Doxorubicin has been encapsulated into “solid” liposomes composed of a mixture of distearoyl analogs of phosphatidylcholine and phosphatidylethanol (in a 3: 2 molar ratio). The liposomes are sterically stabilized by incorporating a conjugate of dipalmitoylphosphatidylethanolamine with poly(ethylene glycol)-2000 in an amount of 5 wt % with respect to the total lipid content. The data of differential scanning microcalorimetry method show that the lipid bilayer of the doxorubicin-containing liposomes occurs in a gel-like (“solid”) state up to a temperature of 47°C. Estimated in terms of inhibition of the growth of solid and ascitic Ehrlich’s carcinoma in mice, the antitumor effect of such liposomes is equal to that of ordinary doxorubicin, whereas sterically non-stabilized “ solid” liposomes are 1.5 times less active.

The toxicity of sterically stabilized doxorubicin-containing "solid" liposomes comprising a mixture of distearoyl analogs of phospatidylcholine and phosphatidylethanol (in a 3 : 2 molar ratio) was evaluated. Upon injection of the ordinary and liposomal doxorubicin in a total dose of 12 mg/kg, the early loss of mice with implanted ascitic Ehrlich's carcinoma was 100 and 50%, respectively, and the average lifetime of the animals treated with liposomal doxorubicin was 1.6 times longer. In comparison to the ordinary doxorubicin, injections of the liposomal preparation resulted in a lower drop of the body weight (10%) and a smaller decrease in leukocyte number (12%). The results of fluorimetric measurements showed that the accumulation of antibiotic in the cardiac muscle 15 - 180 min after injection of liposomal doxorubicin was 30 - 57% lower than that upon the injection of the ordinary preparation.

Doxorubicin has been encapsulated into liposomes composed of a mixture of distearoyl analogs of phosphatidylcholine and phosphatidylethanol (in a 3:2 molar ratio). The liposomes are sterically stabilized by incorporating a conjugate of dipalmitoylphosphatidylethanolamine with poly(ethylene glycol) 2000 (5 wt % with respect to the total lipid content). The data of differential scanning microcalorimetry method show that lipid bilayer of the doxorubicin-containing liposomes occurs in a gel-like (solid) state up to a temperature of 47 °С. Estimated in terms of inhibiting the growth of solid and ascitic Ehrlich's carcinoma in mice, the antitumor effect of such liposomes is equal to that of usual doxorubicin, whereas sterically non-stabilized liposomes are 1.5 times less active.

The toxicity of sterically stabilized doxorubicin-containing “solid” liposomes comprising a mixture of distearoyl analogs of phospatidylcholine and phosphatidylethanol (in a 3: 2 molar ratio) was evaluated. Upon infusion of the ordinary and liposomal doxorubicin in a total dose of 12 mg/kg, the early loss of mice with implanted ascitic Ehrlich’s carcinoma was 100 and 50%, respectively, and the average lifetime of the animals treated with liposomal doxorubicin was 1.6 times longer. In comparison to the ordinary doxorubicin, administration of the liposomal preparation resulted in a lower drop of the body weight (10%) and a smaller decrease in leukocyte number (12%). The results of fluorimetric measurements showed that the accumulation of antibiotic in the cardiac muscle 15–180 min after infusion of the liposomal doxorubicin was 30–57% lower than that upon infusion of the ordinary preparation.

We compared the activities of cabbage phospholipase D during hydrolysis and transesterification of phosphatidylcholine in mixed micelles of surface-active compounds with various physicochemical properties. Mixed micelles of phospholipids and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (ratio, 1 : 2) were among the best substrates. Hydrolysis and transphosphatidylation were studied in micelles containing 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. Mixed micelles of phosphatidylcholine and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate may serve as a new substrate for the measurement of phospholipase D activity and preparation of phospholipids using this enzyme.