Allergy and Anaphylaxis Flashcards
Name 3 examples of systemic corticosteroids and 3 indications for their use:
- prednisolone, hydrocortisone, dexamethasone
- to treat allergic or inflamm disorders (anaphylaxis, asthma)
- supress autoimmune disease e.g. IBD, arthritis
- to treat some cancers (as part of chemo/to reduces tumour swelling)
- hormone replacement in Adrenal insufficiency or hypopituitarism
Corticosteroids MOA..bind to ____ receptors which ___ to the ___ and bind to _____-response elements that regulate ____ expression. They upregulate ___-_____ ___ and down-regulate ___-_____ ___.
They also suppress circulating ___ and __.
Metabolic effects include increased ____ from increased circulating amino and fatty acids released by catabolism of __ and fat.
Also have ______ effects, stimulating Na+ and water ___ and K+ ___ in the renal tubule
- glucocorticoid receptors –> translocate to nucleus, bind to glucocorticoid-REs
- regulate gene expression, upreg anti-inflamm genes, downreg. pro-inflamm genes
- supress circulating monocytes and eosinophils
- increased gluconeogenesis (from catabolism of muscle and fat)
- mineralocorticoid effect, Na+/water retention and K+ excretion
Name 8 important adverse effects that may arise from systemic corticosteroid therapy
(think about MOA to remember these)
- immunosuppression
- metabolic effects: DM, osteoporosis
- increased catabolism: proximal muscle weakness, skin thinning, easy bruising, gastritis
- mood/behaviour: insomnia, confusion, psychosis, suicidal ideation
- mineralocorticoid effects: HT, hypokalaemia, oedema
- adrenal atrophy in prolonged rx (–> addisonian crisis on sudden withdrawal..fatigue, weight loss, arthralgia)
When should you exercise caution in prescribing systemic corticosteroids?
- people with an infection
- children (can supress growth)
corticosteroids increase the risk of peptic ulcers/GI bleeding when used with ____
and enhance hypokalaemia when used in pts also taking __-agonists, th____, ___ or ___ diuretics.
Efficacy can be reduced by cytochrome P450 inducers such as….
- NSAIDS
- B2 agonists, theophylline, loop or thiazide
- rifampicin, phenytoin, carbamazepine
What 2 medication classes should be considered alongside long-term systemic corticosteroid therapy to reduce adverse effects?
- bisphosphonates
- PPIs
In a pt undergoing long-term systemic corticosteroid therapy who becomes acutely ill, what should you do with their dose while unwell and then once recovered?
(atrophic adrenal glands won’t be able to increase cortisol in response to stress - do this artificially)
- double the dose during acute illness
- reduce back to maintenance dose on recovery
H1 receptor antagonist antihistamines
- give 3 examples
- give 3 indications
- e.g. cetirizine, loratadine, fexofenadine, chlorphenamine
- allergy rx e.g. hayfever
- aid itchiness and hives e.g. from insect bites/infection/drug reactions
- as part of anaphylaxis rx
- N&V rx (often motion/vertigo related) as anti-emetics (cyclizine, promethazine)
Describe the effects histamine has when binding to H-1 receptors –> type I hypersensitivity reaction “flare and wheal” etc, and effects if released in nose (–>hayfever) and skin
NB: anti-histamines block these effects of excess histamine
- vasodilation causing erythema (flare)
- increased capillary permeability causing oedema (wheal)
- sensory nerve stimulation -> itch
- nose: nasal irritation, sneezing, rhinorrhoea, congestion, conjunctivitis, itch
- skin: urticaria
- what is an unfavourable side effect of ‘1st generation’ anti-histamines eg. chlo____
- how do newer ‘2nd generation’ ones e.g. cetirizine, loratadine… avoid this effect?
- sedation, e.g. chlorphenamine as H1 receptors have a role in brain in maintaining wakefulness
- new ones do not cross the BBB
- In what group of patients should you exercise caution in prescribing 1st generation anti-histamines e.g. chlorphenamine?
- because they can –>
- avoid in severe liver disease
- can precipitate hepatic encephalopathy
Adrenaline
-give 2 indications
- cardiac arrest as part of ALS for shockable and non-shockable rhythms
- anaphylaxis
- direct injection to induce local vasoconstriction e.g. in endoscopy to control local mucosal bleeding
- ”” with LA e.g. lidocaine to prolong local anaesthesia and reduce systemic effects
Adrenaline MOA
- a1, a2, b1 and b2 agonist…
- sympathetic fight/flight responses induces include..vasoconstriction of….., B1 effects on heart….vasodilation of…. and effect on lungs and mast cell release…?
- vasoconstriction of vessels to skin, mucosa and abdo viscera (a1)
- increased HR, force of contraction and myocardial excitability (b1)
- vasodilation of vessels supplying heart and muscles (b2)
- bronchoconstriction and suppression of inflammatory mediator release from mast cells (b2)
Name 4 unfavourable SEs of Adrenaline? (think about MOA…and effect if given to someone with established heart disease..?)
- adrenaline-induced hypertension
- anxiety
- tremor
- headache
- palpitations
- angina, MI, arrhythmias esp. in pts with existing heart disease
- for cardiac arrest/anaphylaxis there are no CIs to adrenaline use
- if used for vasoconstriction, use with caution in pts with ___ ___
- adrenaline-anaesthetic combos are contraindicated for us in areas…. as can cause…
- caution: heart failure
- CI: AREAS SUPPLIED BY AN END ARTERY e.g. fingers/toes as vasoconstriction can –> tissue necrosis
