inflammation Flashcards
what enzymes do NSAIDs inhibit? and what are the functions of those enzymes?
COX-1 constitutive enzyme
COX-2 induced at the site of inflammation
which enzyme is NSAID toxicity associated with?
COX-1 inhibition
this is can lead to gastric ulceration and massive GI bleeding
how does the anti-pyretic effect of NSAIDs work?
they prevent the formation of PGE in the anterior hypothalamus, PGE formation by endogenous pyrogens in the anterior hypothalamus resets the body’s thermostate
what inflammatory mediators are associated with pyretic effects?
TNF-A and IL-1
how is the analgesic effect of NSAIDs mediated?
PGE formation at the site of inflammation sensitises sensory nerves, lowering pain threshold.
by inhibiting PGE formation, neuronal sensitisation is reduced
how is the anti-inflammatory effect of NSAIDs mediated?
PGE,PDG and PGI are vasodilators and promote oedema
NSAIDs inhibit the formation of those prostanoids and reduce the signs of inflammation by this
how is NSAID toxicity minised?
by making drugs which are more selective for COX-2
when and how is anti-TNF-a therapy used?
used for chronic inflammatory disease
TNF-a antibody or binding protein are used to prevent the molecule from binding to its receptor
humanised antibodies: Infliximab or adalimumab used
soluble TNF-a receptors (E.g. etanercept)
what are the key features of asthma?
- REVERSIBLE bronchonconstriction and airway obstruction
- non-specific airway hyper-reactivity
- inflammation of bronchial mucosa
- loss of bronchial epithelium
- mucus plugging of the airway
what is the main feature of allergic asthma?
its a type I hypersentivity to its allergen binding to IgE - causing histamine release
what is salbutamol?
a short - acting B2 agonist
what is salmeterol?
a long acting B2 agonist
give examples of the bronchodilators used in asthma
B2 agonists
- salbutamol
- salmeterol (long acting)
methylxanthines:
- theopylline
- PDE 4 inhibitor
muscuranic receptor antagonist
- ipratropium bromide
leukotriene receptor antagonists:
- montelukast
what are the anti-inflammatory agents used in asthma?
glucocorticoids:
- beclamethazone (inhaled)
- prednisolone (oral)
anti-allergic:
-cromoglycate
leukotriene receptor antagonists:
- montelukast
what is chromogylcate?
this is an anti-allergic drug
what is prednisolone?
this is a glucocorticoid
what is the mechanism of action of chromoglycate and nedocromil?
what is the difference between them?
those drugs are used as prophylaxis, they cannot prevent an already established attack
- inhibition of the release of inflammatory mediators (from cells involved in asthma: mast cells, eosinophils and neutrophils)
- inhibition of sensory nerve activation
(those activations are involved in reflexes that mediate bronchoconstriction and neurogenic inflammation of the airways)
chromoglycate - given via inhaler
nedocromil: orally active
what is the difference between chromoglycate and nedocromil?
nedocromil is orally active while chromoglycate is not orally active so much be given via an inhaler
how do B2 agonists work?
relax smooth muscle by increasing cAMP
they also prevent the release of mediators from mast cells
what is the difference between salbutamol and salmeterol?
salbutamol is short acting (4hrs)
- can be given iV/orally or via inhalation
salmeterol:
- long acting (12 hours)
- given via inhalation
- very useful for nocturnal asthma
when are muscarnic antagonists given in asthma?
how do they work? what type of asthma is it not effective against?
how is it administered, why?
they’re given, or most effective where reflex bronchoconstriction predominates (this is Ach mediated)
- does not affect histamine mediated bronchoconstriciton
ipratropium is given by inhalation (oral or parenteral administration avoided) this is to avoid extensive side effects associated with muscuranic blockade
what are caffeine, theobromine and theophylline examples of?
methylxanthines
how do methylxanthines work in the cell?
- at high concentrations can release calcium from intracellular pools
- inhibition of cAMP and cGMP phosphodiesterases
- this increases intracellular rise in cAMP mediated by other drugs (E.g. the B2 agonists)
- competitive antagonism of adenosine at the adenosine receptors
what are the overall effects of methylxanthines
- bronchodilation
- relaxation of vascular smooth muscle (although it causes cerebral artery contraction)
- diuresis (weak effect, may inhibit sodium resorption)
- positive ionotropic and chronotropic effect on the heart (causing potential toxicity) narrow TI
- increased GI secretions causing diarrhoea
- CNS stimulant
apart from the use in severe asthma what can methylxanthines be used for? and what is the specific drug?
aminophylline orally can be used for left ventricular failure with pulmonary oedema:
- because of it cardiovascular
respiratory and diuretic effects
what are some of the side-effects of methylxanthines?
tachycardia with dysrhythmias
diarrohea
tremor
wakefullness
why are glucocorticoids not used?
when are they used?
oral use of GC is not used because of major unwanted side-effects
- potent oral GC reserved for severe asthma
- inhaled GC are preferred (E.g. beclomethasone)