Ear drops are liquid preparations meant for instillation
into the ear. In these preparations, the drug is usually dissolved or suspended
in a suitable solvent such as propylene glycol, polyethylene glycol, glycerol,
alcohol, and water, or a mixture of these.
Aqueous vehicle is generally not preferred because the secretions in the
ear are fatty in nature and as such these do not easily mix with water.
Ear drops are generally used for their cleansing, pain
relieving, and antiseptic actions. The main classes of drugs include analgesics
like benzocaine, antibiotics like neomycin and chloramphenicol, and
anti-inflammatory agents such as cortisone and dexamethasone. Wax-softening
agents include hydrogen peroxide and sodium bicarbonate. Ear drops are usually supplied
in amber-coloured, glass bottles with a teat and dropper closure or plastic
squeeze bottles.
Example: Chloramphenicol Ear Drops
Chloramphenicol - 5 g
Propylene glycol q.s to 100 ml
Chloramphenicol ear drops may be prepared by dissolving
Chloramphenicol in a sufficient quantity of Propylene glycol and finally making
up the final volume with it.