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Terms in this set (45)
*Applied topically to the cornea or instilled in the space between the eyeball and the lower eyelid
*4 types of opthalmic preparations?
4. controlled delivery
*What preparation is diluted with tears and washed away through lacrimal apparatus?
*What preparation has a long contact time, but may cause irritation due to particle size?
*Disadvantage of ointments?
puts a film over the eye
*Why are ointments good?
very long contact time and doesn't easily run out
*What preparation releases at a constant rate?
controlled release has poor corneal absorption?
*What decreases absorption in the eye?
the protective mechanisms in the eye
*Examples of protective mechanisms
drainage of the instilled solutions;
lacrimation and tear turnover;
limited corneal area and poor corneal
binding by the lacrimal proteins
**poorly soluble opthalmic drugs can be solubilized using?
**____ is a group of cyclic oligosaccharides capable of forming inclusion complexes with many drugs.
What are three major things cyclodextrins can do?
-increase efficacy of poorly water soluble drugs
-increase corneal penetration
-increase ocular absorption
CDs increase/decrease solubility of LIPOphilic drugs?
CDs affect the drug's intrinsic ability to permeate the biological membrane.
False...they do NOT affect it
Name 2 ways to sterilize and which of the 2 is most effective?
These liquids undergo a viscosity increase when instilled into the eye?
in-situ activated gel forming systems
-they are solutions and change to a gel to increase retention time
3 ways to change viscosity and an in-situ activated gel forming system
-temperature (poloxamer 407)
-electrolyte composition (Gelrite)
a polymer with a solution viscosity that increases when its temperature is raised to the eye temperature.
is a polymer undergoing coagulation when the original pH of the solution (4.5) is raised to 7.4 by the tear fluid
cellulose acetophthalate (CAP)
in-situ activated gel formation when using polymers is a low/high concentration of polymers?
in-situ activated gel formation when using Gelrite is a low/high concentration of Gelrite?
polymers or gelrite interacts with mono or divalent cations in the tears?
How do surfactants enhance permeability in the cornea?
destroying cell membrane, causing lysis (negative effect)
*devices intended to be placed in the conjunctival sac and to deliver the drug at a comparatively slow rate.
*Advantages of inserts?
-accurate dosing (we know how much is in it)
-increased ocular permeance, drug activity, & bioavailability
-reduction of systemic adsorption
*What is Ocusert?
diffusion-controlled unit with a drug reservoir enclosed by 2 release controlling membranes
*Ocusert release controlling membranes are made of?
-ethylene-vinyl acetate copolymer
-enclosed by a white ring, allowing positioning of the system in the eye.
*inserts are good or bad for glaucoma?
good..can control the intraocular pressures with minor side effects
*How is systemic adsorption reduced by using inserts?
-decreases drainage into the nasal cavities, which is one of the major sites for systemic adsorption of topical ocular medications
*What makes it a possibility that inserts could increase the efficacy of ocular hydrophilic drugs?
it may be possible to do non-corneal drug penetration
*Desired properties of antimicrobial agents for opthamlic?
broad spectrum, stable, compatible, non-irritable
*Classes or antimicrobial agent for opthalmic?
quaternary ammonium compounds
*Most common antimicrobial for opthalmic?
-good antimicrobial and chemical stability
antimicrobials are compatible with anionic compounds.
*Types of contact lenses?
-hard (that's what she said)
-Rigid Gas Permeable (RGP)
*What material are hard contacts made of?
rigid plastic resin
*Hard contacts are permeable or impermeable to oxygen and water?
*Which form of contact lenses only partially covers the cornea?
*Soft contacts are made of?
hydrophilic transparent plastic, hydroxyethyl methacrylate, with very small amounts of cross-linking agents that provide a hydrogel network.
*soft contacts are permeable or impermeable to water and oxygen?
permeable....contain 30-80% water
Daily wear vs extended wear?
daily=remove at bedtime
extended=24 hour wear
extended wear should be removed at least how often?
every 4-7 days and cleaned
Rigid gas permeable lenses are permeable to water and oxygen?
oxygen, but not water=hydrophobic
What are some advantages of rigid gas permeable lenses over soft lenses?
provides strength, easy care regimens, visual acuity
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