In situ jejunal uptake from liposomal systems

The in situ uptake from the rat jejunum of liposomes prepared fr >m various saturated phosphatidylcholines in the presence or absence of cholesteol was determined. Liposomes prepared from distearoylphosphatidylcholine. with or without cholesterol, were taken up at the fastest rate (apparent first-order uptake of intact liposomes with a half-life of about 15 min). The lipid components OE liposomes could not be found in compartments where liposomes would be e’vpected to accumulate, i.e. liver, spleen. lymph nodes, or thoracic lymphatic duct. Ftuthermore. inulin, when encapsulated in the liposomes, could not be found in the urine. When either PEG-4000 (a non-absorbable marker) or glucose (an absorbable marker) was entrapped within the liposome, all of the liposomes and markers that we.e taken up still remained associated with the jejunum and the liposomes remained ir,ltact.