| Liposome consists of phospholipid bilayers, which has high biocompatibility, lowtoxicity and irritation. In clinic, an injection of clarithromycin (CLA) is injected as thelactobionate salt caused by the poor water-solubility of CLA. However, the drug itself hasdrawbacks including poor compliance and phlebitis. Thus, the aim of this study was toprepare and evaluate a new preparation—clarithromycin-loaded liposomes (CLA-Lip) forinjection with high stability and less irritation.An HPLC method was established for the analysis of clarithromycin in vitro. Themethod validations were carried out and approved. The stability and total solubility of CLAin different pH phosphate buffer saline (PBS) were determined respectively. The oil/waterpartition coefficients of CLA in different pH value PBS were investigated. The result showedthat the solubility of CLA in the buffers is pH-dependent.CLA-Lip were prepared by the membrane extrusion method. The encapsulationefficiency of CLA in liposomes was determined by using microdialysis method. N-Hexylacid as an auxiliary agent was applied to the liposomes for the first time. Electrostaticinteractions and salt-forming reactions were to ensure the CLA stability encapsulated inliposomes. The preparation technology (solvent, preparation temperature, membrane speedand ultrasonic time) and formulations (hydration medium, membrane regulator, phospholipidand fatty acid) were optimized. This method will30-fold increase the concentration ofclarithromycin relatively to the aqueous solution. Taking physical appearance, particle sizedistribution (PSD), zeta-potential and entrapment efficiency as index, the final formulationwas as follows:15mg·mL-1drug loading,5.4%PC-98T,1.5%SCS and0.75%n-hexanoicacid. The resultant liposome had a particle size of136±50nm, a zeta potential of-28.45mvand an entrapment efficiency (EE) of95.65%.To over the bad satiability of liquid liposomes, freeze-drying was carried out. One ofthe advantages is that liposomes can be stored in the solid form which greatly improve thestability of liposomes, and another is that liposomes can be almost the same as the statebefore lyphilization by reconstituted with normal saline. The products were fast pre-freezingat-40°C for12hours. The lyophiles containing12.5%sucrose had a good appearance and aslightly altered particle size after rehydration. The shapes of CLA-Lip before lyophilizationand after rehydration were investigated by transmission electron microscopy (TEM). Thestructure of the CLA-Lip were multilamellar and homogeneously distributed around100nm. And using differential scanning calorimetry,it was analysed that the exist state of the CLA.The drug release profiles from liposomes before and after lyophilization fitted the weibulldistribution with r values of0.9784and0.9865respectively. In addition, the lyophiles werestable in3months at room temperature (25±2°C).The reconstituted sample could significantly reduce the pain by approximately80%compared with the solution of clarithromycin phosphate, according to the mouse scratch testand the rat paw lick test. Meanwhile, rabbit ear vein experiments showed a similar result.The results of the animal experiments demonstrated that the formulation of CLA-Lipsignificantly relieved symptoms of chemical induced irritation to vein and tissue andexhibited protective effects as compared to free drug. This results unequivocallydemonstrated that the CLA-Lip will be used as a suitable delivery system for CLA and havegood prospects for clinical application. |
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