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Comprehensive Overview of Respiratory
Medications
Upper Respiratory Disorders and Medications
Upper respiratory infections (URIs), including the common cold, acute rhinitis, sinusitis, and acute pharyngitis, are the most prevalent type of respiratory ailment. While not typically life-threatening, they cause significant discomfort and lost time from work and school. Management focuses on symptomatic relief through four primary classes of drugs: antihistamines, decongestants, antitussives, and expectorants.
Antihistamines: Blocking the Allergic Response
Antihistamines work by competing with histamine for H1 receptor sites, thereby preventing the inflammatory response that histamine triggers. When H1 receptors are stimulated, smooth muscles, such as those in the nasal cavity, constrict, leading to congestion and other allergy symptoms. Mechanism and Generations Antihistamines are divided into two main categories:
- First-Generation Antihistamines: These drugs, like diphenhydramine (Benadryl) , are effective but readily cross the blood-brain barrier, leading to significant side effects such as drowsiness. They also possess strong anticholinergic properties.
- Second-Generation Antihistamines: This newer class, including loratadine (Claritin) , cetirizine (Zyrtec) , and fexofenadine (Allegra) , are known as "non- sedating" antihistamines. They have a lower incidence of drowsiness and fewer anticholinergic effects. Memory Aids for Antihistamines
- Generational Difference: Remember that First-Generation antihistamines often have "first-in-line" side effects like sedation. They were developed first and have more widespread effects.
- Anticholinergic Side Effects: A simple mnemonic for the side effects of first- generation antihistamines is "Can't See, Can't Pee, Can't Spit, Can't Poop." o Can't See: Blurred vision o Can't Pee: Urinary retention o Can't Spit: Dry mouth o Can't Poop: Constipation Key Drug Information Drug Class Key Drug(s) Primary Use Common Side Effects Nursing Considerations First- Generatio n Diphenhy dramine (Benadryl) Acute and allergic rhinitis, antitussive Drowsiness , dry mouth, dizziness, blurred vision, urinary retention, constipatio n Warn patient not to drive or operate machinery. Avoid alcohol/CNS depressants. Give with food to decrease GI distress. Second- Generatio n Loratadine (Claritin), Cetirizine (Zyrtec) Allergic rhinitis Minimal sedation, fewer anticholiner gic effects A good option for patients who need to remain alert. May be taken with a moderate amount of alcohol, but this is not recommended.
Decongestants: Shrinking Swollen Nasal Passages
Nasal congestion arises from the dilation of nasal blood vessels due to infection, inflammation, or allergies. This dilation allows fluid to move into the tissue spaces, causing swelling. Mechanism of Action Nasal decongestants, such as pseudoephedrine (Sudafed) and oxymetazoline (Afrin) , stimulate alpha-adrenergic receptors. This action produces vasoconstriction (shrinking) of
- Side Effects: Drowsiness, dizziness, nausea.
Expectorants: Loosening Secretions
Expectorants work by loosening bronchial secretions, making them easier to eliminate through coughing. They are used for dry, nonproductive coughs to help make them more productive. Mechanism and Memory Aid Think of expectorants as the "Clean-Up Crew" for the lungs. They don't stop the cough; they make it more effective by reducing the surface tension of secretions so the "gunk" can be cleared out.
- Key Drug: Guaifenesin (Robitussin) is the most common expectorant.
- The Best Expectorant: Hydration is the best natural expectorant. Patients taking an expectorant should be advised to increase their fluid intake to at least 8 glasses per day to help loosen mucus.
- Side Effects: Drowsiness and nausea.
Intranasal Glucocorticoids (Steroids)
These drugs, such as fluticasone (Flonase) and triamcinolone (Nasacort) , are highly effective for treating allergic rhinitis due to their anti-inflammatory action. They decrease rhinorrhea, sneezing, and congestion. Continuous use may lead to dryness of the nasal mucosa. Dexamethasone should not be used for more than 30 days to avoid systemic effects.
Lower Respiratory Disorders and Medications The two major categories of lower respiratory disorders are Chronic Obstructive Pulmonary Disease (COPD) and Restrictive Pulmonary Disease. COPD is characterized by airway obstruction and increased resistance to airflow, while restrictive lung disease involves a decrease in total lung capacity. There is no cure for COPD.
Bronchodilators: The "Airway Openers"
Bronchodilators are the cornerstone of therapy for obstructive lung diseases like asthma and COPD. They work by relaxing the smooth muscles of the bronchi, leading to dilation of the airways. This action is primarily maintained by cyclic adenosine monophosphate (cAMP); drugs that increase cAMP cause bronchodilation.
1. Sympathomimetics (Beta-Adrenergic Agonists) These drugs mimic the effects of the sympathetic nervous system, increasing cAMP and causing bronchodilation. - Memory Aid: Think "B for Bronchioles" and "2 for the 2 Lungs." Beta2-agonists act primarily on the beta2 receptors in the lungs to open them up. - Types and Key Drugs: o Non-selective (Alpha1, Beta1, Beta2): Epinephrine is used in emergencies (anaphylaxis, acute asthma attack) to restore circulation and increase airway patency. It has significant side effects like tachycardia, hypertension, and tremors. o Selective Beta2-Agonists: These are the preferred drugs for asthma. They include albuterol , metaproterenol (Alupent) , and terbutaline (Brethine). They act primarily on the lungs, resulting in fewer cardiac side effects. However, high doses can still cause nervousness, tremors, and an increased pulse rate. - Patient Education: Patients with diabetes should monitor their blood glucose levels closely, as beta2-agonists can cause hyperglycemia. 2. Anticholinergics These drugs dilate bronchioles by blocking the action of acetylcholine. - Memory Aid: Remember the drug name ipratropium (Atrovent) with the phrase "I- pra-y I can breathe!" - Key Drugs: Ipratropium bromide (Atrovent) and tiotropium (HandiHaler) are used for maintenance treatment of bronchospasms in COPD. - Side Effects: The most common side effect is dry mouth. Other classic anticholinergic effects like constipation and urinary retention can occur. Tiotropium
- Critical Patient Education: Inhaled steroids can cause throat irritation, hoarseness, and Candida albicans (thrush). To prevent this, patients must: o Use a spacer with the inhaler. o Rinse their mouth and throat with water after each dose. o Wash the spacer daily. 2. Leukotriene Receptor Antagonists Leukotrienes are chemical mediators that cause inflammation in the lungs. These drugs block their action.
- Memory Aid: The drug suffix helps remember the mechanism: "Luka"st drugs (like montelukast and zafirlukast ) block "Leuko"trienes.
- Use: Prophylactic and maintenance therapy for chronic asthma. Not for acute attacks.
- Key Drugs: Montelukast (Singulair) , zafirlukast (Accolate). 3. Mast Cell Stabilizers These drugs act by inhibiting the release of histamine from mast cells, preventing an asthma reaction.
- Memory Aid: Cromolyn "calms" the mast cells so they don't release inflammatory mediators.
- Use: Prophylactic treatment of bronchial asthma; must be taken daily. Not for acute attacks.
- Key Drug: Cromolyn sodium.
- Side Effects: Cough and a bad taste, which can be decreased by drinking water before and after use.
Mucolytics: The "Mucus Busters"
Mucolytics act like detergents to liquefy and loosen thick mucous secretions, making them easier to expectorate.
- Key Drug: Acetylcysteine (Mucomyst).
- Dual Role: Besides being a mucolytic, acetylcysteine is the primary antidote for acetaminophen overdose if given within 12 to 24 hours.
- Administration: Given via nebulization for respiratory use. It should not be mixed with other drugs. A bronchodilator should be given 5 minutes before the mucolytic.
- Side Effects: Nausea, vomiting, stomatitis (sore mouth), and a "runny nose."
Medication Administration Techniques Proper technique is crucial for the effectiveness of inhaled respiratory medications.
The Role of a Spacer
A spacer is a device that attaches to a metered-dose inhaler (MDI). Its purpose is to improve the delivery of the drug to the lungs and reduce the amount deposited in the mouth and throat. This is particularly important for inhaled glucocorticoids to prevent local side effects like thrush.
Order of Inhaled Medications: A Simple Rule
When multiple inhalers are prescribed, they must be used in the correct order to be effective.
- The Rule: Bronchodilator FIRST, Anti-inflammatory SECOND.
- The Rationale: The bronchodilator opens the airways, allowing the anti- inflammatory medication (like a steroid) to penetrate deeper into the lungs.
- The Timing: The patient should administer the beta-agonist (bronchodilator) 5 minutes before using an anticholinergic or an inhaled steroid (e.g., ipratropium, glucocorticoid, cromolyn).
