Claims
- 1. A composition comprising liposomes which contain an entrapped pharmaceutical agent and are characterized by:
- (a) liposome sizes predominantly between about 0.05 and 0.5 microns,
- (b) liposomes having substantially homogeneous-phase bilayers composed at at least about 50 mole percent of a membrane-rigidifying lipid selected from the group consisting of sphingomyelin and neutral phospholipids with predominantly saturated acyl chains, and
- (c) between about 5-20 mole percent saturated phosphatidylinositol.
- 2. The composition of claim 1, wherein the liposomes are predominantly in the 0.07 to 0.12 micron size range.
- 3. The composition of claim 1, wherein the membrane-rigidifying lipid is brain sphingomyelin liposomes contain sphingomyelin and the liposomes contain sphingomyelin and phosphatidylcholine, at a mole ratio between 2:1 and 4:1.
- 4. The composition of claim 1, wherein the membrane-rigidifying lipid is predominantly phosphatidylcholine with saturated acyl chains.
- 5. In a therapeutic drug treatment in which a drug is administered intravenously in a suspension of liposomes in which the drug is entrapped and whose sizes are predominantly between about 0.05-0.5 microns, a method of extending the lifetime of liposomes in the bloodstream which comprises preparing the liposomes to contain:
- (a) substantially homogeneous-phase bilayers containing at least about 50 mole percent of a membrane-rigidifying lipid selected from the group consisting of sphingomyelin and neutral phospholipids with predominantly saturated acyl chains, and
- (b) between about 5-20 mole percent saturated phosphatidylinositol.
- 6. The method of claim 5, wherein the liposomes contain sphingomyelin and phosphatidylcholine, at a mole ratio between 2:1 and 4:1.
- 7. The method of claim 5, wherein the membrane-rigidifying lipid is predominantly phosphatidylcholine with saturated acyl chains.
- 8. The method of claim 5, for use in tumor therapeutic drug treatment, wherein the amount of drug which is delivered to the tumor, as measured by the amount drug/tumor weight 24 hours after drug administration, is severalfold greater than that achievable by administering the drug in free form.
- 9. The method of claim 8, wherein drug which is entrapped in the liposomes is bleomycin.
- 10. The method of claim 8, wherein the drug which is entrapped in the liposomes is doxorubicin.
- 11. The method of claim 8, which further includes targeting the liposomes to the tumor by addition of tumor-specific binding molecules to the liposome surfaces.
Parent Case Info
This application is a continuation-in-part of co-pending U.S. patent application for "Liposomes with Enhanced Circulation Time", Ser. No. 946,415, filed 12/24/86, now abandoned.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0146710 |
Sep 1982 |
JPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
946415 |
Dec 1986 |
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