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What is the purpose of decongestant drugs?
to relieve runny, congested nasal passages
Are decongestants more effective in people or in animals? Are decongestants used much in animals?
people. not used much in animals
How do decongestants act?
by stimulating alpha 1 (adrenergic, sympathetic) receptors. may also affect beta 1 adrenergic receptors
Does stimulation of alpha 1 receptors cause vasoconstriction or vasodilation of blood vessels in nasal mucous membranes? What is the result of alpha 1 stimulation?
vasoconstriction - causes nasal mucous membrane swelling and secretions to decrease
If decongestants also stimulate beta 1 receptors, is this an advantage or a disadvantage?
can be a disadvantage - beta 1 stimulations causes the heart to beat harder and faster, and may cause cardiac arrhythmias
List 4 decongestant drugs mentioned in class.
For what non-decongestant purpose is phenylpropanolamine used in dogs?
treatment of spay incontinence
Why was use of phenylpropanolamine discontinued in people?
increased risk of stroke. there are plenty of other good decongestant drugs for use in people - we do not need this one
Are antihistamines more useful in people or in small animals? Why?
in people. small animals do not have as many H1 receptors as people.
What is histamine?
a substance found in granules in mast cells throughout the body, including in the respiratory tract. it is involved in inflammatory reactions, and has many effects in the body
What are H1 receptors, and where are they located?
a particular type of histamine receptor. located on bronchiolar smooth muscle.
What happens with histamine molecules combine with H1 receptors?
bronchoconstriction - bronchiolar smooth muscle contracts
How do antihistamines act?
by blocking histamine H1 receptors on bronchiolar smooth muscle
When is the best time to use antihistamines - before or during the event that causes histamine release (often an allergic reaction)?
before - antihistamines work best if they get to the H1 receptors first, before the histamine does
List 4 antihistamine drugs mentioned in class
- diphenhydramine - Benadryl
- dimenhydrinate - Dramamine
- pyrilamine - Hi stavet
- hydroxyzine - Atarax
What are 3 main causes of bronchoconstriction?
- parasympathetic stimulation
- histamine release
- blockage of sympathetic beta 2 receptors
What does stimulation of sympathetic adrenergic beta 2 receptors on bronchiolar smooth muscle cause?
What are the 2 main categories of bronchodilator drugs?
- beta agonists (beta adrenergic agonists)
Which are preferred for bronchodilation - selective beta 2 agonists or general beta agonists? Why?
selective beta 2 agonists are preferred for bronchodilation. they do not stimulate the heart, possible leading to arrhythmias, as the general adrenergic agonists do
List 3 selective beta 2 agonist bronchodilator drugs
List 3 general beta agonist drugs (affect both beta 1 and beta 2 receptors, some alpha 1).
A patient in moderate congestive heart failure needs a bronchodilator. Would epinephrine be an appropriate drug to use in this patient? Why or why not?
no. this patient does not need his heart speeded up and prone to arrhythmias
Methylxanthines are also bronchodilator drugs. Do they affect beta receptors? How do they work?
no, methylxanthines do not affect beta receptors. they directly affect the metabolism of bronchiolar smooth muscle cells, causing them to relax
List methylxanthine bronchodilator drugs. Which one causes the least GI upset?
- aminophylline, theophylline
- aminophylline causes the least GI upset
If a bacterial infection of the respiratory tract is suspected, what ideally should be done before starting antibiotic therapy?
culture and sensitivity (C&S) - confirm the infection, identify the bacteria, and determine the most effective antibacterial drug to use
If the usual routes of administration (PO, IM, SQ) do not deliver a high enough concentration of antibacterial drug to the infection site in the lumens of the airways, what other method of administration can be used?
When may corticosteriods be useful in respiratory disease?
to reduce swelling, inflammation, airway edema - as in feline asthma, smoke inhalation, allergic reactions
When may corticosteroids be harmful to respiratory disease?
when infection is present - suppresses immune system, delays healing
List 2 short - acting corticosteriod drugs.
Are NSAIDs (non-steroidal anti-inflammatory drugs) used for respiratory problems? Why or why not?
no - they block formation of prostaglandins, including beneficial lung prostaglandins that help to maintain bronchodilation
What do diuretics do, and why are they useful in certain types of respiratory problems?
remove excess fluid from the body and from the lungs. fluid accumulation in the lungs due to congestive heart failure, pneumonia, etc. impairs gas exchange in the lungs
Can diuretics be harmful in patient with respiratory problems? How?
yes - can dehydrate the patient and dry out respiratory and nasal secretions, making it harder for the patient's mucociliary apparatus to remove the secretions - may result in blockage of airways
What is the most commonly used diuretic in veterinary medicine?
furosemide - Lasix
In veterinary patients, is oxygen usually used for short - term or for long - term therapy? Why?
short - term - animals do not tolerate the necessary confinement and tubes very well - would tend to struggle, which is very bad for respiratory patients