| Liposomes are synthetic biologicmembranelike vesicles. They are composed of bilaered lipid membrane surrounding aqueous droplet. In the current study, we report the action of miosis > pharmacokinetics in rabbits and treatment of glaucoma of liposome in which the pilocarpine was entrapped. Drug transit is prolonged from the liposome, since the entrapped drug must cross membranes before escaping. The liposome may prevent rapid dispersion or resorption and sustained delivery of pilocarpine to the eye. The liposome is hard drained from the eye via the lacrimal canaliculus and nasolacrimal duct.1. Pa rts of experiment(1) Action of miosis of 1% pilocarpine liposome in rabbitsObjective To compare the action of miosis of 1% pilocarpine liposome withl%pilocarpine solution in rabbits. Methods 18 white rabbits were used and were randomly divided into 3 groups. Test group received 1% pilocarpine liposome, positive control group received 1% pilocarpine solution, negative control group received liposome. Each eye drop instilled into left eye of rabbits and sterile saline solution instilled into right eye as control. The pupil diameter was measured at time intervals of beginning, 0.25, 0.5, 1, 2, 3, 4, 5, 7h. Results The mean pupil diameter of 3groups in both eyes was not significant(p>0.05)at beginning. The strongest action ofmiosis took place 0.25h in positive control group and 2h in test group after instillation. The dilation of pupil in both groups took place Ih and 3h , and the restoration of pupil in both groups took place 5h and 7h. The mean pupil diameter of negative control group was not significant in seven hours. Conclusion The results suggest that 1% pilocarpine liposome extends the duration of its action.(2) Action of miosis between 1% pilocarpine liposome and 4% pilocarpine gel in rabbitsObjective To compare the action of miosis of l%pilocarpine liposome and the 4%pilocarpine gel in rabbits.Methods 12 rabbits were randomly divided into 2 groups: 1% pilocarpine liposome, 4%pilocarpine gel. The pupil diameter was measured at time intervals of beginning and 0.25, 0.5, 1, 2, 3, 4, 5, 7h after drugs being appliedResults There were no significant different(p>0.05) between the 2 groups in the mean pupil diameter at the beginning.The strongest action of miosis took place 0.5h and 2h in 1%pilocarpine liposome, 0.5h in 4%pilocarpine gel group after instillation.The duration of miosis in the l%pilocarpine liposome group was 5 hours and it was 4 hours in 4%pilocarpine gel group. Conclution The results suggest that l%pilocarpine liposome has a longer duration of action than 4%pilocarpine gel.(3) Evaluation of ocular pharmacokinetics for three formulations of pilocarpine using the rabbit model with RP-HPLCObjective To compare the ocular pharmacokinetics for three formulations of pilocarpine in the aqueous humor of rabbit eyes with RP-HPLC method. Methods The RP-HPLC method was performed on a column of ODS-Cig with the mobile phase consisting of 0.5% of triethylamine (TEA) of phosphate solutions (10 mmol.l-1, pH2.5) and acetonitrile (98:2 v/v). The detection wavelength was 215 run. 90 white rabbits were randomly divided into 30 groups, each consisting of 3 animals. Every 10 groups received 50 μL of 1% pilocarpine solution, 1% pilocarpine liposome and 4% pilocarpine gel, respectively. The aqueous humor was withdrawn at 5, 10, 30,40, 60, 90, 120,180,240 and 360 min after instillation. Pilocarpine was extracted from aqueoushumor with dichloromethane. The drug was analyzed by reversed phase high pressure liquid chromatography (RP-HPLC). Results The linear calibration curve was obtained in the concentration range of 0.1 ~20 μg .mL-1. The average recovery was 68.10%\ 1.9% . The pilocarpine liposome and gel gave higher aqueous humor concentration of drug than pilocarpine solution at all time periods tested(p<0.05). The areas under curve of liposome and gel were 2.8 times as much as that of solution. Measurable amounts of drug following 1% liposome were still observed at 360 min, while drug...
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