Comparison of the Efficacy of Topical Antihistamine/Mast Cell Stabilizers in vitro

PURPOSE: To investigate the biologic effects of topical anti-allergic agents with H1-receptor antagonism and inhibition of histamine release from mast cells in the cultured conjunctival cells of patients with vernal keratoconjunctivitis in vitro. METHODS: Conjunctival cells of vernal keratoconjunctivitis were exposed to the anti-allergic agents SCD-P101 (Fexofenadine, Samchundang, Korea), Patanol(R) (Alcon, USA), Zaditen(R) (Novartis, USA), and Azelan(R) (Taejoon, Korea). Efficacy of the topical antihistamine/mast cell stabilizers was evaluated using the MTT assay, measuring the concentration of procollagen and inflammatory cytokines. Cell damage was determined using the lactate dehydrogenase (LDH) assay with dilution rates of 10, 20, and 30% and compared with the balanced salt solution-treated group. Cellular morphologic results were examined by inverted light microscopy and transmission electromicroscopy. RESULTS: Metabolic activity of conjunctival cells decreased at higher concentrations and longer exposure durations, except for the SCD-P101 agent. The procollagen, laminin, IL-6 and IL-8 titers tended to be lower than that of the control in the eyes exposed to all the anti-allergic drugs tested in this study, but the concentration of TNF-beta was similar to that of the control group. Zaditen(R) and Azelan(R) tended to show a greater LDH titer and edema, as well as cytoplasmic and nuclear degeneration of the conjunctival cells than did SCD-P101 or Patanol(R). CONCLUSIONS: Cellular metabolic activity was the highest in the new anti-allergic agent SCD-P101. SCD-P101 and Patanol(R) caused marginally less damage to cultured conjunctival cells than did Zaditen(R) and Azelan(R).

The Effects of Anti-allergic Ophthalmic Agents on the Cultured Rabbit Conjunctival Cells

PURPOSE: To investigate the biological effects and cytotoxicity of anti-allergic ophthalmic agents on the cultured conjunctival cells of rabbit in vitro. METHODS: Conjunctival cells of rabbit were exposed to anti-allergic ophthalmic agents. Azelan(R) (Taejoon, Korea), Zaditen(R) (Novartis, USA), Patanol(R) (Alcon, USA) at a concentration 10, 20 and 30% for a period of 30 minutes, 4, 12, and 24 hours respectively. Cell injury assay was performed using lactate dehydrogenase (LDH) leakage assay. We checked the composition, pH, osmolarity of three anti-allergic agents. Light and transmission electron microscopy were performed to compare the cellular damage of rabbit conjunctival cells under various culture treatments. RESULTS: In cultured conjunctival cells of rabbit, the LDH titers increased up to 4 hours after exposure, maintained until 12 hours and then decreased 12 hours after exposed. Azelan(R) and Zaditen(R) showed a higher LDH titer and severe cellular damage of the conjunctival cells, compared with Patanol(R). Of anti-allergic solutions, Azelan(R) and Zaditen(R) revealed markedly lower Na+, Cl- and pH levels than Patanol(R). However, there was no difference in the concentration of preservative or osmolarity of the eye solution among the three anti-allergic agents. CONCLUSIONS: Patanol(R) caused markedly more damage to cultured rabbit conjunctival cells than Azelan(R) and Zaditen(R). If these anti-allergic these agents are clinically used for long periods of time, they may induce the cellular damage of conjunctival cells depending on the composition and pH of anti-allergic drugs.