Acute corneal toxicity of latanoprost with different preservatives

In Vitro Toxicity Evaluation of New Generic Latanost® and Latacom® as an Ophthalmic Formulation

Aim and objective

To evaluate the safety of two new generic ophthalmic formulations, Latanost^® (latanoprost) and Latacom^® (latanoprost and timolol) by utilizing the three-dimensional reconstructed human cornea-like epithelium (RhCE) tissue constructs as an in vitro model in the assessment of ocular irritation.

Materials and methods

In vitro irritation test was conducted on Latanost^® (LTN) and Latacom^® (LTC) and their corresponding innovators, Xalatan^® (XLT) and Xalacom^® (XLC), respectively, by using RhCE. According to the OECD guidelines No. 492 on the testing of chemicals, the ophthalmic formulations were assessed via topical exposure of the formulations on in vitro RhCE tissue. Cell viability was measured by MTT assay.

Results

The mean cell viability percentage of LTN and XLT was 70.5 and 75.7%, respectively, whereas, for LTC and XLC, the percentage viability was 95.3 and 85.7%, respectively. The two new generic formulations (LTN and LTC) did not reduce the cell viability of the RhCE tissue to ≤60%. Thus, both can be considered as nonirritant.

Conclusion

Both newly developed generics are nonocular irritants.

Clinical significance

This study informs the safety assessment of new generic antiglaucoma ophthalmic solutions applicable for long-term glaucoma treatment. The formulations aim to keep eye irritation to a minimum level.

How to cite this article

Ng JSC, Tan YX, Alwi NAA, et al. In Vitro Toxicity Evaluation of New Generic Latanost^® and Latacom^® as an Ophthalmic Formulation. J Curr Glaucoma Pract 2021;15(3):139–143.

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.

Acute cytotoxic effects of marketed ophthalmic formulations on human corneal epithelial cells

The purpose of the study was to devise a fast, reliable and sensitive cell viability assay for assessment of acute cytotoxicity on human corneal epithelial cells by using a clinically relevant exposure time. Acute cytotoxic effects of the pharmaceutical excipients benzalkonium chloride (BAC), macrogolglycerol hydroxystearate (MGHS40), polysorbate 80 (PS80) and marketed ophthalmic formulations (Lumigan(®), Monoprost(®), Taflotan(®), Travatan(®), Xalatan(®)) containing these excipients were tested. Human corneal epithelial cell (HCE-T) viability was assessed by measuring the reduction of resazurin to highly fluorescent resorufin. Expression of the tight junction proteins in HCE-T cells were characterized by immunofluorescence staining. Presence of tight junction proteins in HCE-T cells was demonstrated. BAC preserved ophthalmic formulations showed concentration-dependent and time-dependent cytotoxicity to human corneal epithelium. In contrast, no acute cytotoxicity of non-ionic stabilizing/solubilizing excipients (MGSH40 and PS80) or ophthalmic formulation containing these excipients was observed. Marketed ophthalmic formulations used for glaucoma medication show differential toxicity on human corneal epithelial cells. The present study revealed that BAC-preserved ophthalmic formulations were able to induce acute cytotoxic effects even during a clinically relevant exposure time, which was not observed with MGSH40 and PS80 excipients or ophthalmic formulations containing these excipients.