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17 Cards in this Set
- Front
- Back
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topically applied drugs only reach what part of the eye?
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anterior.... except in aphakic patients, where it can reach posterior chamber
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First Order Kinetics involves
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passive diffusion of molecules across a NONsaturated barrier, like the cornea.
The rate of movement is directly proportional to the conetration differences across the parrier |
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Zero order kinetics involves
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a rate limiting barrier that controls the passage of drug
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What is the order kinetcs MOST commonly encoutere in ocular drug movement?
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FIRST order
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Total volume of tears that can be held in eyelid?
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30, so the average size drop of 50 ul does not enter the eye, but enters systemically thru drainaige by the nose
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T/F Concentration of drug available in the tears for transcorneal absorption is PROPORTIONAL to tear flow, due to the drugs dilution and removal by the lacrimal duct and by lid spillover.
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FALSE
INVERSELY PROPRTIONAL The greater the tear flow, the less is avaiblable for absoprtion |
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T/F if more than one drop is given, an interval of 10 minutes between drops should be ued
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True
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T/F elder have a higher eye drop absoprtion than children
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true, they produce less tears, due to decrease basal and reflex tear production
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To penetrate the cornea effectively, the drug must posses a balance of
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hydrophilic (to penetrate functional layers) and lipophilic (to be absorbed) properties
Lipophilic drugs readily enter epithellium and can remain there and be stored, allowing the drug to have a long half life If drug is too hydrophilic, it will not penetrate the epithelium, but if it is too lipophilic, it will enter and remain i the epithlium for a proloonged period of time |
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T/F Iris contains pigment granules that absorb ipophilic drugs, and allows the release of drug over time
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True
Therefore, iris COLOR influences response to a single or multiple dosing of a drug |
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Where is the major ocular source of drug metabolizing enzymes respoisble for the reactions that being the process of drug detox and removal of eyes?
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Ciliary body
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Phase 1 of drug metabolization
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oxidatio nand reduction of drugs. Results in copound that are highly reactive and potentially more toxic than parent compound.
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Melanin granules of pigmented ciliary epithelium absb
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polycyclic compounds
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T/F Passage of drugs from aqueous to vitreous greatly decreases after cataract surgery?
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False
INCREASES |
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What provents the movement of antibiotics and other drugs from blood in the choroid into the retin and vitreous?
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zonula occlude\ns of RPE
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3 Blood vessels responsibe flr the removal of drugs in the eye are?
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Uveal vessels, Retinal vessels, Episcleral veins
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Inactive form of a drug is known as a
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Prodrug
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