Effect of latanoprost or 8-iso prostaglandin E2 alone and in combination on intraocular pressure in glaucomatous monkey eyes

A phase 2, randomized, dose-response trial of taprenepag isopropyl (PF-04217329) versus latanoprost 0.005% in open-angle glaucoma and ocular hypertension

PURPOSE

To evaluate the safety of escalating doses of taprenepag isopropyl (PF-04217329), a selective EP(2) receptor agonist administered as a topical ophthalmic solution, versus its vehicle (Stage I), and dose-response of taprenepag isopropyl alone and in unfixed combination with latanoprost ophthalmic solution 0.005% versus latanoprost alone (Stage II).

SUBJECTS AND METHODS

Randomized, vehicle- and active-controlled, double-masked, two-stage, dose-finding trial in primary open-angle glaucoma (POAG) or ocular hypertension; first taprenepag isopropyl study in patients (NCT00572455). Study eye: 26 mmHg ≤ intraocular pressure (IOP) <36 mmHg at 8 am and 22 mmHg ≤ IOP <36 mmHg at 10 am, 1 pm, 4 pm. Stage I: 3 cohorts (total n = 67) received 1 drop of taprenepag isopropyl unit dose formulation qPM/eye for 14 days: low dose: 0.0025%, 0.005%, vehicle; middle dose: 0.01%, 0.015%, vehicle; high dose: 0.02%, 0.03%, vehicle. Stage II: 7 groups (total n = 250) received 1 drop of taprenepag isopropyl multidose formulation qPM/eye for 28 days: 0.005%, 0.01%, 0.015% monotherapy; each in unfixed combination with latanoprost 0.005%, or latanoprost monotherapy.

MAIN OUTCOMES

mean change in diurnal IOP, baseline to last visit; adverse events.

RESULTS

Stage I at day 14: statistically significantly greater IOP reductions were observed at all taprenepag isopropyl doses versus vehicle. Stage II at day 28: statistically significantly greater IOP reductions were observed at all doses of the unfixed combination versus latanoprost monotherapy. At least 1 treatment-emergent adverse event reported for 29/67 (43.3%) subjects in Stage I and 158/250 (63.2%) in Stage II.

CONCLUSIONS

Taprenepag isopropyl significantly reduces IOP in POAG and ocular hypertension. Taprenepag isopropyl monotherapy is comparable to latanoprost 0.005% in reducing IOP. As demonstrated in this report, the activity of taprenepag isopropyl is additive to that of latanoprost 0.005%. Further studies are required to determine whether it shows similar additivity when administered with other ocular antihypertensive medications.

Effect of SPP 635, a renin inhibitor, on intraocular pressure in glaucomatous monkey eyes

The effect of topical application of SPP 635, a renin inhibitor, on intraocular pressure (IOP) was evaluated in the eyes of monkeys with laser induced unilateral glaucoma. A multiple-dose study was performed in 8 glaucomatous monkey eyes with 3 concentrations of SPP 635, 0.2%, 0.3% and 0.4%. IOP was measured hourly for 6 h on each day of the study beginning at 9:30 a.m. Following one baseline day (untreated) and one vehicle-treated day (50 μl drop of vehicle to the glaucomatous eye at 9:30 a.m.), a 50 μl drop (25 μl × 2) of SPP 635, 0.2%, 0.3% or 0.4%, was topically applied to the glaucomatous eye at 9:30 a.m. and 3:30 p.m. for 5 consecutive days. Twice daily administration of each of the 3 concentrations of SPP 635 for 5 days significantly (p < 0.05) reduced IOP. The maximum reduction in IOP occurred 3 or 4 h after morning dosing and was 4.3 ± 0.8 (mean ± SEM) mmHg (14%) for 0.2% SPP 635, 5.3 ± 1.0 mmHg, (19%) for 0.3% SPP 635, and 8.0 ± 1.3 mmHg (25%) for 0.4% SPP 635. The longest duration of IOP reduction was for 6 h with 0.2% or 0.3% SPP 635, and was for at least 18 h with 0.4% concentration. Compared to 0.2% or 0.3% concentrations, 0.4% SPP 635 produced a greater (p < 0.05) and longer duration of IOP reduction (18 vs. 6 h). Mild conjunctival discharge appeared in 2 of 8 eyes, and hyperemia appeared in 2 eyes with the 0.3% and 0.4% concentrations on treatment days 3 and 5. Topically applied SPP 635, a new renin inhibitor, reduces IOP in glaucomatous monkeys in a dose-dependent manner. Renin inhibitors, are a novel class of compounds which may have potential for the treatment of glaucoma.

Stimulation of prostaglandin EP2 receptors on RGC-5 cells in culture blunts the negative effect of serum withdrawal

Reduced neurotrophic support is one possible cause for retinal ganglion cells dying in glaucoma. Experiments were designed to investigate the effect of EP2 receptor agonist butaprost on transformed retinal ganglion (RGC-5) cells where reduced neurotrophic support was simulated by serum withdrawal. Cultures were analysed for cell viability, flow cytometry, reactive oxygen species and apoptosis. Western blot and immunohistochemistry were used to provide information for the occurrence of PGE(2) receptor-types. We demonstrated the existence of all four types of PGE(2) receptors in RGC-5 cells and exposure of cultures to butaprost resulted in an elevation of cAMP. Serum deprivation induced RGC-5 cell death was significantly attenuated by butaprost as well as by rolipram and forskolin where intracellular cAMP levels were increased. These data are of value in relation to the possible use of EP2 receptor agonists to reduce both elevated intraocular pressure and retinal ganglion cell death as occurs in glaucoma.

Effect of non-steroidal anti-inflammatory ophthalmic solution on intraocular pressure reduction by latanoprost in patients with primary open angle glaucoma or ocular hypertension

AIM

To investigate the effects of a non-steroidal anti-inflammatory drug (NSAID) ophthalmic solution on latanoprost induced intraocular pressure (IOP) reduction in glaucoma patients.

METHODS

Examination was conducted on 16 eyes of 16 glaucoma patients who had been given only latanoprost for at least 6 weeks. The NSAID ophthalmic solution, sodium 2-amino-3-(4-bromobenzoyl) phenylacetate sesquihydrate, was additionally given for 12 weeks into one eye (NSAID group), while sodium hyaluronic acid ophthalmic solution was administered into the other eye (control group) in a double masked fashion. The IOP measurement was performed before the start of additional administration of ophthalmic solutions, 2, 4, 6, 8, 10, and 12 weeks after the start of additional administration, and 2, 4, and 6 weeks after discontinuing additional administration.

RESULTS

No significant difference was observed in the IOPs before additional administration of ophthalmic solution between the NSAID group and the control group. Following the additional administration of ophthalmic solution, IOP in the NSAID group was consistently higher than that in the control group, and a maximum difference in IOP between the two groups was 1.08 (SD 1.75) mm Hg (p = 0.03). This trend was observed even after additional administration was discontinued.

CONCLUSION

NSAID ophthalmic solution may partly affect IOP reduction by latanoprost.

Primate glaucoma models

The monkey model of ocular hypertension (OHT) with its resultant optic neuropathy closely reflects the optic neurodegeneration associated with human glaucoma. Utilization of the experimental glaucoma model (ExpG) in non-human primates (NHP) has led to advances in the understanding of aqueous humor dynamics, glaucomatous changes in the visual pathways from photoreceptors to the visual cortex, and anterior and posterior ocular segment pharmacological effects.

Advances in glaucoma therapeutics

Glaucoma is a major cause of irreversible blindness in the world. The prevalence of glaucomatous loss in vision will continue to grow as our populations age. Ocular hypertension is a major risk factor for the development of glaucoma and current glaucoma therapy is directed at lowering intraocular pressure. Several new ocular hypotensive agents have been introduced in the past several years providing a variety of treatment options. In addition, various classes of neuroprotective agents demonstrating activity in a wide variety of animal models have been proposed as potential new glaucoma therapeutics. Although these approaches will slow the progression of vision loss, they do not directly intervene in the disease process(es). Advances have been made attempting to understand the pathogenic pathways involved in glaucomatous damage to the eye and in methods to clinically measure glaucoma damage. An increased understanding of the pathophysiology of glaucoma will lead to the development of new therapeutic agents that intervene and perhaps even reverse glaucomatous damage to the eye. There also is a need to develop new methods to clinically measure glaucoma damage because, currently, considerable damage occurs before glaucoma is diagnosed and glaucoma remains underdiagnosed in the general population.

Comparison between isopropyl unoprostone and latanoprost by prostaglandin E(2)induction, affinity to prostaglandin transporter, and intraocular metabolism

The pharmacological differences between isopropyl unoprostone (referred to as unoprostone) and latanoprost, concerning their induction of endogenous prostaglandin E(2)(PGE(2)) and affinity to a human prostaglandin transporter (PGT), were investigated. Freshly dissected bovine iris tissues were incubated with major intraocular metabolites of unoprostone, M1 and M2, acid of latanoprost, or PGF(2 alpha), and PGE(2)induction was measured. Affinities of M1, M2, latanoprost, acid of latanoprost, and PGF(2 alpha)to PGT molecule were measured using PGT-cDNA transfected HeLa cells by an isotopic influx assay.(3)H-unoprostone was incubated with freshly prepared serum, aqueous humor, or frozen stored fetal bovine serum (FBS), and the radioactivity of supernatants was measured to investigate their metabolism of(3)H-unoprostone.M2, acid of latanoprost, and PGF(2 alpha)significantly increased a release of PGE(2)compared with the control. 10 microM indomethacin completely inhibited PGE(2)induction by acid of latanoprost and PGF(2 alpha), while 100 microM indomethacin was required to inhibit PGE(2)induction completely by M1 and M2. Unoprostone, M1, M2, and latanoprost showed little affinity to PGT, while acid of latanoprost had an affinity to PGT. Freshly prepared serum and aqueous humor metabolized unoprostone, but frozen stored FBS did not. The release of endogenous PGE(2)may play an important role of action by means of PG analogs, and differences in indomethacin-related inhibition of PGE(2)release and in affinities to PGT may in part cause their different actions.

Effect of pilocarpine 4% in combination with latanoprost 0.005% or 8-iso prostaglandin E2 0.1% on intraocular pressure in laser-induced glaucomatous monkey eyes

PURPOSE

To compare the effect of pilocarpine, an agent that reduces uveoscleral outflow, on the ocular hypotensive efficacy of latanoprost and 8-iso prostaglandin E2 (PGE2).

METHODS

Each of the two treatment groups was composed of the same eight monkeys with unilateral laser-induced glaucoma. Intraocular pressure (IOP) was measured hourly for 6 hours beginning at 9:00 AM on the baseline day (Thursday before treatment week) and on treatment days 1, 3, and 5 (Monday, Wednesday, and Friday). On all five treatment days, one drop of pilocarpine 4% was administered at 9:00 AM and 3:00 PM and one drop of latanoprost 0.005% or 25 microL of 8-iso PGE2 0.1% was administered at 10:00 AM and 4:00 PM.

RESULTS

One hour after pilocarpine instillation on day 1, the reduction of IOP was similar (P > 0.90) in both treatment groups, 7.6 +/- 1.1 mm Hg (mean +/- standard error of the mean ) in the latanoprost group and 7.4 +/- 0.8 mm Hg in the 8-iso PGE2 group. However, the IOP effects of the two treatment groups became significantly different (P < 0.05) beginning 2 hours after dosing with latanoprost or 8-iso PGE, on day 1. A difference (P < 0.05) between the two groups persisted at all subsequent measurements. The reduction of IOP lessened with repeated dosing in the latanoprost and 8-iso PGE2 groups. Three hours after dosing with pilocarpine and two hours after dosing with the prostanoids, the IOP reduction was 8.3 +/- 0.9 mm Hg in the latanoprost group and 9.9 +/- 0.6 mm Hg in the 8-iso PGE2 group on day 1, and 2.1 +/- 1.0 mm Hg in the latanoprost group and 7.3 +/- 0.9 mm Hg in the 8-iso PGE1 group on day 5.

CONCLUSIONS

The smaller reductions in IOP with pilocarpine and latanoprost than with pilocarpine and 8-iso PGE2 show that pilocarpine blocks much more of the ocular hypotensive effect of latanoprost than of 8-iso PGE2. The results also indicate that pilocarpine and latanoprost are mutually antagonistic. Enhancement of uveoscleral outflow appears to account for most of the ocular hypotensive effect of latanoprost and for much less of the ocular hypotensive effect of 8-iso prostaglandin E2.