• What are the general causes of rhinitis and rhinorrhoea?

Rhinitis (inflammation of the mucous membranes of the nose) and rhinorrhoea (runny nose) are usually the results of allergies, cold, chemical or drug damage, cold air or physical damage.

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

α1-agonists, (decongestant) e.g., phenylephrine, ephedrine, phenylpropanolamine,naphazoline,  oxymetazoline and xylometazoline. Vasoconstriction of mucosal blood vessels, ↓ oedema of nasal mucosa

Antihistamines e.g., Diphenhydramine, promethazine, chlorpheniramine, brompheniramine, loratadine,

cetirizine, levocabastine, rupatadine

Corticosteroids e.g., Betamethasone, prednisone, beclomethasone, budesonide, cyclonesonide, mometasone

Mast cell stabilisers e.g., Sodium chromoglycate (Vividrin® eye drops), ketotifen

Mucolytics e.g., Mesna, acetylcysteine

Antibiotics e.g., Mupirocin, neomycin, topical in nostrils

Diverse drugs e.g., steam, normal saline, essential oils such as menthol, eucalyptus oil

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

    short-acting drugs (4 to 6 hours), e.g. ephedrine, phenylephrine, propylhexedrine, naphazoline and tetrahydrozoline;

    intermediary acting drugs (8 to 10 hours), e.g. xylometazoline;

    long-acting drugs (12 hours), e.g. oxymetazoline.

• What is rhinitis medicamentosa?  How is it treated?

Rhinitis medicamentosa (privinism) and rebound rhinitis can result from an overdose of local preparations.  Privinism is a condition that may present following chronic treatment with decongestants, where the permanent vasoconstriction with poor local blood supply leads to damage of the mucous membranes of the nose with permanent inflammation and swelling, as well as deregulation of the a‑adrenergic receptors on the blood vessels, rendering them unresponsive towards the a‑agonists. Tachyphylaxis (l‑noradrenalin storage exhaustion) can be evoked by indirect-acting drugs.

• 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?

There is controversy, however, about the use of antihistamines for the treatment of rhinorrhoea during colds.  Here bradykinin, and not histamine, is the mediator of inflammation.  There is, therefore, no rationale for the application of the antihistaminic characteristics of the antihistamine.  It is, however, true that the old generation antihistamines (multipotent antagonists) are used for cold rhinorrhoea in view of their antimuscarinic characteristics to dry all watery secretions.  There is a feeling among certain experts that the disadvantages (side-effects and serious toxicity, especially in children) outweigh the advantages.  For the treatment of allergic rhinitis the usefulness of the antihistamines is, however, clear.

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

Topical mesna (nasal spray) is especially meaningful to use when the nasal secretion is sticky.  The mesna helps to make the mucus more liquid.

The use of sodium cromoglycate as a nasal spray is very effective for the prophylactic treatment of allergic rhinitis, but the regular dosage makes it less popular.

Normal salt (saline) solution is very safe and effective as nose drops.  It humidifies the dry, inflamed mucous membranes of the nose during colds, dry weather, allergy (hay fever), nose bleeding, overuse of decongestants and other irritations. Volatile oils can, however, potentially cause reflex larynx constriction in very small babies, which can be fatal.