Eye drops:Eye drops are sterile aqueous or oily solutions or suspensions intended for instillation intoThe conjunctiva sac. They usually contain drugs having antiseptic, anti anaesthetic and inflammatory, Mydriatic, miotic properties.Ear drops:Ear dropsare aqueous or oily solutions or suspensions of one or more medicaments intended for instillation into the outer ear.Nasal drops:Nasal drops are aqueous or liquid paraffin solutions meant for instillation into the nostrils. Nasal drops often contain vasoconstrictor drugs to relieve nasal congestion.

Composition of eye, ear and nasal drops:Active ingredientsVehicleAnti microbial preservativesAdjuvantSuitable container for administration

Eye, ear and nasal drops should possess following properties:-Foreign particles- sterility- pH- tonicity- viscosity- surface activity- foreign particles

Foreign particles:All products should be clear and free from:-Foreign particles, fibers and filaments- these solutions should be clarified very carefully by passing through bacteria proof filters such as membrane filters, sintered glass filters

Sterility:Dry heat sterilization at 160 0c for 2 hrs is employed for non aqueous preparations suchas liquid paraffin eye drops.Autoclaving at 1150c for 30min or 1210c for 15minViscosity:Inorder to prolong the contact time of the drug in the eye, various thickening agents are added in the opthalmic preparationsCommonly used thickening agents are:Poly vinyl alcohol (1-4%)Polyethylene glycolMethyl cellulose

Tonicity:All the products should be isotonic with lachrymal secretions to avoid discomfort and irritation. Commonly used agents are:0.5 – 2% NaCl1.9% boric acidSodium acid phosphate bufferpH of the preparations:pH plays an important role in therapeutic activity, solubility, stability and comfort to the patients.Ear drops pH 6-7Eye drops pH 7.4Nasal drops pH 5.5 – 7.5

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 suitable for opthalmic productsCommonly used surfactants are:Benzalkonium chloridePolysorbate 20Polysorbate 80Doctyl sodium sulphosuccinate