P6 - nasal and otic drug delivery 2

what are the 3 structures of the ear

1. external ear - from pinnna to TM

2. middle ear - air filled cavity with temporal bond of skull around it

3. inner ear - cochlea and vestibular system

what it otic drug delivery used for

to treat middle and inner ear disorders

what are middle ear infections usually treated by

systemic drug adminsitration

what is the strucutre of the TM

1. outer layer - stratified dquamous keratinsed epithilum

2. middle layer - collagen rich layer

3. inner layer - cuboidal mucosal epithelium

whats the healing process of a perforation

1. rapid epidermal closure

2. fibrous repair

3. long term collagen remodelling and restoration of TM integrity.

what is ear wax (cerumen) composed of

sebum, shed skin cells, sweat, debris

whats the function of cerumen

provides protective coating and traps particulates helping move them away from TM

acidic pH - inhibits bacterial growth

what are the 3 auditory ossicles

malleus, incus, stapes

smallest bones in the body

transmit and amplify sound vibrations from the TM

transfer sound from air to the fluid filled inner ear

what does the eustachian tube do

connects middle ear to nasopharynx

can clear drugs adminsitered into the middle ear

whats the round window membrane

commnon route for inner ear delivery

has no stratum corneum

where are hair cells located and what do they do

sensory receptors for detecting sounds and motiion - movement of cilia generates nerve impulses and signals transmitted to the brain

located in the spiral cochlea within the organ of corti

what are two invasive methods of drug delivery

1. injection/device crossing TM

2. drug delivery system on RW allowing diffusion of drugs to inner ear

what is good about topical otic drug delivery

1. achieve high local concenrations

2. allow combination drug treatments

3. rapid action

4. generally good patient compliance

whats 4 exmaples of non-invasive delivery system

1. hydrogels - must remain in contact with TM for sufficent time ( liquid at room temp, gel at body temp) - prolonged residence time on TM, sustained drug release and reduced dosing frequency

2. chemical permeation enhancers - increase drug flux across biological barriers by altering lipid structure or membrane permeability

3. combination strategy - CPEs combined with hydrogels to achieve prolonges contact time and enhance barrier penetration

4. nanocarriers - protect drug from degredation, enable controlled or sustained release

whats 4 examples of invasive otic drug delivery systems

1. hydrogels - delivered via intratympanic injfection forms drug depot in the middle ear - reduces clearance through eustachian tube and prolongs contact with RWM

2. nanoparticles and magenetic nanoparticles delivered via intratympanic infection for targeted inner ear therapy - enahnced localisation and retention at the RWM

3. ultrasound mediated inner ear drug delivery - ultrasound induces microbubble cavitation at RW membrane

4. pump/catheter

whats silverstein microwick

wick inserted through TM to access RW

drops administered in outer ear diffuse through wick