Decreased carbohydrate metabolism enzyme activities in the glaucomatous trabecular meshwork.

PURPOSE: To determine whether activity of carbohydrate metabolism enzymes (aldolase, pyruvate kinase, isocitrate dehydrogenase, and malate dehydrogenase) are altered in the glaucomatous trabecular meshwork (TM) compared to controls. METHODS: Tissue specimens were obtained from trabeculectomy (n=45 open angle glaucoma; Caucasian, average age 61+/-8 years of age of both genders) and from cadaver eyes (n=15 control and n=5 glaucoma; Caucasian, average age 63+/-4 years of both genders). Protein extracts from TM tissue were prepared in a non-denaturing buffer containing 0.1% genapol. Aldolase activity was measured spectrophotometrically at 240 nm absorbance using reaction of 3-phosphoglycerate with hydrazine to form hydrazone. Pyruvate kinase activity was measured by coupling lactate dehydrogenase with NADPH and pyruvate absorbance was measured at 340 nm. Isocitrate dehydrogenase activity was measured using reduction of NADP to NADPH at the characteristic absorbance at 340 nm. Malate dehydrogenase catalyzes the interconversion of L-malate and oxaloacetate using NADP as a coenzyme, quantified by its absorbance at 340 nm. RESULTS: Aldolase, pyruvate kinase, isocitrate dehydrogenase, and malate dehyrogenase activities in the glaucomatous TM tissue were found to be reduced 70, 50, 25, and 69 percent, respectively. SDS-PAGE analysis suggests the presence of 4-hydorxynonenal (HNE) modified isocitrate dehydrogenase protein in the glaucomatous TM tissue compared to controls. CONCLUSIONS: Several Krebs cycle enzyme activities are considerably reduced in glaucomatous TM. HNE modified isocitrate dehydrogenase activity is consistent with reduced inactivated form of the protein. Lipid peroxidation product modification of aldolase, pyruvate kinase, and isocitrate dehydrogenase serves as a likely reason for the reduction of enzyme activity.

Bimatoprost 0.03% versus travoprost 0.004% in black Americans with glaucoma or ocular hypertension.

This randomized, investigator-masked, multicenter, parallel-design trial compared the IOP-lowering efficacy of bimatoprost 0.03% and travoprost 0.004% in African Americans with glaucoma or ocular hypertension. After a washout of all ocular hypotensive agents, patients were assigned to bimatoprost once daily (n=16) or travoprost once daily (n=15) for 3 months. Study visits were at baseline and at months 1, 2, and 3. Primary outcome measures were the percentage of patients who achieved selected target pressures and the mean reduction in IOP from baseline at month 3. Both drugs comparably lowered IOP, but bimatoprost was more likely than travoprost to allow achievement of every target pressure from 12 to 19 mm Hg at month 3. After 3 months, the mean IOP reduction from baseline was 8.4 mm Hg (34%) in the bimatoprost group and 7.9 mm Hg (30%) in the travoprost group. These results are being evaluated further in a larger clinical trial.

A 3-month comparison of efficacy and safety of brimonidine-purite 0.15% and brimonidine 0.2% in patients with glaucoma or ocular hypertension.

PURPOSE: To compare the efficacy and safety of brimonidine Purite 0.15% (ALPHAGAN P) BID with brimonidine 0.2% (ALPHAGAN) BID in patients with glaucoma or ocular hypertension. METHODS: 3-month, multicenter, randomized, double-masked trial. Eligible patients were taking brimonidine 0.2% BID for at least 6 weeks prior to study entry and their intraocular pressure (IOP) was < or = 21 mm Hg. Patients were randomly assigned to receive either brimonidine Purite 0.15% BID (n = 203) or brimonidine 0.2% BID (n = 204). Scheduled visits were prestudy, baseline, and weeks 2, 6 and 12. IOP was measured at hour 0 and hour 2 to evaluate efficacy. Safety was measured by monitoring adverse events. Patient satisfaction and comfort were also evaluated at all visits. RESULTS: There was no statistically significant difference between the brimonidine 0.2% and brimonidine Purite 0.15% groups with respect to mean IOP at baseline. The IOP-lowering efficacy of brimonidine Purite 0.15% was equivalent to that of brimonidine 0.2% and both study treatments maintained IOP-lowering effects of brimonidine 0.2%. There were no significant between-group differences in mean IOP. The differences in the mean IOPs were < or = 0.26 mm Hg and the mean change from baseline IOP was < or = 0.35 mm Hg at all follow-up time points. There were no statistically significant differences between the two groups in the overall incidence of adverse events. The most commonly reported treatment-related adverse events were conjunctival hyperemia and allergic conjunctivitis: both were mild in severity. CONCLUSION: Brimonidine Purite 0.15% dosed BID provides equal IOP-lowering efficacy to brimonidine 0.2% BID. Patients previously controlled on brimonidine 0.2% can be successfully switched to brimonidine Purite 0.15%.