Ocular Drug Delivery / Dosage Forms

Question 1

Two routes of ocular drug absorption

Answer 1

1. Corneal Route - primary - ( >aqueous humor > ocular tissues)
2. Conjunctival / Scleral Route (straight to ocular tissues)

Question 2

Amount of dose absorbed via ocular routes

Answer 2

<10% (remaining ~50% is systemically absorbed and eliminated)

Question 3

Eye drop vs conjunctival sac capacity

Answer 3

eye drops = 50uL
sac capacity = 30uL
so you lose most of the drop’s dose most solutions entirely wash away within 15-30 mins

Question 4

Goal of eye dosage…

Answer 4

increase residence time

Question 5

Articulate instructions for administering eyedrops

Answer 5

1. Tilt head back
2. Gently pull lower eyelid down to form pouch
3. Hold dropper directly above eye and look up
4. squeeze a drop into pouch
   * * do not let tip of dropper touch eye or other surface**
   * *close eye for a minute or so**

Question 6

Small, lipophilic drugs take which absorption route?

Answer 6

Corneal

Question 7

Large, hydrophilic drugs take which absorption route?

Answer 7

Conjunctival and scleral

Question 8

If a child accidentally ingests Tetrahydrozoline, oxymetazoline, naphazoline…

Answer 8

All vasoconstrictors, can cause: coma, bradycardia, decreased breathing, sedation

Question 9

Ocular Ointment, 2 benefits

Answer 9

increased residence time

soothing

Question 10

Ocular Ointments, 3 drawbacks

Answer 10

blurred vision
imprecise dosing,
difficult for patients to apply

Question 11

Periocular Injections are indicated for…(3)

Answer 11

1. Reaching behind iris or lens (subconjunctival, subtenon, peritubular, retrobulbar)
2. For drugs with low lipid solubility
3. Local anesthetics, steroids

Question 12

Intraocular injections are indicated for…

Answer 12

1. Intravitreal conditions :
   - Macular edema (steroid),
   - Endopthalmitis (antibiotics),
   - Diabetic Retinopathy (anti-veg-f)

Question 13

Sustained release devices, 5 benefits

Answer 13

1. inceased contact time
2. improved bioavailability
3. prolonged drug release
4. fewer side effects
5. better compliance

Question 14

Sustained release devices, examples

Answer 14

1. Ocusert: pilocarpine, glaucoma
2. Timpotic XE: timolol glaucoma beta blocker
3. Ganciclovir : antiviral, CMV, HSV
4. Collagen shields: corneal protection (surgery, abrasions)

Question 15

Ocular Iontophoresis

Answer 15

• direct current drives pos charged ions into eye
• delivers high concentration to specific sight
• dry eye, bacterial keratitis

Question 16

What are four ways in which a dose is “lost” after a dose is instilled to the pre-corneal area?

Answer 16

1. Drug-protein binding
2. Drug metabolism
3. Normal tear turnover
4. Nasolacrimal drainage

Question 17

Describe the two Ocular Absorption routes of drug delivery

Answer 17

1. Corneal route > aqueous humor (>to systemic>) > ocular tissues (iris, retina, ciliary body)
2. Conjunctival and sclera route > > ocular tissues (iris, retina, ciliary body) /&raquo_space; systemic absorption

Question 18

Area of eye that periocular injections reach

Answer 18

Subconjunctival
Subtenon
Peribulbar
Retrobulbar

Question 19

Periocular injections, good for / examples of

Answer 19

Good for drugs w low lipid solubility (penicillins)

Exs steroids, local anesthetics

Question 20

Area of eye intraocular injections reach

Answer 20

Intracameral or intravitreal

Question 21

Intraocular injection, examples

Answer 21

AcT during cataract surgery

Intravitreal antibiotics for endopthalmitis

Intravitreal steroids for macular edema

Intravitreal VEG F for DR