Appeal No. 2001-1245
Application 08/430,661
In considering the issues in this appeal, one must be careful to distinguish
between the claimed drug lipid complex and liposomes since the method required by
claim 77 prepares the complex in such a manner that the composition is "substantially
free of liposomes." Appellants make clear that the drug-lipid complex of claim 77 can
be made by "techniques substantially the same as those for making liposomes."
Specification, page 1.
The specification sets forth various methods for preparing the drug-lipid complex
of the present invention. For example, appellants explain at page 7 of the specification:
Various methods for preparing the HDLCs [high drug:lipid complexes] of
the invention are disclosed; for example, techniques that first solubilize the drug,
specifically amphotericin B in a solvent such as DMSO or methanol. The lipid
(preferably DMPC:DMPG in a 7:3 mole ratio) is solubilized in a solvent such as
methylene chloride, and the lipid and dug solutions mixed. The solvents may be
evaporated under reduced pressure, resulting in a thin lipid-drug film. The film
may be hydrated in an aqueous solution such as saline, PBS, or glycine buffer,
forming HDLCs. Alternatively, the aqueous solution may be added to the
solvent-containing drug and lipid phase prior to evaporation of the solvent. As
another alternative, the resulting dry lipid-drug film may be resuspended in a
solvent, such as methylene chloride and again evaporated under reduced
pressure prior to hydrating the film. A dehydration procedure may also be used;
in this process a dry lipid-drug film is dehydrated to form a flake which is
hydrated with aqueous solution.
In performing the method described in the specification with an eye to making
compositions which are drug-lipid complexes free of liposomes as opposed to making
compositions which are substantially liposomal with some drug-lipid complex, one must
pay attention to amount of the drug used. Appellants explain "preparations employing
25 mole percent to about 50 mole percent of drug are substantially HDLCs, free of
liposomes. Alternatively, preparations containing 5 mole percent hydrophobic drug and
less are substantially liposomal with some HDLCs." Specification, page 6.
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