Hiromi Osada

Safety comparison of additives in antiglaucoma prostaglandin (PG) analog ophthalmic formulations

Purpose To investigate the safety of five types of antiglaucoma prostaglandin analog ophthalmic formulations, and to clarify their differences in accordance with contained additives (preservatives and surface-active agents). Methods The following five types of ophthalmic solutions and three types of additives were investigated: latanoprost (Xalatan®; latanoprost), tafluprost (Tapros®; tafluprost), bimatoprost (Lumigan®; bimatoprost), travoprost (Travatan®; travoprost), travoprost (Travatan Z®; travoprost-Z), benzalkonium chloride (BAK), polyoxyethylene hardening castor oil 40 (HCO-40), and polysorbate 80 (P-80). These experimental solutions were exposed to the cultured cells of a rabbit-derived corneal cell line for a certain time, and the exposure time causing 50% cell damage (CD50), indicated by the ratio of viable cells to total cells was calculated (in vitro). In addition, corneal resistance (CR) was measured and CR ratio (post-treatment CR/pretreatment CR × 100) was calculated (in vivo). Results CD50 of each ophthalmic solution was the longest with tafluprost, followed by travoprost-Z, bimatoprost, travoprost, and latanoprost. CD50 of 0.005%, 0.01%, and 0.02% BAK was 14.5 minutes, 8.1 minutes, and 4.0 minutes, respectively. The number of viable cells decreased to 60%, 8 minutes after exposure with HCO-40, and 30 minutes after being exposed to P-80. The CR ratio was 81.0% with travoprost and 82.0% with latanoprost, indicating a significant posttreatment reduction of CR (P < 0.05). The CR ratio did not decrease after treatment with tafluprost, travoprost-Z, or bimatoprost. The CR ratio of 0.005%, 0.01%, and 0.02% BAK was 105.0%, 90.5%, and 68.7%, respectively, and that of HCO-40 and P-80 was 108.7% and 114.2%, respectively. Conclusion BAK, HCO-40, and P-80 were thought to be involved in corneal injuries caused by each ophthalmic solution. Corneal injuries due to surface action were observed when using HCO-40 and P-80. When HCO-40 was combined with BAK, it induced micellar BAK and reduced corneal injuries by BAK.

Vitreous and aqueous penetration of orally and topically administered moxifloxacin.

Aim: It was the aim of this study to compare the pharmacokinetics of moxifloxacin (MFLX) hydrochloride in rabbits after topical and oral administration. Methods: Three 50-µl applications of MFLX (0.5%) topical ophthalmic solution were instilled into the cul-de-sac of New Zealand white rabbits at 15-min intervals. Aqueous and vitreous samples were collected and analyzed 30–240 min after the final instillation. Assays were performed using high-performance liquid chromatography. MFLX (16 mg/kg of body weight) was administered orally. Drug concentrations in aqueous, vitreous and serum samples, collected at 30–360 min after administration, were determined using high-performance liquid chromatography. Results: After topical administration, the maximum concentrations of MFLX in the aqueous and vitreous samples were 10.2 ± 1.6 µg/ml (30 min; n = 6) and 0.10 ± 0.03 µg/ml (30 min; n = 6), respectively. After oral administration, the maximum concentrations in the aqueous, vitreous and serum samples were 0.9 ± 0.3 µg/ml (120 min; n = 6), 0.7 ± 0.2 µg/ml (240 min; n = 6) and 1.6 ± 0.9 µg/ml (120 min; n = 6), respectively. The percentages of serum MFLX concentration in the aqueous and vitreous samples after oral administration were 55.2 and 41.7%, respectively. Conclusions: The aqueous concentration of MFLX was about 10-fold higher after topical than after oral administration. However, intravitreal MFLX concentrations after oral administration were about 7-fold higher than those after topical administration. The MFLX concentrations in the aqueous humor following oral administration exceeded the minimum inhibitory concentration for 90% of the bacteria involved in ocular infection.

Cyclin-Dependent Kinase Inhibitor p16 and p21 Expression, and Cell Cycle Change in Human Lens Epithelial Cell Line SRA 01/04 following Contact Inhibition in Normal Culture

Purpose: To describe the pattern of expression of the cyclin-dependent kinase inhibitors (CDKIs) p16, p21 and p27, and the cell cycle in SRA 01/04 cells relative to contact inhibition. Methods: SRA 01/04 cells were grown to overconfluence under normal conditions. At various phases of the cell growth, cells were assayed by flow cytometry and Western blotting for the expression of CDKIs. Results: Expression of p16 was detected from early logarithmic growth to stationary phases, during which the number of cells in G₀/G1 increased from 46 to 69%. Expression of p21 was detected only during the overgrowth phase, when 60% of the cells were in G₀/G1. Expression of p27 was not observed in SRA 01/04 cells. Conclusions: p16 expression was likely mediated by G₀/G1 arrest to induce contact inhibition in SRA 01/04. p21 expression may be related to withdrawal, and p27 deficiency may be related to the immortality of this cell line. It is possible for p16 to stop proliferation of lens epithelial cells like progressing posterior capsular opacification, by overexpression to mimic contact inhibition.