Topic 2I Otic Drug Delivery

Question 0

What effect does swimming have on the external auditory canal (4)

Answer 0

Swimming causes hydration (isoelectric point above pH 5) of the keratin layer, increasing susceptibility to pathogenic organisms

Question 1

How do various glands in the external auditory canal provide anti microbial activity (6)

Answer 1

Sweat glands: muramidase a lysozyme is excreted and may be
effective in lysing staph and a gram + found on the
surface of the ear canal skin.
Sebaceous glands: lipids are excreted and are broken down into
unsaturated fatty acids which exert anti microbial activity
against gram - organisms and fungi

Question 2

Formulation requirements for an ideal cerumenolytic preparation (6)

Answer 2

The ideal cerumenolytic preparation a hypo-osmolar, alkaline, aqueous solution has not yet been developed. It should be able to lyse the keratin cells of cerumen and allow for easy disimpaction.

Question 3

What type of dosage form in not likely to cause pain on administration (1)

Answer 3

Anaesthetic agents are used to eliminate pain associated with infections. They may be used locally before surgical manipulation.

Question 4

Discuss the significance of ototoxicity with respect to otic drug delivery systems (6)

Answer 4

Ototoxicity is of most concern when there is a perforation in the tympanic membrane.
Ototoxic drugs: antiseptics, antibiotics; neomycin, chloramphenicol,
Not Ototoxic: antibiotics; quinolones. Corticosteroids

The risk of hearing loss resulting from otitis media is generally higher than the risk of hearing loss from using an agent known to be Ototoxic.