Section 8 - Ophthalmics

Question 1

What is an ophthalmic product?

Answer 1

Sterile dosage form free from foreign particles suitably compounded and packaged for instillation into the eye

Question 2

Which dosage forms can ophthalmic products be?

Answer 2

Solutions, suspensions, ointments, emulsions, and some solid

Question 3

What is the conjunctiva?

Answer 3

Membrane covering outer surface of the white portion of the eye and inner surface of eyelids

Question 4

Which gland secretes tear film?

Answer 4

Lacrimal glands

Question 5

What are tears made up of?

Answer 5

0.7% protein, electrolytes, and lysozyme

Question 6

What is the purpose of tears?

Answer 6

• Nutrition of cornea
• Protection against bacterial infections
• Removal of cellular debris and foreign matter
• Formation of a continuous film over the cornea to produce a clear optical surface

Question 7

How long does it take for tears to evaporate?

Answer 7

15-30 seconds

Question 8

What are the 3 layers of the precorneal tear film and what is the function of each?

Answer 8

1) Superficial oily layer - consists of wax and cholesterol esters and slows evaporation
2) Middle aqueous layer - contains nutrients and lysozyme (thickest layer)
3) Adsorbed mucus layer - contains mucin and involved in adhesion of aqueous layer to cornea which keeps cornea wettable

Question 9

What is the average tear volume?

Answer 9

7 uL

Question 10

What occurs when tear volume is increased by instillation of an eyedrop?

Answer 10

Rapid reflex blinking restores volume back to normal

Question 11

When an eyedrop is instilled, where does most of it go?

Answer 11

Through lacrimal drainage system and systemic absorption may occur through the membranes of the nasolacrimal duct

Question 12

What can be done if nasolacrimal absorption is undesirable?

Answer 12

Use a smaller drop size

Question 13

What volume do normal dropper tips provide?

Answer 13

25 uL

Question 14

What makes topical ophthalmics different from topical skin products?

Answer 14

Topical ophthalmics must be manufactured as a sterile product and steps taken to ensure sterility

Question 15

What is the drug dissolved in in an ophthalmic solution?

Answer 15

Isotonic medium containing antimicrobial preservative

Question 16

When would an antimicrobial preservative not be needed in a ophthalmic solution?

Answer 16

If unit dose packaging is used

Question 17

What do gel ophthalmics contain?

Answer 17

Viscosity-increasing agent in addition to the components used in a solution

Question 18

How are gel ophthalmics usually packaged?

Answer 18

In ophthalmic ointment tubes

Question 19

What do ophthalmic suspensions usually contain?

Answer 19

A suspending, and sometimes dispersing agents

Question 20

What size of drug particles are best for ophthalmic suspensions?

Answer 20

Submicron size range

Question 21

Most suspending agents used in ophthalmic suspensions are ____ derivatives, ___ molecular weight polymers or _____

Answer 21

• Cellulose
• High
• Surfactants

Question 22

Care must be taken w/ surfactants to avoid ..?

Answer 22

Irritation and disruption of the precorneal tear film

Question 23

What do ophthalmic ointments contain?

Answer 23

Micronized drug dispersed in a petrolatum or other non-aqueous base

Question 24

How are ophthalmic ointments packaged?

Answer 24

In lined metal tubes or plastic-foil laminated tubes

Question 25

Which antimicrobial preservatives are effective against Pseudomonas species?

Answer 25

Benzalkonium chloride in combination w/ EDTA

Question 26

What are advantages to benzalkonium chloride?

Answer 26

- Fast acting - Good stability and wide spectrum of activity - Stable over wide pH and temp ranges

Question 27

What is the usual concentration of benzalkonium chloride? What should the concentration never exceed?

Answer 27

- Usual = 0.01% | - Never exceed 0.02% b/c will cause ocular discomfort

Question 28

When is thimerosal used as an antimicrobial preservative?

Answer 28

When incompatibilities preclude the use of benzalkonium chloride

Question 29

What is a disadvantage to thimerosal?

Answer 29

Slow acting and may cause sensitization and/or toxicity

Question 30

What is the usual concentration of thimerosal for ophthalmics?

Answer 30

0.01%

Question 31

Which parabens are used as ophthalmic preservatives and in what dosage form?

Answer 31

- Usually methyl and propyl esters used in combination | - Most often used in ointments

Question 32

What is a disadvantage to parabens?

Answer 32

May cause burning sensation to eye

Question 33

What are the usual concentrations of parabens used in ophthalmics?

Answer 33

- Methyl = 0.03-0.1% | - Propyl = 0.01-0.02%

Question 34

What happens if a product is irritating to the eye?

Answer 34

Tearing will result and contact time will be reduced

Question 35

What is the ideal buffer capacity for an ophthalmic product?

Answer 35

Adequate to maintain product, but low enough that when the product is instilled pH will rapidly adjust to 7.4

Question 36

Generally, buffer concentration for ophthalmics should not exceed ____

Answer 36

100 mM

Question 37

What is the function of viscosity increasing agents?

Answer 37

Increase contact time, reduce drainage rate, or enhance bioavailability

Question 38

Which viscosity increasing agents are commonly used in ophthalmic products?

Answer 38

- Methylcellulose derivatives (hydroxypropylmethylcellulose, hydroxyethylcellulose, methylcellulose) - Carbomers - Polyvinyl alcohol

Question 39

Why do you want an ophthalmic product to be isotonic?

Answer 39

To avoid ocular discomfort

Question 40

What is the most common tonicity adjusting agent used in ophthalmic products?

Answer 40

Sodium chloride

Question 41

When is sodium chloride not used as a tonicity adjuster and what would replace it?

Answer 41

- Glycerol or sugar | - Used when an ionizable tonicity adjuster will disrupt dispersive action of surfactants in the product

Question 42

What is the most common antioxidant used in ophthalmic products?

Answer 42

Sodium bisulfite

Question 43

Can pH be lowered in an ophthalmic product to prevent oxidation?

Answer 43

No b/c of the sensitive nature of eye tissues

Question 44

What does surfactant selection depend on?

Answer 44

Potential to irritate the eye, damage cell membranes or disrupt precorneal tear film

Question 45

Which surfactants are the only type suitable for ophthalmic products?

Answer 45

Non-ionic surfactants

Question 46

What concentration of surfactant should be used for ophthalmic products?

Answer 46

As low as possible, but usually around 0.1%

Question 47

What is the most common ointment base for ophthalmic products?

Answer 47

White petrolatum w/ mineral oil

Question 48

____ drug particles must be used for ophthalmic ointments

Answer 48

Ultra-fine

Question 49

How are ophthalmic ointments usually preserved?

Answer 49

- W/ parabens - Products w/ broad spectrum antibiotics do not require antimicrobial agents if the product meets an appropriate microbial challenge test

Question 50

For which products is the USP preservative effectiveness test not required for?

Answer 50

Products made w/ anhydrous non-aqueous vehicles