1. Relax bronchial smooth muscle bands
2. Dilate the bronchi and bronchioles that are narrowed
II. Mechanism of Action
1. Prevents binding of cholinergic substances
2. Decreases constriction and secretions
B. Xanthine derivatives
1. Smooth muscle relaxation
2. Dilates the constricted bronchi and bronchioles
1. Dilate airways by stimulating the β2-adrenergic receptors in lungs
a. Nonselective adrenergic drugs
i. Stimulate the a, β1 (cardiac), and β2 (respiratory) receptors, Examples: Norepinephrine, epinephrine, and isopreanline
b. Nonselective β-adrenergic
i. Stimulate both β1 and β2 receptors. Example: Metaproteranol
c. Selective β2 drugs
i. Stimulate the β2 receptors. Example: albuterol.
1. Nonselective Adrenergic–> Metaproterenol, Epinephrine
2. Selective β Adrenergic –> Dobuatimine
3. Selective β2 Adrenergic –> Albuterol, Levalbuterol, Salmeterol, Terbutaline
C. Xanthine derivatives
A. Bronchial asthma
C. Chronic bronchitis
E. Pulmonary diseases
A. Drug allergy
B. Uncontrolled cardiac dysrhythmias
C. High risk of stroke
D. Soy lecithin (inhalations)
A. Nonselective β-blocker
B. Monoamine oxidase inhibitors
VII. Side Effects
1. Dry mouth or throat
2. Nasal congestion
3. Heart palpitations
4. GI distress (N/V/D)
B. Xanthine derivatives
1. GI distress (N/V/D)
2. Sinus tachycardia
4. Ventricular dysrhythmias
3. Cardiac stimulation
6. Vascular headache
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Welcome back and today we’re going to discuss bronchodilators.
Bronchodilators are used to relax bronchial smooth muscle bands and they also dilate narrowed bronchi and bronchioles. Basically, where there is constriction and narrowing on the bronchial tree, these drugs work to reverse that. As constriction and narrowing aren’t really good for breathing.
There are three types of bronchodilators. Let’s discuss the first two. Anticholinergics work by preventing cholinergic substances thereby decreasing constriction and secretions. Xanthine derivatives work by relaxing smooth muscle relaxation, and they also dilate constricted bronchi and bronchioles. Both have a goal is reversing constriction and dilating aka bronchodilating.. get it?
Lastly, we will cover beat-agonists. There are three types, nonselective adrenergic, nonselective beta and selective beta drugs – with each simulating different receptors throughout the body. When you see the word “nonselective” think generalized (all over) and when you see the word “selective: think localized. If you want to focus respiratory reaction, you would focus more on drugs that stimulate B2 (as it’s respiratory in response). Likewise, if you’re looking for an overall reaction, you would pick more of the nonselective adrenergic drugs.
The types of bronchodilators are broken down into three groups. B-agonists, anticholinergics and xanthine derivatives. Most of the B-agonists have an ending of -TEROL. Anticholinergics have a similar ending of -TROPIUM. Xanthine derivatives have an ending of -PHYLLINE. All have a goal of bronchodilation but achieve this in different ways, as constriction can be structural or obstructive based. Think of a clogged drain, is it clogged with something within the drain’s lumen (inner part) or is the drain itself defective (too narrow)? B-agonists with the narrow, anticholinergic work on the inner part (secretions).
As we are focused on airway, indications are airway dysfunction and include bronchial asthma, acute/chronic bronchitis (bronchial inflammation), emphysema (damaged alveoli) – which are crucial for proper oxygenation and pulmonary diseases. Again we are attempting to correct narrowing and obstructed bronchi so we would focus on diseases that would lead to this.
Contraindications involve allergies, uncontrolled cardiac dysrhythmias, patients who are at high risk for strokes and those allergic to soy lecithin (in some inhalations). The dysrhythmias and stroke are a big concern as these drugs cause vasocontraction. Weird? I know but if you already have compromised vasculature, these drugs will exacerbate this condition. So these drugs dilate the lungs and can constrict the vasculature. Keep this in mind.
The interactions are very interesting. Remember the vasoconstriction? Well with nonselective B-blockers and MAOIs, these drugs increase the chances of hypertension. WHen xanthine derivatives are used with digoxin, there is an increased risk for toxicity. And with patients with diabetes, some bronchodilators can cause hyperglycemia. I had a patient who took was administered multiple bronchodilator treatments for an acute asthma attack and had diabetes, his blood glucose was above 200 for 2 days – he needed up needing an insulin drip.
Side effects of anticholinergics are related to these anticholinergic effects, we are decreasing secretions and again vasoconstriction – so you will see dry mouth or throat, nasal congestions, heart palpitations, GI distress and anxiety. Why? We are drying things out and squeezing the vasculature in the body. Side effects of xanthine derivatives are related mainly to the vasoconstriction that can occur and include – GI distress, tachycardia, palpitations and dysrhythmias.
Lastly, the side effects of B-agonists are also related to vasoconstriction and include – cardiac stimulation, tremors and headaches. With other presentations of insomnia, restlessness and hyperglycemia. I had a patient receive an albuterol treatment for respiratory distress and her heart rate was 120 for a full hour afterward. That vasoconstriction is serious and patients should receive proper education on what to expect after drugs are administered. Also, if a person has to use a rescue inhaler (often B-agonists) more than twice a week, it may be a sign that their pulmonary disease is not well managed. If this is the case, speak to a doctor about options for long-term management.
Priority Nursing Concepts for a patient receiving bronchodilators include gas exchange and pharmacology.
Alright, time for a recap. The mechanisms of actions focus on relaxation, dilation and decrease in secretions. With bronchodilator types being B-agonists, anticholinergic and xanthine derivatives. Indications are based on acute and chronic pulmonary disease and dysfunction. Contraindications include cardiac dysrhythmias, stroke (due to their vasoconstriction) and soy lecithin (which is in some inhalations). Side effects include dry mouth, cardiac issues (palpitation and dysrhythmias), GI distress (N/V/D) and hyperglycemia.
Now you know all there is to know about bronchodilators. Now go out and be your best self and happy nursing!