mucosal revised Flashcards
mucoadhesion
state in which a material and the mucus are held together for extended period of time by interfacial forces
reasoning for mucoadhesion
used in controlled release systems
enhancement of poorly absorbed drug molecules
immobilization of dosage form at site of action
mechanisms of mucoadhesion
electrostatic interaction (pos, neg)
hydrogen bonding
covalent bonding (disulfide)
physical interpenetration
mucus properties
secreted by goblet cells or specialized glands
composed of mostly water, mucins (glycoproteins), lipids, and inorganic salts
diffusion barrier for drugs
mucus function
coat nearly all entry points to the human body that are not covered by the skin
protect underlying epithelial tissue (act as barrier)
keep the mucosal membrane moist
mucoadhesive polymers
alginate
carbomer
hyaluronic acid
NaCMC
pectins
polycarbophil
chitosan
polylysine
hydroxypropyl-cellulose
hydroxypropyl-methylcellulose
drug properties desirable for mucosal delivery
high potency
predominantly lipophilic
small MW
maybe hydrophilic macromolecular weight drugs
hydrophilic macromolecular weight drug in mucosal delivery
likely require absorption enhancers like fatty acids, bile salts, or surfactants
may not be stable due to salivary enzymes
SL delivery
relatively permeable
rapid onset
suitable for frequent dosing and short term delivery in an emergency
SL example
nitroglycerin used for relief from acute agina attack
buccal delivery
relatively less permeable than SL
slower absorption and onset of action
less influenced by saliva
suitable for sustained delivery application
can come in tablets, patches, or semisolids
has bioadhesive polymer layer with a matrix containing active ingredient and excipients
how would use a buccal delivery system?
- flat side on fingertip
- push round side against upper gum above the rear molar between the upper cheek and gum
- be sure to push as high as possible so that the flat side will face lip
- hold in place from outside for 30 seconds to stick tablet
- leave until dissolved
respiratory region
main site for systemic drug delivery
relatively large surface area
epithelium covered with mucus
reason for mucus in respiratory region of nasal cavity
humidification and warming of inhaled air
physical and enzymatic protection against foreign compounds as it sticks and removes particles/pathogens through mucociliary clearance
olfactory region
small surface area
provides a direct connection between the CNS and the atmosphere
contains small glands that produce secretions acting as a solvent for odorous substances
requirements for ocular drug delivery
need to be clear
good corneal penetration
prolonged contact time with the corneal epithelium
simplicity of use
non-irritating, comfortable
challenges of ocular drug delivery
loss due to dilution in the tear film, fluid spillage, and drainage
short residence time due to rapid turnover of tears and aqueous humor
not much flexibility in formulation due to pH, osmolarity, and solubility
how would one reduce drainage of eye drops?
the use of viscosity enhances
examples - polyvinyl alcohol, methyl cellulose, timoptix-XE gel, DuraSite (polyacrylic acid formualtions)
features of port delivery system
extrascleral flange
self-sealing septum (where device anchors into eye)
body (drug reservoir)
porous metal release control element (where drug comes out)
vaginal drug delivery systems
gels and creams
films
rings (slowly released hormones)
intrauterine
rectal drug delivery systems
suppositories (local or systemic) and rectal enemas (higher bioavailability)
