# US 2019/0314282 A1 · Remote loading of sparingly water-soluble drugs into liposomes

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- Number: US 2019/0314282 A1
- Document ID: US20190314282A1
- Status: Published application
- Kind: A1
- Application number: 16/454,555
- Filed: 2019-06-27
- Published: 2019-10-17
- Earliest claimed: 2013-02-01
- Assignees: Zoneone Pharma, Inc.
- Applicants: Zoneone Pharma, Inc.
- Inventors: Mark E. HAYES; Charles O. NOBLE; Francis C. SZOKA, JR.
- Web page: https://patentgrep.com/patent/US20190314282A1

## CPC

- A61K 9/1278: Post-loading, e.g. by ion or pH gradient
- A61K 9/0019: {Injectable compositions; Intramuscular, intravenous, arterial, subcutaneous administration; Compositions to be administered through the skin in an invasive manner (non-active ingredients are additionally classified in A61K47/00)}
- A61K 9/1271: Non-conventional liposomes, e.g. PEGylated liposomes or liposomes coated or grafted with polymers (liposomes as conjugates {A61K47/6911})
- A61K 9/1275: Lipoproteins or protein-free species thereof, e.g. chylomicrons; Artificial high-density lipoproteins [HDL], low-density lipoproteins [LDL] or very-low-density lipoproteins [VLDL]; Precursors thereof
- A61K 31/4196: 1,2,4-Triazoles
- A61K 31/496: Non-condensed piperazines containing further heterocyclic rings, e.g. rifampin, thiothixene or sparfloxacin
- A61K 31/5377: not condensed and containing further heterocyclic rings, e.g. timolol
- A61K 38/07: Tetrapeptides
- B01J 13/08: Simple coacervation, i.e. addition of highly hydrophilic material {(combined with spraying B01J13/043; combined with mechanical division B01J13/04)}
- A61K 9/19: lyophilised {, i.e. freeze-dried, solutions or dispersions (lyophilised products with subsequent particle size reduction A61K9/14; granules or pellets made by lyphilisation A61K9/1682; solid oral dosage forms made by lyophilisation A61K9/2095; lyophilisation additives A61K47/00)}
- A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS

## Abstract

The present invention provides liposome compositions containing sparingly soluble drugs that are used to treat life-threatening diseases. A preferred method of encapsulating a drug inside a liposome is by remote or active loading. Remote loading of a drug into liposomes containing a transmembrane electrochemical gradient is initiated by co-mixing a liposome suspension with a solution of drug, whereby the neutral form of the compound freely enters the liposome and becomes electrostatically charged thereby preventing the reverse transfer out of the liposome. There is a continuous build-up of compound within the liposome interior until the electrochemical gradient is dissipated or all the drug is encapsulated in the liposome. However, this process as described in the literature has been limited to drugs that are freely soluble in aqueous solution or solubilized as a water-soluble complex. This invention describes compositions and methods for remote loading drugs with low water solubility (<2 mg/mL). In the preferred embodiment the drug in the solubilizing agent is mixed with the liposomes in aqueous suspension so that the concentration of solubilizing agent is lowered to below its capacity to completely solubilize the drug. This results in the drug precipitating but remote loading capability is retained. The process is scalable and, in liposomes in which the lipid composition and remote loading agent are optimized, the resulting drug-loaded liposomes are characterized by a high drug-to-lipid ratios and prolonged drug retention when the liposome encapsulated drug is administered to a subject.

## Claims

### Claim at position 1

-20. (canceled)

### Claim 21

A method of remotely loading a precipitate of a solid active agent across liposomal membranes of liposomes, into an internal aqueous medium of the liposomes, from an aqueous suspension comprising the precipitate of the solid active agent and the liposomes, the solid active agent having a water solubility of less than 2 mg/mL, the method comprising:
(a) preparing an aqueous suspension of the liposomes having a proton or an ion gradient across the liposome membrane;
(b) preparing a precipitate of the solid active agent: and
(c) forming a loading suspension of (a) and (b), and incubating the loading suspension, thereby remotely loading the precipitate of the solid active agent across the liposomal membrane into the internal aqueous medium of the liposomes by a transmembrane proton- or ion-gradient, forming a suspension of product liposomes encapsulating the precipitate of the solid agent.

### Claim 22

A method of remotely loading a precipitate of a solid active agent across liposomal membranes of liposome, into an internal aqueous medium of the liposomes, from an aqueous suspension comprising a precipitate of the solid active agent and the liposomes, the solid active agent having a water solubility of less than 2 mg/mL, the method comprising:
(a) contacting an aqueous suspension of the liposomes having a proton or an ion gradient across the liposome membrane with the precipitate of the solid active agent, forming a loading suspension; and
(b) incubating the loading suspension, thereby remotely loading the precipitate of the solid active agent across the liposomal membrane into the internal aqueous medium of the liposomes by a transmembrane proton- or ion-gradient, forming a suspension of product liposomes encapsulating the precipitate of the solid agent.

### Claim 23

A method of remotely loading a precipitate of a solid active agent across a liposomal membranes of liposomes, into an internal aqueous medium of the liposomes, from an aqueous suspension comprising a precipitate of the solid active agent and the liposomes, the solid active agent having a water solubility of less than 2 mg/mL, the method comprising:
(a) contacting an aqueous suspension of the liposomes having a proton or an ion gradient across the liposome membrane with the precipitate of the solid active agent, forming a loading suspension; and
(b) incubating the loading suspension, thereby remotely loading the precipitate of the solid active agent across the liposomal membrane into the internal aqueous medium of the liposomes by a transmembrane proton- or ion-gradient, forming a suspension of product liposomes encapsulating the precipitate of the solid agent,
wherein
encapsulation efficiency of the method, defined as amount of the precipitate of the solid agent transferred into the internal aqueous medium of the liposomes divided by amount of the precipitate of the solid active agent in the loading suspension multiplied by 100%, is at least 50%.

### Claim 24 (depends on 21, 22, 23)

The method of any of claims 21 to 23, wherein light scattering at 600 nm of the aqueous suspension comprising a precipitate of the solid active agent is greater than that of the suspension of product liposomes.

### Claim 25 (depends on 21, 22, 23)

The method according to any of claims 21 to 23, the liposomes having a liposome membrane selected from molar ratios:
(i) HSPC/cholesterol/PEG-DSPE (55/40/5); and
(ii) sphingomyelin/cholesterol/PEG-DSPE (55/45/2.8): and
(iii) DSPC/DSPG/cholesterol (70/20/10); and
(iv) POPC/cholesterol/PEG-DSPE (57/40/3); and
(v) POPC/POPG/cholesterol (70/20/10).

### Claim 26 (depends on 21, 22, 23)

The method according to any of claims 21 to 23, wherein the gradient is a gradient of a member selected from a proton, amine or a metal compound of a member selected from a carboxylate, a sulfate, a sulfonate, a phosphate a phosphonate and an acetate.

### Claim 27 (depends on 25)

The method according to claim 25, wherein the gradient is a gradient of a member selected from ammonium sulfate, triethylammonium sulfate, ammonium glucuronate, ammonium sucrose octasulfate, triethylammonium dextran sulfate, ammonium dextran sulfate, calcium acetate, magnesium acetate, ammonium chloride and citric acid.

### Claim 28 (depends on 28)

The method according to claim 28, wherein the liposomes are from about 40 nm to about 200 nm in diameter.

### Claim 29 (depends on 21, 22, 23)

A pharmaceutical formulation of the product liposomes of claims 21 to 23, comprising said product liposomes and a pharmaceutically acceptable excipient.

### Claim 30 (depends on 21, 22, 23)

The method according to any of claims 21 to 23, wherein the solid active agent is carfilzomib and is loaded into the liposome at a ratio of about 60 mg of the carfilzomib to from about 90 mg to about 200 mg of lipid.