1 - General Principles

Question 1

Factors affecting drug bioavailability

-4 possible fates for topical drug concentration

Answer 1

~25% lost via EVAPORATION
DRAINAGE into nasolacrimal apparatus
ABSORPTION into systemic circulation
PENETRATION into cornea

Question 2

Factors affecting drug bioavailability

-define bioavailability

Answer 2

Percent of UNCHANGED drug delivered to desired site

Question 3

Factors affecting drug bioavailability

-tear layer characteristics

Answer 3

Lipid = lipid soluble
Aqueous = water soluble
Mucous = combo

Question 4

Factors affecting drug bioavailability

-corneal layer characteristics

Answer 4

Epi and endo = lipid soluble

Stroma = water soluble

Question 5

Factors affecting drug bioavailability

-drug formulation to maximize bioavailability

Answer 5

Small
Uncharged/non-ionized
Lipid-soluble

Question 6

Factors affecting drug bioavailability

-most ocular drugs are formulated as what type of pH and why

Answer 6

Weak bases

-allows better penetration and bioavailability bc more non-ionized/lipid soluble