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Antiallergic compound and an
antihistamine. The compositions are used
to prevent allergic responses while also
treating existing allergic conditions
present in the eye. The invention is
also directed to methods of preventing
and treating allergic responses with the
compositions.
BACKGROUND
Antiallergics are compounds which
prevent, inhibit or alleviate allergic
reactions. It is believed that these
compounds characteristically function as
cell stabilizers and/or mast cell
inhibitors preventing the usual
degranulation of the mast cells in
response to the presence of allergens.
The eye, particularly the conjunctiva,
has a relatively large number of mast
cells. When allergens are present, they
can bind to the immunoglobulin on the
surface of these mast cells and trigger
the breakdown, or what is known as the
degranulation, of the cell. On
degranulation, mast cell components,
including histamines, are released into
the environment outside the mast cell.
Through a variety of mechanisms, these
components can be responsible for
symptoms associated with allergic
responses such as itching, redness, lid
swelling, vasodilation and chemosis.
Antihistamines are compounds which are
administered to prevent histamines,
released from mast cells in response to
the presence of allergens, from binding
to, for example, nerves and smooth
muscle cells of the conjunctival blood
vessels causing redness, itching and
swelling. They serve to prevent or
alleviate many of the symptoms which can
result from degranulation of mast cells.
It is an object of the present invention
to provide improved ophthalmic
compositions comprising an antiallergic
and an antihistamine, for treating
existing symptoms of mast cell
degranulation caused by the release of
histamines and preventing further
allergic and inflammatory symptoms by
stabilizing the mast cells of the eye,
or by inhibitng the allergic reaction
which results in mast cell degranulation
and ocular irritation.
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