Ophthalmic dosage forms

Ophthalmic dosage forms are preparations designed for application to the eye:

1. For the treatment of diseases

2. For symptomatic relief of symptoms

3. As an aid to surgical procedures

TYPES OF OPHTHALMIC PRODUCT:

Ophthalmic Products may be categorized into a number of groups:

1. Liquid preparations for application to the surface of the eye such as eye drops and eye lotion
2. Semi solid preparations such as eye ointments, creams and gels for application to the margin of the eyelid or for introduction into the conjunctival sac.
3. 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 prolong period.
4. Parenteral products for subconjuctival or intra ocular injection.
5. Liquid products for irrigation of the eye during surgical procedures.

EYE DROP:

Eye drops are aqueous or oily solutions or suspensions of one or more active ingredients for instillation into the congunctival sac of the eye. These are sterile, free from foreign particles and irritating effects. They are usually buffered and sometimes contains auxiliary substances to adjust the tonicity or viscosity, to increase solubility of the active ingredients or to stabilize the preparations. Aqueous preparations supplied to multi dose containers contain suitable antimicrobial preservatives except when. The preparations itself has adequate antimicrobial properties.

The solubility of a few drugs administered as eye drops is too low to allow their formulations as solutions. In such cases aqueous or oily suspensions are generally prepared. The solid particles must be very fine state of subdivision to prevent irritation of the cornea.

Eye drops have generally been used for administrations of antimicrobial substances like sulfacetamide and gentamicin, anti-inflammatory agent such as corticosteroids, miotics like physostigminesulphate or mydriatic drugs like atropine sulphate. Most drugs used for ophthalmic preparations are weak base or weak acids having poor aqueous solubility. In such cases, their salts such as hydrochlorides, sulphates and nitrates for weakly basic drugs and sodium for weakly acidic drugs are commonly employed.

Eye drops are generally supplied in sealed dropping bottles or sealed bottles along with a dropper. The preparation is meant to be used with in 15 to 30 days of the opening of the seal. These are usually supplied in qualities of not more than 10ml to avoid use over too long a period of time.

ADDITIVES USED IN EYE DROP

1. Vehicle: Water is the most commonly employed vehicle for eye drops formulated as aqueous solutions or suspensions. For oily preparations, vegetable oils such as peanut or sesame oil may be used.

2. Buffers: Human tears normally have a pH of about 7.2 with a good buffering capacity. Unbuffered solution with pH values of between 3.5 and 10.5 can usually be tolerated with little discomfort. Outside this pH range irritation of the eye accompanied by increased lachrymation may occur. Buffers are usually added to adjust the pH to a value that is the best with regard to the solubility or stability of the drug and which will be tolerated by the eye. The buffering agents used in eye drops are borate, phosphate and citrate buffers.

3. Tonicity modifiers: Tonicity modifiers are substances added to eye drops in order to make them isotonic with lachrymal secretions. This is essential because very hypnotic solutions can be cause temporary odema of the cornea resulting in impaired vision where as grossly hypertonic solutions can be cause irritation and discomfort to the sensitive tissue of the eye. Theoretically, eye drops should have a tonicity equivalent to 0.9% solution of sodium chloride. However it has been it has been found the human eyes can tolerate tonicity with a ranger equivalent to between 0.7% and 1.5% of sodium chloride. The most commonly employed agents for the adjustment of tonicity of eye drops is sodium chloride although potassium chloride, glucose, glycerol and buffers can also be used.

4. Stabilizers: A number of drugs used in eye drops are susceptible to oxidation in the presence of air and solutions containing such drugs should included antioxidants to improve their stability. The most common antioxidants used include sodium metasulphite, sodium sulphite, ascorbic acid and acetyl cyysteine. Stability of preparations can also be improved by replacing the air in the bottle by an inert gas such as nitrogen.

ENVIRONMENT:

Dispensing, Processing and Filling area: 100 Class

Other Utility Zone: 1000 Class

Temperature 20-25⁰C

Humidity   30-50%

Process Flow Chart:

(Ophthalmic manufacturing)