Preparation And Characterization Of Controlled-Release Formulations For Hydroxycamptothecin

Hydroxycamptothecin is approval of our clinical application of effectively camptothecin cytotoxic drugs, widely used in clinical treatment of various malignant tumors. However, HCPT has toxic side effects, a low solubility in water, characteristics of the short half-life in vivo, and poor stability of lactone ring, limiting their clinical applications. Through the preparation of a new sustained-release formulations, the above-mentioned defects of the drug can be significantly improved, to achieve targeted and sustained release effect, therefore, this article studied three kinds of sustained-release preparations for hydroxycamptothecin, to enhance its antitumor activity.The microcapsules loaded with10-hydroxycamptothecin were prepared using a novel coating technology based on the layer-by-layer (LBL) deposition of oppositely charged polylysine and alginate polyelectrolytes onto microcrystal templates. By monitoring of the surface zeta potential of microcapsules, to prove that the crystal surface will be fully reversed when the polyelectrolyte was adsorbed. The microcapsules fabricated by this method had visible core-shell structure observed by scanning electron microscopy and confocal laser scanning microscopy, The entrapment efficiency of the microcapsules was as high as68.41±0.72%, Detecting the release rate of10-hydroxycamptothecin of0,4,7,10bilayers, The time was4h,5.5h,6h,8h when the cumulative release rate was over of80%, respectively. The release studies in vitro confirmed that the drug releasing of the microcapsules was extended with the increased of wall layers.Cerasome is a new type of organic and inorganic lipids, liposomes are spherical vesicles consisting of phospholipid bilayers surrounding an aqueous cavity the same as cerasome, but its surface is covered with the inorganic silica framework, it can maintain the stability of its structure and morphology of the drug and have a higher encapsulation efficiency. This article prepared the HCPT cerasome successfully which had obvious globular structure by transmission electron microscopy; The size of liposome was198.6±1.2nm with a zeta potential at-32.1mV; The drug loading content and encapsulation efficiency was2.33±0.62%and75.81±0.58%; Detecting the release rate of HCPT cerasome, it was about24h when the cumulative release rate was over of70%, however, it was just4h when the cumulative release rate was over of80%for HCPT. The results confirmed that this new preparations for HCPT cerasome has a significant release effect.HCPT-microbubbles were prepared by a water/oil/water emulsion and solvent evaporation method. The microbubbles had visible core-shell structure and smooth surface observed by scanning electron microscope, the particle size distribution was0.45-5.12μm, fluorescence spectrophotometry was used to determine the drug loading content and encapsulation efficiency which was4.10±1.29%and67.44±2.55%respectively. This kind of microbubbles had obvious release effect, it was still releasing slowly when the cumulative release rate was60%after48h in vitro.This article studied three kinds of sustained-release preparations for hydroxycamptothecin successfully, which laid the foundation for further study and had potential for future application.