Prophylactic and/or therapeutic agent for cardiac infarction

1. A method for treatment of myocardial ischemia-reperfusion injury without an increase in collateral blood flow, the method comprising administering an active agent consisting of a lipid membrane structure retaining adenosine to a subject in need thereof,

wherein said administering is intravenously,

wherein the lipid membrane structure contains (i) a phospholipid, (ii) a cholesterol and/or a cholestanol, and (iii) a polyethylene glycol derivative selected from the group consisting of

N-{carbonyl-methoxypolyethylene glycol-2000}-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine,

N-{carbonyl-methoxypolyethylene glycol-5000}-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine,

N-{carbonyl-methoxy-polyethylene glycol-750}-1,2-distearoyl-sn-glycero-3-phosphoethanolamine,

N-{carbonyl-methoxy-polyethylene glycol-2000}-1,2-distearoyl-sn-glycero-3-phosphoethanolamine, and

N-{carbonyl-methoxy-polyethylene glycol-5000}-1,2-distearoyl-sn-glycero-3-phosphoethanolamine as components thereof,

wherein the lipid membrane structure is a liposome,

wherein the ratio by mole of adenosine to the total lipid content of the phospholipid and cholesterol contained in the lipid membrane structure is ranges from 0.01 to 2,

wherein adenosine is administered in an amount effective to reduce the incidence of myocardial ischemia-reperfusion injury, said amount ranging from 2.25 mg/kg to 36 mg/kg, and

wherein a therapeutic benefit is observed after a single dosage.

2. The method according to claim 1 , wherein the phospholipid is hydrogenated soybean lecithin.

3. The method according to claim 1 , wherein the polyethylene glycol derivative is N-(carbonyl-methoxy-polyethylene glycol-2000}-1,2-distearoyl-sn-glycero-3-phosphoethanolamine.

4. The method according to claim 1 , wherein the polyethylene glycol derivative is N-{carbonyl-methoxypolyethylene glycol-2000}-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine.

5. The method according to claim 1 , wherein the polyethylene glycol derivative is N-{carbonyl-methoxypolyethylene glycol-5000}-1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine.

6. The method according to claim 1 , wherein the polyethylene glycol derivative is N-{carbonyl-methoxy-polyethylene glycol-750}-1,2-distearoyl-sn-glycero-3-phosphoethanolamine.

7. The method according to claim 1 , wherein the polyethylene glycol derivative is N-{carbonyl-methoxy-polyethylene glycol-5000}-1,2-distearoyl-sn-glycero-3-phosphoethanolamine as components thereof.

8. The method according to claim 1 , wherein said liposome is a single-membrane liposome.

9. The method according to claim 1 , wherein said liposome is a multi-layer liposome.

10. The method according to claim 1 , wherein said liposome has a particle size ranging from 50 nm to 5 μm.

11. The method according to claim 1 , wherein said liposome has a particle size ranging from 50 nm to 200 nm.

12. The method according to claim 1 , wherein adenosine is administered at a rate of 900 μg/kg/min or less.

13. The method according to claim 1 , wherein the phospholipid is at least one species selected from the group consisting of phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, cardiolipin, sphingomyelin, plasmalogen, and phosphatidic acid.

14. The method according to claim 1 , wherein the liposome comprises phosphatidylcholine, cholesterol, and N-{carbonyl-methoxy-polyethylene glycol-2000}-1,2-distearoyl-sn-glycero-3-phosphoethanolamine.

15. The method according to claim 1 , wherein the liposome retaining adenosine, adenosine is present in a lipid membrane of the liposome, inside of the liposome, or in a lipid layer of the liposome.

16. The method according to claim 1 , wherein the drug is administered intravenously in an adenosine amount of 30 μg/kg/min to 900 μg/kg/min.

17. The method according to claim 1 , wherein the drug is administered intravenously in an adenosine amount of 225 μg/kg/min to 900 μg/kg/min.