Preparation Of ALD Gelatin Nanoparticles And Related Experimental Studies On Biological Characteristics

With the arrival of the inevitable ageing of population, patients with osteoporosis are increasing. In the world there are about 200 millions patients with osteoporosis, and more than 50 million patients with osteoporosis in our country. Alendronate (ALD) is one of anti-osteoporosis drugs in clinic, which has a good effect on restraining bone resorption and increasing bone mass. Because of restrictions on dosage forms and Characteristics of the drug, oral administration of ALD has some problems such low bioavailability, obvious side effect, inconvenient taking medicine, et al. Targeting Drug Delivery System, TDDS offers a new approach for therapy of the osteoporosis. The naissance of the TDDS occurs in 1970s. Not until recent years was it applicable to the clinic, which has achieved good treatment outcomes. Carrier preparation is an important content in the research of targeting preparation, which always adopted nanoparticle. Targeting preparation nanoparticle is defined that drug is dissolved in solution or macromolecule ground substance and form micro-globular entity, whose particle diameter between 50-150 nm. It belongs to ground substance framework particles. Nanoparticle can have a specified disposition in vivo. First it can increase the local effective concentration, and decrease side effect in body. Secondly, release drug in nanoparticle can be controlled by appropriate methods, which can achieve prolong action, decrease the dosage times, change the phenomenon of peak valley in drug release, increase treatment outcomes. This therapy method has many advantages including high therapeutic effects and small side effect. It will be a important therapeutic method in future. AIM: To exploit a new kind agent of Alendronate-gelatin-nanoparticle ALD-GNP, for the osteoporosis therapy.In this study we apply gelatin to enwrap ALD,the most useful chemotherapy medicine by improved monophase condensation method. In order to test the biological characteristics and sustained release effect of ALD-NP we did some related experiments. METHODS AND RESULTS: This study is divided into three parts:1. Preparation of a sustained-release ALD-NP for use of osteoporosis therapy: On the basis of gelatin's self-crosslink in and its solidification by aldehyde, ALD-NP was prepared. The ALD-NP enwraps alendronate. Result: the roundness of ALD-NP has good roundness and dispensability, and it is stable in refrigerator or room temperature store, the mean diameter is 136.69nm, 91.5% of them ranging from 100-200 nm, which fit the use of sustained release. 2. Physical, chemical and biological characteristics examinations: To test some targets including encapsulation rate, drug content ,drug release vitro, asepsis et al, then we can estimate its value. Methods: A spectrophotometer method was used for testing the encapsulation rate and drug content of ALD-NP. By simulating the circumstance in vivo and using release device, we tested the drug release velocity in ALD-NP. After sterilizing by radioactive ray, we observed the change of ALD-NP. Result: the encapsulation rate is 56.73% and the drug content is 2.14%, and the quality of ALD-NP and drug is stable. 50% drug release time is 1.5h. 70% of the drug was released in 3h, and total release time was more than 6h. After sterilizing by radioactive ray, its shape, size, appearance, chemical constitution and drug content aren't changed. So ALD–NP prepared by this method was stable and the velocity of gelatin decomposition and drug release were proper for clinical use. The sterilization of ALD-NP was processed and they were proved to be of asepsis. 3. The distribution study of ALD-NP in mice: Studies were conducted in mice to evaluate the release characteristics of ALD gelatin nanoparticles by the analysis of different subgroup methods of ALD. ALD solution and ALD-NP was injected into vena caudalis, blood samples and tissue samples were tested at different time and analyzed statistically. Results: a transient higher blood drug concentration (BDC) was produced by ALD group. BDC was kept a longer time by ALD-NP group. ALD-NP group could produce a high BDC level for a longer time in bone tissue, which BDC was 1.54 times as high as in ALD solution group, and increase drug content in vivo, which was about 2.43 times than ALD solution group. ALD-NP group, which significantly increased the drug content in bone tissue, could achieve the purpose of targeted sustained release therapy. CONCLUSION: In our research, the technology of drug-loaded gelatin nanoparticles was successfully applied to the field of anti-osteoporosis. We firstly prepared a new anti-osteoporosis preparation--ALD-NP by using improved simple coacervation. And then we observed its quality index and release behavior in vitro. At the same time, we chose a kind of ALD-NP with certain diameter to do a tail vein injection and analyzed the blood concentration of drug in different tissues. The results showed that ALD gelatin nanoparticles are a perfect new anti-osteoporosis preparation with excellent performance. It is worth while further research and clinical application.