• What are the general causes of rhinitis and rhinorrhoea?

Allergies, colds and flue, cold air, physical damage, chemical or drug damage.

 

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

First generation antihistamines: diphenhydramine, promethazine, chlorpheniramine, brompheniramine

Alpha 1 agonist/decongestants: phenylephrine, ephedrine, phenylpropanolamine, naphazoline, xylometazoline, oxymetazoline

 

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

Ephedrine, pseudoephedrine and propylhexidrine are non-selective for adrenoceptors and thus stimulate alpha and beta adrenoceptors with a potent indirect action and mixed action.

Phenylephrine is direct acting.

Naphazoline, xylometazoline and oxymetazoline are imidazole derivatives with mixed action.

They are administered as nasal sprays, gels/jellies, drops and inhalations.

Short acting (4-6 hours): ephedrine, phenylephrine, naphazoline

Intermediate acting (8-10 hours): xylometazoline

Long acting (more than 12 hours): oxymetazoline

 

• What is rhinitis medicamentosa?  How is it treated?

It happens when decongestants/alpha 1 agonist are used chronically.

The permanent vasoconstriction of nasal capillaries and reduced blood supply to the nasal mucosa/nasal walls, damages the nasal mucosa which cause permanent swelling and inflammation of the nasal walls. Alpha 1 receptor deregulation also happens which leads to the receptors not acting on alpha 1 stimuli. Tachyphylaxis (depletion of l-NA) also occur.

Treatment: Corticosteroid/cortisone nasal sprays such as beclomethasone.

 

• 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 only relieve rhinorrhoea caused by colds. They are multipotent antagonists which also antagonizes muscarinic receptors and thus reduce mucus secretions/mucus production in the upper and lower airways.

Second generation antihistamines only relieve allergic rhinitis. They only antagonize histamine 1 receptors which has an anti-inflammatory effect. The second generation drugs to not cause sedation or reduced concentration and can be used in prophylactic/chronic treatment of allergic rhinitis.

They should not be used to relieve cold rhinitis because they do not have an effect on bradykinin receptors (bradykinin and not histamine are released during colds and thus bradykinin receptors and not histamine receptors should be blocked).

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

Corticosteroids (nasal drops/topical): allergic rhinitis, inflammatory rhinitis, nasal polyps, reversal of rhinitis medicamentosa/privinism

Anti-allergic drugs/mast cell stabilizers (topical): prophylaxis of allergic rhinitis

Mesna (topical/nasal sprays): diluting sticky nasal mucus

Normal salt saline solution (topical/nasal sprays): nasal lavage to dilute mucus caused by sinusitis.