2- pharmacology cough/rhinitis Flashcards
what is rhinitis?
rhinitis is common and often debilitating disease involving acute or chronic, inflammation of nasal mucosa
what is rhinitis characterised by?
- rhinorrhea (runny nose - watery mucus accumulating in nasal cavity)
- sneezing
- itching
- nasal congestion & obstruction (swelling of nasal mucosa largely due to dilated blood vessels - particularly in cavernous sinusoids)
= can be allergic, non-allergic or mixed
what are the different classifications of allergic rhinitis?
- seasonal allergic rhinitis (SAR)
- perennial allergic rhinitis (PAR) = all year round
- episodic allergic rhinitis (EAR) = intermittent or sporadic
what is process from inhalation from allergen to allergic rhinitis symptoms? (not too extensive)
inhalation of allergen increases specific IgE →IgE binds to receptors on mast cells & basophils →re-exposure to allergen causes mast cell & basophil degranulation →released of mediators including histamine, cysLTs (cysteine leukotrienes), tryptase, prostaglandins, causing acute itching, sneezing, rhinorrhea & nasal congestion → delayed response caused by recruitment of lymphocytes and eosinophils to nasal mucosa contributes to congestion & obstruction
what drives non-allergic or occupational rhinitis?
- infection (infectious rhinitis)
- hormonal imbalance e.g. pregnancy
- vasomotor disturbances e.g. iodiopathic
- non-allergic rhinitis with eosinophilia syndrome (NARES)
- medications e.g. aspirin
what is non-allergic rhinitis?
non allergic could be like in exercise etc, any rhinitis acute or chronic, not involving IgE dependant events
what is occupational rhinitis?
working in environments that could be exposed to allergens, may involve both allergic & non-allergic components
what about rhinitis & rhinorrhoea means difficulty breathing in?
both involve increased mucosal blood flow, increased blood vessel permeability = both increase the volume of nasal mucosa and cause difficulty breathing in (you breathe through mouth with blocked nose)
what are anti-inflammatory treatment for rhinitis?
glucocorticoids
what drugs are given for vasoconstrictors?
nasal blood flow
what are anti-allergic drugs?
sodium cromoglicate
what is mechanism of glucocorticoids?
reduce vascular permeability, recruitment & activity of inflammatory cells & release of cytokines & mediators
what is administration of glucocorticoids?
applied topically as a spray to the nasal mucosa (i.e. intranasal administration, usually once daily). can be given orally (short term) in severe cases
what types of rhinitis are treated with glucocorticoids?
seasonal or perennial allergic rhinitis
or non-allergic rhinitis with eosinophilia syndrome (NARES)
what can glucocorticoids be given in combination with for moderate to severe rhinitis?
combined with antihistamines:
- beclometasone
- fluticasone
- prednisolone (oral)
what is mechanism of anti-histamines?
competitive antagonists that reduce effects of mast cell derived histamine including:
- vasodilation & increased capillary permeability (reduce blood flow to nose and increase permeability so dry nose in hayfever)
- activation of sensory nerves
- mucus secretion from submucosal glands
what types of rhinitis are treated with anti-histamines?
as monotherapy in SAR, PAR, EAR
= less effective in non allergic rhinitis and less effect on congestion that other symptoms
how are anti-histamines administered?
orally or as intranasal spray (azelastine)
what are first and second generation agents of antihistamines?
2nd generation preferred as reduced sedation/drowsiness (since do not cross the blood brain barrier) and lack of anticholinergic effects
what are examples of antihistamines?
- loratadine
- fexofenadine
- cetirizine (also has mild anti-inflammatory)
what is mechanism of anticholinergic drugs?
ACh released from post-ganglionic parasympathetic fibres activates muscarinic receptors on nasal glands causing a watery secretion that contributes to rhinorrhoea – blocked by muscarinic antagonists
what types of rhinitis should be treated with muscarinic antagonists?
= reduce rhinorrhoea in PAR and SAR but no influence on itching, sneezing & congestion
(note the anticholinergic activity of first generation H1 blockers may contribute to their ability to suppress rhinorrhoea)
how is muscarinic antagonists administered?
intranasally
what are side effects of muscarinic antagonists?
may cause dryness of nasal membranes, but no other adverse effects
what is preferred muscarinic antagonist for rhinitis?
ipotropium (non selective & sole agent in this class) which may be surprising as remember from last lecture that inhibiting M2 actually increases Ach release but it’s short lived so preferred
what is mechanism of sodium cromoglicate? and what is administration?
mast cell stabilization
= used for maintenance treatment for allergic rhinitis (but less common)
= nasal administration (less effective than nasal corticoids)
what is mechanism of cysteine leukotriene receptor antagonists?
reduce effects of cysteinyl leukotriene on nasal mucosa
how effective is cysteinyl leukotriene receptor antagonists?
= equal effect with H1 receptor antagonists (anti-histamine) in treating PAR and SAR
what is example of cysteinyl leukotriene receptor antagonist?
montelukast (administered orally)
what is an example of a vasoconstrictor given for rhinitis treatment?
oxymetazoline = a selective alpha 1 adrenoceptor agonist (given intranasally)
= reduced congestion in rhinitis
what is the mechanism of vasoconstrictors to treat rhinitis?
act directly or indirectly as noradrenaline (mimicing effect) and producing vasoconstriction via activation of alpha 1 adrenoceptors to decrease swelling in vascular mucosa
