Respiratory system drugs

Question 1

Why does O2 diffuse from the alveolar air to the blood?

Answer 1

Because the pO2 (partial pressure of O2) is higher in alveolar air that in the venous blood that reaches the lungs.

Diffusion aims to “even out” concentration gradients. From high to low.

The pCO2 is higher in the blood is higher – diffusion to the alveoli.

Question 2

What % of O2 is bound to hemoglobin.

Answer 2

About 98.5% of O2 is bound to hemoglobin.

The rest is dissolved in plasma.

Question 3

One hemoglobin molecule can transport how many O2 molecules?

Answer 3

One hemoglobin molecule can transport 4 O2 molecules.

When all the iron atoms in all the hemoglobin molecules in the blood have bound O2, the hemoglobin saturation is 100%.

Saturation is also influenced by pO2.

Question 4

Oxygen consumption per unit body mass is greater in ? than in ?

Answer 4

The oxygen consumption per unit body mass is greater in small animals than in large ones, in small mammals:

High density of capillaries
Low affinity of hemoglobin for O2

Question 5

Respiratory tract defense mechanisms broadly? (3)

Answer 5

Coughing
Sneezing
Production of secretions, change in viscosity of secretion.

Question 6

Describe coughing as a physiological process.

Answer 6

Protective reflex

Role: to remove secretions and foreign particles from the respiratory tract.

Coughing is also triggered by irritation of the mucous membranes due to inflammation, secretions and foreign particles.

Question 7

Cough receptors are located…?

Answer 7

in the mucous membrane of the respiratory tract, mainly at the back of the throat, in the throat, trachea, bronchi, as well as the pleural mucosa.

Signals from the receptors are carried through the vagus nerve to the cough centre.

Question 8

Cough centre is located in

Answer 8

the medulla oblongata and hypothalamus, controlled by the cerebral cortex.

As a result of reflex irritation, the signal is initially carried to the cough centre and thereafter from the centre to the muscles of respiration through motor nerve fibres.

Question 9

Steps of the Cough “mechanism”

Answer 9

1. Deep inhalation, resulting in the closure of the glottis.
2. Increase in the pressure in the lungs.
3. Thereafter, a violent exhalation occurs from the lungs following opening of the glottis. Secretions and foreign particles are also expelled together with the air.

Question 10

Types of cough (2)

Answer 10

Productive cough
Non-productive cough

Question 11

Describe a Productive cough

Answer 11

is a protective reaction, the respiratory tract is cleared of secretions, etc.

Question 12

Describe a non-productive cough.

Answer 12

This cough produces irritation in the respiratory tract, causes decreased blood flow and disorders of the respiratory system.

Pressure in the chest may increase, the blood flow to the heart will be disturbed, blood will accumulate in the brain.

It causes pain and distress to the animal.

Question 13

Cough suppression can be via one of two mechanisms. (2)

Answer 13

1) Direct suppression of the cough center

2) Reduction of irritation of the inflamed mucous membrane of the respiratory tract

Question 14

Substances suppressing the cough centre, name min. 2 opioids.

Answer 14

Codeine, hydrocodone (opium alkaloids that are part of the narcotic analgesics group)

Butorphanol (narcotic analgesic & antitussive)

(Codeine is partially metabolised in the organism into morphine. The effect of codeine itself on the central nervous system is substantially weaker than that of morphine. )

Question 15

Indication for cough suppressant opioids?

Answer 15

a dry, non-productive cough.

Question 16

Mechanism of cough suppression from antitussive opioids?

Answer 16

Suppression of the cough centre in the medulla oblongata.

Question 17

Name 2 Substances suppressing the cough centre, that are non-opioids.

Answer 17

Dextromethorphan – although it is part of the narcotic analgesics group, it is of a non-opioid nature.

Diphenhydramine - antihistamine

Question 18

Describe Dextromethorphan.

Answer 18

Although it is part of the narcotic analgesics group, it is of a non-opioid nature.

Does not have an analgesic or sedative effect.

It only causes depression of the central nervous system in very large doses.

Its effect on the cough centre is weaker than that of opioids.

It is frequently used together with antihistamines, mucolytic drugs or bronchodilators.

Question 19

Describe Diphenhydramine.

Answer 19

an antihistamine

The cough centre suppressant effect is unclear.

Use as a cough suppressant – contradictory data

Question 20

Another term for mucolytics.

Answer 20

Expectorants

Question 21

What are expectorants?

Answer 21

mucolytics

Substances aiding in the clearance of phlegm from the airways, mucolytic drugs.

They ease the excretion of secretions and inflammatory exudate from the respiratory tract.

Increase motility of ciliated columnal epithelium in bronchial region, thinning the secretions, irritating the bronchial mucous membrane, this in turn will increase the production of thin secretions.

Question 22

Bromhexine function.

Answer 22

It makes the secretions thinner.

It increases the permeability of the alveolar – capillary barrier, as a result of which antibiotics, for example, can more easily penetrate into lung tissue.

It increases the number of immunoglobulins in the bronchial secretions.

It is quickly absorbed and distributed when administered through the oral route.

Question 23

Name 4 mucolytic substances.

Answer 23

Bromhexine
Acetylcysteine
Dembrexine
Guaifenesin

Question 24

Describe Acetylcysteine’s role in respiratory disease therapy.

Answer 24

N-acetyl derivative of the amino acid L-cysteine.

It is used as a mucolytic and also for the treatment of paracetamol poisoning in dogs and cats.

It breaks down the di-sulfide bonds in mucoproteins, the sputum becomes thinner.

Binds paracetamol metabolites into conjugates.

As a bi-effect, it irritates the bronchial mucous membrane and may cause bronchial contraction in cats and dogs. Caution with asthmatics!

Question 25

Function of Dembrexine.

Answer 25

It makes the secretions thinner.

Used in horses as a preparation for oral use.

It is not used in human medicine.

Question 26

Describe guaifenesin function.

Answer 26

Mucolytic agent

Primarily used in horses as a preparation for oral use.

First used as muscle relaxant in anesthesia.

Efficacy questionable?

Question 27

Purpose of decongestants?

Answer 27

They „Dry up“ mucus membranes

Stimulate α-adrenergic receptors, cause local vasoconstriction and thus decrease resp. tract mucosa swelling.

Side effects!

Used in human medicine

Question 28

Name a topical and 2 systemic decongestants.

Answer 28

Topical: phenylephrine (spray)

Systemic: pseudoephedrine, phenylpropanolamine (tablets)

In veterinary medicine – phenylpropanolamine is used for treating urinary incontinence in dogs. (increases the tone of urinary sphincter (α effect) and relaxes the detrusor muscle of the bladder wall (β effect).)

Question 29

4 Herbal remedies used in resp. illness.

Answer 29

Common marshmallow
Liquorice root
Linden flowers
Breckland thyme

Question 30

Name 4 types of Bronchodilator agents. (so focus on class/mechanism)

Answer 30

1. Beta(2) - adrenomimetics
2. Antihistamines
3. Antimuscarinic agents
4. Methylxanthines (also referred to as methylated xanthines)

Question 31

Name min 4 Beta - adrenomimetics (adrenergic agonists) used in resp. illness.

Answer 31

Adrenaline

Isoprenaline, ephedrine

Terbutaline, salbutamol

Clenbuterol

Question 32

Describe Adrenaline for resp. illness.

Answer 32

use cautiously for the widening of the bronchi as there are cardiovascular side effects (both an alpha and beta agonist)

Question 33

What class of drugs are Isoprenaline and ephedrine?

Answer 33

non selective beta agonists

Question 34

What class of drugs are Terbutaline, salbutamol?

Answer 34

selective beta2- agonists, used in small animals

Question 35

What class of drug is Clenbuterol?

Answer 35

Clenbuterol - selective beta2- agonist, used in horses and cattle.

Question 36

Function of terbutaline?

Answer 36

Produces β2-receptor-relaxation in bronchial, vascular and uterine tissues.

Little effect on β1 receptors.

To be used with care in patients with pre-existing cardiac disease, diabetes, hypertension, hyperthyroidism.

Salbutamol – similar to terbutaline.

Question 37

Function of clenbuterol?

Answer 37

For treatment of recurrent airway obstruction (RAO), formerly „chronic obstructive pulmonary disease“ in horses.

Muscle relaxants also for cattle, it can be used for relaxation of uterus, but rarely.

Clinical efficacy questionable?

Question 38

Name 3 Antimuscarinic agents that act on the airways.

Answer 38

Atropine
Glycopyrrolate,
propantheline

Question 39

Describe atropine’s actions on the respiratory system.

Answer 39

in addition to the widening of the bronchi, a large number of side effects exist (tachycardia, decrease in the gastrointestinal motility and urinary tract muscle tone, etc.).

It is only used in case of a life-threatening bronchospasm caused by anticholinesterase substances (cholinesterase inhibitors, also known as indirect acting cholinomimetics).

Even then, it is recommended to administer beta - adrenomimetics or glucocorticosteroids in addition.

Question 40

Describe Glycopyrrolate, propantheline actions on the respiratory system.

Answer 40

Antimuscarinic bronchodilators, spasmolytics in small animals, there are less side effects.

Question 41

Give 4 examples of Methylxanthines.

Answer 41

Theophylline,
euphyllin,
aminophylline,
theobromine

Question 42

Describe Methylxanthines.

Answer 42

E.g. Theophylline, euphyllin, aminophylline, theobromine.

These substances relax the smooth muscle of the bronchi.

They increase the activity of the diaphragm.

They also increase cardiac contractility, activity of the central nervous system and diuresis.

An overdose leads to tachycardia, shortness of breath and cramps.

Question 43

Describe some synergism that occurs with theophylline. (3)

Answer 43

Effects of theophylline and β-blockers may be antagonized if they are administered together.

Theophylline increases the likelihood of arrhythmias induced by adrenergic agonists and halothane.

Theophylline increases the likelihood of seizures with ketamine.

Question 44

What is tildipirosin?

Answer 44

An antibiotic used in the treatment of Bovine Respiratory Disease (BRD) associated with sensitive Actinobacillus pleuropneumoniae, Pasteurella multocida, Bordetella bronchiseptica and Haemophilus parasuis.

Question 45

in the case of asthma, or chronic non-infectious inflammatory respiratory diseases, what drug class should be used?

Answer 45

glucocorticosteroids

Question 46

Name 2 Respiratory system stimulants.

Answer 46

doxapram
Heptaminol + diprophyllin combo

Question 47

Describe Doxapram.

Answer 47

Is a central nervous system stimulant.

Used for the stimulation of breathing during and after anesthesia in dogs, cats and horses.

Acts via aortic and carotid sinus chemoreceptors.

Contraindicated in the case of asthma, pulmonary embolism, pulmonary oedema and collapsed lung (smooth muscle contractions).

Side effects are an increase in blood pressure, cramping.

Question 48

Describe the drug combo Heptaminol + diprophyllin.

Answer 48

Supportive treatment in case of acute cardiovascular and/or respiratory insufficiency.

Heptaminol is a cardiovascular analeptic (a CNS stimulant), effect related to peripheral release of norepinephrine.

Ino- and chronotropic action. Increases blood flow in aorta and coronary arteries.

Diprophyllin is a bronchodilator.

Question 49

Describe asthma.

Answer 49

Bronchoconstriction + inflammation in the respiratory tract.

The release of inflammatory mediators triggers an asthma attack.

The inflammation process triggers the permeability of the epithelial layer of the mucous membrane with regard to inflammatory mediators (histamine, cholinergic stimulants).

The mediators thus more easily reach the nerve endings located in mucosa, cholinergic bronchoconstriction occurs.

The vascular permeability of the blood vessels and the production of mucus increase.

The mucosa sustains damage due to the inflammation and becomes extremely sensitive to mediators (vicious circle, an incurable disease).

Question 50

Describe the treatment of asthma.

Answer 50

Is complex.
Aim is to widen the bronchi + treatment of the inflammation (NSAID, steroids, antibiotics) + mucolytic drugs + antihistamines.

Question 51

Define emphysema.

Answer 51

Narrowing of the airways, leads to increased resistance of airflow. The alveoli become abnormally inflated, damaging their walls. Expiration is primarily affected.

Increased flow resistance → elevated pressure in lungs.

Total area available for diffusion is reduced.

Results in severe deficiency of O2 in tissues.

Emphysema leads to increased CO2 supply in body fluids, causing respiratory acidosis.

Question 52

Treatment of emphysema

Answer 52

Bronchodilators
Corticosteroids
NSAIDs
Other?