method for preparing small vesicles using microemulsification

Claim 2

A process according to claim 1 wherein the amphiphilic molecules and other components capable of forming lipid vesicles comprise a phospholipid and cholesterol in a mole ratio of 2 to 1.

Claim 3

A process according to claim 1 or 2 wherein the final concentration of total lipid in the microemulsion is 10 mg/ml.

Claim 4

A process according to claim 1 wherein the step (a) includes: (a) (i)    dissolving said amphiphilic molecules and other components capable of forming lipid vesicles in an organic solvent solution; (a) (ii)    drying said solution to a lipid film; and (a) (iii)    rehydrating the dried lipid film.

Claim 5

A process according to claim 4 for the preparation of vesicles suitable for use in targeting tumors in a body for location and diagnosis of the tumors comprising: in step (a) (i), dissolving the amphiphilic molecules and at least one other component, including an ionophore; in step (a) (iii), rehydrating the dried lipid film with phosphate bufferred saline containing a weak chelating agent; in step (b), dispersing said rehydrated lipid to generate a microemulsion containing lipid vesicles with the ionophore incorporated into the lipid bilayer and said vesicles containing the chelating agent; and, following step (c), (d) loading said vesicles with a radioactive cation for detecting the location of said vesicles when administered into a body.

Claim 6

A process according to claim 4 for the preparation of vesicles for use in treating a tumor in a body comprising: in step (a) (iii), rehydrating the dried lipid film with a solution containing a therapeutic agent; and in step (b) dispersing said hydrated lipid to generate a microemulsion containing lipid vesicles containing the therapeutic agent.

Claim 7

A process according to claim 4, 5 or 6 wherein said organic solvent is an ether, chloroform or alcohol.

Claim 8

A process according to any one of the preceding claims wherein said dispersing step is performed in a homogenizing apparatus in which said lipid solution may be maintained in a selected temperature range.

Claim 9

A process according to claim 8 wherein said apparatus comprises a heat exchange reservoir.

Claim 10

A process according to any one of the preceding claims wherein said step of dispersing is performed by operating said homogenizing apparatus at a pressure of 55 to 83 MPa (8000 to 12000 p.s.i.) and a solution temperature maintained at 50° to 80°C for a time of from 15 to 90 minutes.

Claim 11

A process according to any one of claims 1 to 9 wherein said step of dispersing is performed by operating said homogenizing apparatus at a pressure of 55 to 69 MPa (8000 to 10,000 p.s.i.) and at a reservoir temperature of 70°-75°C for approximately 60 minutes.

Claim 12

A process according to any one of claims 1 to 9 wherein said step of dispersing is performed by operating the homogenizing apparatus at a pressure of 69 to 83 MPa (10,000 to 12,000 p.s.i.) and at a reservoir temperature of 50°-55°C for approximately 60 minutes.

Claim 13

A process according to any one of claims 1 to 9 wherein said step of dispersing is performed by operating said homogenizing apparatus at a pressure of approximately 69 MPa (10,000 p.s.i.) and at a reservoir temperature of 70°-75°C for approximately 60 minutes.

Claim 14

A process according to claim 1 or 6 wherein said amphiphilic molecules are phospholipids which are phosphatidylcholine, phosphatidylethanolamine or phosphatidylserine.

Claim 15

A process according to claim 1 or 5 wherein the phospholipid is distearoyl phosphatidylcholine and/or dipalmitoyl phosphatidylcholine.

Claim 16

A process according to claim 15 when appendant to claim 5 wherein said amphiphilic molecules are phospholipids and said other components capable of forming vesicles comprise cholesterol and an ionophore.

Claim 17

A process according to claim 16 wherein the composition of the vesicles comprises phospholipid, cholesterol and ionophore in the mole ratio 1:2:0.004.

Claim 18

A process according to claim 16 or 17 wherein the ionophore is A23187.

Claim 19

A process according to any one of claims 5, 16, 17 or 18 wherein the chelating agent is nitriloacetic acid.

Claim 20

A process according to any one of claims 5, 16, 17, 18 or 19 wherein the radioactive cation is ¹¹¹In 3₊ .

Claim 21

A process according to any one of claims 5 or 16 to 20 wherein the final concentration of total lipid in the microemulsion is 25 mg/ml.

Claim 22

A process according to claim 6 wherein the phospholipid is distearoyl phosphatidylcholine.

Claim 23

A process according to claim 6 or 22 wherein said step of dissolving lipid substances in an organic solvent further includes the addition of cholesterol.

Claim 24

A process according to any one of claims 6, 22 or 23 wherein the composition of vesicles comprises phospholipid, cholesterol and a therapeutic agent, said therapeutic agent being contained in the solution used to hydrate the amphiphilic molecules.

Claim 25

A process according to any one of claims 6 or 22 to 24 wherein said therapeutic agent is a chemotherapeutic agent.

Claim 26

A process according to claim 25 wherein said chemotherapeutic agent is an antibiotic which comprises Daunomycin, Bleomycin, Adriamycin, Actinomycin D, Mytomycin C or Mithramycin.

Claim 27

A process according to claim 25 where said chemotherapeutic agent is an alkylating agent comprising chlorambucil, cyclophosphamide or Triethylenemelamine.

Claim 28

A process according to claim 25 wherein said chemotherapeutic agent is an antimetabolite comprising methotrexate, 5-Fluorouracil, 6-Mercaptopurine or Arabinosylcytosine.

Claim 29

A process according to claim 25 wherein said chemotherapeutic agent is methotrexate.

Claim 30

A process according to any one of claims 6 or 22 to 24 wherein said therapeutic agent is a radiotherapeutic agent.

Claim 31

A process according to claim 30 wherein said radiotherapeutic agent is a radionuclide which comprises Iodine 131, Yttrium 90 or Phosphorus 32.