OPTHALMIC PREPARATIONS SHUBHRAJIT MANTRY Asst.Prof Kottam Institute of Pharmacy. A.P
Methods of preparation
INTRODUCTION Opthalmic dosage are preparations designed for application to the eye: For the treatment of disease For symptomatic release of symptoms For diagnostic purpose As aid to surgical procedures
Opthalmic products are the sterile products meant to instillation in to the eye in the space between eye lid and the eye ball. These products must be sterile and are prepared under the same condition and by the same methods as other Parenteral preparations. opthalmic products includes: Eye drops Eye lotion Eye ointment Eye suspension Contact lens solution EYE LID EYE BALL
How to Use Eye Ointments and Gels Properly?
Types of opthalmic products Opthalmic products may be categorized into a number of groups: Liquid preparations for application to the surface of the eye such as eye drops and eye lotions. Semi solid preparations such as eye ointments, creams and gels for application to the margin of eye lid or for introduction in to the conjuctival sac. Solid preparations such as Ocular inserts intended to be placed in contact with the surface of the eye to produce modified release of medicament over a prolonged period. Parenteral products for sub conjuctival or intra ocular injection. Liquid products for irrigation of the eye during surgical procedures. All opthalmic products are required to be sterile and free from extraneous particulate matter. Solutions used during surgery should not contain any preservative.
O C U L A R I N J E C T I O N
REQUIREMENTS Opthalmic preparations should possess the following properties: Foreign particles Viscosity Tonicity pH of preparations Sterility Surface activity
Foreign particles: All the opthalmic products should be clear and free from foreign particles, fibers and filaments. Opthalmic solutions should be clarified very carefully by passing through bacteria proof filters such as membrane filters, sintered glass filters. The particle size of the eye suspension should be in an ultrafine state of subdivision to minimize irritation. A separate filter should be used for different opthalmic products in order to avoid the contamination.
2) Viscosity: in order to prolong the contact time of the drug in the eye, various thickening agents are added in the opthalmic preparations. Polyvinyl alcohol (1-4%), polyethylene glycol, methyl cellulose, carboxy methyl cellulose are some of the commonly used thickening agents. These agents improve the viscosity of the preparation. An ideal thickening agent should possess the following properties:- it should be easy to filter. It should be easy to sterilize. It should be compatible with other ingredients. It should possess requisite refractive index and clarity level. Thickening agents are not included in the formulation of eye drops and eye lotions which are required to be used during or after surgery due to some possible adverse effects on the interior of the eye.
3) Tonicity: Opthalmic products should be isotonic with lachrymal secretions to avoid discomfort and irritation. It has been observed that eye can tolerate a range of tonicity from 0.5-2% NaCl. There are certain isotonic vehicles which are used to prepare opthalmic products like 1.9% boric acid, sodium acid phosphate buffer.
4) pH of the preparations: pH plays an important role in therapeutic activity, solubility, stability and comfort to the patient. Tears have a pH of about 7.4. eye can tolerate solution having wide range of pH provided they are not strongly buffered, since the tear will rapidly restore the normal pH value of the eye. Alkaloid salt solutions are stable at pH 2-3 but this pH is irritant to eye. The alkaloids get precipitated at pH above 7 and creates a number of formulation problems.
5) sterility: Opthalmic preparations must be sterile when prepared. Pseudomonas aeroginosa is very common gram –ve bacteria which is generally found to be present in opthalmic products. It may cause serious infections of cornea. It can cause complete loss of eye sight in 24-48 hrs. To maintain sterility in multi dose container, containing opthalmic products, a suitable preservative is added. The preservative should be non-toxic, non-irritant and should be compatible with medicaments. The opthalmic products are generally sterilized by autoclaving, filtration through bacteria proof filters and addition of bactericides at low temperature.
6) Surface activity: Vehicles used in opthalmic preparations must have good wetting ability to penetrate cornea and other tissues. Certain surfactants or wetting agents added which are found suitable for opthalmic products. It should not cause any damage to the tissue of eye. Benzalkonium chloride, polysorbate 20, polysoabate 80, dioctyl sodium sulpho succinate etc., are some of the surfactants which are commonly used.
EYE DROPS Eye drops are sterile aqueous or suspensions of drug that are instilled in to the eye with a dropper. They usually contain drugs having anti septic, anti anesthetic, anti inflammatory, mydriatic or meiotic properties.
FORMULATION Drug Preservative Sterilization Isotonicity Buffer Viscosity Container label
Drug These contains drug of various categories including antiseptic, anti-inflammatory agent, mydriatric or meiotic properties. 2) Preservative Eye drop should be sterile and should contain preservatives to avoid microbial contamination when the container is open. The preservative for opthalmic use includes Benzalkonium chloride, Chlorbutanol, Phenylmercuric acetate, Phenylmercuric nitrate etc 3) Sterilization Eye drops are sterilized by autoclaving at 1210C for 15 minutes or by bacteria filter to avoid thermal degradation; for example- Preservative chlorbutanaol hydrolyzes at high temperature.
4) Isotonicity All the solutes including drug contribute to the osmotic pressure of the eye drop, therefore isotonicity of the formula should be calculated and it is adjusted with sodium chloride, for example- Sodium chloride 0.9% and boric acid 1.9% are iso-osmotic. 5) Buffer The buffer should be added to maintain balance between comfort, solubility, stability and activity of drug. For example-, the hydrolyzed chlorbutanol forms hydrochloride acid making the drop acidic, whereas certain drug like pilocarpine hydrochloride are acidic. On the hand certain drug such as alkaloids show precipitation at lachrymal pH. Boric acid, monobasic sodium phosphate are the common buffers for eye drop.
6) Viscosity The size of drop and its residences in eye depends on viscosity of eye drops. Methylcellulose, hydroxypropyl methylcellulose and polyvinyl alcohol are common viscosity enhancer. 7) Container The commonly used container for opthalmic solutions or suspension is multi-dose container (5ml, 10ml). Glass container is supplied with sterile plastic dropper. Plastic bottles are with built-up nozzle. 8) label Not for injection. For external use only. Shake well before use (if it is suspension)
PREPARATION The eye drops are prepared in 4 stages. These stages are as under— Preparation of bactericidal and fungicidal vehicle: The aqueous or oily vehicle is used in preparation of eye drops. The aqueous vehicle may support bacterial or fungal growth, so one of the following bactericide may be used to prepare the eye drops : Phenyl mercuric nitrate/ acetate – 0.002% Benzalkonium chloride – 0.01% Chlorhexidine acetate-0.01%
2) Preparation of solution of medicaments and adjuvant: The medicaments are dissolved in the aqueous vehicle containing suitable anti microbial agent. The adjuvants are also dissolved in the vehicle at a stage to form a stable preparation. 3) Clarification:The eye drops are clarified by passing the solutions through membrane filter having pore size of 0.8µm. The clarified solution is immediately transferred in to final containers and sealed to exclude micro organisms. 4) Sterilization : the eye drops are sterilized by autoclaving or heating with bactericide at 98⁰ to 100⁰C for 30 mins., or filtration through bacteria proof filter.
5) Containers: The eye drops should be packed in neutral glass containers or in suitable plastic containers. In olden days the eye drops are stored in vertically fluted amber colored glass bottles fitted with a Bakelite cap carrying a dropper. The bottle must confirm to limit test for alkalinity of glass. Now a days neutral glass small bottles having capacity of 4ml to 8ml are used. It has two poly propylene screw caps, one for attaching a silicone rubber teat to the container and the other for covering the teat. The plastic squeeze bottles having ridged plastic cap and polythene friction plug containing baffle that produces uniform drops are also used these days. These are very handy. These bottles are sterilized by gaseous sterilization method.
INTRODUCTION Eye lotion are the sterile aqueous solutions used for washing of the eyes. The eye lotions are supplied in concentrated form and are required to be diluted with warm water immediately before use. They are usually applied with a clean eye-bath or sterilized fabric dressing and a large volume of solutions is allowed to flow quickly over the eye.
Eye lotions should be isotonic and free from foreign particles to avoid irritation to the eye. They are required to be prepared fresh and should not be stored for more than two days as the lotion may get contaminated include sodium chloride, sodium bicarbonate, boric acid, borax or zinc sulphate
FORMULATION OF EYE LOTION Eye lotions are simple solution. They are iso-osmotic with tears because they cause much greater dilution of the lachrymal fluid and hence are more likely to cause discomfort if not adjusted. The eye lotion should be sterile because the large volume is used to irritation from the eye. While removing the irritation from the eye, it become more susceptible to infection. The eye lotions are sterilized by autoclaving or by passing through bacteria proof filters. Sodium chloride eye lotion and sodium bicarbonate eye lotion are commonly used to remove foreign substance from the eye.
PREPARATION OF EYE LOTION EXAMPLE:- To prepare and submit ml of sodium chloride eye lotion B.P.C Rx Sodium chloride 9gm Purified water to produce 1000ml Method:- Dissolve sodium chloride in purified water and made the final volume by adding more of purified water. Filter through sintered glass filter grade 4. The eye lotion is transfer to the bottle. Close and sealed the bottle sterilize it by autoclaving.
Eye ointments are sterile preparation meant for application to the eye. These are prepared under aseptic conditions and packed in sterile collapsible tubes which keep the preparation sterile until whole of it is consumed. Nowadays eye applicaps are available which contain only one application of the eye-ointment preparation.
Formulation of Eye Ointments The ointment based for an eye-ointment must be no-irritating to the eye. The eye ointment base should melt near to the body temperature, so as to permit the diffusion of the drug through the lachrymal secretions of the eye. For the preparation of eye-ointment the following base is used:- Yellow soft paraffin 80g Liquid paraffin 10g Wool fat 10g
Methods of preparation of Eye Ointments Melt wool fat, soft paraffin on a water bath. Add liquid paraffin. Filter through coarse filter placed in heated funnel. It is sterilized by dry heat method (1600C for 2 hours). Incorporate the medicament with the eye ointment base. Pack in sterile containers.
INTRODUCTION Ophthalmic suspensions are also easily placed into the eye. In general, suspensions produce a longer effect than do solutions. Suspensions do have one disadvantage; it is difficult to ensure that the suspension does not contain particles large enough to produce eye irritation. Eye suspensions are not commonly used as compared to eye-drops. They are prepared only in those cases, when the drug is insoluble in the desired vehicle or unstable in liquid form.
CONTACT LENSES Contact lenses are usually made from polymethyl- methacrylate, a hard hydrophobic plastic, but some softer hydrophilic lenses have been developed and are coming to use. Types of contact lenses: 1- Hard contact lenses 2- Soft contact lenses
HARD CONTACT LENSES: Wearers of hard contact lenses generally use two solutions
A wetting solution, which is used primarily for treating the lenses before insertion.
A storage solution, which is used for overnight cleansing, soaking and storage.
Wetting solutions: because of its hydrophobic nature, polymethyl methacrylate is poorly wetted by the lachrymal fluid and requires moistening with a wetting agent to render the surface hydrophilic and make insertion easy and comfortable. This treatment also prevents smudging when the lens is held, on a well –scrubbed finger tip, for insertion. Unlike most eye-drops, contact lens solutions are used daily for years and, therefore, they should be exceptionally bland.
They may contain A wetting agent: An antimicrobial agent: A substance for adjusting the osmotic pressure: A buffering agent: A thickening agent:
A wetting agent : polyvinyl alcohols, which are strongly hydrophilic, and polysorbate 80 , a non-ionic surfactant in which hydrophilic groups predominate, are examples. Polyvinyl alcohols are obtained from polyvinyl acetate by hydrolysis and may contain traces of the parent compound from which irritating amounts of acetic acid may be liberated at neutral or alkaline pHs. Hence, solutions are often adjusted to a pH between 5 and 6. Polysorbate 80, at concentrations of 0.5 percent and above, inactivates Benzalkonium chloride and chlorhexidine acetate and at lower concentrations may increase or decrease their activity according to the conditions.
An antimicrobial agent: prolonged use f solutions containing the concentrations of antimicrobial agents recommended for eye-drops may cause irritation or allergic reactions. Consequently, lower levels are used in lens solutions; e.g. Benzalkonium chloride 0.004 percent, chlorhexidine acetate 0.005 to 0.006 % and chlorbutol 0.3 to 0.4 percent. Using more than one antimicrobial agent is a way of reducing the concentration of each and , at the same time, maintain an acceptable level of preservative activity. For example, disodium edentate(0.1 to 0.2 %) may be combined with Benzalkonium chloride, Benzalkonium chloride and chlorbutol or Benzalkonium chloride and chlorhexidine acetate. Richards points out that phenyl ethyl alcohol enhances the activity of all bactericides commonly used in eye solutions and is not inactivated by up to 1 percent of polysorbate 80; but so far this compound has not been used in wetting solutions.
A substance for adjusting the osmotic pressure: it is customary to adjust wetting solutions to approximately the same osmotic pressure as lachrymal secretion by adding sodium chloride alone or with potassium chloride. Wearing contact lenses seems, by interfering with corneal metabolism, to increase the sensitivity of the eye to solutions that are not iso-osmotic with tears.
A buffering agent: Hind and Goyan found that solutions of pH 8.0 to 8.8 were best tolerated by the eye while more alkaline or acid preparations caused smarting or fogging. Hypromellose Eye Drops B.P.C., which is sometimes used as a contact lens solutions, is buffered to pH 8.4 to 8.6 with boric acid and borax. Sodium bicarbonate 2 per cent , an early contact lens solution, has a pH of about 8.2 and is well tolerated.
A thickening agent: Comfort is significantly increased if the solution contains a substance that raises the viscosity, e.g. polyvinyl alcohols or the cellulose derivatives. The thickener must be compatible with the preservative(s) and produce a clear solution that does not interfere with vision. Generally, the vehicle for lens solutions is properly stored purified water; tap water is unsuitable because it contains salts, that may cause deposits, and chlorine, which may be irritating.
Storage solutions: Hydrophobic lenses attract hydrophobic substances from the eyelids, fingers, etc. and, therefore, require cleaning after use. After removal they are wetted with the wetting solution and rubbed between well-scrubbed fingers until they appear clear after rinsing with purified water. Then they are stored in a soaking solution intended to continue the cleaning process and prevent dehydration. Polymethyl methacrylate, although hydrophobic, does absorb a little water and it is undesirable for this to be taken from the eye.
Storage solutions usually contain
A non-ionic surface active agent – to aid cleaning.
A mixture of antimicrobial agents.
The concentrations can be greater than in wetting solutions because storage solutions are not used in the eye. The solution is changed every few days because the preservatives may be partially inactivated by organic debris.
SOFT CONTACT LENSES: These are soft flexible type of lenses. Certain medicaments from wetting and storage solutions are strongly absorbed by the soft contact lenses. Due to this reason patients wearing soft lenses should be advised to remove them before instilling eye-drops
For cleaning soft contact lenses are heated in 0.9% sodium chloride solution. The Wetting and storage solutions formulated for hard lenses must never be used. Special proprietary storage solutions are available. Wetting is not a problem because of the hydrophilic nature of lens. The wetting of soft contact lenses is not a problem because of hydrophilic nature of the lens. Contact lens solutions should be sterile.
EVALUATION OF OPTHALMIC PREPARATION
Evaluation is test of finish Parenteral product are free from of micro-organism or not. Evaluation of the opthalmic product is done by following tests: Sterility Test Clarity Test Leaker Test Metal particles in opthalmic ointment
STERILITY TEST : Two basic methods for sterility testing: Direct Inoculation Method: It involves the direct introduction of product test samples into the culture media. II) Membrane filtration Method: It involves filtering test sample through membrane filter, washing the filter with fluid to remove inhibitory property and transferring the membrane aseptically to appropriate culture media. Detection of contamination used to two culture media:- A) Soybean-casein digest medium:- Incubated at 20to 250C B) fluid thioglycollate medium:- Incubated at 30 to 350C on 7 Days
2. CLARITY TEST : Opthalmic Solution by definition contain no undissolved ingredients and are essentially free from foreign particles .
Under a good light, baffled against reflection into the eye and viewed against a black and white background with contect set in motion with swilling action.
Instrumental method: It is utilizing the principle of light scattering, light absorption and electrical resistance to obtain particle count and size distribution – destruction of product units- only for quality control testing.
Instrumental method utilizing video image projection detects moving particles without destruction of product units-used for inline detection.
3. LEAKER TEST :
Select 10 tubes of the ointment with seals applied when specified.
Thoroughly clean and dry the exterior surfaces of each tube with an absorbent cloth.
Place the tubes in horizontal position on a sheet of absorbent blotting paper in an oven maintained at temperature of 60 ± 3 for 8 hours.
No significant leakage occurs during or at the completion of the test.
If leakage is observed from one, but more than one of the tubes repeat the test with 20 additional tubes of the ointment.
The requirement is met if no leakage is observed from the first 10 tubes tested or if leakage is observed from not more than one of 30 tubes tested
4. METAL PARTICLES IN OPTHALMIC OINTMENT:
Extrude as completely as practicable the content of 10 tubes individually into separate, clear, flat-bottom, 60-mm petridishes that are free from scratches.
Cover the dishes and heat at 850C for 2 hours, increasing the temperature slightly if necessary to ensure that a fully fluid sate is obtained.
Taking precautions against disturbing the melted sample, allow each to cool to room temperature and to solidify.
Remove the covers and invert each petridish on the stage of suitable microscope adjusted to furnish 30 times magnification and equipped with an eye pieces micrometer disk that has been calibrated at the magnification being used.
Examine the entire bottom of the petridish for metal particles.
Count the number of metal particles that are 50µm on larger in any dimension. The requirements are met if the total number of such particles in all 10 tubes does not exceed 50 and if not more than 1 tube is found to contain more than 8 such particles.
If these results are not obtained, repeat the test on 20 additional tubes.
The requirements are met if the total number of metal particles that are 50µm on larger in any dimension does not exceed 150 in all 30 tubes tested and if not mote than 3 of the tubes are found to contain more than 8 such particles each.
Packaging: Eyedrops have been packaged almost entirely in plastic dropper bottles (the Drop-Tainer® plastic dispenser). The main advantage of the Drop-Tainer are:
convenience of use by the patient
decreased contamination potential
The plastic bottle and dispensing tip is made of low-density polyethylene (LDPE) resin, which provides the necessary flexibility and inertness. The cap is made of harder resin than the bottle.
Packaging: ** Advantage of LDPE resin:
Compatible with a very wide range of drugs and formulation components
** Disadvantage of LDPE resin:
Sorption and permeability characteristics e.g. volatile preservatives such as chlorobutanol
Weight loss by water vapor transmission
LDPE resin is translucent, if the drug is light sensitive, additional package protection is required (using opacifying agent such as titanium dioxide)
-- LDPE resin sterilized by gamma irradiation or ethylene oxide
Packaging: A special plastic ophthalmic package made of polypropylene is introduced. The bottle is filled then sterilized by steam under pressure at 121°C.
Packaging: The glass bottle is made sterile by dry-heat or steam autoclave sterilization. Amber glass is used for light-resistance.