Cholesterol → Calcitonin DSPC

Participants

Reaction Steps

8.27 mg DSPC (1:1 initial L:D ratio) and 1.73 mg cholesterol (7:3 mole % ratio DSPC: cholesterol), both in chloroform, were transferred to a 50 ml round bottom flask. The lipids were dried to a film under vacuum using rotoevaporation. The lipids were then solubilized in 0.500 ml methanol with heating for 1-2 mins. in a 60° C. water bath. Ten milligrams of calcitonin (Mitsubishi Chemical Co., Japan MCI-536) was solubilized in 0.100 ml sodium acetate buffer. This solution was added to the solvent mixture. The solvent was removed under vacuum, using rotoevaporation in a 60° C. water bath. Once the solvent was removed, the lipid/drug film was resuspended in 0.5 ml 60° C. sodium acetate buffer. The preparation was washed by addition of 0.5 ml of 60° C. sodium acetate buffer followed by centrifugation at 12,100×g for 10 minutes. The supernatant was decanted and the liposomal pellet resuspended with 1 ml of 60° C. sodium acetate buffer. The suspension was again centrifuged at 12,100×g for 10 minutes and resuspended. The resuspended DSPC-cholesterol lipomes containing calcitonin were administered s.c. to mice to compare retention of the liposomal preparation to that of free calcitonin. Free calcitonin was undetectable after one hour in mice. The calcitonin of liposomes of the instant invention was at least about 70% present one day after administration and persisted for about 3 to 7 days disclosing a substantial increase in retention time over free calcitonin.

Provenance & Evidence