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Dosage - Exam 3 > Lecture 22 > Flashcards

Lecture 22 Flashcards

Parental Solid Dosage Forms (Mucosal; local) - Yeo

1
Q

mucosal drug delivery

A

via accessible body cavities covered with mucosa
examples - oral mucosa, nasal, vaginal, intrauterine, rectal, ocular, pulmonary
can be systemic or local with mucoadhesion

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2
Q

advantages of mucosal delivery

A

avoids the first-pass effect
non-invasive
relative ease and convenience

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3
Q

disadvantages of mucosal delivery

A

small area of absorption (nasal, oral)
taste (oral)
delivery limited by molecular weight of a drug
local tissue irritation, sensitivity to pathologic conditions

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4
Q

mucus

A

secreted by goblet cells or specialized glands (example - salivary glands in the oral cavity)
components - mostly water, mucins (glycoproteins), lipids, and inorganic salts
thickness of mucus layer differs from under 1mcm (oral cavity) to 450 mcm (stomach)
diffusion barrier for drugs
also a target for mucoadhesion

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5
Q

mucus functions

A

coats nearly all entry points to the human body that are not covered by skin
protects underlying epithelial tissues (example - stomach)
keeps the mucosal membrane moist (lubrication)

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6
Q

mucin

A

glycoportein of 20% protein and 80% carbohydrates (highly glycosylated)
extra large molecules either membrane bound or secreted
provides a gel-like structure of the mucus
carries a negative charge attributed to high content of sialic acid (sugar)

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7
Q

mucin component

A

sialic acid (–)
galactose
N-acetylglucosamine
Core sugars
protein core
cysteine-rich subdomains forming intra and/or intermolecular disulfide bonds

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8
Q

mucoadhesion

A

the state in which a material (polymers) and the mucus are held together for extended periods of time by interfacial forces
prolongs residence time of the dosage form on the mucosal surface

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9
Q

purpose of mucoadhesion

A

controlled release systems (extended/sustained)
enhancement of poorly absorbed drug molecules
immobilization of the dosage form at the desired site of action

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10
Q

mechanism of mucoadhesion

A

electrostatic interaction (positive charge of polymer vs negative charge of sialic acid in mucin)
hydrogen bonding (-COOH, -OH, -NH2)
covalent bonding (disulfide bond between thiolated polymer and cysteine-rich portion of mucin)
physical interpenetration

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11
Q

mucoadhesive polymers

A

alginate
carbomer
hyaluronic acid
carboxymethylcellulose sodium (NaCMC)
pectins
polycarbophil
chitosan
polylysine
hydroxypropyl-cellulose
hydroxypropyl-methylcellulose

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12
Q

oral mucosal

A

systemic or local
could be sublingual (ventral side of the tongue and floor of mouth) or buccal mucosa (on the cheeks)

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13
Q

advantages of oral mucosal

A

avoid first-pass effect
rapid absorption and onset of drug effect
easy to remove if therapy needs to be discontinued

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14
Q

disadvantages of oral mucosal

A

small surface area (around 100cm2) so not suitable for low potency drugs
limited by taste

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15
Q

variations of oral mucosa

A

buccal - thick, NK, dense submucosa
gums - thick, K/NK, no distinct submucosa
floor of mouth - thin, NK, loose submucosa
ventral surface - thin, NK, no very distinct submucosa layer

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16
Q

sublingual specifics

A

relatively permeable
rapid onset
suitable for frequent dosing and short-term delivery (emergency)
examples - nitroglycerin SL tablet (prompts relief from acute angina attack)

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17
Q

buccal specifics

A

relatively less permeable than SL
slower absorption and onset of action than SL
less influenced by saliva
suitable for sustained delivery applications
buccal tablets, patches, and semisolids

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18
Q

drug absorption via oral mucosa

A

epithelium is main barrier
mechanism for drug diffusion is either transcellular(intra) or paracellular(inter) via intercellular lipids
absorbed into the reticulated and jugular veins then drained into systemic circulation to avoid first-pass effect

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19
Q

drugs primarily delivered via oral mucosa

A

predominantly lipophilic
mostly smaller MW drugs
maybe hydrophilic macromolecular weight drugs such as peptides, oligonucleotides, polysaccharides (likely require absorption enhancers; may not be stable due to salivary enzymes)

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20
Q

buccal tablets

A

bioadhesive polymer layer (polyacrylic acids, cellulose derivatives)
second layer to allow unidirectional drug delivery for systemic absorption
matrix containing active ingredient and excipients

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21
Q

Oravig

A

example of buccal tablet used for the local treatment of oropharyngeal candidiasis in adults
active agent - miconazole (antifungal)

22
Q

fentora

A

example of buccal/effervescent tablet that rapidly releases fentanyl into the buccal pouch creating a systemic effect
starting treatment is between the upper cheek and gum
maintenance dose is SL under the tongue

23
Q

Actiq (cephalon)

A

fentanyl citrate
lozenge on a stick
either transmucosal or gastrointestinal absorption

24
Q

buccal patches

A

thinner and more flexible than buccal tablets
less obtrusive, more acceptable to patients
example - dentipatch (lidocaine) and bema

25
Q

advantages of nasal

A

avoidance of hepatic first-pass elimination and destruction in the GI tract
rapid absorption of drug molecules across the nasal membrane
relatively easy and convenient

26
Q

disadvantages of nasal

A

possible tissue irritation
rapid removal of the drug from the site of absorption (mucociliary clearance)
pathologic conditions such as cold or allergies that may alter significantly the nasal bioavailability
limited area of drug absorption

27
Q

nasal examples

A

zicam (zinc ion for cold symptoms)
miacalcin nasal spray (calcitonin, post-menopausal osteoporosis, long term delivery)

28
Q

respiratory region of nasal cavity

A

main site for systemic drug delivery
relatively large surface area (around 150cm2)
epithelium covered with mucus that provides humidification and warming of inhaled air; physical and enzyme protection against foreign compounds (including drugs)

29
Q

olfactory region of nasal cavity

A

small surface area (1-5cm2)
provides a direct connection between the CNS and the atmosphere
contains small glands that produce secretions acting as a solvent for odorous substances

30
Q

systemic nasal

A

via respiratory region
fast and extended drug absorptions
examples - analgesics (morphine), CV drugs (propranolol, carvedilol), hormones (levonorgestrel, progesterone, insulin), anti-inflammatory agents (indomethacin, ketorolac), and anti-viral (Acyclovir)

31
Q

local nasal

A

treatment of topical nasal disorders
examples - antihistamines, corticosteroids (rhinosinusitis) and nasal decongestants (cold symptoms)

32
Q

nasal vaccines

A

nasal mucosa is the first site of contact with inhaled antigens (like influenza a/b virus, proteosoma-influenza, and adenovirus-vectore influenza)
lymphoid tissue underneath the nasal epithelium (dendritic cells, T-cells, and B-cells)
vaccination against respiratory infections

33
Q

advantages of vaginal mucosa

A

rich blood supply
high permeability to certain drugs
advoidance of hepatic first-pass effect

34
Q

disadvantage of vaginal mucosal

A

hormone-dependent changes (like pH)

35
Q

vaginal delivery systems

A

gels and creams
films
vaginal rings

36
Q

vaginal gels and creams

A

most widely used
drawback – leakage, messiness, requires an applicator
types – antimicrobial pessaries or creams, estrogen creams, spermicidal gels and creams
examples - replens (bioadhesive gel)

37
Q

vaginal films

A

example - vaginal contraceptive film

38
Q

vaginal rings

A

pliable drug delivery system that can be inserted into the vagina, where it slowly releases hormones to be absorbed into the blood stream
example - contraceptive rings

39
Q

intrauterine delivery system

A

IUD containing progesterone and levonorgestrel
example - mirena IUD

40
Q

IUD

A

small plastic device placed into the uterine cavity for sustained intrauterine drug release for contraception

41
Q

mirena IUD

A

local progestognenic effects in the uterine cavity
thickening of cervical mucus preventing passage of sperm into uterus, inhibition of sperm capacitation or survival, alternation of endometrium
zero-order release up to 5 years (20mcg/day)

42
Q

rectal drug delivery

A

drugs ordinarily administered by the oral route can be administered by lower enteral route, through the anal portion into the rectum or lower intestine
local effect - inflammatory bowel disease (IBD)
systemic effect - when oral administration is not feasible
less popular now with improvements in other delivery systems, used mostly in pediatrics or geriatrics
either suppositories or rectal emenas

43
Q

rectal suppositories

A

solid dosage forms intended for insertion into the rectum (or vagina) where they melt, soften, or dissolve, and exert local or systemic drug delivery

44
Q

rectal emenas

A

liquids introduced into the rectum and colon via the anus

45
Q

ocular drug delivery

A

local - great need (blood-retina barrier)
requirements
- need to be clear
- good corneal penetration
- prolonged contact time with the corneal epithelium
- simplicity of use
- non-irritating, comfortable

46
Q

challenges in ocular delivery

A

loss due to dilution in the tear film, fluid spillage, drainage (eye drop is around 20-50mcL, but space is only 7mcL)
short residence time (rapid turnover of tears and aqueous humor)
not much flexibility in formulation adjustments (pH, osmolarity, and solubility)

47
Q

ocular dosage forms

A

eye drops
ointments
ocusert
contact lenses
erodible or non-erodible implants

48
Q

improved eye drops

A

reduce drainage by the use of viscosity-enhancers
examples - polyvinyl alcohol, methyl cellulose, timoptix-XE gel, and durasite

49
Q

port delivery system

A

permanent, refillable implant
surgically inserted through a small incision in the sclera and pars plana

50
Q

components of port delivery system

A

extrascleral flange
self-sealing septum
body (drug reservoir)
porous metal release control element

Dosage - Exam 3 (9 decks)

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