Respiratory Pharmacology Flashcards
What is asthma?
A chronic inflammatory airway disease of intermittent airway obstruction and hyper-reactivity of the small airways
Reversible both spontaneously and with drugs
What should you always check before stepping up or down asthma medications?
- Check adherence
- Check inhaler technique
- Eliminate trigger factors
Describe the stepwise approach to asthma management
How are steroids used in the management of asthma?
Inhaled corticosteroids are a regular preventer when relievers alone are not sufficient
Name 3 inhaled corticosteroids
- Beclometasone
- Budesonide
- Fluticasone
How do inhaled corticosteroids work do manage asthma?
- Pass through plasma membrane to activate cytoplasmic receptors and modify transcription in the nucleus
- Increase B2 receptors and decrease inflammatory mediators
- reduces mucosal inflammation, widens airways, reduces mucus
- reduces symptoms, exacerbations and prevent death
What are some of the side effects of using inhaled corticosteroids?
- Can cause local immunosuppresion → candidiasis, hoarse voice
- Pneumonia risk in COPD
- Very few ADRs if taken correctly
What is the bioavailability of inhaled corticosteroids? How is this modfied to improve this?
- Poor oral bioavailability
-
Lipophilic side chain added which causes:
- slow dissolution in aqueous bronchial fluid
- high affinity for glucocorticoid receptor
What are the 2 types of B2 agonist? When is each used respectively?
SABA (short acting) - for symptoms relief through reversal of bronchocontriction
LABA (long acting)- add on therapy to ICS and SABA
Name 2 fast acting, SABAs
- Salbutamol
- Terbutaline
Give an example of a fast acting LABA
Formoterol
Give an example of a slow acting LABA
Salmeterol (12 hr)
Vilanterol (24 hr)
How do B2 agonists work?
- Bind to GPCR Gs in airways smooth muscle
- alpha s stimulates adenylate cyclase
- increase in cAMP → increases PKA
- Causes airways smooth muscle relaxation and increases mucus clearance by action of cilia
What happens if B2 agonists are used too frequently?
Can build a tolerance - reduces effectiveness of asthma control
What are some of the side effects of B2 agonists?
- Adrenergic effects - tachycardia, palpitations, anxiety and tremor
- Suptraventricular Tachycardia (risk in COPD patients)
- increases HR
- decreases refractory period at AVN
- increases glycogenolysis (liver)
- increases renin (kidney)
- Muscle cramps
What heart medications should you be careful about prescribing when prescribing beta 2 agonists?
Beta blockers!
counter the effects
What important prescribing condition must you consider when prescribing LABA?
Must only be Rx’d alongside ICS
Otherwise: increases risk of death when Rx’d alone as can mask airway inflammation
How does formoterol compare to salmeterol?
Formoterol is more potent and more efficacious than salmeterol
What are some of the benefits of a combined inhaler?
- Ease of use
- increased adherance
- less prescriptions- less cost, easier admin
- improved safety
What alternative to LABA do NICE guidelines reccommend?
LTRA- leukotriene receptor antagonist
Give an example of a LTRA?
Montelukast
How do Leukotriene receptor antagonists work?
Leukotriences (LTC4) are released by mast cells/eosinophils causing bronchoconstriction, mucus and oedema through the GPCR CysLT1
LTRA block CysLT1
What are some of the side effects of montelukast (LTRA)?
- Heache
- GI disturbance
- Dry mouth
- Hyperactivity
How do long acting muscarinic antagonists (LAMA) work?
- Selective for M3 receptors in smooth muscle
- Exert anticholinergic effects by inhibiting receptors
What are some of the side effects of long acting muscarinic antagonists?
Typical anticholinergic effects:
- dry mouth
- urinary retention
- dry eyes
Name a LAMA (long acting muscarinic antagonist)
Tiotropium
(inhaled)
How does theophylline work?
Adenosine receceptor antagonist - a methylxanthine
Use in acute asthmatics only
When are oral steroids given to manage asthma?
For severe, uncontrolled asthma (specialist direction only)
given post acute exacerbation for atleast 5 days
post acute COPD for 5-7 days
What is the name of the oral steroid given in special circumstances for asthma maintainance?
Prednisolone
What signs and symptoms indicate acute severe asthma?
- Unable to complete full sentances
- Peak flow > 33-50%
- Respiratory rate >25/min
- Heart rate >110/min
When is asthma considered life threatening?
Acute severe asthma signs +
- peak flow <33%
- SpO2 <92%
- PaO2 <8kPa
- PaCO2 4.6-6.0 kPa
- Silent chest
- Cyanosed
- Poor respiratory effort
- Arrhythmia
- Exhaustion
- Altered conciousness
- Hypotension
How do you treat acute severe and life threatening asthma?
Oxygen
Salbutamol
Hydrocortisone
Ipratropium - short acting
Theophylline - long acting
Magnesium
Escalate to ICU
What is ipratropium?
- Nebulised ipratropium bromide
- short acting muscarinic antagonist (SAMA) alongside B2 agonist
- Selective for M3 receptors
What are the 5 tasks of COPD management?
- Confirm COPD diagnosis
- Stop smoking
- Record MRC dyspnoea score
- Offer vaccination
- Consider medication
What drugs can be given in an acute exacerbation of COPD?
- Nebulised salbutamol and or/ ipratropium
- Nebuliser driven by air not oxygen
- Oral steroids
- Narrow spectrium antibiotics
How are pressurised metered dose inhalers used?
- inhalation of drug
- slow breath in and hold
- can be used with a spacer to improve delivery
How do breath actuated inhalers pMDI work?
Automatic actuation- dose delivered upon inspiration
How do dry powder inhalers work?
- micro ionised drug plus carrier powder
- fast and deep inhalation
What is the ideal particle size for inhalers getting to airways?
1-5 microns
too small: inhaled to alveoli and exhaled without being deposited
too large: deposited in mouth and oropharynx
