Lecture 5: Drugs that Affect the Respiratory System

Ethylenediamine dihydroiodide (EDDI)

[saline expectorant]

• Stimulate bronchial mucus secretions via a vagal-mediated reflex action on the gastric mucosa

• Indication: mild respiratory disease in horses

Ethylenediamine dihydroiodide (EDDI), saline expectorant

Ammonium chloride is an example of? (indicate group and type of drug)

Ethylenediamine dihydroiodide (EDDI), saline expectorant

Ammonium carbonate is an example of? (indicate group and type of drug)

Ethylenediamine dihydroiodide (EDDI), saline expectorant

Potassium iodide is an example of? (indicate group and type of drug)

Ethylenediamine dihydroiodide (EDDI), saline expectorant

Calcium iodide is an example of? (indicate group and type of drug)

Volatile oils

[direct stimulants]

• Thought to directly increase respiratory tract secretions

• With unknown clinical efficacy in veterinary medicine

Volatile oils

[direct stimulants]

Eucalyptus oil is an example of? (indicate group and type of drug)

Volatile oils

[direct stimulants]

Oil of lemon is an example of? (indicate group and type of drug)

Guaifenesin (glyceryl guaiacolate)

Muscle relaxant in the horse with an expectorant effect

Guaifenesin (glyceryl guaiacolate)

Stimulates bronchial secretion through its action on the vagus nerve

Mucolytics

Improve the mobility of mucus by decreasing its viscosity or thickness

Mucolytics

Alters mucus composition via breakdown of disulfide bonds

Acetylcysteine (n-acetylcysteine)

Indication: respiratory ds. with tenacious mucus

Acetylcysteine (n-acetylcysteine)

Also used for paracetamol poisoning in cats

Decongestant

MOA: stimulate the α-adrenergic receptors in mucus membranes leading to local vasoconstriction

Decongestant

• decrease the congestion of nasal passages by reducing swelling

• With limited veterinary use, e.g. feline upper respiratory tract disease

Topical decongestant

Type of decongestant that is typically to decrease bleeding associated with some surgical procedures

Systemic decongestant

Type of decongestant that is also used for treating urinary incontinence

Decongestant, topical

Phenylephrine is an example of? (indicate group and type of drug)

Decongestant, topical

Oxymetazoline is an example of? (indicate group and type of drug)

Decongestant, topical

Xylometazoline is an example of? (indicate group and type of drug)

Decongestant, systemic

Pseudoephedrine is an example of? (indicate group and type of drug)

Decongestant, systemic

Phenylpropanolamine is an example of? (indicate group and type of drug)

Antitussives

Also known as cough suppressants

Antitussives

• Indication: persistent and unproductive cough

• Mainly used in dogs

• Contraindication: excessive respiratory secretions

Locally acting antitussives

• Soothe irritated respiratory mucous membranes

• Seldom used in veterinary medicine

Locally acting antitussives

Methanol is an example of? (indicate group and type of drug)

Locally acting antitussives

Tincture of benzoin is an example of? (indicate group and type of drug)

Locally acting antitussives

Benzonatate is an example of? (indicate group and type of drug)

Centrally acting antitussive

• MOA: inhibition of the cough center

• Indication: severe, nonproductive cough

• Adverse side effects: sedation and constipation

Centrally acting antitussive

Butorphanol is an example of? (indicate group and type of drug)

Centrally acting antitussive

Codeine is an example of? (indicate group and type of drug)

Centrally acting antitussive

Morphine is an example of? (indicate group and type of drug)

Centrally acting antitussive

Methadone is an example of? (indicate group and type of drug)

Hydrocodone

Drug that has antitussive effect in dogs

Nonnarcotic antitussive

Suppress the cough center but non-addicting ¡ Indication: nonproductive cough

Nonnarcotic antitussive

Dextromethorphan is an example of? (indicate group and type of drug)

Dextromethorphan

Drug that has been shown to be an effective antitussive in dogs after IV injection

Dyspnea

Bronchoconstriction results in?

Acetylcholine

[Acetylcholine/Catecholamine] release from PS nerve endings is one of the causes of bronchoconstriction

Acetylcholinesterase

___________ inhibition causes bronchoconstriction

True

Histamine release via inflammatory/allergic mechanisms causes bronchoconstriction

Beta-2

Which adrenergic receptor can be blocked by drugs (e.g. propranolol) that may cause bronchoconstriction?

Beta-2 receptor agonists, bronchodilator

• Most effective because these are functional antagonists of airway obstruction, regardless of the stimulus

• Adverse side effects: tachycardia, hypertension

Epinephrine

Potent bronchodilator for life-threatening situations

Selective beta-2 receptor agonists, bronchodilator

Terbutaline is an example of? (indicate group and type of drug)

Selective beta-2 receptor agonists, bronchodilator

Albuterol (salbutamol) is an example of? (indicate group and type of drug)

Selective beta-2 receptor agonists, bronchodilator

Metaproterenol is an example of? (indicate group and type of drug)

Selective beta-2 receptor agonists, bronchodilator

Pirbuterol is an example of? (indicate group and type of drug)

Selective beta-2 receptor agonists, bronchodilator

Clenbuterol is an example of? (indicate group and type of drug)

Selective beta-2 receptor agonists, bronchodilator

Salmeterol is an example of? (indicate group and type of drug)

Beta-2 receptor agonists, bronchodilator

Pseudoephedrine is an example of? (indicate group and type of drug)

Beta-2 receptor agonists, bronchodilator

Isoproterenol is an example of? (indicate group and type of drug)

Methylxanthines

[bronchodilator]

• Inhibit phosphodiesterase (PDE) in smooth mm. cells

• Also cause mild cardiac stimulation and diuresis

Methylxanthines

[bronchodilator]

Indications: respiratory and cardiac ds. that would benefit from BD; myocardial stimulation

Methylxanthines, bronchodilator

Aminophylline is an example of? (indicate group and type of drug)

Methylxanthines, bronchodilator

Etamiphylline is an example of? (indicate group and type of drug)

Methylxanthines, bronchodilator

Theophylline is an example of? (indicate group and type of drug)

Methylxanthines, bronchodilator

Camsylate is an example of? (indicate group and type of drug)

H1 antihistamines

[bronchodilator]

Indications: Allergic and respiratory conditions like heaves in horses, pneumonia in cattle, feline asthma

H1 antihistamines, bronchodilator

Pyrilamine is an example of? (indicate group and type of drug)

H1 antihistamines, bronchodilator

Tripelennamine is an example of? (indicate group and type of drug)

H1 antihistamines, bronchodilator

Diphenhydramine is an example of? (indicate group and type of drug)

H1 antihistamines, bronchodilator

Doxylamine is an example of? (indicate group and type of drug)

H1 antihistamines, bronchodilator

Clemastine is an example of? (indicate group and type of drug)

H1 antihistamines, bronchodilator

Cetirizine is an example of? (indicate group and type of drug)

H1 antihistamines, bronchodilator

Cyproheptadine is an example of? (indicate group and type of drug)

Anticholinergics

Counteracts BC caused by acetylcholine by blocking receptors

Ipratropium bromide

Indication: Bronchospasm in recurrent airway obstruction in the horse

Anticholinergics

Ipratropium bromide is an example of what type of drug?

Corticosteroids

Clinical uses: equine heaves, feline asthma, acute respiratory stress syndrome, allergic pneumonia

Corticosteroids

Fluticasone, beclomethasone, prednisone, prednisolone, triamcinolone are all examples of what group of drugs?

Oral GGCs

Are the drugs of choice for chronic airway inflammation in the dog or cat

Prednisone

Is a prodrug that is converted into prednisolone

Prednisolone

In cats, which drug is more preferred because of the following reasons:

• It does not require conversion

• It is more readily available for the body to use

• It is more potent

• Has a shorter duration of action.

a. prednisolone

b. prednisone

Analeptics (respiratory stimulants)

MOA: stimulate the respiratory center in the medulla via its stimulation of the carotid or aortic chemoreceptors à this increases the rate and depth of respiration

Analeptics (respiratory stimulants)

Indication: respiratory depression caused by general anesthesia, sedatives or hypnotics, apneic neonates and preterm animals

Analeptics (respiratory stimulants)

Indication: treatment of hypercapnia associated with hypoxic-ischemic encephalopathy in foals

Analeptics (respiratory stimulants)

Doxapram belongs to what group of drugs?

Analeptics (respiratory stimulants)

Methylxantines belong to what group of drugs?

Parasympathetic NS

Responsible for the baseline tone of the respiratory muscles —> mild bronchoconstriction (BC)

alpha-1

What receptor of the sympathetic NS causes adrenergic stimulation leading to bronchoconstriction?

beta-2

What receptor of the sympathetic NS causes adrenergic stimulation leading to bronchodilation?

alveolar macrophages

Type of immune cell that bind, engulfs, kill and digest deposited particles

WBCs

Type of immune cell that phagocytize and kill pathogens

mast cells

Type of immune cell involved in allergic reaction

respiratory epithelial cells

Type of immune cell that is responsible for protecting the respiratory system

goblet cells

Found in the mucociliary escalator that produces mucus that traps inhaled foreign particles

cilia

Found in the mucociliary escalator that propels trapped foreign particles upward and out of the respiratory tract where it can be swallowed or expelled

medulla oblongata

Cough center is found in the

c. inhibit mucus section

[STUMULATE mucus secretion]

Inflammatory mediators if the respiratory system causes the following EXCEPT:

a. increase mucosal epithelial permeability

b. increase microvascular permeability

c. inhibit mucus secretion

d. inhibit mucociliary function

early inflammatory phase

Usually associated with low volume of thick & viscous mucus:

• dry, inflamed, painful mucosa

• harsh, dry, painful, useless cough

early inflammatory phase

If the treatment aims to:

• Increase mucus secretion to protect the mucosa

• Reduce frequency of damaging cough

What phase of inflammation is being described?

late inflammatory phase

• There is excess mucus formation and tissue debris in the airways, which prevent free passage of air

• Coughing is stimulated

late inflammatory phase

If the treatment aims to:

• Increase fluidity of mucus

• Stimulate mucociliary escalator

What phase of inflammation is being described?

• Expectorants

• Mucolytics

Drug/s used in controlling respiratory secretions

Antitussives

Drug/s used for the control of cough reflex

• Bronchodilators

• Decongestants

Drug/s used in maintaining normal airflow to the alveoli

Inhalation therapy - nebulization/aerosolization

What dosage form is ideal for respiratory diseases as it permits the delivery of a high drug concentration into the airways while minimizing their blood levels?

nebulizer

Type of aerosol delivery system that deliver small particles that reach the lower RT