Description of the Related Art Atherosclerosis is a complex and chronic disease involving the gradual accumulation of lipids, collagen, elastic fibers and proteoglycans in the cell wall. Current methods of managing atherosclerosis include a low-fat diet, exercise and various cholesterol-lowering drugs.

Arginine, an essential amino acid, is the biosynthetic precursor for the nitric oxide (NO) produced by vascular endothelium (Moncada, New Engl. J. Med. 329: 2002-2012,1990). NO exerts vasodilatory, antiatherosclerotic and antithrombotic effects, and deficient endothelial production of NO may play a prominent pathogenic role in atherosclerosis, hypertension and diabetes (Calver et al., J. Hypertension 10: 1025-1031,1992; Cooke et al., Arterioscler. Thromb. 14: 653-655,1994). In some though not all clinical studies, parenteral or oral administration of arginine has enhanced vascular NO synthesis (Drexler et al., Lancet 338: 1546-1550,1991). In animal models of hypertension, arginine supplementation has moderated the increase in blood pressure (Chen et al., J. Clin. Invest 88: 1559-1567,1991).

D-saccharic acid (glucaric acid) has been shown to reduce total and LDL cholesterol levels in animals, to enhance the excretion of waste products and to inhibit beta-glucuronidase.

There is a constant need for therapeutic/prophylactic agents capable of preventing or inhibiting the progression of atherosclerosis and other disorders. The present invention provides such agents.

Summary of the Invention One embodiment of the present invention is a compound having the formula: wherein RI is a metal. Preferably, R1 is potassium. In one aspect of this preferred embodiment, the metal is sodium, calcium, magnesium or manganese.

The present invention also provides an arginine-saccharic acid salt or complex in which the molar ratio of arginine to saccharic acid is about 1: 1.

Another embodiment of the invention is a method of making an arginine-saccharic acid salt, comprising combining arginine with saccharic acid in aqueous solution; removing the aqueous solution to obtain a residue; and drying the residue. Preferably, the salt a metal cation. In one aspect of this preferred embodiment, the salt is potassium. In another aspect of this embodiment, the salt is sodium, calcium, magnesium or manganese. Advantageously, the arginine and saccharic acid are mixed for about one hour after the combining step. The drying step may further comprise heating the residue.

The present invention also provides a method for preventing or treating a cardiovascular or circulatory disorder in a mammal, comprising administering to the mammal an effective amount of the compounds described above. Advantageously, the mammal is a human. Preferably, the arginine saccharate is administered parenterally or orally. In one aspect of this preferred embodiment, the effective amount provides between about 200 mg and about 10 g of arginine, and about 200 mg to about 2,000 mg of saccharic acid. In another aspect of this preferred embodiment, the effective amount provides between about 500 mg and about 5 g of arginine, and about 500 mg to about 1,000 mg of saccharic acid.

Another embodiment of the present invention is a method for supplementing dietary arginine comprising administering to a mammal the arginine saccharate compounds described above.

Advantageously, the mammal is a human.

Detailed Description of the Preferred Embodiments The present invention provides arginine saccharate (arginine glucarate) having the formula: wherein R1 is a metal including, but not limited to, potassium, sodium, calcium, magnesium and manganese, methods of synthesis and its use for preventing and treating cardiovascular and/or circulatory disorders.

Arginine saccharate is synthesized by reacting arginine (free base) and a D-saccharic acid salt in aqueous solution at room temperature with stirring as shown below.

Potassium d-saccharic acid arginine The arginine and saccharic acid salt are mixed for between 15 minutes and three hours, preferably for about one hour, The resulting residue is vacuum dried, preferably while heating, resulting in a foamy solid.

The resulting salt has excellent solubility, and is more soluble than either arginine or the D-saccharic acid salt.

Arginine saccharate provides both arginine and saccharic acid in bioavailable forms which have good nutritional availability. In a preferred embodiment, the combining molar ratio of arginine to the D-saccharic acid salt is about 1 : 1, although ratios of between about 0.5: 1 and 1.5: 1 may also be used. Although the potassium salt of D-saccharic acid is exemplified herein, other salts may also be used including, but not limited to, calcium, magnesium, manganese, sodium, and the like. In addition, although D-saccharic acid is used herein, the use of L-saccharic acid salts in the preparation of arginine saccharate is also contemplated.

Arginine saccharate may be used both as a source of the essential amino acid arginine and as a source of saccharic acid, both of which exert beneficial cardiovascular and/or circulatory effects. Because the mechanism of action of arginine and saccharic acid acts through different pathways, arginine saccharate exerts a synergistic effect compared to each of its components. Arginine saccharate is useful as a therapeutic or preventative agent for atherosclerosis and other cardiovascular/circulatory disorders including, but not limited to, hypercholesterolemia, hypertension, Raynaud's Syndrome, macular degeneration, erectile dysfunction, muscle growth/recovery, wound healing, immune dysfunction, cancer, acquired immunodeficiency syndrome, infections and other acute and chronic disorders.

The oral administration of arginine saccharate delivers arginine and saccharic acid to appropriate sites of action. Arginine saccharate is useful as a therapeutic or preventative agent for atherosclerosis and for the disorders discussed above, and may also be given as a dietary supplement to prevent these disorders.

Thus, the administration of arginine glutarate has prophylactic as well as therapeutic applications. In addition to providing saccharic acid, arginine saccharate is also a good dietary supplement for the essential amino acid arginine.

The compounds of the invention, or pharmaceutical acceptable formulations thereof, may be administered parenterally or orally, in any systemic fashion, in appropriate dosage units, as desired.

Parenteral routes of administration are any routes other than oral administration, including, but not limited to, intravenous, intraarterial, subcutaneous, intramuscular, and the like. However, oral administration is preferred. For oral administration, the compounds of the invention may be provided as a tablet, aqueous or oral suspension, dispersible powder or granule, emulsion, hard or soft capsule, syrup or elixir. Compositions

intended for oral use may be prepared according to any method well known in the art for the manufacture of pharmaceutical compositions, and such compositions may contain one or more of the following agents: sweeteners, flavoring agents, coloring agents, preservatives, solubilizers, wetting agents, stabilizers, colorants, antioxidants, coating agents and diluents. The sweetening agents and flavoring agents will increase the palatability of the preparation. Tablets containing arginine glucarate in admixture with non-toxic pharmaceutical acceptable excipients suitable for tablet manufacture are acceptable. Such excipients include inert diluents such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents such as corn starch or alginic acid; binding agents such as starch, gelatin or acacia; and lubricating agents such as magnesium stearate, stearic acid or talc. Tablets may be uncoated or may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period of time. For example, a time delay material such as glyceryl monostearate or glyceryl distearate alone or with a wax may be employed.

Formulations for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example calcium carbonate, calcium phosphate or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, such as peanut oil, liquid paraffin or olive oil.

Aqueous suspensions may contain the compounds of the invention in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients include suspending agents, dispersing or wetting agents, one or more preservatives, one or more coloring agents, one or more flavoring agents and one or more sweetening agents such as sucrose or saccharin.

Oil suspensions may be formulated by suspending the active ingredient in a vegetable oil, such as arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. The oil suspension may contain a thickening agent such as beeswax, hard paraffin or cetyl alcohol. Sweetening agents, such as those set forth above, and flavoring agents may be added to provide a palatable preparation. These compositions may be preserved by an added antioxidant such as ascorbic acid. Dispersible powders and granules of the invention suitable for preparation of an aqueous suspension by the addition of water provide the active ingredient in admixture with a dispersing or wetting agent, a suspending agent and one or more preservatives. Additional excipients, for example sweetening, flavoring and coloring agents, may also be present. Syrups and elixirs may be formulated with sweetening agents such as glycerol, sorbitol or sucrose.

Such formulations may also include a demulcent, a preservative, a flavoring agent or a coloring agent. For further assistance in formulating the compositions of the present invention, one may refer to Remington's Pharmaceutical Sciences, 15'h Edition, Mack Publishing Co., Easton, PA.

The arginine saccharate preparations for parenteral administration may be in the form of a sterile injectable preparation, such as a sterile injectable aqueous or oleaginous suspension. This suspension may be formulated according to methods well known in the art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation may also be a sterile injectable solution or suspension

in a non-toxic parenterally acceptable diluent or solvent, such as a solution in 1,3-butanediol. Suitable diluents include, for example, water, Ringer's solution and isotonic sodium chloride solution. In addition, sterile fixed oils may be employed conventionally as a solvent or suspending medium. For this purpose, any bland fixed oil may be employed including synthetic mono-or diglycerides. In addition, fatty acids such as oleic acid may likewise be used to prepare injectable preparations.

The arginine saccharate of the present invention may also be administered in combination with additional arginine, saccharic acid, or both. The additional arginine and/or saccharic acid are provided in any of the formulations, and are administered by any of the routes, described above.

In another embodiment, the pharmaceutical preparations of the invention may be provided as an adjunct to conventional pharmaceutical preparations and/or therapies. For example, arginine saccharate may be administered to an individual with atherosclerosis in combination with a cholesterol-lowering drug such as a"statin" (e. g., lipitor, mevacor, zocor), or an antihypertensive drug such as calcium channel blockers (e. g., diluazem, felodipine, nicardipine, nifedipine, verapamil), angiotensin 11 receptor antagonists (e. g., losartan, irbesartan, valsartan, candesartan, tasosartan, eprosartan), angiotensin converting enzyme (ACE) inhibitors (e. g., enalapril, captopril, fosimopril, ceronapril, lisinopril), Sadrenergic blockers (e. g., atenolol) and diuretics (e. g., furosemide, hydrochorothiazide). Such drugs would be administered in standard, FDA-approved dosages, or in lower dosages (e. g., 10%-50% or 75% of the FDA-approved dosage).

The amount of arginine saccharate to administer to a mammal, preferably a human, will vary depending on the condition to be prevented or treated, the form of administration, the severity of the condition, and the size of the individual. In a preferred embodiment, arginine saccharate is administered at daily dosages which provide between about 200 mg and about 10 g of arginine, and between about 200 mg and about 2,000 mg of D-saccharic acid; more preferably between about 500 mg and 5 g of arginine and between about 500 mg and about 1,000 mg of D-saccharic acid. The amounts of arginine and D-saccharic acid are selected together to provide a greater than additive effect.

One example of the synthesis of arginine saccharate is described in the following example.

However, it will be appreciated by one of ordinary skill in the art that arginine saccharate may also be synthesized using many variations of the method described below and that its synthesis is not thereby limited, except as set forth in the appended claims.

Example 1 Synthesis of arginine saccharate A solution of the potassium salt of D-saccharic acid (1g, 0.004 mol) and L-arginine (free base, 0.7 g, 0.004 mol) in 25 ml of water was stirred for one hour at room temperature. The water was removed in vacuo at 35°C and 1 torr. The glassy residue was dried in a vacuum overnight at 40°C and <1 torr, resulting in 0.8 g of product. The foamy solid was analyzed by proton and carbon NMR and found to be consistent with the argininium potassium salt of D-saccharic acid as shown below. The resulting compound had a molecular weight of about 422 daltons.

The proton spectrum of arginine shows the triplet for the proton a to the amine at 3.28 ppm, while arginine saccharate has this triplet shifted downfield to 4.09 ppm. The carboxylate peak of arginine appears in the carbon NMR at 183.3 ppm, while in arginine saccharate the carboxylate has been shifted upfield to 174.2 ppm. Both of these changes are consistent with protonation of the carboxylate during salt formation.

Comparing the proton and carbon of arginine hydrochloride to arginine shows that the same changes observed for arginine saccharate. Finally, comparison of the proton and carbon NMRs of D-saccharic acid with arginine saccharate shows that the protons a to the carboxylic acid have been shifted upfield from about 4.25 ppm to 4.1 ppm. In addition, three of the hydroxylic carbons have shifted from 73 ppm to 74 ppm after salt formation. Physically, the arginine saccharate salt is markedly different in terms of crystallinity and much more soluble in water than either starting material.

The reaction was repeated on a larger scale. A solution of the potassium salt of D-saccharic acid (5 g, 0.02 mol) and arginine (3.5 g, 0. 02 mol) in 100 mL water was stirred for one hour at room temperature. The water was removed in vacuo at 35°C and 1 torr. The glassy residue was dried in a vacuum overnight at 40°C and <1 torr, resulting in 7.2 g of product (glassy solid). The proton NMR was identical to the small scale preparation.

While particular embodiments of the invention have been described in detail, it will be apparent to those skilled in the art that these embodiments are exemplary rather than limiting, and that the true scope of the invention is that defined by the appended claims.