Cytotoxicity of prostaglandin analog eye drops preserved with benzalkonium chloride in multiple corneoconjunctival cell lines

Figures & data

Figure 1 Effects of prostaglandin analog ophthalmic solutions on the viability of cultured rabbit corneal cells (RC-1) using the neutral red (NR) assay and MTT assay. Data are means ± standard deviations. Note that Travatan Z exhibits the greatest viability and shows minimal differences among exposure times or dilution. The cell viabilities for the other solutions depend on exposure times and dilutions except for Rescula, which shows small cell viabilities even in diluted solutions. These are common findings in all cell lines. Detailed comparisons were made with cell viability score and statistical analysis (Tables 1–3).

Figure 2 Effects of prostaglandin analog ophthalmic solutions on the viability of cultured rabbit corneal cells (SIRC) using the neutral red (NR) assay and MTT assay. Data are means ± standard deviations.

Figure 3 Effects of prostaglandin analog ophthalmic solutions on the viability of cultured bovine corneal cells (BCE C/D 1-b) using the neutral red (NR) assay and MTT assay. Data are means ± standard deviations.

Figure 4 Effects of prostaglandin analog ophthalmic solutions on the viability of cultured human conjunctival cells (Chang) conjunctiva using the neutral red (NR) assay and MTT assay. Data are means ± standard deviations. Travatan Z exhibited a proliferative effect (cell viability > 100%) with the 10-fold dilution.

Table 1 Cell viability score of the drugs

Drugs	Fold dilution and exposure time (min)									Total of CVS50
	1 ×			2 ×			10 ×
	10	30	60	10	30	60	10	30	60
Xalatan	0	0	0	0	0	0	8	8	7	23
Rescula	0	0	0	0	0	0	4	2	1	7
Travatan	0	0	0	1	0	0	8	7	7	23
Travatan Z	8	8	8	8	8	8	8	8	8	72
Tapros	0	0	0	6	2	0	8	8	8	32

Notes: The full number of assay is eight (four cell lines × two assays for each time and dilution).

Abbreviations: CVS₅₀, number of cell lines with viability ≥50% in the presence of the drug; min, minutes.

Table 2 Comparison of cell viability between Xalatan and other prostaglandins

Drugs and comparison results		Summary of comparisons for each exposure time and fold dilution
		1 ×			2 ×			10 ×
		10	30	60	10	30	60	10	30	60
Rescula	>Xalatan*	0	1	0	0	0	0	0	3	0
	NS*	5	6	7	8	8	7	6	2	1
	<Xalatan*	3	1	1	0	0	1	2	3	7
Travatan	>Xalatan	4	2	2	6	6	3	0	0	0
	NS	4	6	5	2	2	5	4	4	3
	<Xalatan	0	0	1	0	0	0	4	4	5
Travatan Z	>Xalatan	8	8	8	8	8	8	4	5	3
	NS	0	0	0	0	0	0	4	2	4
	<Xalatan	0	0	0	0	0	0	0	1	1
Tapros	>Xalatan	4	1	0	7	6	3	3	2	2
	NS	4	6	7	1	2	4	4	5	5
	<Xalatan	0	1	1	0	0	1	1	1	1

Notes: Each comparison includes eight experiments (two assays for four cell lines);

* P < 0.05 (result of t-test).

Abbreviation: NS, not significant.

Table 3 Comparison of cell viability between undiluted Tapros and 0.01% BAK

Cell lines		Exposure time for neutral red assay			Exposure time for MTT assay
		10 min	30 min	60 min	10 min	30 min	60 min
SIRC	Tapros	26.1 ± 12.7	14.4 ± 8.0	9.6 ± 1.4	16.7 ± 11.8	3.9 ± 1.1*	4.0 ± 1.3
	BAK	58.2 ± 19.8**	13.8 ± 7.1	8.1 ± 3.0	37.5 ± 5.8**	2.4 ± 0.7	3.8 ± 3.4
RC-1	Tapros	9.2 ± 3.6	9.1 ± 4.6	7.3 ± 1.2	3.5 ± 0.2	3.5 ± 0.9	4.3 ± 1.4
	BAK	30.2 ± 5.6**	6.8 ± 0.3	7.0 ± 0.4	26.4 ± 14.8**	3.7 ± 0.3	4.3 ± 0.7
BCE	Tapros	18.2 ± 9.2	11.5 ± 8.6	7.3 ± 2.2	11.9 ± 11.1	2.4 ± 1.2	2.8 ± 1.8
	BAK	49.8 ± 20.8**	7.4 ± 0.6	7.5 ± 0.6	33.3 ± 6.9**	1.5 ± 0.5	1.7 ± 0.2
Chang	Tapros	11.2 ± 5.9	12.0 ± 5.6*	11.0 ± 4.6	3.4 ± 1.8	2.6 ± 0.6*	2.7 ± 1.2
Conjunctiva	BAK	20.4 ± 3.6**	7.0 ± 0.7	7.5 ± 1.6	14.0 ± 3.8**	2.0 ± 0.2	2.1 ± 0.3

Notes:

* Tapros-treated cells show greater viability (P < 0.05, t-test);

** BAK is greater (P < 0.05, t-test).

Abbreviations: BAK, benzalkonium chloride; min, minute.