Flashcards in L56 – Principles of Respiratory Pharmacology Deck (79):
What are the afferent sensory nerves from the airways to the CNS?
Periphery (airway) >> nodose ganglion >> CNS (brain stem)
Periphery (airway) >> dorsal root ganglion >> CNS (spinal cord)
What are the 2 efferent nerves from the CNS to the airways?
Parasympathetic nerve > Vagus
Give pathway of vagus nerve from preganglionic nuclei to muscarinic receptors? (from brain stem to lungs)
preganglionic nuclei in brain stem >> Release Ach to nicotinic receptors in nodose ganglion >> post-ganglionic fibers >> Release Ach to muscarinic receptors
What are the 3 types of muscarinic receptors in the lungs?
M1, M3 on:
Bronchial smooth muscle
What does the efferent parasympathetic vagal nerve innervate in the airways?
Bronchial smooth muscle (constrict)
Submocosal glands (secrete)
What do the sympathetic nerves innervate in the airways?
NOT bronchial smooth muscle
In asthma patients, which muscarinic receptor is dysfunctional?
In the parasympathetic vagal nerve ending:
M2 dysfunctions >> all Ach released in vagal nerve to M1, M3
Normally M2 acts as autoreceptor and inhibits Ach release to M1, M3
Give the INDIRECT pathway of sympathetic nerve from CNS to airway?
Preganglionic fibers >> release Ach to nicotinic receptors on Adrenal medulla > secrete Adrenaline through blood circulation > binds to β2 receptors on bronchial smooth muscle > airway relaxation
Give the DIRECT pathway of sympathetic nerve from CNS to airway?
Preganglionic neurons in sympathetic chain ganglia (T1-L2) of spinal cord > cervical thoracic ganglion > innervate submucosal glands, blood vessels
What is the role of respiratory stimulants?
Help increase the urge to breathe in the treatment of respiratory failure
What is the action of Doxapram (resp. stimulant)?
CNS stimulant > acts on both:
a) carotid chemoreceptors +
b) respiratory centre in brain stem
to increase respiration
How does breathing pattern and blood gas change after taking Doxapram?
Increase respiratory rate and tidal volume
Fall in pCO2, Increase in pO2
Route of admin for Doxapram?
3 target patient groups of Doxapram?
Preterm infants with apnea
Old patients with sleep apnea
COPD patient with acute resp. failure
What is the action of respiratory depressants?
Diffuses into cell membranes of nerve cells
>> inhibits passive neuronal flux of Na+
>> stop respiration
Name some respiratory depressants?
A BB HEN
H1-histamine receptor antagonists (promethazine)
Narcotic analgesics (opioids: morphine, codeine)
What is the risk of taking excessive respiratory depressant?
Excessive dosage = decrease sensitivity of respiration to CO2 and abolish hypoxic drive
What receptors regulate hypoxic drive of respiration?
@ carotid and aortic bodies
What drugs provoke asthma?
NSAIDs: Aspirin, ibuprofen
Nonselective beta-adrenergic receptor antagonists (Beta-blockers)
Explain how NSAIDs can lead to bronchoconstriction?
NSAIDs block cyclooxygenase in the Arachidonic acid pathway > inhibit synthesis of lipid mediators of inflammation
All Arachidonic acid directed to 5-lipoxygenase pathway to make Leukotrienes >> potent bronchoconstrictor
Airway smooth muscle B receptor is the same or different from heat B receptor?
Heart = B1
Airway SM = B2
How does propanolol act on the heart and the airway?
Propanolol is a NON-selective Beta blocker
> block both B1 on heart and B2 on airway smooth muscle
Can propanolol be used with inhaler?
Opposite action, contraindicate
What are the 3 types of drugs used to treat coughs?
Name some causes for production of cough?
Drug induced cough
Environmental: irritant, dust, smoking...
Chronic pulmonary ailments
Upper respiratory tract infection
Name one drug for heart problems that can cause cough?
2 types of cough?
Productive/ Congested cough (remove excess secretions)
Non-productive/ Dry cough
Antitussives is only used for which type of cough?
ONLY for Non-productive/ dry cough
What is the function of Antitussives?
Suppress the intensity and frequency of coughing
What is the site of action for antitussives?
Peripheral or Central nervous system
How does antitiussive affect peripheral nervous system to decrease intensity and frequency of coughing?
DECREASE sensitivity of peripheral sensory ‘cough
receptors’ in pharynx and larynx to irritation
How does antitiussive affect Central nervous system to decrease intensity and frewquency of coughing?
DECREASE sensitivity of cough centres in medulla
oblongata to peripheral stimulus
>> Decrease cough reflex
Different administrations for Antitussives acting on peripheral NS?
Above larynx = Oral = use demulcent, e.g. syrups, lozenges
Below larynx = Inhalation = inhale water aerosol, warm environment
What are the 2 classes of antitussives that act on the CNS? Which one is more popular?
Codein (opioid/ opiate agonist)
Dextromethorphan (non-opiod) ** more popular **
Why is codein rarely recommended for children?
What are the gross effects of codeine? good and bad effects
Produce constipation, nausea, respiratory depression
Strong cough suppressant
What is the action of Dextromethorphan?
Selectively depresses the cough center in medulla oblongata
What are some side effects of Dextromethorphan?
Mild and rare:
Compare the adverse effects between Codeine and Dextromethorphan?
Codein = addictive, euphoria, respiratory depression, constipation
Dextromethorphan = No addictive, no euphoria, no respiratory depression, no constipation
Which antitussive is over the counter, which is not?
Codein (opioid) is prescription drug
Dextromethorphan is OTC
What is the function of expectorants?
Act locally to help remove secretions/ exudates from the trachea, bronchi, lungs
How do expectorants change the mucus and affect the CNS?
Stimulate mucin secreting cells:
Produce increased volume of thinner mucin with
high water content (low viscosity)
Increased mucin > Stimulate cough centre to help clear the bronchial tract
Name one expectorant
Compare the action between expectorants and mucolytics on mucus? *think volume*
Mucolytics = decrease viscosity of mucus but **Not change volume of mucus**
Expectorants = Decrease viscosity of mucus BY CHANGING VOLUME
Explain the action of Mucolytics on mucus?
Break disulphide bonds cross-linking mucus glycoprotein molecules >> thinner mucin > easier to clear
Why is mucolytics especially good for bronchitis patients?
Bronchitis patients produce very thick sputum with many polysaccharide fibres
Name 3 mucolytics? NBC
What is Dornase Alpha?
Recombinant human deoxyribonuclease I
Why is Recombinant human deoxyribonuclease I (dornase alpha) used for patients with cystic fibrosis? (think DNA)
CF > DNA leak out of dead neutrophils makes mucin very thick and tenacious >> Viscous purulent exudate
Dornase Alpha has rhDNase I to hydrolyze extracellular DNA in mucus >> decrease viscosity
Name the 2 types of pulmonary surfactants and give an example for each?
Natural surfactant = Curosurf
Synthetic surfactant = Colfosceril
Action of pulmonary surfactant?
Decrease surface tension of alveoli > prevent alveoli collapse
How are pulmonary surfactants administered?
Endotracheal tube directly into pulmonary tree
When are pulmonary surfactants used?
Management of respiratory distress syndrome (esp. premature babies)
What is oxygen therapy used for and what is the threshold in PaO2 for starting it?
Used in the management of acute pulmonary disorders, Chronic obstructive diseases
Used when PaO2 falls below 55mmHg/ 7.3kPa
What are the 2 effects of drugs used to treat COPD?
Dilate airway smooth muscle
Inhibit airway inflammation
What type of HS is allergic rhinitis?
Describe the symptoms caused by allergic rhinitis?
nasal congestion, itching, redness, sneezing, runny nose, teary eyes
What is the drug used for allergic rhinitis and what is the action?
H1 Antihistamines (H1 receptor antagonist)
Block histamine released by Mast cells from receptor >> stop vasodilation and stop increased capillary permeability
Name 2 first generation H1 antihistamines and name the side effects? CD
Sedative/ drowsiness/ dizziness
Hypotention and dry mouth
Why is the second generation of H1- antihistamines non-drowsy?
2nd gen. works peripherally to block action of histamine
**NEVER CROSSES BBB
Name the three 2nd generation H1 Antihistamines and name which ones are OTC or not.
Fexofenadine : potent, effective,prescription
What are some other effects of 2nd generation H1 Antihistamines apart from treating allergic rhinitis?
anti-emetic, local anaethesia (if high dose)
What is the function of decongestants?
Reduce congestion of nasal passages
>> open clogged nasal passages, enhances drainages of sinuses
What are the 2 decongestants? PP
Phenylephrine > selective α1-adrenergic agonist
Pseudoephedrine > sympathomimetic drug
What is the action of Phenylephrine ?
Constrict dilated arterioles in nasal mucosa and reduces airway resistance
2 forms of phenylephrine? Compare their onset and systemic effects?
Aerosol: rapid onset of action, few systemic effects
Oral: longer duration, more systemic effects
Name one combo therapy (1 pellet containing 2 classes of respiratory drug)
cetirizine (2nd generation antihistamine)
What is the function of a glucocorticoid nasal spray?
anti-inflammatory drug, immune suppressor
What is the function of Cromolyn sodium? When is it mostly used?
Intranasal spray > Anti-allergic mast-cell stabilizers
Mostly for prophylaxis: stop mast cell degranulation to avoid allergic rhinitis
What drug classes do the following drugs belong to:
Dextromethorpan = non-opioid Antitussive
Guaifenesin = expectorant
Dornase alpfa = mucolytics
Phenylephine = selective α1-adrenergic agonist decongestant
Chlorpheamine = 1st gen H1 antihistamine
Doxapram = resp. CNS stimulant
3 routes of administering resp. drugs?
Nasal spray (topical )
Which method of resp. drug admin. results in lowest effective dose and least side effects?
Greatest and quickest deposition of drug into lungs
What are the 3 types of inhalation devices? Which one is most common
pressurized Metered-dose inhaler (pMDI)
Dry powder inhaler (DPI): Turbuhaler and Diskhaler
*DPI is most common
What drugs are put into pMDIs? (4)
-Short acting B2 agonist
Compare the propellant in pMDI and DPI? Which needs coordinated inhalation?
pMDI = CFC profellant, need coordinated inhalation
DPI = no propellant, no need for coordinated inhalation
Which type of drug delivery system is not great for patients with low Peak Expiratory Flow Rate?
Dry powder inhaler
Problem in patients with low PEFR (<60L/min)
What is the site of pulmonary absorption via inhalation?
Pulmonary epithelium, mucosa of respiratory tract
What are some advantages of pulmonary absorption via inhalation? Disadvantages?
Advantages: fast at site of action, avoid hepatic first pass
Disadvantages: poor to regulate doses, cumbersome, local irritation (e.g. dry cough, dry mouth)