Unit 8 - Respiratory Drugs Flashcards
What is doxapram?
A respiratory stimulant, emerg drug and brain stimulant
stims breathing if apnea or bradypnea
Reveres resp depression caused by CNS depressants (premeds, anesthetics)
Can use w/ opioi-induced resp depression if antagonists not available
S/e: due to non-specific brain stimulation = aggression, tremors, seizure, inc BP, arrhythmia)
give 1 drop under tongue of C-sec puppies
2nd choice to true reversal
Naloxone if opioid premed
yohimbine, antiseden if A2-premed
What does an antitussive mean? What is an example of it?
Used to treat non-productive (dry) coughs. Productive is normally indicated by a swallow afterwards
Ex. collapsing trachea; tracheitis from kennel cough, heart enlargement (heart pushes on trachea)
How do antitussives work?
stops by blocking cough reflex
1. centrally acting - act on cough center loc in the brain stem
2. local acting - sooth and coat the mucus lining where there is inflam/trauma/irritation so signals not sent to cough center
What are some locally acting antitussives OTC for dogs and horses?
buckley’s Zev OTC
may have some herbs that test pos a competitions so stop use 4 days before
What is dextromethorphan
(DM)
not controlled, easily found OTC
benylin - DM, robitussin - DM
often mixed w/ other drugs including acetaminophen, ibuprofen (must read labels)
How do opioids work as antitussives?
excellent cough suppresion. more effective than DM. controlled. can be addictive so risk of owner abuse
antitussive dose has no resp depression, minimal analgesia, possible constipation w/ chronic use, may see mild sedation
butorphanol, hydrocodone, codeine
what are expectorants and mucolytis?
for productive cough - increase fluid secretion in airways or reduce viscosity of airway mucus = mucus easier to remove. must keep patient hydrated, inhaled steam helps too
What role does guaifenesin play in respiratory drugs?
expectorant and mucolytic
expectorant in human OTC cough meds, mostly used for anes in vet patients
What role does sodium iodine play in resp drugs?
expectorant and mucolytic
cattle/horses given IV, not in preg or hyperthyroid patients
What role does dembrexine (sputolysin) play in resp drugs
mucolytic and some antitussive properties
oral powder for horses
What role does acetycysteine (mucomyst) play in resp drugs?
human product
oral, IV, nebulized
more commonly used to tx acetaminophen toxicity in cats
How do decongestants work?
A1 receptor agonist = vasoconstriction of vessels in MM = dec edema and secretions
BUT, most have some B1 activity therefore cause in HR as a side effect
commonly found in human cough/cold meds - Ex. pseudoephedrine, ephedrine, phenylephrine (poor oral bioavailability)
How do we treat asthma?
- remove any allergic triggers and dust
- anti-histamines; used more as prevention than treatment
- dilate airways - bronchodilators (very mild effect w/ anti-histamines
- Reduce inflammation - steroids - fluticasone, prednisolone, dexamethasone
What are anti-histamines and some commonly used drugs?
H1-blockers, blocks histamine from binding to receptors. they are better for longterm PREVENTIOn than tx; used in COPD, allergy, asthma
S/E: sedation; anticholinergic effects (dry mouth)
Pyrilamine - powder labeled for horses (with ephedrine)
Diphenyhydramine (benadryl) OTC human label, oral, injectable
What are some options of bronchodilators?
- beta-2 adrenergic agonists
- methylxanthines (aminophylline, theophylline) - CNS stimulation like caffeine
- Anticholinergic (atropine) - emergency/CPR bronchidilator
- Antihistamines - very mild bronchodilation; inhibits the histamine response that causes inflamm
What are b2 adrenergic agonists?
airway irritation leads to bronchoconstriction
b2 adrenergic agonists bind to and activate b2 receptors in the lungs causing bronchodilator and stabilize mast cells = less histamine response
Salbutamol (ventolin), terbutaline, albuterol - given w/ an MDI dispenser(puffer), in small anims, local admin dec dose and systemic s/e
Indicated for collapsing trachea, asthma. s/e is stim of b1-receptors in heart inc HR
What does MDI stand for?
meter dose inhaler. its a puffer
What b2 adrenergic agonists are used for equine asthma?
clenbuterol (ventipulmin) oral syrup/injectable
caution at end of pregnancy - reduces uterine contractions
What are methylxanthines?
theophyline, aminophylline
Related to caffeine, theobromine (in chocolate)
available in injectable and oral form
less commonly used than the b2-agonists due to more s/e: GI irritation (Vomiting, nausea), CNS stimulation (excitement, tachycardia)
can alter liver metabolism of other drugs
Low TI so easy to overdose
How are steroids used as resp drugs?
no bronchodilatory effect
used to treat inflam component of lung dz - in feline/equine asthma or w/ infection/neoplasia where edema and inflam are damaging lungs
can be given systemically with more s/e or as an inhaler (don’t use in breeding horses)
What are the side effects of using steroids for resp drugs? WHat is a common drug used?
depends on dose and chronicity (see previous notes), inhaler has fewest s/e. but can inc risk of secondary airway infection
fluticasone as inhaler (flovent)
$$$ - can be chronically along w/ a b2-adrenergic agonist, always give b2 agonist first
Why is local delivery of airway drugs preferred?
- inc conc at site of action
- dec systemic s/e
- faster onset of action
What is the preferred delivery of b2 adrenergic agonists and steroids for tx of asthma/COPD?
local delivery
What are the 2 local delivery methods?
nebulizer
measured-dose inhaler (MDI
