Respiratory pharmacology Flashcards
(42 cards)
What is a cough?
Cough = a protective mechanism that prevents the lungs from aspiration (entry of foreign material) and a common symptom of respiratory disease.
What are useless coughs? What conditions cause this? Should it be suppressed?
- Persistent and unproductive- dry cough
- Asthma, oesophageal reflux, sinusitis, psychogenic (cough when you over think about coughing)
- Should it be supressed- yes- cough suppressants are called antitussives- remember to treat underlying cause
What are useful coughs? What is an example of this? Should it be suppressed?
- Persistent and unproductive- dry cough
- Asthma, oesophageal reflux, sinusitis, psychogenic (cough when you over think about coughing)
- Should it be supressed- yes- cough suppressants are called antitussives- remember to treat underlying cause
What is the mechanism of a cough?
Cough receptors or lung irritant receptors to cough centre in medulla to vagal simulation leading to cough
What is a linctus?
A cough preparation that gently soothes and relieves your child’s cough
What are dry cough suppressants?
Afferent side- reduce stimuli
Efferent side- medullary cough centre
Where is the afferent side?
- Above larynx: Linctuses (demulscents)
* Below larynx: Steam inhalation- nebulised local anaesthetics (numb efferent receptors in larynx or trachea)
Where is the efferent side?
- Opiods (codeine, methadone, pholcodeine)- side effects making people sleepy, can cause overdose
- Non opiods (dextromethorphan, noscapine)
- Sedatives: diphenhydramine, chlorpheniramine
What do expectorants do?
A medication that helps bring up mucus and other material from the lungs, bronchi, and trachea.
How do expectorants work? What are these drugs?
Increase volume of secretion- making them R more
-Guaiphenesin, ipecacuanha, oils
What do mucolytics do?
Medication that thins mucous
How do mucolytics work and what are these drugs? What is an example of a disease that patient need mucolytics for?
- Decrease the viscosity- provide more fluidity
- Acetyl cysteine, carbocystine, mecysteine
- Recombinant human DNAse
- Cystic fibrosis
What are the most common obstructive pulmonary diseases?
Upper airways cough syndrome (post nasal drip)
- Bronchial asthma
- Chronic Obstructive Pulmonary Disease (COPD)
- Gastroesophageal reflux disease
What are the four types of bronchial asthma?
- Asthma associated with allergic reactions- IgE mediated
- Asthma not associated with specific allergen- intrinsic asthma
- Exercise induced asthma
- Asthma associated with COPD- due to obstructive of elastic tissues in the airways
How does bronchoconstriction occur ?
When exposed to antigen, lymphocyte system is activated, T cells stimulate B cells and make lots of IgE’s. IgE’s bind to mast cells and then become activated. Release mediators which activate pathways which secrete substances. They then cause inflammation of mucosa, swelling of the mucosa layer and constriction of smooth muscle leading to bronchoconstriction.
How to treat asthma?
• Prevention of Ag:Ab reaction
• Non-specific reduction of bronchial hyperactivity:
-Nonpharmacological: Stop smoking, weight reduction
-Pharmacological: Corticosteroids
• Dilatation of narrowed bronchi:
-Mimicking dilator neurotransmitter: Sympathomimetics
-Direct acting bronchodilators: Methylxanthines
-Blockade of constrictor transmitter: Anticholinergics
• Prevention of release of transmitter
-Mast cell stabilisers
• Antagonism of released transmitter:
-Leukotriene receptor antagonists
Prevention of Ag:Ab reaction- how does it work?
• Avoidance of allergen:
-Difficult to find
-Insufficient evidence
• Avoidance of tobacco and weight reduction
Non-specific reduction of bronchial hyperactivity- how does it work?
• Corticosteroids
- Anti-inflammatory
- Inhibition of influx of inflammatory cells after exposure
- Reduced micro-vascular leakage: decreased oedema
- Inhibit release of mediators i.e. cytokines
- Inhibition of cyclooxygenase enzyme
• Reduced bronchial reactivity:
- Reduce asthma exacerbations
- Don’t relax bronchial smooth muscle
What are corticosteroids?- Inhaled and exhaled
• Inhaled corticosteroids (ICS): Brown inhaler -Beclomethasone, Budesonide -Fluticasone, Flunisolide, Triamcinolone -First line regular therapy (mild to mod Asthma) • Oral corticosteroids -Prednisone, Methylprednisolone -Betamethasone and Triamcinolone -Severe asthma (status asthmaticus)
What are corticosteroid adverse effects?
• Iatrogenic: Cushing’s syndrome
-Diabetes, hypertension, Peptic ulcer, psychosis, delayed puberty
• Inhibition of hypothalamic pituitary axis
• Other side effects
-Oropharyngeal candidiasis
-Hoarseness: direct effect vocal cords
What risks are minimised from corticosteroids?
• Inhalational route
• Administration in early morning
• Gargle and spit after every treatment- reduce oropharyngeal candidiasis and reduce hoarseness
• Newer drugs- cyclesonide- prodrug- activated in bronchial epithelium
- When absorbed in circulation very tightly bound to proteins and thus little effect on glucocorticoid receptors elsewhere
What are mast cell stabilisers?
• Cromolyn sodium, Nedocromil sodium
• Inhibit release of mast cell mediators
• Administered by inhalation and very poorly absorbed
• No effect on bronchial smooth muscle
-No use in acute bronchospasm
• Only valuable if taken prophylactically
-Main uses: Allergic rhinitis, allergic conjunctivitis
-Side effects: Throat irritation, cough, dermatitis, myositis, gastroenteritis
What inhibits leukotriene synthesis?
- Inhibit 5-lipoxygenase
- Zileuton (discontinued) – liver toxicity
What are the inhibitors of leukotriene receptors?
Inhibitors of leukotriene receptors
-Inhibit binding of leukotriene to receptor- Montelukast, zafirlukast
