• What are the general causes of rhinitis and rhinorrhoea?

1.  Rhinitis associasted with colds and flue
2. Mucosal Rhinitis (associated with sinusitis)
3. Allergic rhinitis (allergen exposure, IgE mediated inflammation)
4. Non-allergic rhinitis (physiological response due to stimuli such as cold, heat or smoke)

 

• Which drug groups can be used for the treatment of rhinorrhoea? Name examples from each group.

1. Alpha1-agonists eg: naphazoline
2. Antihistamines eg: loratadine
3. Corticosteroids eg: budesonide
4. Mast cell stabilisers eg: ketotifen
5. Mucolytics eg: mesna
6. Antibiotics eg: neomycin
7. Diverse drugs eg: normal saline

 

• How do the decongestants differ with respect to the mechanism of action and duration of action?  How are they administered typically?

MOA: The decongestants are alpha-adrenoreceptor sympathomimmetics, which causes vasoconstriction, which opposes vasodilation; this will reduce the nasal airway resistance and thus facilitate nose breathing.

Duration of action: Decongestants provide rapid relief that my last up to 12 hours, but may only be used 5-7 days.

Decongestants are usually administered topically via metered-dose sprays (which is the safest).

 

• What is rhinitis medicamentosa?  How is it treated?

Rhinitis medicamentosa is a condition which develops if topical decongestants are used for a period longer than 7 days. This conditions happens when there is an overstimulation of the alpha receptors in the nasal mucosa, which leads to the drying out of the mucosal  tissue. This leads to a blocked nose which is difficult to treat with medication. It can however be treated by cortisone nasal sprays.

 

• How does the first and second generations of antihistamines differ with respect to the mechanisms according to which rhinitis and rhinorrhoea are relieved?  What are the advantages of the second generation of antihistamines?  Why should they not be used to relieve cold rhinitis?

First generation antihistamines can be used for non-allergic rhinorrhoea, because it reduces the inflammation in the nose and in effect treats the symptom.

Second generation antihistamines can be used to treat allergic rhinitis. This medicine acts by inhibiting mast cell release of histamine and some other mediators of inflammation.

The advantages of the second generation of antihistamines are that they have little to no CNS distribution and in effect have a low incidence of patients who experience sedation and anticholinergic side effects.  

Antihistamines should not be used to relieve cold rhinitis, because some symptoms caused by body`s responses are not related to histamine production, in effect antihistamines will have no effect. In other words histamine is not the major cause of a runny nose. (Bradykinin plays a role.)

 

• When are corticosteroids, anti-allergic drugs, mesna and normal salt solution valid and how are they administered? 

*Corticosteroids: These drugs are valid for the use of allergic rhinitis and is administered topically in the form of a nasal spray.

*Anti-allergic drugs: These drugs are valid for the prophylactic treatment of allergic rhinitis and is administered topically in the form of a nasal spray.

*Mesna: This drug is valid when the nasal secretion is sticky as it helps to make the mucus more liquid. It is administered topically in the form of a nasal spray.

*Normal salt solution: This drug is valid for the use of humidifying the dry  and inflamed mucous membranes of the nose during colds, dry weather, allergy (hay fever), nose bleeding, overuse of decongestants and other irritations. This drug is administered topically in the form of nasal drops.