Unoprostone
Unoprostone Isopropylate is a docosanoid, a structural analogue of an inactive biosynthetic cyclic derivative of arachidonic acid, 13, 14-dihydro-15-keto-prostaglandin F2a. Its chemical name is isopropyl (+)-(Z)-7-[(1R, 2R, 3R, 5S)-3,5-dihydroxy-2-(3oxodecyl) cyclopentyl] -5-heptenoate. It differs structurally from other PGAs in that it has a 22-carbon chain backbone, instead of the typical truncated 20-carbon structure found in other agents [Figure 1] It is available in 0.15% ophthalmic formulation, to be applied twice daily.
Unoprostone decreases IOP by increasing the outflow facility without affecting aqueous humor production.[63] When used in monotherapy, Unoprostone provided a clinically significant IOP-lowering effect, equivalent to that of betaxolol but not to those of timolol and latanoprost.[6465] However, in another study, an aqueous solution of 0.12% unoprostone isopropyl, applied topically to the eye twice daily for six weeks, was as effective as 0.5% timolol in maintaining control of IOP in subjects with chronic open angle glaucoma or ocular hypertension.[66] In a six-month study, it was found that unoprostone isopropyl beneficially provides additive IOP lowering effect to topical β-blocker in patients with primary open angle glaucoma. No serious systemic side effects were found in the present study.[67]
A study involving thirty healthy volunteers, Unoprostone significantly increased microcirculation in the optic nerve head (ONH) in control subjects and in normal tension glaucoma patients, without reducing the IOP significantly.[68] A long term comparative study between topical antiglaucoma therapy of timolol and unoprostone as against betaxolol and unoprostone revealed that both combined treatments were effective for IOP reduction in glaucoma patients, and the data from the Betaxolol and Unoprostone treatment group suggested that Betaxolol and Unoprostone was more effective in maintaining visual field than timolol and unoprostone.[69] Unoprostone instillation increases blood flow in the choroidretina in human eyes.[70] Iris hyperpigmentation and abnormal eyelash changes may occur after treatment with unoprostone, but the incidence of these events were low in the two-year clinical study.[71]