Pharmacology for Nursing Unit II - Chapter 9

Pharmacology for Nursing - Unit II

• Course Title: Pharmacology for Nursing
• Unit: II
• Chapter: 9 - Drugs Acting on the Respiratory Tract
• Instructor: Dr. Hanan A. M. Youssef
• Credentials: RN, MNS, DNS, Associate Professor- Emergency & Critical Care Nursing, Nursing Department – Taif University

Learning Objectives

• Define pharmacology key terms
• Describe the physiological events in upper respiratory disorders
• Detail therapeutic actions, indications, pharmacokinetics, contraindications, adverse reactions, and drug-drug interactions of drugs acting on the upper respiratory tract
• Discuss drug use across the lifespan
• Compare and contrast prototype drugs with other agents in their class and other drugs acting on the respiratory tract
• Outline nursing considerations (teaching) for patients receiving these drugs

Drugs Acting on the Respiratory Tract

• Key Terms: Histamine, antihistamines, mucolytics, antitussives, cilia, common cold (URT), decongestants, expectorants, seasonal rhinitis, sinusitis, sneezing, ventilation, nasal spray, defense mechanisms.
• Drugs Acting on the Upper Respiratory Tract: Includes nasal cavity, larynx, pharynx, trachea, bronchi, bronchioles, goblet cells, mucus, cilia, alveolar sacs.
• Most common upper respiratory infections are caused primarily by viral infections (rhinovirus or influenza virus).
• Excessive mucus production is a result of the inflammatory response.

Treatment of Common Cold

• Treatment involves combined use of antihistamines, nasal decongestants, antitussives, and expectorants.
• Treatment is primarily symptomatic.
• Difficult to definitively determine if the cause is viral or bacterial.
• Treatment is often "empirical therapy"—treating the most likely cause.
• Antivirals and antibiotics may be used, but a definitive viral or bacterial cause may not always be easily identified.

Pediatric Concerns

• In 2008, the FDA issued recommendations against giving over-the-counter (OTC) cough and cold medicine to children under 4-years-old. Extreme caution is advised for those 4-6 years old.
• Evidence suggests that such medications are not effective in children and may be harmful, leading to adverse events like over-sedation, seizures, tachycardia, and even death.
• Parents should consult pediatricians for the best ways to manage illnesses.

Adults & Geriatric (Older Adults) Concerns

• Adults may accidentally overdose on OTC medications, especially if taking multiple products.
• The safety of these drugs during pregnancy and lactation is not always established.
• Older adults are more prone to adverse effects such as sedation, confusion, and dizziness.
• Renal and/or hepatic impairment can affect the metabolism and excretion of these drugs.

Drugs Used to Treat Upper Respiratory Infections

• Antitussives: Block the cough reflex (centrally) acting on the medulla.
• Decongestants: Decrease blood flow to the upper respiratory tract, decreasing secretion production.
• Antihistamines: Block the release or action of histamine, decreasing secretions and narrowing airways.
• Expectorants: Increase productive cough.
• Mucolytics: Increase or liquefy respiratory secretions which aid in clearing airways.

Oral Decongestants

• Actions: Decrease nasal congestion, shrink nasal mucosa by stimulating alpha-adrenergic receptors, and promote drainage.
• Indications: Common cold, sinusitis, and allergic rhinitis.
• Pharmacokinetics: Well-absorbed and widely distributed, metabolized in the liver, primarily excreted in urine.
• Contraindications: Conditions exacerbated by sympathetic activity.
• Adverse Effects: Rebound congestion and sympathetic effects.
• Nursing Considerations: Assess for history of conditions such as pregnancy or lactation; hypertension; CAD; and history of allergies.

Prototype Oral Decongestants (e.g., pseudoephedrine)

• Indications: Temporary relief of nasal congestion.
• Actions: Sympathomimetic effects, causing vasoconstriction in nasal passages to increase drainage and improve ventilation.
• Route: Oral
• Onset: 30 minutes
• Duration: 4-6 hours

Antihistamines and Histamine Antagonists

• Histamine is a major inflammatory mediator in many allergic disorders, including allergic rhinitis, anaphylaxis, angioedema, drug fevers, and urticaria (itching).
• Antihistamines have sedative, antihistaminic, and anticholinergic properties. H1 antagonists (e.g., diphenhydramine) block H1 histamine receptors, reducing allergic responses.
• H2 blockers (e.g., cimetidine) reduce gastric acid in peptic ulcer disease.

Prototype Antihistamines (e.g., diphenhydramine)

• Indications: Symptomatic relief of allergic symptoms, seasonal and perennial allergic rhinitis, and for managing sleep and coughs.
• Actions: Competitively blocks histamine at H1 receptors, resulting in sedation, anticholinergic effects.
• Route: Oral, Intramuscular (IM), intravenous (IV).
• Onset: Ranges from 15-30 minutes to rapid (IV)
• Duration: Wide range, typically 4–8 hours.

Nursing Considerations for Antihistamines

• Assess for allergies and conditions like pregnancy, prolonged QT interval, renal or hepatic impairment, and skin, orientation, affect, and reflexes.
• Monitor respiration rate, adventitious sounds, and appropriate laboratory values such as kidney function.