| Sirolimus(SR),also known as rapamycin,was clinically used as an immunosuppressive agent in the treatment of anti-immune rejection after liver and kidney transplantation.Some studies had shown that SR owned a wide range of pharmacological effects,and was suitable for the treatment of various immune-related diseases,which made it a hot compound in the field of pharmaceutical research.However,the poor solubility in water and low oral bioavailability limited SR further application in clinical practice.This work was intended to prepare the ophthalmic SR nanosuspension to promote the absorption of the eye with good stability suitable for long-term storage.Furthermore,to investigate it’s in vitro and in vivo characteristics and potential for the treatment of ocular diseases.Specifically,the work of this paper mainly includes the following four aspects:1.The SR nanosuspension was prepared by precipitation method,which utilized the insolubility of drugs in aqueous solution to form nanoparticles precipitation.On the basis of the preparation process and excipient exploration in pre-experiment,the parameters of the preparation process and the kinds of excipient to be added were determined.Through the design of experiment,a series of prescriptions with different levels of combination were obtained.Using the artificial neural network of Matlab R2016 a software to acquire optimized prescription with the particle size,polydispersity,and physical stability as the index.The results showed that there was a complex interaction between the prescription level and the indexes.The optimal formulation was: 0.08% of P407,0.08% of HPMC,0.28% of PVA.2.The optimized nanosuspension was characterized by particle size,polydispersity,morphology and so on.The osmotic pressure and p H value of SR nanosuspension were adjusted and measured so as to make it accord with the standard of ophthalmic preparation.Through the stability experiment,the physical and content stability of nanosuspension at different temperature were investigated.The results showed that the appearance of the preparation was blue transparent and had milky light,the size was about 150 nm,the drug crystal shape was round and uniform.The osmotic pressure and p H value were in accordance with the standard of ophthalmic preparation.The results of stability test showed that the particle size,PDI,and content of SR nanosuspension had no significant change within 6 months where the temperature below 20℃.3.The in vitro release characteristics of nanosuspension were investigated by dialysis bag release test with SR ethanol solution as control.Investigated the permeability of formulation to ocular surface barrier through the permeability test of cornea and sclera from isolated rabbit eyes in Franz cell with self-made SR micelle as control.The results showed that the SR nanosuspension had the characteristics of rapid drug release,and was only slightly slower than that of SR ethanol solution.The release curve fitting results showed that the release behavior of SR nanosuspension was consistent with the first order kinetic process.The results of permeation test showed that the cumulative permeability of SR nanosuspension was much higher than that of SR micelle,which indicated that nanosuspension had the potential to improve the permeability of the drug to cornea and sclera.4.The aqueous humor samples of insoluble drugs were consecutively sampled by the method of corneal puncture and tissue glue fixation.At the same time,a sensitive and accurate HPLC-MS/MS method was established to study the rabbit eye pharmacokinetics of SR nanosuspension,with self-made SR micelle as control.The pharmacokinetic results showed that the drug concentration of SR nanosuspension in aqueous humor was significantly higher than that of micelle,which reached the effective concentration of drug therapy and could be maintained for a long time.The result further demonstrated that the nanosuspension can promote the penetration and absorption of the drug in the eye,and had the potential for further research and development. |
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