Eye drops are sterile aqueous or oily solutions or suspensions that are used for instillation into the eye. They are applied into the cul-de-sac, the space between the eyeball and eyelid. Eye drops solution should have the following essential characteristics:

1.  It should be sterile.
2. It should be iso-osmotic with lachrymal secretions.
3.  It should have neutral pH.
4. It should be free from foreign particles.
5. It should remain stable during its storage.

Preparation of eye drops consists of the following four stages:

1. Preparation of bactericidal and fungicidal vehicles
2. Solution of the medicaments or active ingredients and if needed the appropriate adjuvants
3. Clarification
4. Sterilization

The preservative is dissolved in purified water in the prescribed concentration. All the medicaments and adjuvants are dissolved in the antimicrobial solutions to form a stable mixture. The solution is clarified by passing through a membrane filter having pore size of 0.2 mm to remove any particulate matter. The clarified solution is immediately transferred into final containers and sealed. Eye drops are sterilized by any one of the sterilization methods such as autoclaving, heating at 98°C–100°C for 30 minutes or filtration through 0.22 mm membrane filter. Eye drops are dispensed in neutral glass containers. Either a glass dropper or plastic cap-nozzle is used for administration. Eye drops should be labeled “For external use only” along with the storage conditions to maintain its activity during storage.

Example

Sodium chloride eye lotion BPC

 

	Sodium chloride	9 g
	Purified water (q.s.)	1000 ml

 

This is a simple solution prepared by dissolving sodium chloride in purified water filtered and sterilized. This is also called as normal saline solution.