Pharmacology - Allergy

Question 1

Allergy general mechanism

Answer 1

Allergen cross links IgE to mast cell surface, allowing Ca+ entry –> degranulation of mast cells and release of inflammatory mediators –>
permeability, chemotaxis, mucus, oedema

Question 2

Common allergen typoes

Answer 2

perennial: house dust mite, animal hair, fur
seasonal: hay fever
occupational: latex

association with atopy (genetic predisposition)

Question 3

Types of allergic responses

Answer 3

Allergic rhinitus:
nasal itching
rhinorrhoea
sneezing
conjungtival symptoms 
(itchy, worsened by irritants, tend to be both eyes)

Question 4

Types of allergic responses

Answer 4

Allergic rhinitus:
nasal itching
rhinorrhoea
sneezing
conjungtival symptoms 
(itchy, worsened by irritants, tend to be both eyes)

Question 5

Allergy management

Answer 5

avoidance:
pollen in spring, stay indoors/glasses

dust mite:
vacuum house, wash bed and clothes at 60 c
freeze pillows

Question 6

Allergy management

Answer 6

avoidance:
pollen in spring, stay indoors/glasses

dust mite:
vacuum house, wash bed and clothes at 60 c
freeze pillows

Question 7

First choice to treat allergy

Answer 7

Antihistamines

• do not remove nasal obstruction
• effect of alcohol enhanced
• not ideal

Question 8

Sedating antihistamines

Answer 8

(can cross BBB)

chlorphenamine (piriton)

promethazine (phenergan)

Question 9

Non-sedating antihistamines

Answer 9

Cetrizine (zirtek)

loratidine (clarityn)

Question 10

Nasal antihistamines

Answer 10

Azelastine (rhionolast)

does not treat itchy eye

Question 11

Azelastine eye drops

Answer 11

allergic conjunctivitis rapid relief

Question 12

how to apply nasal sprays

Answer 12

do not push head back

put head down
lay down etc

Question 13

Intransal steroids

Answer 13

Beclometasone
Budenoside
Fluticasone

Question 14

Steroid counselling points

Answer 14

-maximum days/weeks of use
-take a while to work (few days), take a week or 2 before season
-children: monitor height
-low dose/local: use along inhaler for asthmatic okay
-severe: oral steroids
-

Question 15

antihistmaine counselling points

Answer 15

-almost immediate relief

Question 16

cromones for allergy

Answer 16

nasal and eye (OTC)

mast cell stabiliser

Question 17

Most effective for conjunctivital symptoms

Answer 17

sodium cromoglicate / nedocromil sodium eye drops

Question 18

LT receptor antagonists uses

Answer 18

seasonal allergic rhinitus and asthma

Question 19

Nasal congestion cause

Answer 19

histamine casues increased blood flow to nasal tissue (oedema)

increased mucus production

Question 20

Decongestants

Answer 20

nasal vasoconstriction to reduce nasal tissue swelling and mucus flow

Question 21

α1-adrenoceptors on blood vessels

Answer 21

cause vasoconstriction

Question 22

Decongestant topical drugs

Answer 22

Xylometazoline/oxymetazoline ( α2 selective)
phenylephrine ( α1 selective)

7 days maximum (otherwise rebound congestion)

Question 23

Systemic decongestants

Answer 23

Pheylephrine tablets (questionable effectiveness, dose not high enough)

Question 24

Systemic decongestants contra-indications

Answer 24

hypertension, hyperthyrodism, diabetes, ischaemic heart disease

Question 25

Anaphylaxis

Answer 25

• life threatening
• angioedema
• wheezing
• itch
• hypotension

Question 26

Anaphylaxis treatment

Answer 26

• oxygen
• fluid - BP
• adrenaline im or iv: bronchodilation
• salbutamol for wheeze
• antihistamine im or iv (chlorphenamine)
• hydrocortisone iv
• shock boxes
• epipens (MHRA: 2 at all times, call ambulance after use)
• medic alert bracelet