Date of Award


Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)


Pharmaceutical and Chemical Sciences

First Advisor

Xin Guo

First Committee Member

Bhaskara R. Jasti

Second Committee Member

Qinliang Zhao

Third Committee Member

William K. Chan

Fourth Committee Member

James A. Uchizono


Drug delivery using liposomes is a promising technology that has the potential to deliver drugs to the site of action. Stability of liposomal drug delivery system under physiological conditions plays a crucial role in achieving desired therapeutic efficacy. Stability of the liposomal delivery systems can be determined by performing certain in-vitro studies which have the ability to predict in-vivo stability of liposomes. The aim of our study was to evaluate current available in-vitro methods that are used in predicting stability of liposomal drug delivery systems to determine which one of them is a better predictor of in-vivo stability of liposomes. Our second aim was to evaluate the in-vitro stability of the pHsensitive liposomes (contains morpholine based pH-sensitive lipid MOR) that were developed by our group.

Liposomes with different lipid compositions were prepared using thin film hydration method to perform protein adsorption study. Since serum proteins adsorb on to liposomes surface (which might include substantial amount of opsonins that can trigger immune response against liposomes) upon intravenous administration, in-vitro protein adsorption Study is used as an indicator of in-vivo circulation half-life of liposomal carrier. In-vitro protein adsorption study includes two major Steps, first step is separation of liposomes with adsorbed protein from unadsorbed serum proteins and the second step is to evaluate the adsorbed protein quantitatively as well as qualitatively. The separation of liposomes from serum was achieved through size exclusion chromatography (SEC) using sepharose CL-4B gel. From the results obtained and upon discussion with vendors of sepharose gel we concluded that SEC using sepharose cl-4b is not a suitable method to separate liposomes from serum, because the stationary phase can interact with liposomes and lipoproteins.

The second in-vitro method studied was drug release from liposomes. Doxorubicin loaded liposomes with different lipid compositions were prepared to perform drug release assay. An indirect method (where drug retained inside liposomes was measured) developed by our group was used, which takes the advantage of interaction between dowex resin and doxorubicin. Upon comparing the drug release study data obtained with previously reported in-vivo data we observed that drug release assay has the potential to predict invivo stability of liposomes. From the in-vitro drug release study data it was observed that introduction of the pH-sensitive lipid compromised the stability of pegylated liposomes.



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