Preparation And Study Of Etoposide-loaded Chitosan Microspheres For The Nasal Administration

Objective: Cerebrovascular disease severely threaten humans'health, no mattet children, youth but the aged would fall to ill, the disease has many features,just like: the disease rate is high,death rate is high, relapse rate is high and with many complications, which acutely effect patient's quality of life.Vinpoctine can cure many cerebrovascular diseases effectually such as: cerebral infarction, brain hemorrhage lingering effects, cerebral arteriosclerosis and so on, it also can improve brain function, ehance remembrance, delay aging, tolerance and safety of long-term application is high. Vinpoctine is a kind of indole alkaloid, because of its low dissolubility and intensive hepatic metabolism, the bioavailability of the oral application is extraordinary low. For the purpose of raise bioavailability and patients'compliance, this article study and research to prepare vinpoctine chitosan microsphere to intranasal administration. The intranasal administration has many advantages, such as convenient application, rapid absorption. The molecular weight of vinpoctine is 350.5, since its high liposolubility indissolvable, little dosage 10-15mg/day and suitable coefficient of distribution between water and oil, it fits mucous membrane use extremely. We adopt chitosan as carrier material, with favourable biologic adhesiveness, which can extend the contiguous time of the drug and nasal mucosa, finally facilitate drug's absorption.Methods: Prepare vinpoctine chitosan micropheres using the method -emulsion crosslinking technique. Based on the single test, the orthogonal design was used to optimize the prepare technology. the average diameter, the diameter distribution, the drug loading and the entrapment efficiency of microspheres were selected as combined indexe.Directly observe the appearance and the the size distribution of microsphers by scanning electron microscope. We also investigated the release behavior. The release data of the optimalist technology were analyzed with classical release models to study the release mechanism.Mucoadhesive property and cili toxicity were evaluated with in vivo toad palate model. The last time of ciliary movement and the mucociliary transport rate (MRT) were selected as evaluation indexes.The stability of optimal formula was investigated under following circumstances: high humidity, high tempreture and strong light and long natural store condition.Pharmacokinetics study in vivo: The rat was selected as the experimental animal. Investigated the pharmacokinetics of chitosan microspheres by nasal administration, compared with the injection of vinpoctine following intravenous administration. HPLC with Ultraviolet detector was used to determine the vinpoctine blood drug level. The pharmacokinetics parameters were handlled by 3p97 software. On the basis of the data and the Pharmacokinetics parameter, analyze the drug absorption course after the intranasal administration.Results: Based on the consideration single factors of preparation technology, it was found that concertration of chitosan, the drug loading, the volume of the cross linking agent and rotation speed had much influence on indexs of microsphere. The optimal formulation and process were defined through the orthogonal experiment. Three batches of Chitosan microspheres made from the optimal formula have good sphericity and narrow size distribution, besides the optimal formula and process had fine reproducity and stability. The average diameter of microsphere was 43.72±1.70μm. The drug loading was 7.73±0.29%. A little of crystal of drug were observed on surface of microspheres.The release process fitted Higuichi equation very well. From the release curve, we can see that the drug released a lot in the initial stage, which is good to the absorption of the drug by the intranasal administration. The test of the MRT proved that chitosan microspheres had good mucoadhesive property. The experiment of the lasting times of ciliary movement indicated that the toxicity was very low, which did not affect the nasal administration.Stability experiment: Under the condition of RH 92.5%, the weight increasing ratios of microsphere was more than 5%, but under the condition of RH75%, the increasing ratios was less than 5%. Under the condition of 60℃, the appearance, content and the release characteristics of microspheres changed little. But under the condition of highlight, the content lowered a lot, accordingly, the microsphere must be conserved away from the light. After stored at ordinary temperature for 6 months, microsphere had no significant difference in appearance, content and release characteristics.Pharmacokinetics study in rats: The rat was used as test animals, investigated the pharmacokinetics of chitosan microspheres nasal administration and solution intravenous injection respectively. Pharmacokinetics test indicated that vinpoctine in blood plamsa complied with 2-compartment modle in vivo after intravenous injection; vinpoctine in blood plamsa complied with 1-compartment modle in vivo after nasal administration; vinpoctine in brain tissue complied with 1-compartment modle both after nasal administration and intravenous injection. From the main pharmacokinetics parameters, it was found that the blood plasma half life became 1.52 from 0.80, the brain tissue half life became 1.85 from 1.08, the absolute bioavailability was 56.5% following nasal administration. The AUC(0-6h) value in blood plasma following nasal administration was 0.57 times of that following intravenous injection,but the AUC(0-6h) value in brain tissue following nasal administration was 1.08 times of that following intravenous injection, DTI was 1.89. The results showed that nasal administration vinpoctine chitosan microsphere increased the absorption rate, prolonged the half life, increased the bioavailability of vinpoctine and possessded the ability of brain targeting.Conclusions: The optimal formulation and process defined through the orthogonal experiment, had fine reproducity and stability. The study of in vitro and in vivo indicated that the chitosan microsphere could prolong the residence time of drug in the nasal cavity and increase the bioavailability of vinpocetine. The preparation with apply convenience, high bioavailability, has a prosperous perspective.