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Dosage Forms Final- Mobley
UF COP
81
Health Care
Graduate
12/15/2008

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Term
Topical Opthalmic drugs can be used to treat
Definition
glaucoma, infection, dry eyes and inflammation
Term
An injection would be used in opthalmics when...
Definition
faster and higher ocular drug levels
Term
3 concentric layers of the eye
Definition
outermost: conjunctiva/sclera and cornea
middle: uveal tract(iris, choroid and ciliary body)
innermost: retina
Term
The lens divides the eye into:
Definition
The aqueous (anterior segement) and vitreous (posterior segment) humors
Term
The aqueous humor is divided into the
Definition
anterior and posterior CHAMBERS
Term
The aqueous humor is generated by what?
Definition
ciliary bodies
Term
The aqueous humor flows through where into the posterior chamber?
Definition
pupil
Term
where does the aqueous humor exit into systemic circulation?
Definition
Schlemm's Canal
Term
A thin transparent, vascularised mucous membrane the extends from the edge of the cornea across a portion of the sclera
Definition
Conjunctiva
Term
the gland responsible for tear production
Definition
lacrimal gland
Term
small openings into the lacrimal canaliculi
Definition
puncta
Term
the drainage system for lacrimal fluid
Definition
nasolacrimal apparatus
Term
the two major pathways for a topical opthalmic to reach intraocular tissues
Definition
cornea and sclera (cornea dominates)
Term
covers the cornea
Definition
tear film
Term
three layers of the tear film
Definition
mucoid layer- adhesion, keeps cornea wettable
tear fluid- inorganic electrolytes, proteins and glucose
lipid film- wax and cholesterol esters to reduce evaporation
Term
what produces the driving force for passive diffusion throgh the cornea?
Definition
the concentration of the drug
Term
layers of the cornea
Definition
epithelium-bowman's membrane-stroma-descemet's membrane-endothelium
Term
3 most impt. layers of the cornea for drug absorption
Definition
epithelium-lipophilic, stroma-hydrophilic, endothelium- lipophilic
Term
stratified epithelium of the cornea
Definition
3-5 layer at middle, 8-10 on the side
Term
T or F: the epithelium of the cornea contains enzymes for drug metabolism.
Definition
True
Term
60 thin lamella, each composed of collagen fibers: made of mostly water
Definition
stroma
Term
the endothelium of the cornea is how much more permeable than the epithelium?
Definition
200x
Term
Single cell layer that provides metabolic exchange b/w the cornea and the aqueous humor
Definition
endothelium of the cornea
Term
What type of drugs are best absorbed opthamlmically?
Definition
drugs with a moderate octanol/water partition at physiological pH
Term
how do you increase the rate drug penetration at the cornea?
Definition
increase the concentration
Term
T or F: greater absorption occurs through damaged epithelium
Definition
true
Term
what percent of the dose in eye drops will cross the cornea?
Definition
5%
Term
most of the drug is removed from the surface of the eye through what two mechanisms?
Definition
spillage and nasolacrimal drainage
Term
the volume that can be accomodated int he lower cul-de-sac withough spillage
Definition
30 ul (normal eye drop ~39ul)
Term
fates of drug after crossing the cornea
Definition
penetration into deeper intraocular tissues
binding to proteins
elimination
Term
the concentration within the anterior chamber will be how much less than the applied product
Definition
2 orders of magnitude (100x less)
Term
T or F: treatment of the posterior region is achievable with a topical product
Definition
False
Term
some lipophilic drugs bind to what protein in the iris?
Definition
melanin (dark irides-less drug effect)
Term
elimination of drug after penetrating the cornea is through:
Definition
the canal of schlemm and uveal blood vessels
Term
The lumen of the esophagus is lined with what?
Definition
mucus and little water
Term
prepared and formulated like hard candy, dissolve slowly for local effect
Definition
lozenge
Term
compressed into a hard disc, intended to dissolve slowly in the mouth
Definition
troche
Term
thrush
Definition
yeast infection in the mouth, treated with lozenges or troches
Term
prepared by wet granulation, sometimes without a disintegrant and often have high mannitol or xylitol
Definition
chewable tablets
Term
what excipients are used in effervescent tablets?
Definition
sodium bicarbonate and citric acid
Term
claims of fast dissolving tablets
Definition
easier to take or swallow, possible faster onset of action
Term
methods of formulation of fast dissolving tablets
Definition
lyophilization (porous product) and direct compression (with effervescent exipients: problem-makes hygroscopic) and molding
Term
lining of the cheek
Definition
buccal
Term
ventral surface of the tongue and the floor of the mouth
Definition
sublingual
Term
epithelium of the mouth is...
Definition
highly vascularized
Term
T or F: Buccal and sublingual membranes are keratinized
Definition
False
Term
which membrane is thicker? more permeable?
Definition
buccal: Sublingual
Term
pH of saliva?
Definition
7
Term
where does saliva pool?
Definition
under the tongue
Term
drainage of drugs via the sublingual route occurs through what vein?
Definition
jugular
Term
disadv of sublingual
Definition
relatively low permeability for most drugs, drug can be washed away by saliva, unpredictable bioavailabity (mucosal variations)
Term
why should drugs and exipients of subllingual/buccal dosage forms be bland?
Definition
so you dont stimulate saliva flow
Term
sublingual tablets
Definition
compressed tablets-lightly (to facilitate disintegration)
Term
what is lactose used for in nitroglycerin tablets?
Definition
adsops to NO to reduce volatility and explosive risk
Term
which tend to be softer; molded or compressed tablets?
Definition
molded
Term
why are tablets dried under ambient conditions?
Definition
limit evaporation of NTG
Term
What is polyethylene glycol used in NTG tablets?
Definition
lowers vapor pressure: more stable
Term
T or F: NTG interacts with plastic
Definition
True (should be stored in glass)
Term
adv of NTG spray?
Definition
longer shelf life
Term
Nicorette
Definition
nicotine is bound to a cation exchange resin and is formulated to a pH of 8.5 to increase the unionized form
Term
lollipops
Definition
rapid absorption followed by prolonged: mouth and GI
Term
mucoadhesive tablets have what type of excipient?
Definition
cellulose derivative to make them stick
Term
examples of mucoadhesive tablets
Definition
striant-testosterone, nitroguard
Term
zelapar
Definition
for parkinsons disease, orally disintegrating tablet, absorption is buccal
Term
most widely used antimicrobial excipient, can increase corneal penetration
Definition
BAC, effective against p. aeruginosa
Term
what is an alternative to BAC but does not penetrate the corneal wall
Definition
polyquad
Term
and organic mercurial antimicrobial preservative
Definition
thimerosal
Term
examples of important buffers
Definition
acetate, phosphate, citrate, borate
Term
use drugs in this pH range to avoid irritation
Definition
6.6-9
Term
the normal osmolarity of tears
Definition
302-318mOsm/kg
Term
increased viscosity can:
Definition
increase retention time/bioavailability although can irritate if too high
Term
viscosity excipients
Definition
glycerin, cellulose, polyvinyl alcohol, PEGs (can be lubricating)
Term
suspension particle size
Definition
less than 10micrometers
Term
suspensions are used for what type of drugs?
Definition
poorly water soluble
Term
T or F: you can filter sterilize suspensions of eye drops.
Definition
false
Term
EDTA
Definition
chelator, and increase the activity of BAC ag. P. aeruginosa
Term
polysorbate
Definition
wetting agent, surfactant, facilitate spreading
Term
eyedrops are packaged in?
Definition
drop-tainer
Term
typical ointment base
Definition
white petrolatum
Term
main disadv of ointments
Definition
can cause blurred vision
Term
if the drug is in an aqueous vehicle
Definition
Partition coefficient increases with molecular weight
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