Method of lyophilizing liposomes
View Patent ↗Lyophilized liposomal formulations with two or more encapsulated drugs are disclosed. These formulations display superior drug retention profiles and also maintain size distribution following lyophilization and reconstitution.
1. A lyophilized gel-phase liposomal composition, wherein said gel-phase liposomes exhibit a melting phase temperature (T c ) of at least 37° C. and the liposome membrane is comprised of distearyl phosphatidyl choline (DSPC):distearyl phosphatidyl glycerol (DSPG):cholesterol at a molar ratio of 7:2:1; and
said liposomes are stably associated with daunorubicin:cytarabine at a molar ratio of 1:5; and
contain less than 50 mM internal cryoprotectant; and
wherein a cryoprotectant that consists of one or more saccharides is present external to said liposomes; and
wherein when said gel-phase liposomal composition is reconstituted, the mean diameter of the liposomes increases by no more than 25% as compared to said value measured prior to lyophilization and at least 90% of each agent is retained.
2. The composition of claim 1 wherein the ratio of daunorubicin:cytarabine changes by no more than 25% as compared to said composition prior to lyophilization.
3. The composition of claim 1 wherein the mean diameter of the liposomes increases by no more than 15% after lyophilization and upon reconstitution of said liposomes as compared to said value measured prior to lyophilization.
4. The composition of claim 3 wherein the mean diameter of the liposomes increases by no more than 10% after lyophilization and upon reconstitution of said liposomes as compared to said value measured prior to lyophilization.
5. The composition of claim 1 wherein the size distribution of the liposomes changes by no more than 25% after lyophilization and upon reconstitution of said liposomes.
6. The composition of claim 5 wherein the size distribution of the liposomes changes by no more than 15% after lyophilization and upon reconstitution of said liposomes.
7. The composition of claim 6 wherein the size distribution of the liposomes changes by no more than 10% after lyophilization and upon reconstitution of said liposomes.
8. A method to prepare the composition of claim 1 which method comprises subjecting to lyophilization an aqueous medium comprising gel-phase liposomes that exhibit a melting phase temperature (T c ) of at least 37° C. and the liposome membrane is comprised of distearyl phosphatidyl choline (DSPC):distearyl phosphatidyl glycerol (DSPG):cholesterol at a molar ratio of 7:2:1 and said liposomes are stably associated with daunorubicin:cytarabine at a molar ratio of 1:5 and contain less than 50 mM internal cryoprotectant, in the presence of external protectant that consists of one or more saccharides.
9. The method of claim 8 wherein said medium comprising gel-phase liposomes is frozen at a temperature which is below the glass transition temperature (T g ) of said medium.
10. A method to prepare a pharmaceutical composition for administering therapeutic and/or diagnostic agents to a subject which method comprises reconstituting the liposomal composition of claim 1 in a pharmaceutical carrier to obtain a reconstituted composition.
11. A method to administer therapeutic and/or diagnostic agents to an animal subject which method comprises administering to said subject the reconstituted composition of claim 10 .
12. The method of claim 11 wherein said administering is parenteral.
13. The method of claim 11 wherein the subject is human.
14. The composition of claim 1 wherein said mean diameter is maintained for at least 6 months upon storage at 5° C. or at 25° C.
15. The composition of claim 1 wherein said retaining is maintained for at least 6 months upon storage at 5° C. or at 25° C.
16. The composition of claim 1 wherein said cryoprotectant external to said liposomes comprises sucrose.
17. The composition of claim 1 wherein the external medium contains 250 mM-400 mM cryoprotectant.
18. The composition of claim 17 wherein the medium contains about 300 mM cryoprotectant.