Term
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Definition
| Pharmaceutical preparations which are applied topically to the eye to treat surface or intraocular conditions |
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Term
| What sort of conditions would require ophthalmic drug? |
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Definition
-Infections of the eye or eyelids
-Allergenic or infectious conjunctivitis or inflammation
-Elevated intraocular pressure and glaucoma
-Dry eye |
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Term
| What is normal tear fluid volume? |
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Definition
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Term
| What is non-blinking state tear fluid volume? |
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Definition
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Term
| What is blink tear fluid volume? |
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Definition
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Term
| How much volume is in one eyedrop? How much volume is in an optimal dose? |
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Definition
A single drop measures about 50 µl
Optimal volume for a dose would be 5 to 10 µl
Therefore, a drop has much more medicine than actually needed |
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Term
| How much ophthalmic drug is absorbed? |
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Definition
| The retention time of an ophthalmic solution is short, and the amount of drug absorbed is usually only a small fraction of the quantity administered. |
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Term
| What physiological factors affect ocular bioavailability? |
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Definition
1. Protein binding
2. Drug metabolism (lysosymes degrade drugs)
3. Lacrimal drainage |
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Term
| What drugs (lipophyllic or hydrophilic) permeate the cornea most effectively? |
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Definition
| The cornea is a membrane that contains both lipophilic and hydrophilic layers. It is permeated most effectively by drug substances having both lipophilic and hydrophilic characteristics. |
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Term
| What is the effect of increasing an ophthalmic viscosity? |
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Definition
Mixes with lacrimal fluids easier, greater bio-availability
Less frequency of dosing, higher compliance |
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Term
| What are the two ways to sterilize an ophthalmic solution? |
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Definition
121 degrees for 15 minutes in an autoclave
Bacterial filter (not as reliable) |
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Term
| When can't an antimicrobial preservative be used in an ophthalmic? |
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Definition
When they are used during surgery or in the treatment of traumatized eyes because of the capacity of preservatives to be irritating.
These are typically packaged in single-use containers. |
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Term
| What are the considerations of antimicrobial preservative selection? |
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Definition
Concentration
pH
Odor
Stability |
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Term
| List some common antimicrobial preservatives for use in ophthalmics |
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Definition
Benzalkonium chloride
Benzethonium chloride
Chlorobutanol Phenylmercuric acetate
Phenylmercuric nitrite
Thimerosal |
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Term
| Define pseudomonas aeruginosa. How is it treated? |
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Definition
It is an organism that can invade an abraded cornea and cause ulceration and even blindness.
Preservative mixtures of benzalkonium chloride and either polymyxin B sulfate (1000 USP Units/ml) or disodium ethylenediaminetetraacetate are effective against most strains of Pseudomonas. |
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Term
| What is the isotonicity range for an ophthalmic solution without eye discomfort? |
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Definition
| 0.9% plus or minus 0.1%-2% |
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Term
| How does boric acid compare to NaCl as an isotonic agent? |
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Definition
| Boric acid in a concentration of 1.9% produces the same osmotic pressure as does 0.9% sodium chloride. |
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Term
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Definition
Approximately 7.4
(More acidic in contact lens wearers) |
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Term
| If you had to change the pH of an ophthalmic from 7.4, should you make it more acidic or alkaline if you have a choice? |
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Definition
| Alkaline; the eye can tolerate a greater deviation from physiological pH toward alkalinity (and less discomfort) than toward the acidic range). |
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Term
| Is it possible for an ophthalmic solution to have a pH of 7.4? |
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Definition
| No, at pH 7.4, many drugs are insoluble in water |
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Term
| What pH is used for an ophthalmic solution? |
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Definition
| A compromise pH between therapeutically active and thermodynamically stable |
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Term
| List some viscosity enhancers |
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Definition
Hydroxyethylcellulose
Hydroxypropylmethylcellulose
Methylcellulose
Polyvinyl alcohol
polyvinylpyrrolidone |
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Term
| What is the most common viscosity in an ophthalmic solution, and what is the optimal range? |
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Definition
Between 25 and 50 cps, optimal range from 15-25 cps
(cps= centipoise) |
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Term
| Define Newtonian flow for ophthalmics |
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Definition
| Loss of drug solution due to drainage should be inversely proportional to its viscosity |
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Term
| Define pseudoplastic flow for ophthalmics |
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Definition
| As blinking occurs, the system will thin out and drain from the eye |
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Term
| What are the three types of contact lenses? |
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Definition
1. Hard
2. Soft
3. Rigid gas permeable |
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Term
| Describe hard contact lenses |
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Definition
-Rigid plastic resin
-Covers only part of the cornea
-Uncomfortable
-Impermeable to O2 and moisture
-Must prevent lens from damaging epithelial tissue |
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Term
| How do you care for hard contact lenses? |
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Definition
Clean to remove debris and deposits from the lens
Soaking the lens in a storage disinfecting solution while not in use
Wetting the lenses to decrease their hydrophobic characteristics |
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Term
| Describe soft contact lenses |
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Definition
-Hydrophillic, transparent
-30-80% water
-Cover entire cornea
-More comfortable, less dislodging
-Might absorb medication
-Less durable |
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Term
| What are the two type of soft contact lenses |
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Definition
| Daily wear and extended wear (Note: it is advisable that lenses not be left in the eye for longer than 4 to 7 days without removal for cleaning and disinfection |
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Term
| Describe care of soft contact lenses |
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Definition
Cleaning to loosen and remove lipid and protein deposits
Rinsing to remove the cleaning solutions and material loosened by cleaning
Disinfection to kill microorganisms |
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Term
| List some products for soft contacts |
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Definition
Cleaners
Rinsing and Storage Solutions
Disinfection and Neutralization |
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Term
| Describe Rigid Gas Permeable (RGP) lenses |
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Definition
-Oxygen permeable but hydrophobic
-More comfortable than hard lenses
-Basic type of lens for daily wear |
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Term
| Should an ophthalmic drug be used with contacts? |
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Definition
No, the drug can build up between the cornea and contact lens
May cloud vision and discolor the lens |
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Term
| How does rifampin affect contact lenses? |
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Definition
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Term
| How does ribavirin affect contact lenses? |
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Definition
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Term
| How do salicylates affect contact lenses? |
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Definition
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Term
| How does acetazolamide affect contact lenses? |
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Definition
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Term
| How do drugs with anticholinergic effects (antihistamines, tricyclic antidepresants) affect the eyes? |
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Definition
| They decrease tear secretion (so probably should not be taken with contacts in) |
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Term
| Define Acanthamoeba keratisis |
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Definition
An amoeba infection of the eye that does not have a commercially available product in the US (must be compounded)
One of the chemicals, Bacquanil, is a pool cleaner |
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Term
| What are some special considerations of ophthalmic suspensions? |
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Definition
Suspension particles must be of a size that doesn't irritate or scratch the cornea
Micronized form is require
Free of agglomeration or caking |
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Term
| What are some special considerations of ophthalmic ointments? |
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Definition
Ointments must be nonirritating, permit diffusion, and retain activity when stored
Base: white petrolatum
Powders must be micronized and sterilized, free from grittiness
Ointments are better for neonates/pediatrics to lessen systemic absorption |
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Term
| What is a compatibility issue with zinc salts in ophthalmics? |
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Definition
| Zinc salts form insoluble hydroxides above pH 6.4 (use a boric acid solution, pH 5) |
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Term
| What is a compatibility issue with nitrates/salicytiates in ophthalmics? |
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Definition
| They are incompatible with benzalkonium chloride (so use a different preservative) |
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Term
| What is a compatibility issue with silver nitrate in ophthalmics? |
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Definition
| It will precipitate silver chloride when mixed with sodium chloride |
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