Drugs Acting on the Respiratory System

Antitussives

drugs that suppress the cough reflex and indicated for treatment of a nonproductive cough.

Traditional antitussives

• codeine (generic)

• hydrocodone (available in some combination products),

• dextromethorphan (generic and in combination products)

Traditional antitussives

Antitussives that act directly on the medullary cough center of the brain to depress the cough reflex.

• due to this: not the drugs of choice for anyone who has a head injury or who could be impaired by central nervous system (CNS) depression.

Local Acting antitussives

Antitussives that have a direct effect on the respiratory tract.

Local Acting antitussives

• Benzonatate (Tessalon)

Benzonatate (Tessalon)

acts as a local anesthetic on the respiratory passages, lungs, and pleurae, blocking the effectiveness of the stretch receptors that stimulate a cough reflex.

codeine, hydrocodone, and dextromethorphan

antitussives that can cause sedation and drowsiness.

Antitussives

Contraindications and Cautions:

• Patients who need to cough to maintain airways (post-surgical)

• Use caution in asthma/emphysema (may cause secretion accumulation)

• History of narcotic addiction

• Pregnancy/lactation

Codeine and hydrocodone

are narcotics and have addiction potential

Antitussives

Adverse Effects (has a very drying effect)

• CNS: Drowsiness, sedation

• Anticholinergic: Dry mouth, constipation, increased secretion viscosity

• Local agents: GI upset, headache, congestion

Decongestants

Decrease the overproduction of secretions by causing local vasoconstriction to the upper respiratory tract

rebound congestion or rhinitis medicamentosa

a prolonged use of Decongestants is often accompanied by?

Topical Nasal Decongestants

oxymetazoline (Afrin and others)

phenylephrine (Coricidin and many others)

tetrahydrozoline (Tyzine)

xylometazoline (Otrivin).

Topical Nasal Decongestants

• Clear nasal passages first and immediately upon administration

• Proper spray technique to avoid sinus problems

• Limit use to 3-5 days to prevent rebound congestion

Topical Nasal Decongestants

are sympathomimetics, meaning they imitate the effects of the sympathetic nervous system to cause vasoconstriction, leading to decreased edema and inflammation of the nasal membranes.

Decongestants

Contraindications and Cautions:
- lesion or erosion in the mucous membranes
- patients with any condition that might be exacerbated by sympathetic activity ( glaucoma, hypertension, diabetes, thyroid disease, coronary disease, or prostate problems)

Decongestants

Adverse Effects:
- local stinging and burning; which may occur the first few times of druge use

• rebound congestion - used longer than 3-5 days

cyclopropane or halothane anesthesia

topical nasal decongestants is contraindicated with these drugs because serious cardiovascular (CV) effects could occur?

Oral Decongestants

Pseudoephedrine - the only oral decongestant currently available for this drug classification

Oral decongestants

shrink the nasal mucous membrane by stimulating the alpha-adrenergic receptors in the nasal mucous membranes. It is generally well absorbed and reaches peak levels quickly, in 20 to 45 minutes.

Topical Steroid Decongestants

beclomethasone (Beconase and others)

budesonide (Pulmicort Respules)

flunisolide (generic)

fluticasone (generic)

triamcinolone (generic).

Topical Steroid Decongestants

treatment of allergic rhinitis and to relieve inflammation after the removal of nasal polyps. They have been found to be effective in patients who are no longer getting a response with other decongestants.

• Onset = immediate

• may actually require up to 1 week to cause any changes.

• discontinued = no effects are seen after 3 weeks

Topical Steroid Decongestants

Contraindications and Cautions:

• presence of acute infections (block the inflammatory response)

• Increased incidence of Candida albicans

• patient who has an active infection (tuberculosis)

• exposure to any airborne infection, such as chickenpox or measles

Topical Steroid Decongestants

Adverse effects:
local burning, irritation, stinging, dryness of the mucosa, and headache.

Antihistamines

block the release or action of histamine, a chemical released during inflammation that increases secretions and narrows airways.

First Generation Antihistamines

• Diphenhydramine (Benadryl), chlorpheniramine, promethazine

• Greater anticholinergic effects 

• More sedating

Second Generation Antihistamines

• Loratadine (Claritin), cetirizine (Zyrtec), fexofenadine (Allegra)

• Less Sedating

Antihistamines

selectively block the effects of histamine at the histamine-1 receptor sites, decreasing the allergic response. They also have anticholinergic (atropine-like) and antipruritic effects.

• Most effective when used before symptom onset

Antihistamines

Used for relief of symptoms associated with seasonal and perennial allergic rhinitis, allergic conjunctivitis, uncomplicated urticaria, and angioedema.

• relief of exercise- and hyperventilation-induced asthma and histamine-induced bronchoconstriction in asthmatics.

Antihistamines

Contraindications and Cautions:

• renal or hepatic impairment

• patient with a history of arrhythmias or prolonged QT intervals

Antihistamines

Adverse Effects:

• Drowsiness and sedation (especially first generation)

• Anticholinergic effects: dry mouth, urinary retention, GI upset

• Cardiac arrhythmias (rare but serious)

MAO inhibitor

anticholinergic effects may be prolonged diphenhydramine is taken with what drug classification?

Expectorants

increase productive cough to clear the airways. They liquefy lower respiratory tract secretions, reducing the viscosity of these secretions and making it easier for the patient to cough them up.

• available in many OTC preparations

Expectorants

Guaifenesin (Mucinex): the Only available drug in this classification

Expectorants

enhances the output of respiratory tract fluids by reducing the adhesiveness and surface tension of these fluids, allowing easier movement of the less viscous secretions → more productive cough → decrease cough frequency

• should not be used for more than 1 week: if the cough persists, encourage the patient to seek healthcare

Expectorants

Adverse Effects:

• GI symptoms (e.g., nausea, vomiting, anorexia)

• Some patients experience headache, dizziness, or both; occasionally, a mild rash develops

Mucolytics

Increase or liquefy respiratory secretions to aid the clearing of the airways in high-risk respiratory patients who are coughing up thick, tenacious secretions.

• Associated patients: (COPD), cystic fibrosis, pneumonia, or tuberculosis.

Mucolytics

• acetylcysteine (generic)

• dornase alfa (Pulmozyme).

Acetylcysteine

A Mucolytic used orally to protect liver cells from being damaged during episodes of acetaminophen toxicity because it normalizes hepatic glutathione levels and binds with a reactive hepatotoxic metabolite of acetaminophen.

• affects the mucoproteins in the respiratory secretions by splitting apart disulfide bonds that are responsible for holding the mucus material together.

Dornase alfa

Mucolytic prepared by recombinant DNA techniques that selectively break down respiratory tract mucus by separating extracellular DNA from proteins.

• used in cystic fibrosis

Mucolytics

The medication may be administered by nebulization or by direct instillation into the trachea via an endotracheal tube or tracheostomy.

• Avoid mixing with other drugs in nebulizer

Mucolytics

Contraindications and Cautions:

• acute bronchospasm

• peptic ulcer

• esophageal varices

Mucolytics

Adverse Effects:

• GI upset

• stomatitis

• rhinorrhea

• bronchospasm

• occasionally a rash.