Abstract: Dehydrated liposomes are prepared by drying liposome preparations under reduced pressure in the presence of one or more protective sugars, e.g., the disaccharides trehalose and sucrose. Preferably, the protective sugars are present at both the inside and outside surfaces of the liposome membranes. Freezing of the liposome preparation prior to dehydration is optional. Alternatively, the protective sugar can be omitted if: (1) the liposomes are of the type which have multiple lipid layers; (2) the dehydration is done without prior freezing; and (3) the dehydration is performed to an end point which results in sufficient water being left in the preparation (e.g., at least 12 moles water/mole lipid) so that the integrity of a substantial portion of the multiple lipid layers is retained upon rehydration.

Abstract: A method of extruding liposomes from liposomal material comprising extruding the liposomal material through a frit, and apparatus for extrusion.

Abstract: A liposome composition is provided which contains a liposome having: (i) an outermost lipid bilayer containing, in addition to a neutral, bilayer preferring lipid, a fusion-promoting effective amount of an ionizable lipid having a protonatable, cationic headgroup and an unsaturated acyl chain; and (ii) a compartment adjacent to the outermost lipid bilayer which contains an aqueous solution having a first pH. External to the liposome in the composition is an aqueous solution having a second pH. The first pH is less than the pK.sub.a of the ionizable lipid in the outermost lipid bilayer and the second pH is greater than the pK.sub.a of the ionizable lipid in the outermost lipid bilayer, such that there is a pH gradient across the outermost lipid bilayer and the ionizable lipid is accumulated in the inner monolayer of the outermost lipid bilayer in response to the gradient.

Abstract: This invention provides a process for the production of liposomes by combining an organic phase and an aqueous at a volume ratio of less than 3:1; the process can be conducted under conditions which obtain a single-modal population distribution of liposomes encompassing a pre-selected mean particle size. A novel intermediate product obtained during the process, which can itself be used for the topical delivery of a bioactive agent, is also provided.

Abstract: Methods are disclosed for entrapment of a cation in a vesicle having a membrane and an acidic aqueous compartment comprising contacting the vesicle with a buffer solution comprising the cation and a lipophilic, carboxylic ionophoretic antibiotic capable of complexing with the cation and increasing the cation's permeability across the vesicle membrane, wherein there is a pH gradient between the acidic aqueous compartment and the buffer solution. The cation can be for example iron or calcium and the ionophore A23187. The pH gradient can be established across the bilayer by a relatively acidic or basic intravesicular aqueous compartment of the unilamellar vesicle and the buffer solution and the cation loads via the pH gradient. The invention also contemplates a unilamellar vesicle comprising an aqueous compartment including a cationic species in a concentration between 100 mM and 500 mM.

Abstract: Aminoglycosides, analogs and derivatives thereof, in the form of phosphate salts are described as well as the process for making and utilizing same. Aminoglycoside phosphate liposomes and nonguanadino aminoglycoside phosphate liposomes, their preparation and use, are particularly described.

Abstract: This invention relates to a method for synthesizing a substantially pure reactive lipid including, for example, N-[4-(p-maleimidophenyl)-butyryl]phosphatidylethanolamine (MPB-PE) and related compositions. The compositions of the present invention are useful as coupling agents and may be incorporated into liposomes and subsequently coupled to proteins, cofactors and a number of other molecules. A preferred coupling method is also disclosed as are protein conjugates.

Abstract: The present invention relates to liposomal compositions having a concentration gradient which load amino acids and peptides exhibiting weak acid or base characteristics into liposomes. Specifically loaded into liposomes by the methods of the present invention are C-terminal substituted amino acids or peptides. The liposomes are preferably large unilamellar vesicles. The concentration gradient is formed by encapsulating a first medium in the liposomes, said medium having a first concentration of the one or more charged species, and suspending the liposomes in a second medium having a second concentration of the one or more charged species, such as for example a pH gradient. Also disclosed are pharmaceutical preparations comprising such C-terminal substituted amino acids or peptides which have been loaded into the liposomes by the method of the invention.

Abstract: Methods are described for controlling the transbilayer distribution of ionizable lipids and proteins in vesicles. Control of the ion gradient of the exterior bathing medium in relation to that of the interior entrapped aqueous compartment of the vesicles induces migration of ionizable lipids or proteins to one or the other of the monolayers comprising the bilayer. This can result in an asymmetric distribution of the ionizable lipid or ionizable protein. The basic ionizable lipids, such as stearylamine and sphingosine, are sequestered into the inner monolayer when the liposome interior is acidic relative to the liposome exterior. Conversely, acidic ionizable lipids such as oleic acid and stearic acid are sequestered into the inner monolayer when the liposome interior is basic relative to the liposome exterior bathing solution.

Abstract: Methods are described for controlling the transbilayer distribution of ionizable lipids and proteins in vesicles. Control of the ion gradient of the exterior bathing medium in relation to that of the interior entrapped aqueous compartment of the vesicles induces migration of ionizable lipids or proteins to one or the other of the monolayers comprising the bilayer. This can result in an asymmetric distribution of the ionizable lipid or ionizable protein. The basic ionizable lipids, such as stearylamine and sphingosine, are sequestered into the inner monolayer when the liposome interior is acidic relative to the liposome exterior. Conversely, acidic ionizable lipids such as oleic acid and stearic acid are sequestered into the inner monolayer when the liposome interior is basic relative to the liposome exterior bathing solution.