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

rhinitis - caused by colds and flu and are presented as inflammation of the nasal mucosa

              - can also be due to allergens, physiological due to heat/smoke, or sinusitis.

rhinorrhoea - caused by cold, allergen, chemical or drug damage, cold air, physical damage

                      - presented as a runny nose

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

α1- agonists such as phenylephrine 

antihistamine such as chlorpheniramine

corticosteroids such as prednisone

mast cell stabilisers such as ketotifen

mucolytic such as mesna 

antibiotic like neomycin

divers drugs like steam/eucalyptus oil

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

Mechanism of action - alpha adrenergic receptors on nasal cavity stimulated, vasoconstriction of mucosal blood vessels. Decrease in nasal mucosa.

Duration of action - long and short acting(nasal spray)

                                 - short acting preferred, long acting can effect the heart and CNS(concentration decreases).

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

Develops when topical decongestants such as nasal spray or gels(oxymetazoline or xylometazoline) are used for longer than a few days or as prescribed. Tolerance builds up, and worsens symptoms. 

Treatment - progressively lower use of drug, but do not stop suddenly, as it can worsen symptoms

                    - nasal corticosteroids such as mometasone 

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?

First generation antihistamine - lead to sedation, lipophilic, cross blood brain barrier(lowered concentration)

                                                      - muscarinic blocker( decreased mucus secretion)

Second generation antihistamine - no muscarinic blocking effect, only used for allergic rhinitis 

                                                            - not lipophilic, do not cross blood brain barrier, no sedation

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

Corticosteroids - nasal spray

                            - used in allergic rhinitis and to reverse rhinitis medicamentosa

Anti-allergic drugs - nasal spray

                                  - allergic rhinitis /(stabilize mast cells)

Mesna - mucolytic drug administered through steam inhalation

             - liquify tough mucus 

Salt solution - nasal drops

                       - hydrate inflamed and dry mucus membranes