Ophthalmic 2012

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ObjectivesStudents will be able to discuss: Definition of Eye drops Factors to concern for the preparation of

eye drops

The component of eye drop formulation Preparation of eye drops.


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Definition

Ophthalmic preparations are sterile, liquid, semi-solid or solid preparations intended foradministration upon the eyeball and/or to theconjunctiva or to be inserted in the conjunctival sac.


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Types of ophthalmic preparations

Several categories of eye preparations may bedistinguished:

1) Eye drops.2) Eye lotions.3) Semi-solid eye preparations.

4) Ophthalmic inserts.


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Depending on the condition being

treated, they may contain :

Steroids (e.g dexamethasone ), Antihistamines Sympathomimetics Beta receptor blockers


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parasympathomimetics (e.g

pilocarpine .), parasympatholytics (e.g. atropine ), prostaglandins , non-steroidal anti-inflammatory drugs

(NSAIDs) or topical anesthetics .


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Eye drops sometimes do not have

medications in them and are onlylubricating and tear-replacing solutions

and they can also contain anti-rednessand similar chemicals.


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Extemporaneous preparation of eye drops involvesthe following:

I. Preparation of the solution.

II. Clarification.III. Filling and sterilization.


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Factors to be considered in theformulation of ophthalmic preparations

includes 1. pH

2. Isotonicity3. Viscosity

4. Sterilization5. Preservation


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Preparation of the solution

1.Active ingredient(s) to produce desiredtherapeutic effect.

2.Vehicle , usually aqueous but occasionally may beoil.

3.Antimicrobial preservative to eliminate any

microbial contamination during use and thusmaintain sterile.


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4. Adjuvants to adjust tonicity , viscosity or pH in order to increase the comfort

in use and to increase the stability of the active ingredient(s).

5. Suitable containers for administrationof eye drop which maintains the

preparation in a stable form and protectsfrom contamination during preparation,storage and use.


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Excipients used

1. viscosity inhancers : Increasing the viscosity of an eye drop increases the

residence time of the drop in the eye and results in

increased penetration and therapeutic action of thedrug.

The common agents and their maximumconcentration used in ophthalmic formulations arein the below:


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Viscosity Enhancers:

Hydroxy ethyl cellulose Hydroxy propyl methyl cellulose Methyl cellulose

Polyvinyl alcohol


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. Buffers1 They are compounds that resist changes in pH upon

the addition of limited amounts of acids or bases.

Buffer systems are usually composed of a weak acidor weak base and its conjugate salts.

Examples:Borate buffer.Phosphate buffer.

Citrate buffer .


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Solution pH : The physiologic pH of tears is

approximately 7.4 . Thus, this would bethe optimal pH of ophthalmic solutions

for eye comfort.

Ophthalmic solutions may range frompH 4.5 - 11.5. But the useful range toprevent corneal damage is 6.5 to 8.5.


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The components act in such a way that

addition of an acid or base results in theformulation of a salt causing only a smallchange in pH.

Buffer capacity is a measure of theefficiency of a buffer in resistingchanges in pH.


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Antioxidant :

Sodium bisulfite

Sodium meta bisulfite Thiourea


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Preservatives should be used that do notcause patient sensitivity or that are

incompatible with the other ingredients in theformulation.

This is to ensure that the eye drops aremaintained sterile during use and will notintroduce contamination into the eyes being

treated.

exampel: Benzalkonium chloride


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Preparation procedure

It involves the following procedure :

Preparation of the solution. Clarification Filling and sterilization


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Preparation of the solution

The aqueous eye drop vehicle containing anynecessary preservative, antioxidant, stabilizer,tonicity modifier, viscolizer or buffer should beprepared first.

Then the active ingredient is added and thevehicle made up to volume.


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The clarified solution is either:

1. Filled directly into the final containers whichare sealed prior to heat sterilization.

or

2. Filled into suitable container prior to filtration

sterilization.


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Osmotic and PH

pH control importance:

1. The pH offering the best stability during

preparation and storage.2. Offering the best therapeutic activity.3. The comfort of the patient.4. The lacrimal fluid has a pH of 7.2-7.4, so

when possible eye drops should be bufferedto reduce stinging on instillation


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A 0 9% solution of NaCl (Normal Saline) is iso


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A 0.9% solution of NaCl (Normal Saline) is iso-osmotic with blood and tears.

isotonic or iso-osmotic solutions do not damagetissue or produce pain when administered.

Solutions which contain fewer particles and exert alower osmotic pressure than 0.9% saline are calledhypotonic

Administration of a hypotonic solution producespainful swelling of tissues as water passes from theadministration site into the tissues or blood cells.


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:Hypotonic

Water enters cell.Cell swells and bursts.


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Solutions which contain particles and

exert higher osmotic pressures arereferred to as hypertonic .

Hypertonic solutions produce shrinking of tissues as water is pulled from thebiological cells in an attempt to dilute thehypertonic solution.


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Hypertonic:

Water exit cell.

Cell shrinks dueto water loss.


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Objectives

Sample calculationContainers & packaging

Contact lens productsEye & ear drops


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Sample calculation:Calculate the amount of NaCl required to make the

following ophthalmic solution isotonic.

Oxytetracyline HCl 0.5%Sodium Chloride Q.S.Purified water add30mlMake isotonic solution

E = 0.12

Determine the amount of NaCl to make 30 ml of an


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Determine the amount of NaCl to make 30 ml of anisotonic solution

0.9 g 100 mlX 30ml

X = 0.27 g Nacl ---------------------

2 Calculate the contribution of


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2- Calculate the contribution of Oxytetracyline HCl to the NaCl equivalent

30 ml 0.5 g/100 ml = 0.15 g Oxytetracyline HClE of Oxy tetHcl = 0.12 Nacl

1 g 0.12 g NaCl0.15 g ?

0.15 g x 0.12 / 1 = 0.018 g NaCl --------------------

5% oxytet. HCl5100 ml

? 30 ml


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3. Determine the amount of NaCl to add tomake the solution isotonic by subtracting

from

0.27 g - 0.018 g = 0.252 g.

P bl i t i l ti l l ti


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Problem on isotonic solutions calculationsusing the NaCl E-value:

How many grams of NaCl should be used incompounding the following prescription?

Pilocarpine nitrate 0.3 gSod. Chloride Q.S.

Purified water add 30 ml

Make isotonic solution.

E =0.23

I Normal saline 0.9% means :


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I Normal saline 0.9% means :0.9 g ---------------------- 100 ml

X g ---------------------- 30 mlX = 0.9 x 30 / 100 = 0.27 g

II E = 0.23 Means :1 g Pilocarpine nitrate = 0.23 g NaCl

0.3 g -------------------------- Y NaClY = 0.3 g x 0.23 / 1 = 0.069 g

III Q.S. means :o.27 0.069 = o.2 g

C t i d k i


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Containers and packaging Glass container:

The containers are usually fitted withdroppers attached to the closures.

The droppers are made from natural glassand the rubber teats must be compatible with

all the constituents of the eye drops.


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Amber glass is usually used to protectand minimize the amount of against light

alkali released into the contents.

Pl i i


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Plastic container:Plastic containers fitted with nozzles that dispense

the eye drops by gently squeezing the walls of thecontainer are also employed.Here by eliminating the dropper, the risk of

contaminating the contents is reduced.


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Plastic such as polyethylene can adsorbthe bactericides usually added to eye

drops and packaging made from themmust be tested for absorption and

compatibility with the active ingredients


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Ideal container: The ideal type of packaging for eye drops is a

disposable "one - shot Minims containerwhich eliminates the need for anypreservative and reduces the risk of infectingthe eye during applications almost to zero.

St diti


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Storage condition:

The stability of several drugs used in eyedrops is improved by refrigerated storage(2-8 C) and to minimize degradation of eye drops ingredients, storagetemperature and conditions must be

considered.


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Contact lens

Product

Contact lenses are thin transparent plastic discs that


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p psit on the cornea.

A contact lens is used as :1) corrective ,2) cosmetic , or

3) therapeutic
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of thecorneausually placed on thelens .eye
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The aim in making contact lenses:

Correct patient 's vision. Allow respiration of the cornea. Permit free flow of tears. Not introduce microbial contamination


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Containers used: Contact lens solutions are usually packed

in plastic container .

It's important that these containers are

kept in a hygienic condition by keepingthem clean and using the disinfecting /storage solution.


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gas permeable contact lenses)2(


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gas permeable contact lenses)2( For that reason rigid contact lenses were

replaced by gas permeable contact lenses ,

which although still being rigid , but allow oxygen to reach the cornea

eliminating the possibility of swelling andusually allowing better vision witheyeglasses when they are removed.

(3) S ft l


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(3) Soft lenses Soft lenses are made of a soft plastic and are more comfortable than hard

lenses because they hold more water.

(4) Disposable lenses


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(4) Disposable lenses(A healthy choice):

Disposable contacts are worn for aspecific period of time ,

then thrown out and replaced with fresh lenses .

Disposables have become the mostcommon type of contact lenses.

Hard lens solutions


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Hard lens solutions1) Wetting solution: Achieve rapid wetting by the lachrymal

fluid and thus promotes comfort.

Facilitates insertion of lens. It's formulation is :

Wetting and viscolizing agent- polyvinylalcohol and hypermellose Antimicrobials: benzalkonium chloride

2) Soaking and storing solution


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2) Soaking and storing solution Achieves cleaning and microbial

inactivation. Hydrating.

It's formulation is :- Surface active agent not inactivating

antimicrobials- Antimicrobial s: benzalkonium chloride

2) Soaking and storing solution


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2) Soaking and storing solution Achieves cleaning and microbial

inactivation. Hydrating.

It's formulation is :- Surface active agent not inactivating

antimicrobials- Antimicrobial s: benzalkonium chloride

Soft lens solutions


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Soft lens solutions They are subjected to deposits of lipids ,

proteins and other substances from thelacrimal fluid.

1. Cleaning solutions:To remove deposits such as lipoprotein

adhering to the lens after wear.


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2. Enzyme protein digest: It should be followed by suitable washing and

cleansing before wear.

3. All purpose solutions Can be used for hard and soft contacts.

PREPARATION OF EYE LOTIONS


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PREPARATION OF EYE LOTIONS The purpose of eye lotions is to

assist in the cleaning of the external surfaces of theeye.This might be to help remove a non-impacted foreignbody or to clean away conjunctival discharge.intended for use in surgical or first-aid procedures.There is no intention to use an eye lotion to deliver anyactive ingredient to the eye but rather to remove

unwanted gross contaminants from the eye.


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Properties of eye lotions

should not contain antimicrobial preservativesand should be in single-use containers.

Thus these preparations should be very simpleand the most common eye lotion consists of sterile normal saline.


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Ophthalmic 2012

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