-2, beta-1, and beta-2. They are involved one way or another in the body's automatic fight or flight response, which you may have heard of.
In brief, the body is hard-wired to quickly make adaptations in the event of a threatening situation. Pupils dilate for better vision in the dark, circulation diverts away from peripheral tissue to minimize bleeding should it come to that, the heart is prepared to pump quickly, and airways dilate for maximum oxygen exchange. When the predator is detected, the body gets ready.
The beta-2 receptors are involved in dilating the airways. Humans don't generally spend much time running from or fighting with predators, but there are other situations where a drug might be needed to help open up airways: asthma and bronchitis.
How This Medication Is Used
Beta2 agonists have another effect that might be useful: they delay labor during pregnancy. This is not a common use in veterinary medicine, but this medication could be used to prevent premature labor should a patient be deemed at risk for this situation.
Terbutaline sulfate can be given as a tablet to treat dogs with bronchitis or other lung diseases. It is not helpful for tracheal collapse.
It can be kept on hand as an injectable to use at home for asthmatic cats when they have an after-hours breathing crisis.
Terbutaline sulfate can be used as a metered dose inhaler for dogs or cats who need periodic airway dilation.
Terbutaline sulfate can be used to increase heart rate in patients where the natural heart rate is too slow and causes collapse.
Terbutaline sulfate tablets are typically given 2-3 times daily. If a dose is accidentally skipped, do not double up on the next dose, as an overdose can result. Store terbutaline sulfate at room temperature, protected from light. Partially used injectable bottles should be discarded.
Side Effects
The most common side effects from terbutaline are: Increased heart rate, tremors, anxiety, blood pressure drop. These are usually temporary and minor.
At higher doses, the heart's Beta-1 receptors could be stimulated, leading to rhythm disturbance. Vomiting or fever could result.
Interactions With Other Drugs
Using terbutaline sulfate with any other drug that stimulates the sympathetic nervous system can increase the chance of getting a heart arrhythmia side effect.
Propranolol is a beta-blocker used in the treatment of heart disease. It has some ability to block beta2 receptors, although it is mostly used for its beta1 receptor effects. This means that propranolol can inactivate terbutaline sulfate.
Digitalis, a heart medication, can also increase the chance of heart arrhythmia with terbutaline sulfate.
Tricyclic antidepressants (such as clomipramine) and MAO inhibitors (like amitraz or selegiline) can increase vascular dilation, another beta receptor effect that is not generally significant with terbutaline sulfate alone.
Concerns And Cautions
There are plenty of situations where the stimulation of either beta1 or beta2 beta receptors would be a bad idea:
If possible, the use of terbutaline sulfate should be avoided in these situations.
If using this medication to treat a feline asthma crisis at home, expect the injection to take approximately 15 minutes to show an effect.