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Biopharmaceutics > nasal/ear/eye delivery > Flashcards

nasal/ear/eye delivery Flashcards

1
Q

name the 4 liquid filled compartments of the eye

A

outside eyeball, behind cornea, between iris and lens, behind lens

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2
Q

structures of the eye involved in ophthalmic delivery

A

eyelids- removes debri
cornea- no blood vessel, delicate but repairs quickly, multi-layered
tears wash eye continually
^all protective/cleaning mechanisms

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3
Q

describe the internal structure of the eye

A

4 fluid filled regions, only tear chamber and anterior are accessible by topical dose forms (eg. eyedrops), vitreous chamber requires systemic drugs/direct injection

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4
Q

common targets of eye delivery

A

tear deficiency, bacterial/viral infections, reduction of inflammation/redness, glaucoma, analgesia, pupil dilation, diagnostic dyes

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5
Q

problems with eye delivery and why

A

very low bioavailability and poor absorption

caused by
drainage- most of eye drop dose drained into nose/swallowed
higher dose dont have higher ocular conc
blinking/rubbing eyes- increase rate of drainage
protein binding
schlera well vascularised- diffusion drugs removed into bloodstream quickly
cornea is a barrier

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6
Q

why is the epithelial layer a major barrier to water soluble drugs

A

it has tight junctions

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7
Q

describe the formulation design for eye delivery- pH/buffering

A

buffers can be used to get drugs into a suitable ionisation state for absorption, acidic pH causes more discomfort, corneal damage in pH outside of 3-11

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8
Q

describe the formulation design for eye delivery- tonicity

A

tears are 0.9% NaCl, isotonic is the best, 0.6-2% NaCl is tolerable

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9
Q

why are eye delivery usually single dose units

A

minimise cross infection

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10
Q

describe the formulation design for eye delivery- multi dose containers

A

more convenient but must contain preservatives, sensitivity with long term use

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11
Q

describe the formulation design for eye delivery- irritancy/toxicity

A

everything in contact with eye gets tested, FDA in vivo test in rabbit eyes, some preservatives

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12
Q

describe the formulation design for eye delivery- preps for eye surgery

A

no preservatives, safe as it penetrates eye interior, isotonic, neutral pH, single dose

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13
Q

3 formulation types of eye delivery

A

eye drops- transient effect, viscosity agents increase residence

eye ointment- more prolonged effect, better absorption but causes blurred vision, useful for non aq drug and eyelid problems

inserts- collagen or polymer base

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14
Q

components of ear wax

A

fatty acids, lipids, polypeptides, debris, epithelial cells

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15
Q

what is earwax

A

ear canal gland secretions that dry to give a water repellent coat, hydrophobic wax

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16
Q

describe structure of eustachian tube

A

ciliated, mucus and debris wafted down throat, channel for infection to middle ear, self cleaning

17
Q

name 3 important structures in ear delivery

A

ear canal, eustachian tube, eardrum

18
Q

things that ear delivery is used to treat

A

excessive earwax/earwax remover, bacterial infection/inflammation, boils, eczema at ear canal entrance, steroid, middle ear, viral/bacterial infection, systemic analgesics/antibiotics (otitis media)

19
Q

formulation designs of topicals for external ear

A

non aqueous vehicles used as water in ear canal promotes bacterial growth, sensitivity to PG, oil/surfactants to soften wax as penetration of wax is hard bc of high viscosity and lack of movement, aqueous peroxide to disintegrate wax

20
Q

what does nasal mean

A

inside the nose

21
Q

why use nasal route

A

treat local infections, access to local receptors to reduce inflammation and excess secretion

22
Q

methods of nasal delivery administration

A

nose drops- solutions/suspensions from a dropper bottle

nasal spray- fine droplets/powder for penetration into nasal cavity

creams/ointment- topical for external/internal areas around nostrils

23
Q

functions of the nose

A

detection of smell- olfactory receptors in nasal cavity

air conditioning of inhaled air- lots of capillaries, fast flowing, humidifies, water loss though

particle/debri cleanrance- mucocilary clearance

24
Q

describe stages of mucociliary clearance

A

particles get trapped in mucus layer, mucus wafted towards larynx by cilia, swallowed

25
Q

composition of mucus

A

glycoproteins, salts, water, proteins, lysosymes

26
Q

properties of mucus (pH and tonicity)

A

pH= 5.5-7
tonicity= 0.9% NaCl

27
Q

biopharmaceutical issues with nasal delivery

A

alters internal environment (mucus secretion/dryness/inflammation)

mucociliary clearance- mucus renewed fast, short residence time for drug action

deposition from sprays depend on particle size, nose drops spread better but sprays penetrate deeper and longer action

systemic absorption- epithelium permeable to drug diffusion but barriers

28
Q

why is nasal cavity a good target for systemic delivery for difficult drugs like proteins and peptides

A

permeable and plentiful blood supple

29
Q

problems with systemic absorption in nasal delivery

A

mucocilary clearance- short residence time
mucus- binds to drug
enzymes- metabolises drug
irritation/inflammation/damage to nasal mucosa
epithelial barrier requires drug to have an appropriate ionisation state

30
Q

ways to enhance nasal delivery

A

absorption enhancers- bile salts/surfactants (damages)

solubility enhancers

prodrugs with good penetration properties- metabolised to active drug after absorption

bioadhesives

microparticulates-increases retention time and bioavailabiltiy

31
Q

how do microparticulates enhance nasal delivery

A

increases retention time and bioavailability

32
Q

formulation design of nasal delivery

A

sensitive when inflamed so dosage form must be comfortable and avoids stinging, liquid and creams match nasal secretion, neutral pH, non irritating, water vehicle, sterile, drug cant interfere with ciliary clearance

33
Q

systemic drugs for nasal delivery

A

hormones- calcitonin, pituitary hormones
migraine- sumatriptan
smoking- nicotine

34
Q

local drugs for nasal delivery

A

nasal allergy- antihistamines
decongestants
sympathomimetics- mimic effects of epinephrine/dopamine/norepinephrine/catecholamines
infections
epistaxis (nose bleed after nasal surgery)

Biopharmaceutics (11 decks)

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