Appeal No. 2004-2202 Page 3
Application No. 10/016,324
outer surface coating of hydrophilic polymer chains, . . . which are preferably densely
packed to form a brushlike coating effective to shield liposome surface components.”
Pages 9-10 (reference numerals omitted).
In addition to their role in “solubilizing” the hydrophobic chains, and
shielding them from interactions with other bilayer membranes, the
hydrophilic chains also preferably have a surface density sufficient to
create a molecular barrier effective to substantially prevent interaction of
serum proteins with the liposome surface. As such, the hydrophilic chain
coating is effective to extend the circulation time of liposomes in the
bloodstream for periods up to several hours to several days.
In the latter embodiment, the hydrophilic chains are preferably present in
the outer lipid layer of the liposomes in an amount corresponding to
between about 1-20 mole percent of the liposome surface lipids.
Page 11.
“Suitable hydrophilic polymers for use in the conjugates, where the polymers
are also intended to extend liposome-circulation time, include polyvinylpyrrolidone, . . .
polyethyleneglycol, and polyaspartamide. In a preferred embodiment, the hydrophilic
polymer is polyethyleneglycol.” Page 16
“Finally, the liposome is prepared to contain one or more therapeutic or
diagnostic[ ] agents which are to be delivered to the target cell site. . . . The agent may
be entrapped in the inner aqueous compartment of the liposome or in the lipid bilayer,
depending on the nature of the agent.” Page 13.
Discussion
Claim 29, the broadest claim on appeal, is directed to a method of administering
a therapeutic agent by inhalation, where the therapeutic agent is entrapped in
liposomes “formed of vesicle-forming lipids and having a coating of hydrophilic polymer
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