Ointments and Inserts
In an effort to maintain longer contact between the drug and ocular tissue,
ointments and inserts have been used.
Ophthalmic ointments tend to keep the
drug in contact with the eye longer than suspensions. Most ophthalmic ointment
bases are a mixture of mineral oil and white petrolatum and have a melting point
close to body temperature. Sometimes anhydrous lanolin is used to take up an
ingredient that was dissolved in a small amount of water to affect dissolution.
The aqueous solution is incorporated into the lanolin and then the lanolin is
mixed with the remaining ointment base ingredients.
be nonirritating and free from grittiness so the micronized form of the ingredients
is required. Sterile ointments are prepared by first sterilizing all of the
individual ingredients and then combining them under aseptic conditions. The
prepared ointment is then packaged in a sterile container such as an ointment
Most ointments tend to blur patient vision as they remain viscous and are
not removed easily by the tear fluid. Thus ointments are generally used at night
as adjunctive therapy to eye drops used during the day. Ophthalmic ointment
tubes are typically small holding approximately 3.5 g of ointment and fitted
with narrow gauge tips which permit the extrusion of narrow bands of ointment.
are not compounded but must be manufactured. Ocusert® is a nonerodible device
designed to deliver pilocarpine for several days in the treatment of glaucoma.
Some inserts are designed to dissolve in tear fluid. These inserts are made
of dried polymeric solutions that have been fashioned into a film or rod. An
example of this type of insert is Lacrisert® used to treat moderate to severe
dry eye syndrome. Inserts are placed in the cul-de-sac between the eyeball and
the eyelid. The biggest disadvantage of inserts is their tendency to float on
the eyeball, particularly in the morning upon arising.