Respiratory pharmacology Flashcards
Antihistamine
What are the drugs names and clinical indications?
What is the MOA?
What are the adverse side effects?
What are the warnings?
names:chlorphenamine (1st generation), cetirizine, loratidine, fexofenadine
Clinical indications:
- Allergies (including hayfever)
- Aid in pruritus and urticaria (hives)
- Adjunct to anaphylaxis treatment
MOA:
- allergen binds onto IgE receptor on mast cell, causes degranulation of histamine
- Histamine binds to H1 receptors on tissues like BV to stimulate allergic effects. Antihistamines antagonize that.
Adverse side effects:
- chlorphenamine (1st generation) causes sleepiness due to role of histamine being important in wakefulness.
Warnings:
- Chlorphenamine not to be used in those with chronic liver disease as it can cause hepatic encephalopathy
Beta 2 agonists
What are the drug names?
What are common indications?
What are mechanism of action?
Important adverse effects?
Warnings?
Important interactions?
- Drugs- short acting (salbutamol, terbutaline); long acting (salmeterol, formoterol)
- Common indications:
- asthma (LABA must be used with ICS if not lactate may cause asthma deaths)
- COPD
- hyperkalaemia (along with insulin, glucose, calcium gluconate)
- MOA
- stimulate B2 adrenergic receptors in airways-> smooth uscle relaxation and bronchodialtion
- stimulate Na+/K+ ATPase pump-> K+ goes into cell while Na+ goes out-> decrease in extracellular K+
- Adverse effects
- tachycardia, palpitations, tremor, anxiety (fight or flight response) due to activation of B2 receptors in other tissues
- increase in lactate-> muscle cramps
- Warnings
- not to be given in CVS disease-> increase risk of arrhythias
- LABA must be given with ICS for asthma-> if not increase risk of asthma deaths
- Important interactions
- not to be used w B blockers
Antimuscarinics, bronchodilators
What are the drug names?
What are common indications?
What are mechanism of action?
Important adverse effects?
Warnings?
Important interactions?
- Drug names-short acting (ipratroprium); long acting (tiotropium, glycopyrronium)
- Common indications
- asthma
- COPD
- MOA- antagnoize muscarinic Ach receptors, preventing PNS, “rest and digest effects”
- eyes: pupil dilation and prevent acommodation of eyes (unable to read in short distances)
- heart: tachycardic
- respiratory tract: reduce glandular secretion and cause bronchodilation
- digestive tract: reduce glandular secretion
- Important adverse effects
- dry mouth
- Warnings
- don’t give those with angle-closure glaucoma as this will further relax ciliary muscle and cause increase in intraocular pressure
- Important interactions
- no systemic absorption so few side effects
Corticosteroids
What are the drug names?
What are common indications?
What are mechanism of action?
Important adverse effects?
Warnings?
Important interactions?
- Drugs names- beclomethasone, budesonide, fluticasone
- Common indications
- asthma
- COPD
- MOA
- passes through cytoplasm and binds to receptor-> complex activates genes in nucleus-> increasing anti-inflammatory mediators and decreases pro-inflammatory mediators
- Important adverse effects
- oral candidasis in mouth; may spread to VC causing hoarse voice
- pneumonia in COPD patients
- growth suppression in children
- Warnings
- should not be used in COPD patients with pneumonia
- or in children due to growth suppression
Phosphodiesterase 5 inhibitors
What are the drug names?
What are common indications?
What are mechanism of action?
Important adverse effects?
Warnings?
Important interactions?
- sildenafil
- for erectile dysfunction
- for primary pulmonary hypertension
MOA-it inhibits PDE5, increases cGMP and therefore improves vascular smooth muscle relaxation
Adverse effects-hypotension, flushing, dizziness due to reduced BP. Increased compensatory tachycardia and palpitations. At risk of priaprism and visual defects (due to inhibition of PDE6)
Warnings- do not give with haemorrhagic stroke and ACS as this will increase bleeding.
Important interactions-do not give with nitrates and nicorandil as this further increases cGMP and may cause cardiovascular collapse. Do not give with alpha blockers and calcium blockers as this may cause further CVS collapse.
O2
What are different forms of O2?
What are common indications?
What are mechanism of action?
Important adverse effects?
Warnings?
Important interactions?
What are different forms of O2?
- Venturi mask-deliver air with fixed amount of O2. Used for type 2 RF (24-28% O2)
- Reservoir mask-with reservoir bag that delivers 15l O2/min
- Nasal cannulae-deliver 2-6l O2/min
- Variable mask-deliver variable amount of O2
What are common indications?
- Hypoxaemia
- Pneumothorax
- CO poisoning
What are mechanism of action?
- Hypoxaemia-increase PaO2
- Pneumothorax- decreases %of Nitrogen in alveolar gas. Pleural gas has a lot of nitrogen-> increases diffusion gradient.
- CO poisoning-> decrease half life of carboxyhaemoglobin
Important adverse effects?
- Face mask discomfort
- Dry throat due to reduced water vapour
Warnings?
- Careful in T2RF-> increase risk of hypercapnia and risk of respiratory acidosis
- Avoid O2 use in naked flame
A 72-year-old man with hypertension, COPD and irritable bowel syndrome sees his GP for a medication review. His medicines are amlodipine, doxazocin, fluticasone, hyoscine butylbromide, ipratropium and salmeterol.
Which receptors have been activated by this treatment?
A. Alpha1-adrenoceptors
B. Alpha2-adrenoceptors
C. Beta1-adrenoceptors
D. Beta2-adrenoceptors
E. Muscarinic receptors
D. Beta2-adrenoceptors. Beta2-adrenoceptors are activated by salmeterol, a long-acting β2-agonistbronchodilator.
Doxazocin is an α-blocker, which antagonises α1-adrenoceptors. Ipratropium and hyoscine butylbromide block muscarinic receptors (see Antimuscarinics, bronchodilators and Antimuscarinics, cardiovascular and gastrointestinal uses, respectively). Amlodipine is a calcium channel blocker. Fluticasone is an inhaled corticosteroid which activates glucocorticoid receptors to influence gene transcription.
A 12-year-old boy sees his general practitioner following hospital admission for an acute asthma attack. He has made a good recovery and is now asymptomatic.
What is the most appropriate treatment to prevent future asthma attacks?
A. Beclometasone
B. Formoterol
C. Chlorphenamine
D. Ipratropium
E. Salbutamol
A. Beclometasone. Corticosteroids such as beclometasone suppress inflammation in the airways, addressing underlying cause. Topical administration by inhaler reduces systemic side effects.
Ipratropium (an antimuscarinic) and salbutamol (a β2-agonist) are short-acting bronchodilators. They are used to relieve breathlessness in acute attacks. They may also be taken before activities that are expected to provoke symptoms, such as exercise. However, they have no role as a regular treatment to prevent attacks. Formoterol is a long-acting β2-agonist. It is taken regularly to improve lung function, but it does not address the underlying pathology (inflammation). For this reason, it must not be given without an inhaled corticosteroid, so would be an inappropriate choice at this stage. Antihistamines (e.g. chlorphenamine) can improve symptoms of histamine-mediated allergic disease such as hayfever and skin itching, but do not prevent or control airways inflammation in asthma.
A 62-year-old man with COPD complains that one of his medications is causing a dry mouth. He is taking aminophylline, fluticasone, salbutamol, salmeterol and tiotropium.
What is the most likely cause of his dry mouth?
A. Aminophylline
B. Fluticasone
C. Salbutamol
D. Salmeterol
E.Tiotropium
E. Tiotropium. Tiotropium is a long-acting antimuscarinic bronchodilator which inhibits parasympathetic stimulation of salivation, causing a dry mouth. None of the other drugs listed cause a dry mouth, although inhaled fluticasone (an inhaled corticosteroid) can cause oral thrush, the risk of which is reduced by rinsing and gargling after inhalation.
