Pharmacology Flashcards
What are the 3 main categories of drugs for asthma?
Relievers, Controllers/Preventers and those that are both (methylxanthines)
Reminder, what is the inflammatory cascade for airflow asthma?
- Genetic predisposition + triggers 2. Eosinophilic Inflammation 3. Mediators (TH2 cytokines) 4. Twitchy smooth muscle (hyper-reactivity) (Need to treat the top, down - as this dampens the downstream events)
What is SMART therapy?
Single maintenance and reliever therapy (combining bronchodilator relievers and corticosteroids for long-term therapy)
**What are the steps in the pharmacological management of asthma?
Step 1 Intermittent: SABA
Step 2 Mild Persistent: SABA + ICS
Step 3 Moderate Persistent: SABA + ICS + LABA
Step 4 Severe Persistant: SABA + ICS + LABA + add on drug eg. cyst-leukotriene receptor antagonists, theophylline or B2 agonist tablet
Step 5: all of these + oral steroids
What classes as ‘brittle asthma’?
Wide PEF variability or sudden attacks when otherwise well controlled
What are the main types of anti-inflammatories?
- Corticosteroids - Chromones - Leukotriene Receptor Antagonists - Anti IgEs
What is the mechanism of action of corticosteroids
Counteract key underlying process of airway inflammation by suppressing genes for inflammatory proteins and activate genes which code for anti-inflammatory mediators
What is a main possible side effect of corticosteroids in COPD patients?
Pneumonia due to local immune suppression
What are the main advantages of inhaled steroids (e.g. beclamethasone) over oral steroids (e.g. prednisolone)?
- Higher therapeutic ratio - Better local therapy (goes where needed) - Used for maintenance therapy, while oral is only acute - Smaller dose - Gives a more stable peak flow
What are Beclometasone, budesonide or fluticasone propionate?
inhaled corticosteroids
Prednisolone
Oral steroid
What is Cushings Syndrome?
Pathological hypercortisolism (caused by excessive oral steroids)
What are the advantages of spacers?
-Avoids coordination problems with pMDI -Reduces oropharyngeal and laryngeal side effects • E.g. oral thrush - Reduces systemic absorption from swallowed fraction - Acts a holding chamber for aerosol - Reduces particle size and velocity - Improves lung deposition
What are Dry powder inhalers (e.g. acuhaler/turbohaler)?
Breath actuated - release a dose automatically when breath taken
When are cromones used?
Only used in asthma but has relatively poor efficacy
What is the mechanism of action of CysLT1 (leukotriene) receptor agonists?
They act competitively at the CysLT1 receptor and stop CysLT1s (metabolites of arachidonic acid from inflammatory cells) from causing muscle contraction, mucus secretion and oedema.
How and when are Leukotriene Receptor Antagonists taken?
Orally and as an add on therapy in asthma in Step 4
Montelukast or zafirlukast
Leukotriene receptor antagonists
What is an example of Anti-IgE treatment?
Omalizunab
What do Anti IgEs do?
Only used in patients with raised IgE-mediated allergic asthma who aren’t controlled by inhaled corticosteroid or LABA
What drugs are in development for asthma?
Monoclonal antibodies for severe refractory asthma: anti TH2 cytokines e.g. Mepolizumab for anti-Il5
What are the main bronchodilators?
- B2 agonists - Anti-cholinergics - Methylxanthines - Magnesium
What do B2 agonists do?
Stimulate bronchial smooth muscle beta 2 receptors to increase cAMP and promote sympathetic system to cause bronchodilation
When are SABAs used?
Acute relief in both asthma and COPD
Salbutamol and terbutaline
SABAs
When are LABAs used?
Step 3, as an add on to SABAs and inhaled corticosteroids (often as a combined inhaler)
Salmetarol and formetarol
LABAs
What is an example of a SMART combination inhaler?
beclometasone (cotricosteroid) and formoterol (LABA)
What is the advantage of formetarol over salmetarol?
Is has both a longer duration and faster onset
What do anticholinergics /anti-muscarinics do?
Block post junctional end plate M3 receptors by ACh- essentially block bronchoconstrictor and hyper secretion effect of vagal nerve stimulation
When are anti-muscarinic bronchodilators used?
Mostly in COPD to reduce exacerbations, or as an add on in asthma at step 4
Ipratropium and tiotropium
Antimuscarinic bronchodilators (SAMA and LAMAs)
What is the main short acting muscarinic antagonist (SAMA)?
Ipratropium
What is the main long acting muscarinic antagonist (LAMA)?
Tiotropium and glycopyrronium
How do methylxanthines work?
They inhibit the metabolism of cAMP by enzyme phosphodiesterase
What type of drug has both bronchodilator and anti-inflammatory activity?
Methylxanthines (eg. theophylline)
What are the aims of treatment of chronic asthma?
- Abolish symptoms
- Minimise B2 use
- Normalise FEV1
- Reduce PEF variability
- Reduce exacerbations
- Prevent long term airway remodelling
How would you treat acute asthma exacerbation?
- Oxygen (60%)
- Nebulised high dose salbutamol (2.5-5mg)
- Hydrocortisone (oral) 100mg
- Ipitropium 500mcg nebuliser
- Theophylline: aminophylline infusion
- Magnesium sulphate 2g IV
- Escalate to mechanical intubation if going into respiratory failure
What are non-pharmacological treatments of COPD?
- Smoking cessation - Immunisation against influenza and pneumococcal - Physical activity - Oxygen - Lung volume reduction surgery - Stenting
What are the main pharmacological treatments of COPD?
Step 1: SABA/SAMA
Step 2: if FV1 is >60% then LABA or LAMA ; if it is <60% then LAMA or LAMA/ICS combination inhaler
Step 3: LABA/combined inhaler or LAMA + LABA + ICS
What aren’t steroids used much in COPD treatment?
Because it is neutrophils, rather than a eosinophilic inflammatory response
How would you treat acute COPD
- Nebulised high dose ipratropium
- Nebulae high dose salbutamol
- Oxygen
- Amoxicillin if infective
- Oral prednisolone
What kind of transmission causes contraction of airway muscle?
Cholinergic
Where are parasympathetic cell bodies of the preganglionic fibres are located?
Brainstem
Where are parasympathetic cell bodies of the postganglionic fibres are located?
Walls of the bronchi and bronchioles
What occurs with stimulation of postganglionic cholinergic fibres on M3 muscarnic ACh receptors?
- Bronchial smooth muscle contraction - Increased mucus secretion
What neurotransmitter is always used in preganglionic cells?
Acetylcholine (cholinergic)
What different types of post ganglionic fibres are there?
- Cholinergic - Nitric (VIP or NO)
What is caused by stimulation of postganglionic parasympathetic noncholinergic fibres?
Bronchial smooth muscle relaxation mediated by NO and VIP
What does VIP stand for?
Vasoactive Intestinal Peptide
Why is ASM relaxation a non-direct process?
ASM doesn’t receive a postganglionic sympathetic innervation
What ares do receive post ganglionic sympathetic innervation?
Submucosal glands and smooth muscle of blood vessels
What are the effects of stimulation of sympathetic system on ASM?
- Bronchial smooth muscle relaxation via B2 adrenoreceptors activated by adrenaline from adrenal gland
- Decreased mucous secretion
- Increased mucociliary clearance
- Vascular smooth muscle contraction
What are the 2 processes of contraction in smooth muscle?
1) Via GPCRs and IP3 receptors 2) Via Calcium Induced Calcium Release
What are the steps in excitation-contraction coupling via GPCRs and IP3 receptors?
1) Transmitter or hormone activates GPCR 2) GPCR couples with Gq/11 3) Activated Gq/11 activated Phospholipase C in membrane 4) PLC degrades PIP2 into IP3 5) IP3 activates IP3 receptors, which opens and allows calcium to move down gradient from SR into cell
What are the steps in excitation-contraction coupling via calcium-indued calcium-release?
1) Depolarisation activated calcium channel 2) Influx of calcium activates ryanodine receptors on the SR, releasing calcium into the cell down gradient
How does calcium cause contraction once in the cell?
1) Calcium enters the cell and binds to calmodulin (a calcium binding, regulatory molecule) to become Ca2+-calmodulin complex
2) This activates inactive myosin light chain kinase (MLCK) enzyme
3) Active MLCK produces phosphorylation reactions, converting ATP to ADP
4) Stripped inorganic Pi added to inactive myosin cross bridge
5) Forms an active phosphorylated myosin cross bridge which binds actin
6) Myosin and actin then slide over each other to contract as normal
How does relaxation of smooth muscle occur (overview)?
Dephosporylation of MLC by myosin phosphatase (opposite of contraction which occurs via phosphorylation of MLC)
What governs whether relaxation or contraction occurs?
Balance between rate of phosphorylation and dephosphorylation, dependent on the levels of intracellular Ca2+
Where does salbutamol act and how?
Inhibits myosin light chain kinase to prevent MLC phosphorylation and cause relaxation
What is the process of relaxation in smooth muscle?
1) Adrenaline activates B2 receptors which are linked to Gs GPCRs
2) These activate adenylate cyclase enzyme
3) This concerts ATP to cAMP
4) cAMP binds to protein kinase A
5) PKA phosphorylates and inhibits MLCK to inhibit contraction
6) It also phosphorylates and stimulates myosin phosphatase which dephosphorylates myosin light chain
In what direction of respiration does asthma affect?
Outward direction (on expiration). In normal expiration the airways become narrower, however in asthma the airways are too narrowed already and can collapse
What are the long-term pathological changes to bronchioles that occur due to chronic inflammation from asthma?
1) Increased mass of smooth muscle
2) Accumulation of interstitial fluid
3) Increased secretion and accumulation of mucus
4) Epithelial damage
5) Sub-epithelial fibrosis (les compliance)
What is a consequence of epithelial damage and exposure of sensory nerve endings?
Increased sensitivity of the airways to bronchoconstrictor influences and neurogenic inflammation
What can be used to reveal hyper-responsiveness?
Provocation tests with inhaled bromchocontrictors e.g. histamine
What are the two components to hyper-responsiveness?
1) Hypersensitivity (less bronchoconstrictor is needed to cause a response) 2) Hyper-reactivity (theres is a greater fall in FEV1)
What are the two phases of an asthma attack?
1) Immediate phase (mainly bronchospasm) 2) Delayed phase (mainly inflammatory)
What type of hypersensitivity reaction is the immediate bronchospasm phase?
Type I
What type of hypersensitivity reaction is the delayed inflammation phase?
Type IV
What is the difference in response to phagocytosis of allergens in non-atopic individuals vs. atopic individuals?
In non-atopic, there is a low level TH1 reponse, which is a cell-mediates immune response involving IgG and macrophages. While in atopic, there sis a strong Th2 response which is antibody mediated involving IgE
What are the steps in the induction phase of the development of allergic asthma?
1) Initial presentation of antigen causes adaptive immune response
2) Antigen recognised by APC
3) Antigen is process and then presented with MHCII to T CD4+ cells
4) These then activate TH0 cells - from here can be atopic or non-atopic route
5) In atopic route, Th0 cells mature and proliferate into Th2 cells
6) They bind to B cells and also produce IL-4
7) B cells interact with IL-4 and undergo clonal expansion
8) Eventually mature into plasma cells which secrete IgE eventually
What are the steps in the Effector phase of the development of allergic asthma?
1) Plasma cells start to produce IgE
2) IgE receptors then expressed on the surface of these cells under direct of IL-4 and IL-3 for mast cells, and IL-5 for eosinophils
3) IgE can then be bound to these cells
What happens in subsequent exposure to allergens in the development of an allergic response (late phase)?
1) Antigens bind to the IgE receptors in mast cells and forms cross links between IgE receptors
2) This stimulates calcium entry into mast cells and also the release of calcium
3) Calcium causes released of secretory granules containing preformed mediators including histamine, leukotrienes, and other pro-inflammatory factors to the ares e.g. Prostaglandins (basically invasion of inflammatory cells)
What effect do these inflammatory cells have on the airways?
They act as spasmogens and cause the ASM to contract. They also cause hyper-responsiveness due to epithelial damage from eosinophils and further inflammation.
What are the advantages of aerosol treatment over oral?
-Slow absorption with rapid clearance of anything not absorbed - Low dose - rapidly to target - Low systemic concentration - low risk of adverse effects
What are the advantages of oral treatment over aerosol?
- Distribution unaffected by airway disease - Ease of administration - Effective even in severe disease
When is the maximal effects and duration of SABAs?
Maximal effect at 30 mins, and lasts for 3-5 hours.
What are the adverse effects of SABAs?
Fine tremor, tachycardia, dysrhythmia and hypokalaemia
When should LABAs not be used?
- As acute relief (can actually worsen asthma) - As a mono therapy (but always be given with glucocorticoid)
How long to LABAs normally last for?
Around 8 hours (so useful for nocturnal therapy)
When shouldn’t leukotriene receptors be used?
-As a mono therapy (should be used as add ons) - For acute relie
What are the disadvantaged of methylxanthines?
- Very narrow therapeutic window - Adverse effects including dysrhtymia, seizures, hypotension, GI issues - Several drug interactions
When should methylxanthines be used?
As second line drugs along side B2 agents and glucocorticoids
What is the main use of glucocorticoids?
Prophylaxis of asthma to reduce underlying inflammation
Why are synthetic derivates of cortisol used, rather than cortisol itself used?
Avoids the retention of salt and water caused by mineralocorticoids, as endogenous steroids may have both glucocorticoid and mineralocorticoid actions
What are some of the cellular effects of glucocorticoids relevant to asthma?
- decrease numbers of eosinophils, macrophages, meat cells, cytokines and dendritic cells - decreases cytokine mediators in epithelial cells - decrease leak from endothelial cells, reducing oedema - Increases B2 adrenoceptors in ASM, which improves responsiveness to SABAs/LABAs - Decrease mucous secretion
What are the main adverse effects of glucocorticoids?
- dysphonia (hoarse and weak voice) - oropharyngeal thrush
What are the main actions of cromones?
‘mast cell stabilisers’ - suppress histamine release from mast cells
What are main examples of glucocorticoids?
Beclometasone, budesonide or fluticasone
What is the function of omalizumab?
Monoclonal antibody against IgE, by preventing attachment to Fce receptors to prevent degranulation
What is the function of mepolizumab?
Monoclonal antibody against IL-5 which play a role in the development of asthma
What are the disadvantages of monoclonal antibodies as treatment?
- Very expensive - Inconvenient as need IV administration 2x weekly
What is the specific agent of cromones?
Sodium cromoglicate
What is the cornerstone of treatment of COPD?
Reducing parasympathetic activity with muscarinic receptor antagonists
How are SAMAs and LAMAs given?
Inhalation
Why is tiotropium superior to ipratropium?
Ipratropium is a non-selector muscarinic blocker so blocks M1-3, while tiatropium is selective to M3. Dont want to block M2 as that increases the release of ACh from parasympathetic postganglionic neutrons
What are ultra-LABAs and what is an example?
Bronchodilator with rapid onset of action and long duration - example is Indacaterol
Why are LABA/LAMA combinations so effective e.g. salmetarol/tiotropium?
They have a synergistic effect - they work by different but complimentary mechanisms
What is rhinitis?
Common and often debilitating disease involving acute, or chronic, inflammation of the nasal mucosa which is characterised by • rhinorrohea (‘runny nose’ ) • sneezing • itching • nasal congestion and obstruction
What are 3 main types of rhinitis?
1) Allergic (seasonal/perennial/episodic) 2) Non- allergic 3) Mixed
What are the steps in allergic rhinitis?
1) Inhalation of allergic increase specific IgE levels
2) IgE binds to receptors on mast cells and basophils
3) Re-exposure cause mast cell and basophil degranulation
4) Release of mediators including histamine and cysLT1a and prostaglandins cause symptoms
5) Delayed response caused by recruitment of lymphocytes and eosinophils to nasal mucosa which contributes to congestion
What is non-allergic rhinitis?
Any rhinitis, acute or chronic, that does not involve IgE
What are some of the causes of non-allergic rhinitis?
•Infection - infectious rhinitis (largely viral) •hormonal imbalance - hormonal rhinitis (e.g. pregnancy) •vasomotor disturbances - vasomotor rhinitis • Nonallergic rhinitis with eosinophilia syndrome (NARES) • Medications - drug induced rhinitis
What happened to blood flow in rhinitis and rhinorrhea?
- increased mucosal blood flow - increased blood vessel permeability
What are the main targets of treatment of rhinitis and main treatment for these?
1) Anti-inflamamtory
2) Mediator receptor blockade
3) Nasal blood flow
4) Anti-allergic
What is main treatment for the anti-inflammatory target of rhinitis?
glucocorticoids
What is main treatment for the mediator receptor blockage target of rhinitis?
histamine and cysLT1 receptor antagonists
What is main treatment for the nasal blood flow target of rhinitis?
vasoconstrictors
What is the mechanism of glucocorticoids in rhinitis?
Reduce vascular permeability, activity of inflammatory cells and the release of cytokines and mediators
What is main treatment for the anti-allergic target of rhinitis?
sodium cromoglicate
How are glucocorticoids most often administered in rhinitis?
Nasal spray often as a monotherapy
What is the mechanism of anti-histamines (H1 antagonists) in rhinitis?
Competitive antagonists of H1 receptors reduce effects of mast cell derived histamine that include:
- vasodilatation and increased capillary permeability
- activation of sensory nerves
- mucus secretion from submucosal glands
What are the effects of anti-histamines?
-reduced vasodilatation and increased capillary permeability -reduced activation of sensory nerves -reduced mucus secretion from submucosal glands
What are examples of anti-histamines?
Loratadine, Fexofenadine and cetirizine
What is the main function of anti-muscarinics in rhinitis?
inhibit the production of secretion from nasal glands due to ACh released from parasymp. fibres
What is the main anti-muscarinic used in rhinitis?
Ipratropium
What is the main leukortrine receptor antagonist used in rhinitis?
Montelukast
What is mechanism of vasoconstrictors in rhinitis?
Mimic the effects of noradrenaline to have vasoconstrictive actions via alpha 1 adrenceptors. This reduces the swelling in vascular mucosa.
What is the main vasoconstrictor used in rhinitis?
Oxymetazoline - a selective alpha 1 adrenorecepetor agonist
Where are the M3, M2 and M1 receptors located?
M1 - ganglia
M2 - postganglionic
M3 - smooth muscle (present in the airways)
