Products By Therapeutical Index
Ophthalmic Drugs
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Glaucoma
Composition
Dorzolamide (As Hydrochloride) 2%
Timolol maleate 0.5%
Action
I.O.P plus is comprised of two components: Dorzolamide hydrochloride and Timolol maleate. Each of
these two components decreases elevated intraocular pressure, whether or not associated with
glaucoma, by reducing aqueous humor secretion. Elevated intraocular pressure is a major risk factor
in the pathogenesis of optic nerve damage and glaucomatous visual field loss. The higher the level of
intraocular pressure, the greater the likelihood of glaucomatous field loss and optic nerve damage
Dorzolamide hydrochloride is an inhibitor of human carbonic anhydrase II. Inhibition of carbonic
anhydrase in the ciliary processes of the eye decreases aqueous humor secretion, presumably by
slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport.
Timolol maleate is a beta 2 (non-selective) adrenergic receptor-blocking agent that does not have
significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membranestabilizing) activity. The combined effect of these two agents administered as I.O.P plus b.i.d. results
in additional intraocular pressure reduction compared to either component administered alone, but
the reduction is not as much as when Dorzolamide t.i.d. and Timolol b.i.d. are administered
concomitantly
