Determination of drug concentration in aqueous humor of cataract patients administered gatifloxacin ophthalmic gel

Background Ophthalmic gel has been developed to increase the drug concentration in aqueous humor and to retard the loss of drug from the conjunctival sac.The research was to compare the drug concentration in aqueous humor of cataract patients administered 0.3% gatifloxacin ophthalmic gel with that in patients administered 0.3% gatifloxacin ophthalmic solution.Methods Ninety-six patients with cataract （96 eyes） were randomly assigned to 8 groups.The patients in groups 1-4received topical gatifloxacin 0.3% ophthalmic gel and those in groups 5-8 received gatifloxacin 0.3% ophthalmic solution.The dose regimen was 1 drop, 4 times a day for 3 consecutive days prior to cataract surgery.On the day of surgery, 1drop was applied at 15, 30, 60 or 120 minutes before commencement of cataract surgery in groups 1 and 5, groups 2 and 6, goups 3 and 7, and groups 4 and 8, respectively.Aqueous humor was extracted during the cataract surgery for the analysis of gatifloxacin concentration..Results The concentrations of gatifloxacin in aqueous humor were （0.24±0.25） μg/ml, （1.11±0.74） μg/ml, （2.32±2.01）μg/ml and （1.85±1.14） μg/ml in groups 1 to 4, and （0.16±0.25） μg/ml, （0.31±0.24） μg/ml, （0.75±0.28） μg/ml and （0.33±0.22） μg/ml in groups 5 to 8, respectively.Patients receiving gatifloxacin ophthalmic gel showed greater mean values of gatifloxacin concentration in aqueous humor than those receiving gatifloxacin solution, and such differences were significant with P 〈0.05 for all comparisons except that between groups 1 and 5.Conclusion Topical gatifloxacin ophthalmic gel can attain significantly greater drug concentrations in human aqueous humor than gatifloxacin ophthalmic solution.

Study on Rheology and Release Kinetics of Chuanqi Ophthalmic Microemulsion in situ Gel

[Objectives] To study the rheology and release kinetics of Chuanqi ophthalmic microemulsion in situ gel,so as to provide references for its future study and development. [Methods]The fluid properties and linear viscoelastic regions of this preparation were investigated by MCR 102 rheometer. The release kinetics of Chuanqi ophthalmic microemulsion in situ gel was evaluated by modified Franz diffusion cell method,the ligustrazine and ligustilide were selected as the indictors,and semi-permeable membrane was used as a barrier,sampling time point was 0. 5,1,2,4,6,and 8 h respectively. [Results]Chuanqi ophthalmic microemulsion in situ gel was a pseudoplastic fluid and it had a linear viscoelastic region. Taking the shear stress as the indicator,the linear viscoelastic region was 0-302. 74 Pa; taking the strain as the indicator,the linear viscoelastic region was 0-7. 45%. At the critical point,the storage modulus( G') = the loss modulus( G″) =2 976. 60 Pa,critical shear stress was 302. 74 Pa and critical strain was 7. 45%. The average cumulative release of ligustrazine of 6 samples within 8 h was 33. 71 μg,the average cumulative release rate reached 90. 08%,and the release kinetics followed Higuchi equation. The average cumulative release of ligustilide of 6 samples within 8 h was 68. 46 μg,the average cumulative release rate reached 84. 32%,and the release kinetics followed the zero-order kinetics equation. [Conclusions] Chuanqi ophthalmic microemulsion in situ gel has excellent viscoelasticity and its strain is reversible in a certain range. The release kinetics of ligustrazine is the result from synergistic effect of its physicochemical properties and matrix skeleton,while the release kinetics of ligustilide is mainly affected by its physicochemical properties.