Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmaceutics > Opthalmics > Flashcards

Opthalmics Flashcards

1
Q

What is the conjunctiva and corneal surfaces lubricated by?

A
  • they are lubricated by a thin film of liquid (pre corneal tear film) secreted by the lacrimal glands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the additional components of tears?

A

0.7% protein, electrolytes and lysozyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why are tears necessary to the eye?

A

tears are necessary for the nutrition of the cornea, protection against bacterial infections, removal of cellular debris and foreign matter and the formation of a continuos film over the cornea to product a clear optical surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 layers of the pre corneal tear film?

A

1) Superficial oily layer
- consists of wax and cholesterol esters and it functions to slow evaporation
2) Middle aqueous layer - contains nutrients and lysozyme
3) adsorbed mucous layer- contains mucin and is involved in adhesion of the aqueous layer to the cornea which keeps the cornea wettable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the average tear volume?

A

7 microliters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens to most of the eyedrop when it is placed in the eye?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What can be done if systemic absorption of eyedrops is not desirable?

A

use a smaller drop size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What volume do normal dropper tips dispense?

A

provide about 25 micrometers but specialized tips can provide about 10 microliters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Topical ophthalmics must be manufactured as a _____

A

sterile product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the dose forms generally used in the eye?

A

Solutions, suspensions, gels, ointments, emulsions and some solid products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe ophthalmic solutions?

A
  • drugs dissolved in an isotonic medium containing an antimicrobial preservative
  • can be buffered but all products must be sterile
  • administration via blunt dropper or a plastic container with a dropper tip
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe ophthalmic gels?

A

contain a viscosity increasing agent in addition to the components used in a solution
- usually packaged in ophthalmic ointment tubes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe ophthalmic suspensions

A
  • contain a suspending and sometimes dispersing agents
  • suspended drug particles in the sub micron size range for ocular comfort, bioavailability and dispersibility
  • most of the suspending agents are cellulose derivatives, high molecular weight polymers or surfactants
  • care must be taken with surfactants to avoid irritation and disruption of the pre corneal tear film
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe ophthalmic ointments

A
  • contain micronized drug dispersed in a petrolatum or other non-aqueous base
  • they are packaged in lined metal tubes or plastic-foil laminated tubes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Are there many or few preservatives available to those wanting to put a preservative in an ophthalmic product?

A

few

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is benzalkonium chloride commonly used with as a preservative?

A
  • used in combination with EDTA to giver better activity against pseudomonas species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are some of the benefits of benzalkonium chloride?

A

fast acting with good stability and wide spectrum of activity

  • stable over wide pH and temperature ranges
  • surfactant properties aid in corneal penetration of the drug
18
Q

What is the usual concentration of benzalkonium chloride?

A
  • usual concentration is 0.01% and should never exceed 0.02% as this will cause ocular discomfort
19
Q

What does thimerosal have in it?

A

Mercury

20
Q

When is thimerosal usually used?

A

when incompatibilities preclude the use of benzalkonium chloride

21
Q

Is thimerosal fast acting or slow acting?

A

slow acting and may cause sensitization and toxicity

22
Q

What is the usual concentration of thimerosal for ophthalmics?

A

0.01%

23
Q

___ and ___ esters are used in combination and are most often used in ointments

A

methyl and propyl

24
Q

What is the usual concentration of methyl and propyl esters?

A

methyl: 0.03-0.1%
propyl: 0.01-0.02%

25
Q

pH of a solution with affect the chemical ___, ____ and _____

A

stability, solubility and ocular comfort

26
Q

What are the 2 reasons that ocular comfort is important when selecting a buffer?

A

import for compliance and if the product is irritating the tearing that is associated will result in a decreased contact time

27
Q

Buffer concentration should not exceed what value?

A

100 mM

28
Q

What is the function viscosity increasing agents? What is commonly used?

A
  • increase contact time, reduce drainage rate and enhance bioavailability
  • methylcellulose derivatives, crabbers and polyvinyl alcohol are all commonly used
29
Q

What do we want to tonicity of the ophthalmic product to be? Why do we want this?

A
  • we want the product to be isotonic to avoid ocular discomfort (this can lead to poor compliance and washout)
30
Q

What is generally used as a tonicity adjuster?

A

sodium chloride (sometimes glycerol or sugar is added)

31
Q

What is the most common antioxidant in ophthalmic products? What other ones are used?

A
  • sodium bisulfite

- other antioxidants used are acetylcysteine, ascorbic acid and sodium thiosulfate

32
Q

Non ionic surfactants are the only type suitable for ophthalmic products- true or false

A

True

33
Q

What is the general concentration range for surfactants?

A

0.1%

34
Q

What is the most common base for ointments?

A

white petrolatum with mineral oil

sometimes liquid petrolatum/polyethylene combinations have been used

35
Q

What are ophthalmic ointments typically preserved with?

A

they are typically preserved with parabens - those containing broad spectrum antibiotics do not require antimicrobial agents if the product meets an appropriate microbial challenge test

36
Q

The USP preservative effectiveness test is not required for what products?

A

for anhydrous non-aqueous vehicles

37
Q

List the antibacterial preservatives

A 
benzalkonium chloride 
benzethonium chloride 
chlorobutanol 
phenylmercuric acetate 
phenylmercurinic nitrate 
thimerosal
38
Q

List the antioxidants

A

sodium bisulfite
sodium metabisulfite
thiourea
ethylenediaminetetraacetic acid

39
Q

List the wetting/clarifying agents

A
  • polysorbate 80

- polysorbate 20

40
Q

List the viscosity agents

A
  • polvinyl alcohol
  • polyvinylpyrrolidone
  • methylcellulose
  • hydroxypropyl methylcellulose
  • hydroxyethylcellulose

Pharmaceutics (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions