Patent ID: 7025988

Claim:
A liposome forming process comprising the steps: (a) forming a solution of a lipophilic active ingredient in a solvent; (b) adding to the resulting solution a precipitant which precipitates the active ingredient; (c) recovering precipitated particulate active ingredient; (d) resuspending the precipitated particulate active ingredient in an aqueous medium; (e) mixing an aqueous suspension of preformed empty liposomes having an average diameter less than 200 nm formed of liposome forming compounds which have an overall negative charge or have no overall charge with the resuspended particulate active ingredient; (f) dissolving sugar into the aqueous suspension of in an amount such that the weight ratio of sugar:liposome forming compounds is 5:1 to 20:1; (g) dehydrating the aqueous suspension containing empty liposomes, particulate active ingredient and dissolved sugar; and (h) rehydrating the dehydrated product in an aqueous rehydration medium to form dehydration/rehydration vesicles having an average diameter larger than the average diameter of the empty liposomes and less than 500 nm.