1. What are the general causes of rhinitis and rhinorrhoea?

Rhinitis-cold and flu, sinusitis, allergen exposure, response to stimuli such as heat, smoke, cold

Rhinorrhoea- allergy, cold, chemical or drug damage, cold air or physical damage  

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

1^st generation antihistamines e.g., diphenhydramine

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

Short acting (4 to 6 hours) – e.g., ephedrine

Long acting (12 hours) – e.g., Oxymetazoline

Decongestants causes vasoconstriction of the mucosal blood vessels and decreases oedema of the nasal mucosa

Can be administered topically or orally, typically they are administered topically as they distribute the drug best this way, it drops easily into the GIT and the metred dose sprays are the safest. The oral decongestants lead to more side effects and slower commencement of action.

4. What is rhinitis medicamentosa?  How is it treated?

Rhinitis medicamentosa is caused by overuse of a decongestant, the permanent vasoconstriction with poor blood supply leads to damage of the mucous membranes of the nose with permanent inflammation and swelling as well as deregulation of alpha receptors on the blood vessels rendering them unresponsive to the alpha agonists.

It can be treated by corticosteroids

5. 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?

1^st generation antihistamines are multipotent competing agonists and block muscarinic receptors. Thus, reducing the secretions of both upper and lower airways and frequently included in cold preparations to clear up rhinorrhoea. They however cause sedation and thus negatively affect the ability to concentrate.  

2^nd generation antihistamines do not block muscarinic receptors and are useful for long term or short-term treatment of allergic rhinitis. 2^nd generation antihistamines do not have sedation as a side effect

 Histamine plays no role in cold rhinitis, but bradykinin does these drugs do not help clear up cold rhinitis.

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

• Corticosteroids- valid for allergic rhinitis, inflammatory rhinitis, nasal polyps, and reversal of rhinitis medicamentosa and administered topically (nasal sprays)
• Anti-allergic drugs- prophylactic treatment for allergic rhinitis administered as a nasal spray
• Mesna- used when nasal secretion is sticky administered topically