Abstract
Purpose: :
To investigate the effect of vehicles on ocular absorption of topically applied Cyclosporin A (CSA) in the rabbit eye.
Methods: :
0.05% Cyclosporine nanoemulsion (CSA-NE) was prepared. A single dose of 50μl CSA was applied using CSA-NE or oil dissolved drug (CSA-OD), the loading dose (50μlx5 times with an interval of 5min) of CSA-NE or CSA-OD was also performed. CSA concentrations were measured at intervals of 5, 15, 30, 6, 120, 180, 240min, 6, 8, 24 and 48 hours for the single dose and 30, 120, 240min, 6, 24, 48 and 72 hours for the loading dose by high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS).
Results: :
The size of nanoemulsion was 29.0±0.5nm and zeta potential was -0.036±0.135mv. After single application of CSA-NE, the highest concentrations of CSA in cornea and conjunctiva were 1433.1±340.1ng/g and 1445.5±410.2ng/g, respectively at 30min and remained 236.15±95.03ng/g in cornea at 48h while CSA in cornea and conjunctiva could not be detected after 8 hours for CSA-OD group. The concentrations in cornea at all the time points were significantly higher than the CSA-OD group at the corresponding time points (p<0.01), respectively. The concentrations in conjunctiva were at all the time points except 3h, 4h and 8h were significantly higher than the CSA-OD group at the corresponding time points (p<0.05) , respectively. Relatively low concentrations were measured in the aqueous for both CSA-NE and CSA-OD group 7.60±9.81 and 6.22±5.68ng/ml) and no significant difference were found between the two groups (p>0.05). After loading dose application of CSA-NE, The highest concentrations in cornea and conjunctiva were 2790.8±409.2 and 3365.0±806.1ng/g at 30min, respectively. CSA levels in cornea and conjunctiva were significantly higher than the corresponding time points (p<0.0001 and <0.05),respectively while the drug in both cornea and conjunctiva could not be detected after 8 hours for CSA-OD group. Relatively low concentrations were measured in the aqueous for both CSA-NE and CSA-OD group (7.02±4.36 ng/ml and 4.29±5.35 ng/ml) and no significant difference were found between the two groups (p>0.05). The concentrations in blood for single and loading dose all groups were below the detection limit (5ng/ml).
Conclusions: :
These findings indicate that nanoemulsion may be a promising delivery system for topical use of CSA in ocular immune-mediated diseases.
Keywords: conjunctiva • cyclosporine