Temperature-sensitive liposomal formulation
First Claim
1. A liposome containing an active agent entrapped within the liposome interior space, said liposome having a gel-phase lipid bilayer membrane comprising phospholipid which is dipalmitoylphosphatidylcholine (DPPC) and lysolipid which is monopalmitoylphosphatidylcholine (MPPC), wherein phospholipid and lysolipid are contained in the bilayer membrane in a ratio of from 99:
- 10 to 80;
20 by molar weight and wherein phospholipids are the primary lipid source for the lipid bilayer membrane and wherein lysolipid is contained in the bilayer membrane in an amount sufficient to increase the percentage of active agent released at the phase transition temperature compared to that which would occur in the absence of said lysolipid.
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Abstract
Temperature sensitive liposomes containing active agents are described. The liposomes comprise phospholipids and a surface active agent, such as a lysolipid, that increases the amount of active agent released by the liposome at the phase transition temperature of the liposome. Such liposomes are useful in methods of administering active agents using mild hyperthermic conditions.
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Citations
24 Claims
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1. A liposome containing an active agent entrapped within the liposome interior space, said liposome having a gel-phase lipid bilayer membrane comprising phospholipid which is dipalmitoylphosphatidylcholine (DPPC) and lysolipid which is monopalmitoylphosphatidylcholine (MPPC), wherein phospholipid and lysolipid are contained in the bilayer membrane in a ratio of from 99:
- 10 to 80;
20 by molar weight and wherein phospholipids are the primary lipid source for the lipid bilayer membrane and wherein lysolipid is contained in the bilayer membrane in an amount sufficient to increase the percentage of active agent released at the phase transition temperature compared to that which would occur in the absence of said lysolipid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- 10 to 80;
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10. A liposome containing an active agent entrapped within the liposome interior space and having a gel-phase lipid bilayer membrane comprising a phospholipid which is dipalmitoylphosphatidylcholine (DPPC) and lysolipid which is monopalmitoylphosphatidylcholine (MPPC), wherein phospholipids are the primary lipid source for the lipid bilayer membrane, and wherein phospholipid and lysolipid are contained in the bilayer membrane in a ratio of from 90:
- 10 to 80;
20 by molar weight. - View Dependent Claims (11, 12, 13, 14, 15)
- 10 to 80;
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16. A method of administering an active agent to a preselected hyperthermic target site in a subject, the improvement comprising:
entrapping said active agent in the aqueous interior of a liposome, said liposome having a gel-phase lipid bilayer membrane comprising phospholipid which is dipalmitoylphosphatidylcholine (DPPC) and lysolipid which is monopalmitoylphosphatidylcholine (MPPC), wherein phospholipids are the primary lipid source for the lipid bilayer membrane, and wherein the aqueous interior of the liposome further comprises lysolipid in an equilibrating amount to the lysolipid contained in the lipid bilayer, and wherein phospholipid and lysolipid are contained in the bilayer membrane in a ratio of from 90;
10 to 80;
20 by molar weight.- View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
Specification