Terbutaline
A short-acting beta-2 agonist used as a reliever inhaler, or by injection or tablet, to reverse bronchospasm in asthma.
Drug card
- How it works
- Activating airway beta-2 receptors to relax bronchial muscle within minutes
- Used for
- Preventing and reversing bronchospasm in asthma
- Bronchospasm in chronic bronchitis and emphysema
- Known for
- Shaky hands (tremor)
- Palpitations and fast heartbeat
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does terbutaline work?
Selectively activates beta-2 receptors; through a G protein, adenylyl cyclase raises cyclic AMP, and protein kinase A relaxes bronchial and vascular smooth muscle. It also speeds mucociliary clearance and cuts mediator release from inflammatory cells. Beta-2 stimulation relaxes the uterus too, which is why it has tocolytic activity.
Like other short-acting beta-2 agonists: SABAs stimulate the beta-2 receptors of airway smooth muscle. Through a G protein the receptor switches on adenylyl cyclase; the rise in cyclic AMP activates protein kinase A, which lowers calcium inside the cell and relaxes the muscle from the trachea down to the smallest bronchioles. Inhaled, they open the airways almost at once and work for 4 to 6 hours, so they serve as relievers.
Uses
What is terbutaline used for?
- Preventing and reversing bronchospasm in asthma
- Bronchospasm in chronic bronchitis and emphysema
Side effects
Side effects of terbutaline
- Shaky hands (tremor)Known for
- Palpitations and fast heartbeatKnown for
- Nervousness
- Headache and dizziness
- Drowsiness
- Nausea and vomiting
- Sweating and flushing
- Pain at the injection site
- Low potassium (hypokalemia)Serious
- Raised blood sugar; ketoacidosis in diabetesSerious
- Arrhythmias and ECG changesSerious
- Seizures (rare)Serious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Boxed warning: it must not be used to hold off labor beyond 48 to 72 hours; mothers have had arrhythmias, lung edema, heart ischemia and died.
- Beta blockers block its effect and can provoke bronchospasm in asthma.
- Care in heart disease, hypertension, hyperthyroidism, diabetes or seizure disorders.
- MAO inhibitors and tricyclics can magnify its effects on the heart and blood vessels.
Good to know: Like other beta-2 agonists it relaxes the uterus, but it is not approved for delaying labor beyond 48 to 72 hours because of serious harm to mothers.
Remember it
A way to remember it
Relievers rattle: shaky hands, racing heart.
Beta-2 stimulation opens the airways within minutes, but the commonest side effects are a tremor and a fast heartbeat, and potassium falls as it shifts into cells.
Written for biofideX
Its class
Short-acting beta-2 agonists
Other short-acting beta-2 agonists with a card:
Easily mixed up with long-acting beta-2 agonists, inhaled antimuscarinics and beta blockers.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Lungs and allergy
Terbutaline is one of 16 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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