Drugs Affecting the Upper Respiratory System PDF

19/04/1446 1 19/04/1446 Antitussive Drugs Antitussives are drugs that suppress the cough reflex. Many disorders of the upper and lower respiratory tracts are accompanied by an uncomfortable, nonproductive cough....

19/04/1446 1 19/04/1446 Antitussive Drugs Antitussives are drugs that suppress the cough reflex. Many disorders of the upper and lower respiratory tracts are accompanied by an uncomfortable, nonproductive cough. Coughing normally is a protective mechanism that forces foreign irritants out of the respiratory system, opening it for more efficient flow of air. Prototype drug: Dextromethorphan (PediaCare, Vicks 44, etc.) Dextromethorphan: Core Drug Knowledge  Pharmacotherapeutics: Is used in treating nonproductive cough. Available as:  Capsules  Lozenges  Chewable  Syrups &  Extended-release oral suspension 2 19/04/1446 Dextromethorphan: Core Drug Knowledge  Pharmacokinetics: Absorbed rapidly from the GIT. Onset of action within 15 – 30 minutes. Metabolism: Liver Excretion: Kidneys (some drug is also eliminated unchanged). Dextromethorphan: Core Drug Knowledge  Pharmacodynamics: Is related chemically to the opiate agonists. Cough suppression occurs with the drug directly affecting the cough center in the medulla. Therapeutic doses do not affect ciliary action. 3 19/04/1446 Dextromethorphan: Core Drug Knowledge  Contraindications: For treating chronic coughs resulting from emphysema & asthma.  Precautions: Use in caution in patients with:  Hepatic impairment &  During pregnancy. Dextromethorphan: Core Drug Knowledge  Adverse Effects: Dextromethorphan toxicity:  Nausea  Vomiting  Drowsiness  Dizziness  Irritability &  Restlessness In excessive doses, dextromethorphan poisoning may occur. Box 34.1, Pg. No:695 4 19/04/1446 Dextromethorphan: Core Drug Knowledge  Drug Interactions: Dextromethorphan interact with other CNS depressants:  MAOIs  Fluoxetine (SSRI)  Quinidine  Sibutramine 5 19/04/1446 Dextromethorphan: Core Patient Variables  Health Status: This drug is contraindicated for patients with emphysema or asthma. Review the patient’s record for drugs that may interact with dextromethorphan, especially antidepressants. Also, evaluate the patient for a history of hepatic insufficiency, because dextromethorphan is processed by the liver. Dextromethorphan: Core Patient Variables  Life Span and Gender: Dextromethorphan, a pregnancy category C drug, should be used with caution during pregnancy. Dextromethorphan is not indicated for use in children younger than 2 years old. With adolescent patients, assess the potential for abuse. 6 19/04/1446 Dextromethorphan: Core Patient Variables  Lifestyle, Diet, and Habits: Advice the patient not to drive or perform other tasks that require alertness. Alert patients not to consume alcohol while taking dextromethorphan because doing so could increase sedation. Caution about the potential for abuse of dextromethorphan. Assess the frequency of grapefruit or orange juice ingestion, because these juices can substantially increase the concentration of dextromethorphan. Dextromethorphan: Core Patient Variables  Environment: Alert patients not to take any OTC drugs while taking dextromethorphan because doing so could increase sedation.  Nursing Diagnoses and Outcomes:  Risk for Injury related to sensory-perceptual alteration from drug-induced drowsiness and sedation Desired outcome: The patient will remain free from injury related to sedation and drowsiness.  Risk for Ineffective Airway Clearance related to suppression of cough reflex Desired outcome: The patient will maintain his or her baseline respiratory function. 7 19/04/1446 Dextromethorphan: Planning and Intervention  Maximizing Therapeutic Effects: In acute or long-term care settings, administer dextromethorphan at evenly spaced intervals to maintain blood levels of the drug at steady state. Provide environmental controls, including appropriate lighting, reduced noise, and comfortable temperature, to ease sensory- perceptual alteration and aid relaxation. Dextromethorphan: Planning and Intervention  Minimizing Adverse Effects: During therapy, ensure that safety precautions are used, such as side rails and ambulation assistance. Assess respiratory status and movement of air periodically during drug use. Refrain from administering dextromethorphan with grapefruit or orange juice. 8 19/04/1446 Dextromethorphan: Core Drug Knowledge  Providing Patient & Family Education: Emphasize that sedation, drowsiness and impaired orientation can occur. Caution patients who are taking certain antidepressants. Pg. No:696 - 697 Antihistamines Antihistamines are used to relieve symptoms of allergies. These drugs block the action of histamine as it is released during the inflammatory response to an antigen. Very effective for allergic rhinitis. Their action restores normal airflow through the upper respiratory system. First-generation (Sedating antihistamine) Antihistamines Second-generation (Nonsedating antihistamine) Prototype drug: Fexofenadine (Allegra) (second- generation). 9 19/04/1446 Drugs Closely Related to Fexofenadine 1. Cetrizine It is the active metabolite of hydroxyzine (first-generation antihistamine). It differs from the parent compound by having greater affinity for H1 receptor. It is effective in treating:  Chronic idiopathic urticaria  Perennial allergic rhinitis  Seasonal allergic rhinitis 10 19/04/1446 1. Cetrizine Causes more sedation than other second-generation antihistamines like loratadine and fexofenadine. But causes much less sedation than first-generation antihistamines. Contraindicated in breast feeding, as the drug is secreted through breast milk. 11