Comparison of intraocular pressure in glaucoma subjects treated with Xalatan versus generic latanoprost

Effects of the pharmaceutical formulation of topical medications on corneal epithelial healing after phototherapeutic keratectomy

PURPOSE

To determine the effect of the formulation of topical medications on the healing of corneal epithelial cells after phototherapeutic keratectomy (PTK).

STUDY DESIGN

Retrospective cohort study.

METHODS

We studied 271 eyes of 189 consecutive patients (aged 67.6 ± 11.8 years) who had undergone PTK for granular corneal dystrophy (n = 140), band keratopathy (n = 47), or lattice corneal dystrophy (n = 2). Postoperatively, generic or brand-named levofloxacin, 0.1% betamethasone, or 0.1% bromfenac sodium hydrate was applied topically. Patients were examined on postoperative days 1, 2, and 5 and weekly thereafter. The time to re-epithelialization was assessed by use of Kaplan-Meier and Cox proportional hazards analyses.

RESULTS

The time to re-epithelialization was significantly longer with generic 0.5% levofloxacin, at 8.2 ± 3.5 days, than with 0.5% Cravit (levofloxacin), at 6.7 ± 3.5 days (P = 0.018), or with 1.5% Cravit, at 6.3 ± 2.6 days (P = 0.000). In addition, the time to re-epithelialization was significantly longer with generic 0.1% betamethasone (Sanbetason), at 7.3 ± 3.4 days, than with brand-name 0.1% betamethasone (Rinderon), at 6.1 ± 2.5 days (P = 0.0002). The Cox proportional hazards model indicated that the use of generic formulations for levofloxacin eye drops and 0.1% betamethasone was a significant factor that delayed corneal re-epithelialization (hazard ratio [HR] = 0.72, P = 0.002 and HR = 0.77, P = 0.006, after adjustment for age). Re-epithelialization was significantly shorter in band keratopathy than in corneal dystrophy (HR = 1.56, P = 0.004). No other factors, including age, bandage contact lens, and diabetes mellitus, were significantly associated with time to re-epithelialization.

CONCLUSION

Corneal epithelial healing can be significantly affected by different antibacterial or steroid eye drops. Clinicians need to be aware that a generic formulation may affect corneal epithelial healing.

Comparative Effectiveness of Generic Latanoprost Versus Branded Prostaglandin Analogs for Primary Open Angle Glaucoma

PURPOSE

The purpose of the study is to determine the comparative effectiveness of generic latanoprost (GL) to its branded (BL) counterpart and other brand-name prostaglandin analogs (bPGAs) in preventing the need for additional therapy in the treatment of primary open angle glaucoma (POAG).

METHODS

Retrospective cohort study using US commercial medical claims data. All new POAG patients from 2000 to 2015 who initiated treatment with either GL or BL were included. Exclusion occurred for having less than 2 years of time in the plan prior to diagnosis, previous use of glaucoma medications, or any diagnosis of glaucoma other than POAG at any time. Analyses compared GL to BL and also to those who received any branded PGA after 2011 (when the generic became available). Cox proportional hazard regression was used to assess the hazards of filling a prescription for a second IOP-lowering medication or having surgical intervention, individually and either outcome combined.

RESULTS

A total of 6317 and 4150 POAG patients were treated with GL and BL, respectively. After 2010, 6317 GL and 3703 brand-name prostaglandin analog (bPGA) POAG patients met criteria for inclusion. After adjustment, compared to BL, the GL conferred a reduced hazard of having a glaucoma procedure performed (hazard ratio [HR] = 0.72, 95% CI: 0.62-0.84, p < 0.001) and the combined outcome (HR = 0.90, 95% CI: 0.83-0.97, p = 0.006) but was not associated with having a second IOP medication (HR = 0.95, 95% CI: 0.87-1.03, p = 0.18). Compared to the bPGAs, however, GL conferred a reduced hazard in each comparison (second IOP medication HR = 0.87, 95% CI: 0.81-0.94, p < 0.001; surgery HR = 0.70, 95% CI: 0.61-0.81, p < 0.001; combined HR = 0.85, 95% CI: 0.79-0.92, p < 0.001). Sensitivity analyses confirmed these findings.

CONCLUSIONS

GL was no less and possibly more effective in preventing the need for additional intervention than branded PGAs.

The physical properties of generic latanoprost ophthalmic solutions are not identical

PURPOSE

To compare various characteristics of Xalatan^® and five generic latanoprost ophthalmic solutions.

METHODS

Drop size, volume, pH values, buffer capacity, viscosity, hardness of bottles and costs were determined. Drop sizes were measured in triplicates by micropipettes, and the number of drops counted in three separate bottles of each generic product was determined. pH values were measured in triplicates by a calibrated pH meter. Buffer capacity was exploited by titrating known quantities of strong base into 2.5 ml of each brand and interpolated to neutral pH. Kinematic viscosity was determined by linear regression of timed gravity flow from a vertical syringe through a 21-G cannula. The hardness of the bottles was evaluated by gradually increasing tension on a hook placed around each bottle until a drop was expelled reading the tension on an attached spring scale.

RESULTS

Drop sizes and the number of drops in the bottles varied significantly between the generic drugs. The control value of pH in the brand version (Xalatan^® ) was markedly lower compared to the generic latanoprost products. Titration of Xalatan^® to neutrality required substantially more NaOH compared to the generic latanoprost products. Finally, the viscosity revealed a significant variability between brands. Remarkable differences were found in bottle shapes, bottle hardness and costs of the latanoprost generics.

CONCLUSION

Generic latanoprost eye drops should not be considered identical to the original brand version as regards to drop size, volumes, pH values, buffer capacity, viscosity, hardness of bottles and costs. It is likely that these issues affect compliance and intraocular pressure (IOP)-lowering effect. Therefore, re-evaluation of the requirements for introducing generic eye drops seems reasonable.