| Etoposide, a derivative of podophyllotoxin, has significant anti-tumor activity. Since be first used in1967, it has become representative of clinical anticancer drugs so far. The PEG-modified long-circulating liposomes can increase the flexibility of its membranes and the steric hindrance on the surface, which effectively protect the structure of Lipid bilayer, avoid the phagocytosis and destruction of RES, extend the time of the drug in the blood circulation. I PEG-modified liposomes also can play a role of retention effect, which selectively target to tumor tissue. Therefore, our study are aimed to develop etoposide into PEG-modified etoposide long-circulating liposome (PEG-ETP-LP). And we have completed the research of the preparation process of PEG-ETP-LP and its quality standards. On this basis, my paper mainly incestigated its preliminary stability so as to determine its expiry date, as well as studied its internal pharmacokinetic, and elaborates its long-circulating and targeting.First of all, referring to "Chinese Pharmacopoeia" of the2010version establish a HPLC method for ETP’s determination. PEG-ETP-LP samples ared prepared according to the pre-preparation and so their encapsulation efficiency is measured according to pre-entrapment efficiency methods. The results show that the average encapsulation efficiency of three batches of samples was91.56%.On the study of PEG-ETP-LP’s stability, appearance, particle size, surface potential, acidity, eakage rate, content, oxidation index, stability factor are selected as the primary study projects. The results can be seen that the appearance of PEG-ETP-LP is milky white, no precipitation, distributed evenly and has obvious opalescence phenomenon. PEG-ETP-LP’s average diameter was164.9±17nm, Zeta potential was-36.11±23mV, pH was6.5, the encapsulation efficiency was91.76%, drug loading was8.17%, the oxidation index was0.168, the stability factor was7.03.Factors test, including the temperature, the light and the oxygen, was used to mesure the impacts on PEG-ETP-LP. Examine the changes of projects at4℃,25℃,40℃temperature or45001x±5001x illumination or oxygenation conditions. The results showed that temperature, light and oxygen have a great impact on the samples. At40℃or45001x±5001x or under the oxygenation conditions, the surface potential, acidity and content had no much change, while the rate of leakage, the oxidation index and stability factor increased largely.Accelerated test was tested at25±2℃conditions according to "Chinese Pharmacopoeia" of the2010edition, and inspect the changes of projects in the next six months. The results showed that PEG-ETP-LP’s particle size, leakage rate, oxidation index, stability factor, have changed. Long-term tests is that examine the changes of projects at4±2℃, internal environment filled with N2conditions. In addtion, the amount of drug encapsulated in the liposomes was used to calculate the validity. The results of three batches of samples’validity were33.98months,36.76months and35.04months. According to the lowest value data (33.98months), speculate the validity of PEG-ETP-LP was two and a half years.Compatibility stability test is that PEG-ETP-LP was diluted with the water for injection or5% glucose solution or0.9% sodium chloride injection and placed8hours at25℃and indoor lighting conditions. Then studied its stability. The results showed that PEG-ETP-LP had no delamination, flocculation, sedimentation, leakage, breaking and other phenomena after being diluted with the three solvent.Rats internal pharmacokinetic study is that rats were randomly divided into three groups (ETP solution group, ETP-LP group, PEG-ETP-LP group) and injected the tail vein with the same dose of drugs.And took blood at the canthus vein within the specified time, treated plasma with methanol. Then the processing good serum was to determine their plasma concentrations by HPLC method. The result showed that t1/20of PEG-ETP-LP group, ETP-LP group and ETP solution group were9.35,5.243,2.295h, AUC were25.008,15.119,4.188mg/L*h. These datas indicated that PEG-ETP-LP group had higher blood concentrations and lower total clearance. It has facilitated the retention of drug and played EPR effect.Tissue distribution study in mice is that mice were randomly divided into three groups (ETP solution group, ETP-LP group, PEG-ETP-LP group) and injected the tail vein with the same dose of drugs. Taken blood at the canthus vein within the specified time, then killed the mice immediately and removed their hearts, livers, spleens, lungs, kidneys organs. Plasma was treated with methanol and tissue homogenate was treated with ether. Then their concentrations were determined by HPLC method. The result showed that distributions of ETP-LP group in the liver and spleen were significantly increased, and were respectively1.54times,1.27times of ETP group.While distribution of PEG-ETP-LP group in the liver reduced and spleen’s had no significant changes. Meanwhile, distributions of ETP-LP group and PEG-ETP-LP group in heart and kidney were less than ETPsolution group’s.In conclusion, in this study, prepare PEG-ETP-LP samples according to the pre-preparation and inspect its stability, which include factors test, accelerated test, long-term tests and compatibility stability test. Rat internal pharmacokinetic study and tissue distribution study in mice of PEG-ETP-LP have been done and we have tried to elaborate its long-circulating and targeting. |
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