Respiratory Pharmacology Flashcards by Emma J

List the structures of the upper and lower respiratory system:

Upper resp
- everything above the larynx

Lower resp
- conducting system (trachea/bronchi) - mucociliary apparatus
- transitional system (bronchioles) - smooth muscle walls that can constrict and dialate
- exchange system (alveoli) -pneumocytes and capillary network

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List 5 categories of respiratory disease

allergy/inflammation

pulmonary edema

exercise induced pulmonary hemorrhage

cough

pneumonia

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What are the therapeutic goals of treating allergy or inflammatory respiratory disease? What treatments are used to reach these goals?

Goals
- reduce inflammation
- increase mucociliary clearance
- increase gas exchange

How
- steroid/cromolyn sodium
- expectorant/mucolytic
- bronchodilators

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What are the therapeutic goals of treating coughing in respiratory disease? What treatments are used to reach these goals?

Goals
- reduce cough
- reduce inflammation

How
- anti-tussive
- steroid

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What are the therapeutic goals of treating pulmonary edema in respiratory disease? What treatments are used to reach these goals?

Goals
- reduce fluid
- increase gas exchange
- reduce mucus

How
- expectorant/mucolytic
- diuretic

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What are the therapeutic goals of treating exercise induce pulmonary hemorrhage respiratory disease? What treatments are used to reach these goals?

Goals
- reduce trans-capillary pressure

How
- diuretic

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What are the therapeutic goals of treating pneumonia in respiratory disease? What treatments are used to reach these goals?

Goal
- reduce infection
- reduce inflammation
- increase gas exchange

How
- antimicrobials
- steroid/NSAID
- expectorant/mucolytic
- bronchodilator

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What are 2 mechanisms that can cause pulmonary edema in horses?

cardiogenic

secondary to equine anesthesia
- nares become obstructed (flaccid) and cause increased negative pressure and edema

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How is the cough reflex stimulated

stimuli from upper and/or lower respiratory tract via chemo and/or mechanoreceptors

signal the cough center in the medulla

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What are the 3 phases of the cough reflex

inspiratory
contraction (diaphragm muscles/intercostal muscles/abdominal muscles)
expiratory (open glottis - causes sound)

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What is fluticasone used for in relation to respiratory disease?

It is an inhaled steroid

To treat allergy or inflammatory respiratory disease

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How does Pousielles law impact the action of bronchodilators

Pouiselles law
- 4x impact of radius on the resistance

this means that bronchodilator effect is very impactful in reducing resistance

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What is the mechanism of action of bronchodilators

It functions by stimulating PSNS receptors in the bronchioles specifically M3 receptor with also beta 2 effects

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List 3 types of bronchodilators commonly used

anticholinergics

methylxanthine

beta 2 agonists

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What is the mechanism of action of methylxanthine

It stimulated relaxation of smooth muscle by adenosine and phosphodiesterase inhibition

Normally, adenylate cyclase makes cAMP and adenosine inhibits adenylate cyclase. So inhibition of adenosine will increase cAMP

Normally PDE breaks down cAMP. Inhibition of PDE results in increased cAMP

Both mechanisms increase cAMP
- cAMP results in less interaction between actin and myosin

This is because normally, MLCK allow actin and myosin binding. cAMP inhibits MLCK.

It has a narrow therapeutic window

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Provide examples of methylxanthine drugs

theophylline*

aminophylline/caffeine/theobromine (in chocolate)

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List 2 common situations where antitussives are used in dogs

tracheal collapse or kennel cough

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List a common situation in which antitussives are used in horses

BAL

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In what situation should you give an antitussive

If the cough is non productive (no swallowing after and tiring to the animal or owner

or diagnostics (BAL)

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What is the safest antitussive used in cats

dextromethorphan ( poorly absorbed in dogs)

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What is the mechanism of action for dextromethorphan

It is an NMDA receptor antagonist
- in the CNS these receptors these are part of the pain pathway = may have some analgesic effect/improve effects of other drugs

It is an alpha 1 agonist impacting glutamate signalling in the cough center in the medulla
- reduces sensitivity to inputs

It is an opioid derivative but it doesn’t bind opioid receptors

What are the 3 main functions of expectorants

increase bronchial secretions

increase mucociliary clearance

increase productive cough

List 2 examples of expectorants

volatile oils

saline

What is the function of mucolytics

break down mucus

List 3 main mucolytics

acetlycysteine dembrexine guaifenesin

What 3 drugs reduce respiratory function

anesthetics opioids benzodiazpines

What 3 drugs increase respiratory function

Any CNS stimulant doxaprom* almitrine caffeine

What situation would caffeine be utilized as a respiratory stimulant

dummy foal situation hypercapnia associated with - hypoxic ischemic encephalopathy - neonatal encephalopathy

What is butorphanol used for primarily in the context of respiratory impacts

To reduce cough in horses for BAL

What is another name for acetylcysteine and what is the mechanism of action

Mucomyst It breaks the disulfide bonds in the mucoproteins because of its free sulfydryl groups

What are 2 potential adverse effects of acetylcysteine

hypersensitivity reaction or bronchoconstriction after inhalation

What are some common uses of acetylcysteine

Infused into guttoral pouches to break up chondroids Given as enema to foals to break up meconium impaction break down respiratory mucus and enhance clearance Used IV to support the liver during acetaminophen or xylitol toxicity

How is acetylcysteine administered

Either via nebulizer (inhale) or IV (to tx toxicity) or enema or infuse guttoral pouch

What is another name for dembrexine? What are its effects?

Sputolysin - a phenolic benzylamine some antitussive effects reduce tracheal mucus no effect on inflammation there is minimal research

What is dembrexine used for commonly in large and small animals

horses: - reduce mucus in RAO/IAD/pneumonia dog - otitis media (infuse into ear)

How is dembrexine administered

PO or infused into ear (dog)

What is the mechanism of action for guaifenesin

It is a CNS muscle relaxant PSNS impact - vagal stimulation resulting in bronchial secretions - irritation of gastric mucosa resulting in the gastropulmonary reflex (increases secretion of submucosal glands in airway/mucus hydration)

What are the 2 main impacts of guaifenesin

increased mucociliary function expectorant impacts

What species can guaifenesin be used in

horse cat dog human

What is triple drip

guaifenesin + ketamine + xylazine IV field anesthetic

List 3 anticholinergic drugs that can be used as bronchodilators

atropine glycopyrrolate hyoscine butylbromide (buscopan)

List 3 beta 2 agonists used as bronchodilators

albuterol salbutamol clenbuterol

What is the function of salbutamol and albuterol

short acting bronchodilators - used for asthmatic flare ups (not chronic use) If used chronically it can become pro-inflammatory

How is albuteral and salbutamol administered

inhaled

Asthma is most common in which animal species

cats and horses

What is another name for clenbuterol?

ventipulmin

What is clenbuterol primarily used for

Treatment of equine asthma Use for less than 30 days - max benefit is seen after 14d Tachyphylaxis (reduced efficacy) and sometimes rebound hypersensitivity is seen if administration occurs >21d of continuous administration

What is commonly combined with administration of clenbuterol (or even albuterol/salbutamol) to increase efficacy?

environmental change - reduce exposure to allergen

What is the mechanism of action of doxapram

CNS stimulant stimulated chemoreceptors in the carotid artery and aorta resulting in reflex stimulation directly stimulate respiratory centers in brain

What is the physiologic impact of doxapram administration

increased respiratory rate and volume no impact on arterial PaO2 (potentially because the increased respiration results in increased O2 demands) reduce arterial PaCO2