Blog #3.4

What are the general causes of rhinitis and rhinorrhoea?

• General causes of these two conditions are usually allergies, colds, Drug damage, Chemical damage, cold air and Physical damage

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

• Alfa 1 agonists such as phenylephrine, ephedrine  and naphazoline, etc
• Antihistamines such as the 1^st generation diphenhydramine, promethazine, chlorpheniramine, etc
• Corticosteroids such as Betamethazone, prednisone, budesonide, etc
• Mast cell stabilizers such as sodium chromoglycate and ketotifen
• Mucolytics such as acetylcysteine
• Antibiotics such as mupirocin, neomycin, etc
• Diverse drugs such as steaming with essential oils (menthol/eucalyptus oil)

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

Decongestants can work in 2 ways – they can be systemic decongestants, or they can be topical decongestants. They are probably mediated by alfa 1 receptors – thus leading to vasoconstriction of mucosal blood vessels and decreased oedema of nasal mucosa. Duration of action for systemic decongestants is longer than for those administered topically – but longer duration of action increases risk of CNS toxicity. Systemic decongestants are designed to be administered orally, whilst topical decongestants are prepared as nasal sprays and gels/drops.

What is rhinitis medicamentosa?  How is it treated?

Rhinitis medicamentosa is a condition that develops as a side effect of overuse of topical nasal decongestants – It is the Drying of nasal tissue that develops after 5 – 7 days of topical use (more than 3 days ) – leading to a blocked nose.

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?

1st generation antihistamines have a lot of side effects due to their high lipophilicity – leading to their ability to easily cross the BBB and cause CNS side effects, such as sedation – It thus must be used in a decreased concentration – whereas 2^nd generation antihistamines are less lipophilic and doesn’t cross the BBB easily – thus not having those side effects. It is thus a good medication to use long term in allergic rhinitis where stimulus can continue for long periods of time (months). They work by blocking the histamine 1 receptors that would have been stimulated by different allergens. Cold rhinitis (caused by colds and flu) is not caused by stimulants such as pollen, they also cause mucus thickening which is undesirable in cold rhinitis.

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

• Corticosteroids are used in cortisone nasal sprays for prophylactic use. They are used chronically in allergic rhinitis, nasal polyps, inflammatory rhinitis and reversal of rhinitis medicamentosa
• Antihistamines are rarely indicated, but is used for prophylaxis of allergic rhinitis as a nasal spray

Mesna and normal salt solution are both used to loosen touch nasal mucus by diluting it. It is administered via nasal lavage. Can also be administered via steaming