Allergic Rhinitis

Question 1

Inflammation of nasal passage

Causes congestion rhinorrhea, sneezing and itching

Answer 1

Allergic rhinitis

Question 2

Amine synthesized from amino acid L-histamine

Autacoid (local secreation)

Answer 2

Histamine

Question 3

Antigen (allergen) deliver via LOCALLY or systemically

Allergen stim Beta lymphocytes to produce igE antibodies - which bind in a complex in mast cell …….. allow future sensitisation

H1 recpetor on vascular endo cell and smooth muscle cell get activated

Activation triggers histamine to release Ca++
> lead to relax of smooth muscle in capillaries
> contraction of bronchical

Answer 3

Histamine and inflam response

Question 4

Causes

Local blood flow ^
Vascular permeability ^
Access of other ‘immune’ agents into injured area

Answer 4

Mediator histamine

Question 5

Allergen-antigen

Antigen attach to antibodies to star reaction

Mastcell degranulate - release of mediators (histamine) -act on H1 receptor

Result : itching, sneezing, runny nose , tears.

Answer 5

Local inflam disorders

Question 6

Antihistamines

Cromoglycate

Ipratropium

Answer 6

Symptom treatment

Question 7

Corticosteroids

Answer 7

Preventative treatment

Question 8

H1 antihistamines = INVERSE agonist ( shifting equib to inactive state )

DO NOT inhibit/block active .. only shift

Active: histamine working - allergic reaction
Inactive : antihistamines promotes this state - no activity of histamine

Answer 8

Antihistamines

Question 9

Bind to igE antibodies on mast

Prevent degranulation and release of histamine

Also inhibit release of mediators from other cells : inc. lymphocytes, neutrophil, macrophages

Answer 9

Cromoclycate ( mast cell stabliser )

Nedocromil

Question 10

Anticholinergic - dries nasal secretions

Answer 10

Ipratropium

Question 11

Encounters effects of histamine

Leads to brochoDilation and vasoConstration

Answer 11

Adrenaline

Question 12

Neutral pH
> readily to cross BBB
>sedating

Answer 12

1st gen antihistamines

Question 13

Ionised
>less likely to cross BBB (low penetration)
> less sedating ( genetic diff is important)

Answer 13

2nd GEN antihistamines

Question 14

Urticaria ( formation of itchy red or white raised patches , caused by allergy)

Pruritis

Allergic rhinitis

Conjunctivitis

Answer 14

Clinical applicationof H1 antihistamine

Question 15

Good oral absorption

Peak conc at 2-3 hrs

Liver metabolized

Inducers of P450 enzymes - drug drug interaction

SE: largely related to penetration of BBB

Answer 15

Pharmacokinetics of drug

Question 16

Anticholinergic (anti-mus) effect
AE1: dry mouth and eyes, dilated pupil, urinary retention, constipation

AE2: prolonged QT interval 
Ie terfenadin (produg)-> fexofenadine (metabolite) 

T is witdrawn but uses F (considered cardio-safe)

Answer 16

AE1 :especially 1st generation

AE2: especially 2nd generations

Question 17

Self limiting (no cure)

Viral infection

Answer 17

Acute/infectious rhinitis

Question 18

Saline

Oral decongestant (pseudo,phenyl)

Topical decongestant
(Xylometazoline) : vasoC reduces blood flow in nasal mucosa
REBOUND with this drug >5 days

Answer 18

Symptom relief (not curing)

Of Acute / infectious rhinitis

Question 19

In 15% having AR (allergic rhinitis) 10% have asthma

75% asthmatics have allergic rhinitis

Answer 19

Asthma and AR co-exist

Question 20

Dex-chlor-phenir-amine

Dexchlorpheniramine

Promethazine

Answer 20

1st Gen antihistamines

Question 21

Loratadine

Certrizine

Fexofenadine

Answer 21

2nd GEN antihistamines