Ophthalmic preparations

solutions, suspensions, intraocular inserts/injections, ointments

What are the desired properties of ophthalmic preparation?

sterile, free from particulate materials, physiological pH, isotonic, Stable, non-toxic

In solutions all ingredients and excipients are _____

completely in solution

What are the advantages of ophthalmic solutions?

uniform dosing, little physical interference with vision, convenience, clarity, rapid onset

What are the disadvantages of ophthalmic solutions?

short contact time due to small volume capacity of the eye (7microL)
tear turnover and blinking washes the drug away within 1-2 min
low bioavailability (1-5%)
needs frequent dosing

How does the corneal barrier affect drug absorption?

The cornea has lipid-rich epithelial cells that only allow moderately lipophilic and small molecules enter (restriction of hydrophilic drug diffusion)
Aqueous stroma restricts lipophilic drugs

How does lacrimal drainage affect drug absorption?

Fluids are removed from the eye rapidly and clear the drug
Leads to systemic absorption and decreases local efficacy

What excipients do ophthalmic solutions contain?

Vehicle
Buffers
Tonic adjustors
preservatives
antioxidants
viscosity inducing agents

Water for ophthalmic solutions must be ____

Sterile

A pH that is too low or too high may cause ____ and ____which leads to ___ ___

stinging, tearing, drug loss

what is the normal pH range for ophthalmic preparations?

6.5-8.5

What are the two buffers for ophthalmic preparations?

Boric acid (isotonic with tears, pH 5)
Sorensen’s modified phosphate buffer (NaH₂PO₄ , Na₂HPO₄ Not isotonic)

what is the purpose of tonicity modifiers?

to adjust and match the osmotic pressure of the formulation to that of tear fluid

The eye can tolerate a range of ___ - ___ % NaCl without discomfort

0.6 to 2

T/F: sodium chloride, sodium nitrate, sodium sulfate, and dextrose are tonicity adjustors

True

What is the purpose of preservatives in the ophthalmic preparations?

they maintain sterility

When should ophthalmic preparations that contain preservatives not be used?

During eye surgery
traumatized eyes
(they can cause irritation)

How are PF preparations typically packaged?

Single-use containers

T/F: the pharmacist’s key role is to ensure the patient has no allergy or sensitivity to preservatives

True

what is the purpose of antioxidants in ophthalmic preparations?

to neutralize reactive oxygen species and free radicals

What is the purpose of a wetting agent?

to ensure proper penetration of eye drops in the cornea

T/F: Polysorbate 80 and polysorbate 20 are wetting agents

true

T/F: viscosity enhancers are used to thin the tear and prolong corneal contact

False, the are used to thicken the tear

Why Artificial Tears Contain Carboxymethylcellulose Sodium (CMC-Na) 0.5%

It is a viscosity enhancer and acts as the active ingredient to prevent tears from drying rapidly (refresh tears)

T/F: Drug is present and finely divided in an aqueous vehicle

containing suitable suspending and dispersing agents. This is a ophthalmic solution.

False, this is a ophthalmic suspension

What are advantages of suspensions?

enables use of poorly soluble drugs
may provide prolonged drug contact as particles slowly dissolve

What are the disadvantages of suspensions?

Requires shaking
Risk of non-uniform dosing if not mixed well
Larger particles may irritate the cornea

What are the advantages of ophthalmic ointment?

Longer contact time
Greater total drug bioavailability

What are the disadvantages of ophthalmic ointments?

Slower onset and time for peak absorption
Higher dosage variability than with solutions (don’t know what dose is being applied)
Interference with vision unless limited to bedtime
Must be sterile and free from particulate matter

Why are ophthalmic ointments recommended for bedtime use?

They can cause blurry vision
Nighttime allows prolonged contact time while eyes are closed

T/F: Ocular inserts are a solid dosage form and release drugs at a constant rate

True

What are disadvantaged of Ocular inserts?

Difficult to wear for non-contact users
Non-biodegradable must be removed from eye
Inner eyelid discomfort

Where are ocular packs inserted and why?

into the superior or inferior fornix
b/c they give prolonged contact of the solution with the eye

What are the characteristics of intraocular dosage forms?

Sterile and pyrogen free
strict control of particulate matter
compatible with sensitive internal tissues
packaged as PF single dosage provides sustained or controlled release

T/F: Intraocular solutions are used for surgical procedures such as cataract removal

True
Used as irrigating solution to maintain hydration
Used to maintain and preserve space as well as displace and stabilize tissues

What should be avoided in intraocular solutions?

Preservatives

What is the advantage of intraocular injections?

They can be applied directly to affected area with minimal systemic side effects
Eye is anesthetized before

How is sterility achieved?

-filtering final solution using a membrane filter
-packaged in a clean, particle-free, sterile container
-longer than 24 hours or multi-dose, a preservative must be added
-Use aseptic technique in clean and aseptic area
-use of laminar-flow hoods and proper garments

What are the types of sterilization?

-Dry heat

-filtration
-gas sterilization
-ionizing radiation
-moist heat under pressure

What is not an advantage regarding plastic dropper bottles used for ophthalmic preparations?
-they are flexible
-have low contamination potential
-low cost
-they are permeable to labels glues, inks and dyes

they are permeable to labels glues, inks and dyes

Which package is not paired correctly?
-glass bottles —> used for oxidation sensitive or permeable solutions
-Metal tube —> suspensions that have high contamination probability
-Plastic dropper bottle —→ suspensions or solutions

Metal tube —> used for ophthalmic ointments to provide a barrier to air and light, easy to sterilize and prevents evaporation
Disadvantage: can react with some components