Biodistribution and gastrointestinal drug delivery of new lipidic multilamellar vesicles.

Encapsulation of therapeutic molecules in a new noncationic multilamellar vector (Spherulites), composed of phosphatidylcholine, cholesterol, and polyoxyethylene alcohol, is described here. Spherulites with entrapped drugs were prepared by shearing a phospholipidic lyotropic lamellar phase using a recently discovered method. The average size of these vesicles is approximately 300 nm. Our formulation did not show cytotoxicity to human cells and could be used as a drug delivery system. Our previous experiments showed that this new multilamellar vector is stable in many different buffers such as serum, acidic or basic buffers, and enzymatic buffers and may deliver drugs in vivo. We describe two ways of administration for drug delivery. The tissue biodistribution of radiolabeled Spherulites entrapping 125I protein A was studied after intravenous injection in Wistar rats using the major organs of the body. Approximately 70% of the radioactivity was found in the spleen 60 min after injection and about half this percentage was found in the liver. By 6 hr, only 52% remained in the spleen. The other tissues accumulated <30% of the dose throughout the duration of the study. On the other hand, oral administration of Spherulites, entrapping111 In-NTA, in fasting rats showed a significant increase of radioactivity in blood.