Treatment of Allergic Rhinitis (Hay Fever)
Allergic Rhinitis in general
1. ↑ vascular permeability due to vasodilation
leading to
a. Runny nose
1. Allergic rhinitis is having collection of
symptoms which include
a. Itchy
b. Tearing eyes
2. Stimulation of sensory neuron leading to
i. Nose
a. Itching
ii. Mouth
b. Sneezing
iii. Eyes
b. Runny nose
c. Sneezing
3. Hypersecretion of glandular tissues
Distribution of Histamine receptors
1. H1
d. Tearing eyes
a. Smooth muscle cells
e. Nasal decongestion
b. Endothelial cells
2. Due to hypersensitivity of nasal mucosa to
allergens
2. H2
The fundamental cause of allergic rhinitis is release
of histamine
3. H3
The released of histamine by Mast cells and
Basophils will lead to
a. Gastric parietal cells
a. Central nervous system
Drugs used in the treatment of Allergic Rhinitis
1. Anti-histamines
a. 1st generation
i. Diphenhydramine
ii. Promethazine
iii. Clorpheniramine
b. 2nd generation
i. Cetrizine
ii. Loratadine
c. Decongestants (A1 receptor agonist)
i. Xylometazoline
ii. Ephedrine
d. Anti-inflammatory agents
i. Beclomethasone
Antihistamine
Mechanism of Action
Drugs/Infos
1st
generation
2nd
generation
Diphehydramine
Promethazine
Cetrizine
Loratadine
Non – selective
1. Binds to
a. H1 receptor
b. H3 receptor (CNS)
2. Cross BBB
3. Thus causing sedation
Shorter duration of action
Selective
1. Binds to only H1 receptor
2. Thus, NOT causing any
sedation
Causing
4. CNS depression
5. Anticholinergic action
a. Dry mouth
b. Urinary retention
6. Alpha adrenergic
blocking effect
a. Orthostatic
hypotension
DOES NOT cause
1. CNS depression
2. Anticholinergic action
3. Alpha adrenergic
blocking effect
Longer duration of action
1. Blocks the H1 receptor of
nasal mucosa leading to
a. Vasoconstriction
b. reduce in
i. Swelling
ii. Tearing
iii. Capillary permeability
iv. Runny nose
Side Effects
1st
Generation
Causing
1. CNS depression
2. Anticholinergic
action
a. Dry mouth
b. Urinary retention
3. Alpha adrenergic
blocking effect
Orthostatic hypotension
2nd generation
Interaction with drugs
metabolized by hepatic
metabolism (CYP450
inhibitor)
1. Antifungal
a. Ketonazole
2. Antibiotics
a. Erythromycin
3. Prokinetics
a. Cisapride
Leading to cardiac
arrhythmias
Nasal Decongestion (A1 Receptor Agonist)
Drugs/Infos
Mechanism of Action
Xylomethazoline
Epherdrine
1. Binds to nasal blood vessel
a1 adrenergic receptor
leading to vasodilation
2. Which therefore will
a. Reduce nasal mucosa
swelling
b. Reduce capillary
permeability
Anti-inflammatory Agents (Intranasal Glucocorticoid)
Drugs/Infos
Mechanism of Action
Beclamethasone
Info
1. Given intranasal
1. Inhibits Phospholipase A2 in which involve in
the formation of Arachidonic Acid;
precursor of
a. Cyclooxygenase, in return will form
i. Prostaglandin
b. Lypooxygenase, in return will from
i. Leukotriene
2. This will then lead to reduction in
a. Sneezing
b. Rhinorrhea
c. Nasal itching
Side Effects
1. Rebound congestion
a. If used more than
few days
2. Tolerance
3. CNS stimulation
Side Effects
Hardly any, due to its
topical admin
1. Dry of nasal mucosa
2. Burning sensation