Opthalmic Preparations

Question 1

Definition of opthalmic preparations

Answer 1

Sterile, liquid, semi-solid or solid preparations that may contain 1 or more active ingredient intended for conjunctiva, conjunctival sac and eyelids

Question 2

Palpebral conjunctiva

Answer 2

-cover eyelids
-firm adherent
-highly vascular
-extremely thin
-strongly bound to the tarsal plate

Question 3

Bulbar conjunctiva

Answer 3

-cover the eyeball
-thin, translucent and loosely attached to underlying sclera

Question 4

Anatomy of the eye

Answer 4

-Inside of the eyeballs is divided by the lens into two fluid-filled
-The larger the back of the eye is filled with colorless gelatinous mass called VITREOUS HUMOR
-AQUEOUS HUMOR: water-like material at the small section in front of the eyeballs
-CONJUNCTIVA: mucous membranes begins at the edge of the cornea and lines inside the surface of the eyelids and sclera to lubricate the eye

Question 5

Drugs used in the eye

Answer 5

-miotics (pilocarpine)
-mydriatics (atropine)
-cycloplegics (atropine)
-anti-inflammatories (corticosteroids)
-anti-infectives (antivirals)
-anti-glaucoma (piloocarpine Hcl)
-surgical adjuncts (irrigating solutions)
-diagnostic drugs (sodium fluorescein)
-anesthetics (tetracaine)

Question 6

Factors affecting drug availability

Answer 6

-rapid solution drainage by gravity
-superficial absorption of drug into the conjunctiva and sclera and rapid removal by peripheral blood flow
-low corneal permeability

Question 7

Corneal absorption process

Answer 7

1. Poor bioavailability
2. Protective mechanisms > 3. Blinking, reflex lacrimation, nasolacrimal drainage
3. Anatomy of the eye > barrier properties of the cornea

Question 8

Pharmaceutical requirements

Answer 8

-sterility and preservatives
-isotonicity
-buffering
-viscosity and thickening agents
-ocular bioavailability

Question 9

Sterility and preservatives

Answer 9

-sterilised by autoclave at 121°C for 15min or filtration
-antimicrobial preservatives
-eg: benzalkonium chloride

Question 10

Isotonicity

Answer 10

-hypotonic vs hypertonic
-must be with lacrimal fluid
-adjusted with sodium chloride, boric acid and mannitol
-eyes can adjust isotonicity 0.6-2%

Question 11

Buffering

Answer 11

-pH adjuster
-greater comfort
-render formulation more stable
-enhance aqueous drug solubility
-eg: boric acid

Question 12

Viscosity and thickening agents

Answer 12

-decrease with increasing temprature
-advantages:
•increase ocular contact time
•increase mucoadhesiveness
•decrease drainage rate

-disadvantages:
•blur vision
•filtration more difficult
-eg”: hydroxypropyl methyl cellulose

Question 13

Ocular bioavailability

Answer 13

Factors affecting:
-protein binding
-drug metabolism
-lacrimal drainage

Question 14

Manufacturing considerations

Answer 14

1. Environment (sterile or particle free through laminar flow, ultraviolet lamps, separate entrance)
2. Techniques
   -aqueous opthqlmic solutions (dissolution of active ingredients)
   -aqueous suspensions (sterilize by heat, ionizebby radiation or electron, aseptic crystallisation)
   -opthalmic ointment (ointment. base sterilised by heat and filtered while molten, may be passed to sterilized colloid mill)

Question 15

Eyedrops

Answer 15

-eye drops (sterile aqueous@solution@suspension for application to conjunctiva sac of the eye
-requirements: sterile, isotonic, free from particles
-preparation:
1. Drug dissolved in distilled water to solution by filtration
2. Sterilised by heating in autoclave with closed containers
3. Dispensed in glass or suitable plastic container

Administration:
1- pull down eyelid
2- tilt head backwards, look at ceiling
3- apply slight pressure to bottle
4- drop fall to the eye
5- dont squeeze lids

Eyedropper solutions (sterile, free from particles, suitably compounded)

Disadvantages:
-solution stays for a short time
-poor bioavailability instability of dissolved drug

Question 16

Gel forming solutions

Answer 16

-Gel on contact with tear fluid
-rarely according to particular polymers employed at their mechanisms for triggering transition to gel phase of the eye
-eg: Timolol Maleate

Question 17

Opthalmic inserts

Answer 17

-sterile solid or semi-solid preparations with thin, flexible structure for insertion in conjunctival sac

Advantages:
•increase time
•provide prolong drug release
•reduction of adverse effects

1. Ocular
   -soluble (types: based on natural polymers, synthetic or semi / synthetic)
   -insoluble
2. Intraocular
   -opthalmic products for interior eye
   -requirements: sterile, strict control / particular matter, compatible with sensitive internal tissues

Question 18

Eye ointments

Answer 18

Formulation:
-mixture of mineral oil and petrolatum base
-adjunctive therapy
-greasy, blurring vision

Packaged in:
-small collapsible tin tube
-aluminium tubes
-plastic tubes from flexible LPDE resins

Question 19

Eye lotions

Answer 19

-sterile aqueous solutions used for irrigating eyes
-free from foreign particles
-isotonic

Question 20

Eye suspensions

Answer 20

-drug is not soluble or to improve stability
-improve bioavailability and efficacy
-particles 95% or more, diameter 10microns or less

Question 21

Opthalmic product

Answer 21

Advantages:
-easy to administer
-quick absorption
-quick effect
-less systemic side effects
-better patient compliance

Disadvantages:
-short contact time
-poor bioavailability
-necessary add preservatives

Question 22

Ideal opthalmic delivery system

Answer 22

-Good corneal penetration
-prolong contact time with corneal tissue
-simplicity of installation for the patient

Question 23

Classification of ocular delivery systems

Answer 23

1. conventional
   -liquid (Topical eyedropper, suspension, reconstitution powder)
   -semi-solid (ointments, gels)
   -solid (ocular inserts)
   -intraocular (injections, implants)
2. particulate
3. advanced
4. vesicular
5. controlled release

Question 24

Packaging

Answer 24

-plastic dropper bottles
-low density polyethylene resin
-glass dropper bottles
-glass containers