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Drugs Affecting the Respiratory System

Review A&P and Know key terms

Mucolytic Drugs

Mucomyst (acetylecysteine)MOA: Decreases viscosity of mucous by breaking specific bonds in the mucous molecule. Blocks formation of toxic metabolites in Acetaminophen overdose.Uses: Relief of abnormal viscous mucous that decrease airflow and gas exchange (inhalation). Prevention of hepatotoxicity due to acetaminophen overdose (PO).

Mucomyst

Adverse Effects: Anorexia, N&V – smells like rotten eggs. Bronchospasm.Nursing Measures: Warn about smell. Instruct to report N&V, dyspnea. Wash nebulizer after use – causes a sticky coating. Be sure patient coughs and clears airway prior to administering. Be sure patient is able to clear airway after dose or use suction.

Expectorants

Example: Robitussin (guaifenesin)MOA: Reduces adhesiveness and decreases surface tension of mucous making it easier to be expectorated.Uses: Expectorant Nursing Measures: Instruct to take each dose with glass of water and increase intake of water.

Decongestants

Examples: Neosynepherine, Afrin, (nasal sprays. Sudafed (PO).MOA: Reduce congestion and edema by constricting arterioles to reduce blood flow to nasal mucosa.Uses: Rhinitis associated with respiratory infections and allergies.Contraindications: Hypertension, heart disease, glaucoma.Caution re: rebound congestion with sprays.

Antitussives

Examples: Codeine (central acting narcotic) Tessalon (local anesthesia of stretch receptors in lungs) Swallow whole.MOA: Suppress cough by depression of the cough center in the medulla or the cough receptors in the throat, trachea or lungs.Contraindicated in supportive lung disease where pus that needs to be expectorated.Uses: Dry cough that interferes with sleep.

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Antihistamines

Block action of histamine by occupying H1receptors, the same receptors as histamine. They prevent edema, itching and bronchoconstriction associated with the action of histamine.Examples: 1st generation: Benadryl (diphenhydramine) (prototype), Tavist (clemastine) 2nd generation: Claritin (loratadine), Allerga (fexofenadine)

Antihistamines

Uses: Allergic rhinitis, rash and pruitus in anaphylaxis.Adverse Effects: 1st generation – sedation, anticholinergic effects. 2nd generation – less sedation.Contraindications: glaucoma, pregnancy, urinary obstruction.Nursing Measures: Teach to avoid alcohol and other CNS depressants. D/C 72 hr. prior to allergy testing.

Bronchodilator & Antiasthma Drugs

Adernergic bronchodilatorsExamples: Epinephrine (SC or inhaled)MOA: Stimulates beta 2 receptors to relax bronchospasms, constricts bronchial arterioles and blocks histamine to reduce congestion and edema and increase tidal volume and vital capacity.Most all OTC asthma inhalers contain epinephrine.Uses: Asthma, anaphylaxis, cardiac arrest.

Proventil (albuterol)

MOA: Short acting beta 2-adernergic agonist relaxes bronchial smooth muscles to relieve bronchospasms and reduce airway resistance.Uses: Acute asthma attacks (reliever) – inhalation onset in 5 – 10 min. Adverse Effects: tremors, nausea, palpatations.Nursing Measures: Teach the short acting beta2 agonits lose their brochodilating effects with overuse. Teach how to use inhaler.

Serevent (salmeterol)

MOA: Long acting beta 2 agonist acts to relax bronchospasms and reduce airway resistance.Uses: Prophylaxis (controller) of acute bronchoconstriction. Slower onset up to 20 min., duration 12 hours or more.

Anticholinergic Bronchodilators

Example: Atrovent (ipratropium)MOA: When given by inhalation, anticholinergics block the action of acetylcholine in bronchial smooth muscles and reduces intracellular GMP, a bronchoconstrictor.Uses: Emphysema, chronic bronchitis, COPD, acts synergistically with beta 2 agonists to improve lung function up to 15% in asthma.Adverse Effects: Cough, nervousness, N, HA, dizziness.

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Xanthine Bronchodilators

Examples: Short acting - Aminophylline (theophylline), Long acting – Theo-DurMOA: Directly relax bronchial smooth muscles. Stimulate the respiratory center which strengthens diaphragmatic contractions and prevents fatigue in COPD.Uses: Asthma uncontrolled by other drugs, COPD. Adverse Effects: tachycardia, N,V,D,GI bleed, restlessness.Nursing Measures: Check levels (5-15 mcg/ml.)

Antiinflammatory Asthma Drugs

Leukotrine modifiers:Example: Singular (montelukast)MOA: Occupy receptors to prevent leukotrien from acting on tissues and causing bronchoconstriction and mucous production.Uses: Prophylaxis and chronic treatment of asthma. (controller). May decrease need for beta 2 agonists.Adverse Effects: HA, N, infection.

Corticosteroids

Examples: Prednisone (PO) Azmacort (triamcinolone), Pulmocort (budesonide), Flovent (fluticasone)MOA: Suppress inflammation by inhibiting movement of fluids and protein into tissues, migration and function of neutrophils and eosinophils, synthesis of histamine in mast cells, and production of inflammatory sub. such as prostaglandins, interleukins, leukotrienes. They also increase the number (4 hr) and sensitivity (2 hr) of beta2 receptors.

Corticosteroids

Uses: Acute, severe asthma given IV, PO if repeated inhalations are not effective. Chronic asthma (inhalers), COPD.Adverse Effects: GI bleeding, edema. May be given for 7-10 days for acute attacks. Taper if over a week.

Mast Cell StablilzersExamples: Fivent (cromolyn) and Tilade (nedocromil)

MOA: Antiinflammatory effect by inhibiting release of histamine and other mediators of inflammation. No effect on bronchodilation.

Uses: Prophylaxis of acute asthma attacks. Not used much since leukotrine modifiers available.

Adverse Effects: Generally well tolerated.