Opthalmic Formulations, Deliveries, PK, Rx, Diagnostics

Question 1

pros and cons of preservatives in opthalmic solutions, and the most common preservative

Answer 1

decrease microorganisms
can cause epithelial toxicity
BAK

Question 2

benefit of viscosity-increasing agents

Answer 2

slow drainage of drug from eye (more time for drug to act)

Question 3

benefit of antioxidants

Answer 3

delay breakdown by oxygen

Question 4

benefit of wetting agents

Answer 4

help solution spread across surface (by decreasing surface tension)

Question 5

benefit of buffers

Answer 5

keep solution in pH range of 6-8, to reduce sting

Question 6

benefit of tonicity agents

Answer 6

keep solution isotonic with tear film (to prevent eye irritation and tissue damage)

Question 7

when could a hypertonic solution be used opthalmically? example

Answer 7

to draw fluid out of cornea when swollen (as with contact lens overuse or Fuch’s syndrome)
5% NaCl

Question 8

important instructions to pt when giving them a supsension

Answer 8

shake it before use

Question 9

some drugs in gel/ointment form

Answer 9

pilocarpine (for glaucoma)
timolol maleate (for high IOP in pt's with ocular HTN or open-angle glaucoma)
GenTeal Gel (for dry eye)

Question 10

uses for lid scrubs

Answer 10

for blepharitis Tx and prevention (cleaning eyelids, applying antibiotics or ointments)

Question 11

what is cotton pledget, and use in optometry

Answer 11

cotton compress
it is saturated with opthalmic solution and put in conjunctival sac
it is used for administering mydriatics, such as to dilate stubborn pupils or to break a posterior synechia

Question 12

uses for contact lenses (other than refractive)

Answer 12

as a bandage

for sustained-release of water-soluble drugs (since they are absorbed into the contact lens)

Question 13

use for corneal shields

Answer 13

bandage after surgery/injury

Question 14

use for filter paper strips, advantage

Answer 14

to apply dyes, which are for diagnosis of infections, dry eye, and corneal injuries
ensures sterility (eye drops don't always)

Question 15

use of artificial tear insert

Answer 15

sustained-release of artificial tear for Tx of dry eye

Question 16

use of slow-release intravitreal inserts

Answer 16

for release of antiviral agent or steroid over long periods

Question 17

how can you deal with a patient who won’t let you administer ophthalmic drops directly onto the eye?

Answer 17

drop in medial canthus
practice with artificial tears at home beforehand
spray

Question 18

what % of 50 mL of glaucoma solution would be present in the tear film after 5 minutes?

Answer 18

8%
max lacrimal volume (10 microL) / volume of drop = best retention
???

Question 19

effect of reflex tearing, and way to minimize it

Answer 19

flushes out more drug, decreasing absorption

use a local anesthetic beforehand

Question 20

ways to occlude punctum, and benefits

Answer 20

digital pressure at nasal canthal area
plug (total occlusion)
both increase drug absorption (closing eyes also helps)

Question 21

characteristic needed for drugs to be absorbed into cornea, and forms that absorb through what layer

Answer 21

differential solubility (solubility in water and lipid)
non-ionized forms of weak bases are lipid soluble, pass through corneal epithelium and endothelium (outer layers)
ionized forms of weak bases are water soluble, pass through corneal stroma
??? why does ppt slide show charged molecule passing through all layers ???

Question 22

which routes of absorption have been overlooked, though they look promising?

Answer 22

conjunctiva and sclera

Question 23

what are the effects of age and race on ophthalmic drug absorption?

Answer 23

increased age = prolonged efficacy (a toddler will recover from atropine mydriasis in 1-2 days)
blacks and asians (those with more pigment) are less affected by mydriasis or miosis (from all such drugs???)

Question 24

other name for Rx drug

Answer 24

legend drug

Question 25

when might a pt need a standing order?

Answer 25

if the pt is in a facility and needs an ongoing prescription (such as in a nursing home)

Question 26

how can the orange book benefit your pts?

Answer 26

it is the FDA’s list of generics (drugs with the same active ingredients and with therapeutic equivalence), so you can use this list to prescribe cheaper drugs that will still have the needed effect

Question 27

Why would you not want to prescribe generics for some drugs?

Answer 27

Some drugs have unique ingredients, different bioavailability, or a narrow therapeutic index

Question 28

what is bioavailability?

Answer 28

the amount of administered drug that reaches systemic circulation

Question 29

why is a narrow therapeutic index a concern?

Answer 29

because it means small changes in bioavailability can lead to adverse effects

Question 30

John Poag, a 55 year old male with primary open angle glaucoma in both eyes
Prescribe Travatan Z 0.004% ophthalmic solution 1 drop both eyes before bed time
Travatan Z comes in 2.5mL bottle
3 refills
How long does a bottle of Travatan Z last?

Answer 30

?

Question 31

what does a cholinergic agonist do at the receptor, and how does this explain what pilocarpine does?

Answer 31

a CAg binds to the receptor, and activates it

pilocarpine contracts the iris sphincter and ciliary muscle (miosis and accomodation)

Question 32

what does a cholinergic antagonist do at the receptor, and how does this explain what tropicamide does?

Answer 32

a CAnt binds to the receptor, but does not activate it

Tropicamide relaxes the iris sphincter and ciliary muscle (mydriasis and relaxed accomodation)