Allergy treatment

Question 1

Antihistamines

Answer 1

H1 antagonists remove rhinorrhoea, itching, conjunctivitis and sneezing but not nasal obstruction.
-ine ending
Those that penetrate the BBB are sedating: Chlorphenamine, Promethazine, Alimemazine
Non-sedating forms include: Acrivastine, Cetirizine, Fexofenadine, Loratadine (Clarityn)
Topical antihistamines, such as Azelastine, can be used nasally for rhinitis, or as eye drops for allergic conjunctivitis.

Question 2

Cromones

Answer 2

Include sodium cromoglicate and nedocromil sodium
Act as mast cell stabilisers, inhibiting degranulation.
Nasal spray and eyedrop forms

Question 3

Corticosteroids

Answer 3

Intranasal steroids for rhinitis include: Beclomethasone, Budesonide, Fluticasone, Triamcinolone
Reduce the inflammatory response itself by reducing cytokines and chemokines, reducing the recruitment of immune cells in the mucosa.
Produce changes in gene transcription so take longer to act.

Question 4

Decongestants

Answer 4

Histamine increases blood flow leading to oedema of the nasal tissue. Decongestants cause nasal vasoconstriction to reduce nasal tissue swelling and mucus flow.
α1 agonists, include xylometazoline/oxymetazoline, phenylephrine
Cause rebound congestion if used for >7 days - smooth muscle fatigue or receptor desensitisation