DESC:FIELD OF THE INVENTION
The invention relates to iron polysaccharide complexes derived from modified icodextrin, useful in the treatment of iron deficiency anemia.

BACKGROUND OF THE INVENTION
Iron deficiency anemia (IDA), which affects 1.6 billion people across the globe, has been recognized by the World Health Organization (WHO) as one of the most prevalent nutrient deficiencies. Iron being an essential component of many cells, iron containing enzymes are crucial for various metabolic processes, mainly including synthesis of Hemoglobin (Hb) for oxygen transport, cellular respiration by redox enzymes, and cellular proliferation. Consequently, iron deficiency can lead to severe and harmful effects on both cells and tissues.

Various causes for iron deficiency include poor nutrition, conditions such as Inflammatory Bowel Disease (IBD) and chronic kidney disease (CKD) etc. It is also well known that severe iron deficiency can occur due to blood loss and patients undergoing treatments such as chemotherapy or gastric bypass surgery are also at risk of developing iron deficiency.

Oral iron supplementation is a convenient and cost-effective mode of treatment in the treatment of IDA, although it is associated with commonly reported gastrointestinal.

side-effects such as nausea, flatulence, constipation etc. The said therapy also has certain limitations like intolerance or unresponsiveness to oral iron from patients with certain medical conditions such as celiac disease, autoimmune gastritis etc.

On the other hand, parenteral iron supplementations which consist of spheroidal polynuclear iron (III)-oxyhydroxide/oxide cores shielded by carbohydrate / polysaccharide shells offer an effective option for treatment for iron deficiency anemia. The iron polysaccharide complexes slow down the release of bioactive iron, protect iron (III) particles from further aggregation, and sustain the particles in a colloidal suspension. Therefore, these complexes allow rapid correction of the iron deficit and help in improvement of quality of life in the patients undergoing the treatment.

Thus, for many patients, oral iron is the first line of therapy, while parenteral administration may be carried out in case of need or emergency and requires medical assistance. Parenteral formulations also have stability related problems as many are not able to sustain the high temperature of 100°C during sterilization. Hence, it is desirable to have iron formulations which are stable and can be safely administered either orally or parenterally for treatment of needy patients.

It is well known that IDA is treated by the parenteral administration of formulations containing iron (III), whereas the route of oral administration is followed for medicaments containing iron (II) or iron (III). Due to the high toxicity and associated side effects, parenteral administration of iron (II) compounds is generally not preferred, although these compounds are absorbed more rapidly in the system.

On the other hand, references are available in the prior art disclosing iron (III) polysaccharide complexes, which are administered parenterally but can also be given orally.

WO2004037865 discloses an iron (III) carbohydrate complex comprising oxidized maltodextrins wherein the molecular weight of the complex is between 80 to 400 kilodalton (kDa). The medicaments, as disclosed, can be used preferably parenterally, but also orally.

US 8,993,748 discloses a process for the preparation of trivalent iron complexes with mono-, di- and polysaccharide sugars, wherein the process consists of activation of sugar by oxidation with nascent bromine, complexation of the activated sugar with a ferric salt, purification of resulting solution through ultrafiltration and stabilization of the resulting complex by heating between 60°C to 100°C.

The present invention relates to the therapeutically useful Iron polysaccharide complexes derived from modified icodextrins, comprising both iron (II) and iron (III). The iron in the complex is absorbed rapidly, but the toxicity is minimized, and tolerability is enhanced, owing to the shielding of iron cores by icodextrins.

The object of the instant invention is achieved by providing iron polysaccharide complexes wherein the iron in the complex is available as iron (II) as well as iron (III).

The invention provides iron polysaccharide complexes derived from icodextrin, comprising iron in both the oxidation states, (II) and (III).

Icodextrin is also a polysaccharide and was approved by USFDA on December 20, 2002, with proprietary name Extraneal (Icodextrin active ingredient) as a solution for intraperitoneal administration. Kidney International 62(81), 2002, S80-S87 and Carbohydrate Polymers 310, 2023, 120696 discloses that Icodextrin is a starch-derived, with up to 90% of water-soluble glucose polymer linked by alpha (1-4) and up to 10% alpha (1-6) glycosidic bonds and has an average molecular weight between 13,000 and 19,000 daltons. On the other hand, dextrans are predominantly with alpha (1-6) linkages and lesser extent of alpha (1-4) linkages.

The limited extent of a-1,6 linkage imparts various advantageous properties to the iron complexes of icodextrin and its derivatives. It helps in the appropriate binding of iron oxyhydroxide core with the polysaccharide shell, which in turn is advantageous for the desired therapeutic effect.

Icodextrin (I)

It was further observed by the inventors that icodextrin and its derivatives impart characteristic advantageous properties to the corresponding iron complexes, which enhances its therapeutic efficacy. The iron complex obtained were found to have weight average molecular weight in the range of 100 kilodaltons to 250 kilodaltons and the products so obtained had the following advantageous properties:
1. lower toxicity,
2. lower incidences of adverse reactions,
3. Better absorption of iron,
4. ease of oral as well as parenteral administration,
5. reduced content of free iron,
6. Improved rate of release of iron from the complex

The present invention comprises preparation of the iron complexes of modified icodextrin which are suitable for oral and/or parenteral administration.

OBJECT OF THE INVENTION
An objective of the present invention is for the preparation of iron polysaccharide complexes comprising of iron and icodextrin derivatives, useful in the treatment of iron deficiency.

Another objective of the present invention is for the preparation of an iron modified icodextrin complex in the solid form having iron content between 20.0 and 35.0% (w/w).

Another objective of the present invention is for the preparation of an iron modified icodextrin complex in the liquid form having iron content between 5.0 and 9.0% (w/w).

Yet another objective of the present invention is for the preparation of an iron icodextrin complex having weight average molecular weight between 100 and 250 kilodaltons.

SUMMARY OF THE INVENTION
An aspect of the invention relates to the preparation of modified icodextrin and its use in the synthesis of iron polysaccharide complexes, which are useful in the oral and /or parenteral treatment of iron deficiency anemia.

The objectives of the present invention will become more apparent from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION
Starch is a polymeric polysaccharide consisting of numerous glucose units joined by glycosidic bonds. Starch is composed of two types of glucose polymers, amylose, and amylopectin. Amylose comprises straight chains of glucose polymers bound by a-1,4 glycosidic bonds, whereas amylopectin contains around ten percent of a-1,6 glycosidic bonds, introducing branching into the saccharide polymer.

Starch, when hydrolyzed, furnishes dextrin, which are polysaccharides consisting of glucose units, typically comprising a-1,4 and/or a-1,6 glycosidic bonds to a variable extent.

Peritoneal Dialysis International, Vol. 14, Suppl. 2, 1994 mentions that Icodextrin is a specific fraction of dextrin (a starch-derived, water-soluble, glucose polymer), with a weight-average molecular weight of 16.8 (range 13–19) kDa and a number-average molecular weight of 5.3 (range 5.0 – 6.5) kDa. Further, it also discloses that Icodextrin molecules range from to 2–300 glucose units in length, although only a small proportion are under 10 units, which limits systemic absorption. The links between the individual glucose moieties are predominantly a1–4 glycosidic bonds which are highly susceptible to degradation by enzymes, such as amylases; the proportion of less susceptible a1–6 linkages is <10%. The name icodextrin is derived from the Greek word icasa (twenty) and the chemical name, dextrin, describing a glucose polymer obtained by the partial hydrolysis of starch with a molecular weight of about 20000 daltons.

Drugs 2003, 63(19), 2079-2105 mentions that Icodextrin, a starch-derived, water-soluble, glucose polymer (average molecular weight 16.8kDa) is linked predominantly by a-1–4 glycosidic bonds.

The present inventors, after observing the superior role of icodextrin during peritoneal dialysis tried out complexation of icodextrin especially the oxidized derivative and the reduced and alkylated derivatives for complexation with iron salts in an alkaline medium to provide an iron polysaccharide complex. Therefore, to achieve this objective, the present inventors carried out meticulous and extensive experimentation aimed at an iron polysaccharide complexes, having desired properties, such as low toxicity, good absorption of iron, ease of administration, reduced content of free iron, etc. found that icodextrin was a suitable starting material for the development of the said complexes.

The inventors observed that chemically modified icodextrins were found suitable for the said complexation. The chemical modification reactions on icodextrins involved oxidation, or reduction followed by alkylation or substitution with a suitable chemical moiety such as allyl, vinyl etc. The icodextrin derivative thus formed was complexed with iron salts in an alkaline medium to provide an iron polysaccharide complex.

In an embodiment, icodextrin is treated with an oxidizing agent selected from sodium hypochlorite, organic hypohalite, potassium peroxymonosulfate (oxone), 2,2,6,6-tetramethyl-piperidinyl-1-oxy (TEMPO), hydrogen peroxide etc., and combinations thereof, optionally in presence of phase transfer catalysts (PTC), other catalysts such as sodium tungstate, alkali metal and alkaline earth metal halides.

The reaction is carried out in the temperature range of 20 to 50°C, wherein the pH of reaction mixture is maintained in the range of 9 to 12, using a suitable base selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide etc. and combinations thereof.

After the oxidation reaction, the resultant reaction mixture containing the chemically modified (oxidized) icodextrin is cooled and used for further complexation reactions with iron salts selected from ferric chloride, ferrous chloride, ferrous sulfate etc. and mixtures thereof. The complexation reaction in an alkaline medium was carried out either using a single iron salt in Fe+3 or Fe+2 state or a mixture of the iron salts.

The reaction of iron salts and modified (oxidized) icodextrin was carried out in the temperature range of 200C to 800C wherein the initial temperature is around 300C to 500C, later increased to 800C.

The said reaction was carried out in presence of an inorganic base like sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and combinations thereof.

After reaction completion, the reaction mass was filtered to give icodextrin modified iron complex in the liquid form or was concentrated, treated with alcohol and dried to provide iron polysaccharide complex having weight average molecular weight (Mw), between 100-250 kilodaltons.

In a further embodiment, icodextrin was treated with a reducing agent comprising from the group selected from sodium borohydride, palladium on carbon, platinum on carbon, Raney nickel etc. The reaction was carried out in the temperature range of 200C to 800C, in the presence of a base selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide etc. and combinations thereof.

The reducing agent such as borohydride is either added in a single portion or in lots of suitable quantities.

After completion of the reaction, the reaction mixture was optionally purified by passing through an ion exchange resin, followed by concentration, addition of an alcohol such as methanol and drying.

The reduced alcohol compound was then treated with a bromoalkyl acid in presence of an inorganic base like sodium hydroxide and stirred till completion of reaction. The reaction mixture was neutralized with HCl and concentrated, filtered and the filtrate was diluted with methanol to give the alkylated icodextrin.

The bromoalkyl acid is selected from the group comprising of bromoacetic acid, bromo propionic acid, and bromo butanoic acid.

In yet another embodiment, the reduced icodextrin was treated with alkyl halides wherein the alkyl group is selected from the group comprising of methyl, ethyl, hydroxyalkyls like 2-hydroxyethyl, aminoalkyls and unsaturated alkyls such as vinyl, methacryl etc.

In a further embodiment, the alkylated reduced icodextrin was treated with iron salts selected from ferric chloride, ferrous chloride, ferrous sulfate etc. and mixtures thereof, in presence of a base like sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide or mixtures thereof and refluxed till completion of the reaction.

The reaction mass was filtered to give alkylated icodextrin iron complex which was then concentrated and treated with an alcohol like methanol to separate the modified icodextrin iron complex which was filtered and dried to provide iron polysaccharide complex having weight average molecular weight (Mw), between 100-250 kilodaltons.

The present inventors also found that the iron content of the modified icodextrin iron complex was between 5.0 and 9.0 % (w/w) for the liquid form and between 20.0 and 35.0 % (w/w) for the solid form.

The present invention provides pharmaceutical compositions which include at least one compound described herein and at least one pharmaceutically acceptable excipient. The composition can be formulated in the form of an oral delivery system either as dosage forms for intact swallowing or as dosage forms capable of rapid disintegration in the oral cavity or as chewable dosage form or as liquid dosage form.

The pharmaceutically acceptable excipient for the purpose of this invention includes but not limited to diluents or carrier, fillers, binders, bulking agent, lubricants, glidants, disintegrants, salts for influencing osmotic pressure, sweetening agents, flavouring agents, colorants, sweetened vehicle, or any combination of the foregoing.

The pharmaceutical composition of the invention may be formulated to provide quick, sustained, or delayed release of the active ingredient after administration to the subject by employing procedures known in the art. The pharmaceutical compositions may be, for example, capsules, tablets, rapidly disintegrating tablets, chewable tablets, solutions, and suspensions.

Examples of suitable diluents include lactose, in particular lactose monohydrate, cellulose and derivatives, such as powdered cellulose, microcrystalline or silicified microcrystalline cellulose, cellulose acetate, starches and derivatives such as pregelatinized starch, corn starch, wheat starch, rice starch, potato starch, sterilizable maize, sodium chloride, calcium carbonate, calcium phosphate, particularly dibasic calcium phosphate, calcium sulphate, dicalcium or tricalcium phosphate, magnesium carbonate, magnesium oxide, sugars and derivatives such as confectioner's sugar, fructose, sucrose, dextrates, dextrin, D-sorbitol sulfobutylether B-cyclodextrin, dextrose, polydextrose, trehalose, maltose, maltitol, mannitol, maltodextrin, sorbitol, inulin, xylitol, erythritol, isomalt, kaolin and lactitol.

Examples of Suitable disintegrants according to the invention are for example powdered cellulose, crospovidone, croscarmellose sodium, docusate sodium, low-substituted hydroxypropyl cellulose, magnesium aluminum silicate, microcrystalline cellulose, polacrilin potassium, sodium starch glycolate, starch, particularly pregelatinized starch and corn starch.

Examples of suitable binders are for example naturally occurring or partially or totally synthetic polymers selected from acacia, agar, alginic acid, carbomers, carmellose sodium, carrageenan, cellulose acetate phthalate, ceratonia, chitosan, confectioner’s sugar, copovidone, povidone, cottonseed oil, dextrate, dextrin, dextrose, polydextrose, maltodextrin, maltose, cellulose and derivatives thereof such as microcrystalline cellulose, methylcellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxyethyl methylcellulose, hydroxypropyl cellulose, carboxymethylcelluloses, Hypromellose (cellulose hydroxypropyl methyl ether), starch and derivatives thereof, such as pregelatinized starch, hydroxypropyl starch, corn starch, gelatin, glyceryl behenate, tragacanth, guar gum, hydrogenated vegetable oils, inulin, poloxamer, polycarbophils, polyethylene oxide, polyvinylpyrrolidone, copolymers of N-vinylpyrrolidone and vinyl acetate, polymethacrylates, polyethylene glycols, alginates such as sodium alginate, gelatin, sucrose, sunflower oil, zein as well as derivatives and mixtures thereof. The carrier or diluent may include a sustained release material, such as, for example, glyceryl monostearate or glyceryl distearate, alone or mixed with a wax.

The composition of the present invention can also be formulated in the form of parenteral/injectable dosage form. The dosage form can be in the form of lyophilized powder, ready to use or ready to dilute liquid or liquid concentrate. The route of administration may be any route which effectively transports the active compound to the appropriate or desired site of action and includes subcutaneous, intravenous, and intramuscular routes.

Parenteral composition includes at least one compound described herein and at least one pharmaceutically acceptable excipients/carriers. Suitable excipients/carriers include a buffering agent, an antioxidant, chelating agent, preservatives, a surfactant, tonicity agent, pH modifying agent, viscosity increasing agents or mixtures thereof.

Examples of suitable carriers include, but are not limited to, water, salt solutions, alcohols, polyethylene glycols, polyhydroxy ethoxylated castor oil, peanut oil, olive oil, gelatine, lactose, terra alba, sucrose, magnesium carbonate, amylose, magnesium stearate, talc, gelatine, agar, pectin, acacia, stearic acid or lower alkyl ethers of cellulose, silicic acid, fatty acids, fatty acid amines, fatty acid monoglycerides and diglycerides, pentaerythritol fatty acid esters, polyoxyethylene, hydroxymethylcellulose and polyvinylpyrrolidone. For parenteral application, particularly suitable are injectable solutions or suspensions, preferably aqueous solutions with the active compound dissolved in polyhydroxylated castor oil.

These parenteral formulations can be prepared by the processes known in the art. The solution can be filled into ampoules or vials after being sterilized by filtration. Alternatively, the sterilization can take place by autoclaving after filling into ampoules or vials.

The pharmaceutical compositions described herein may be prepared by conventional techniques.; e.g., as described in Remington: The Science and Practice of Pharmacy, 20th Ed., 2003 (Lippincott Williams & Wilkins). For example, the active compound can be mixed with a carrier, or diluted by a carrier, or enclosed within a carrier, which may be in the form of an ampoule, capsule, or sachet. When the carrier serves as a diluent, it may be a solid, semisolid, or liquid material that acts as a vehicle, excipient, or medium for the active compound.

Preferably, the contemplated pharmaceutical compositions include a compound(s) described herein in therapeutically effective amount sufficient to treat conditions related to icodextrin iron complex in a subject. The subjects contemplated include, for example, a living cell and a mammal, including human.

A further embodiment involves methods of treating a disease, disorder, or condition characterized by iron deficiency or dysfunctional iron metabolism through the administration of an iron polysaccharide complex to a subject in need of such therapy.

In a related embodiment, the method treats iron deficiency anemia, such as that associated with chronic blood loss, acute blood loss, pregnancy, childbirth, childhood development, psychomotor and cognitive development in children, heavy uterine bleeding, menstruation, idiopathic pulmonary siderosis, chronic internal bleeding, gastrointestinal bleeding, chronic kidney disease, dialysis, and chronic ingestion of erythropoiesis stimulating agents. In some respects, the anemia is related to chronic disease, such as rheumatoid arthritis; cancer, Hodgkin's leukemia; non-Hodgkin's leukemia; cancer chemotherapy, inflammatory bowel disease, ulcerative colitis thyroiditis, hepatitis, systemic lupus erythematosus, polymyalgia rheumatica, scleroderma, Sjogren's syndrome, congestive heart failure/cardiomyopathy, or idiopathic geriatric anemia. In some embodiments, the anemia is due to impaired iron absorption or poor nutrition, such as anemia associated with Crohn's Disease; gastric surgery, ingestion of drug products that inhibit iron absorption; and chronic use of calcium. The method also treats restless leg syndrome and related ailments.

The following examples are meant to be illustrative of the present invention. These examples exemplify the invention and are not to be construed as limiting the scope of the invention.

EXAMPLES

Example 1: Preparation of Oxidized Icodextrin (EIC-O)
Sodium hypochlorite solution (266.1 g; 9-11% w/v) was gradually added to the mixture of icodextrin (100.0 g) and water (200 ml), stirred at 40 to 45°C. The pH of the reaction mixture was maintained between 9.5 to 11.5 by gradual addition of sodium hydroxide (2N aqueous solution) to the stirred mixture. The reaction mixture was stirred at 40 to 45°C for 180 to 240 min. The resultant reaction mixture containing oxidized icodextrin (EIC-O) was cooled and utilized for further reactions.

Example 2: Preparation of EIC-O-Fb
Ferric chloride hexahydrate (14.4 g) is added to the nitrogen purged water for injection (200 ml) at 50 to 550C under nitrogen atmosphere, followed by stirring and addition of ferrous chloride tetrahydrate (10.8 g). The solution containing oxidized icodextrin (EIC-O, prepared following the procedure described in example 1, 10 g in 50 ml water for injection) is added to the mixture with continued stirring. Aqueous ammonia (30 ml) is then gradually added to the stirred mass at 50 to 550C. After 6 to 10 hours, the reaction mass is cooled, pH is adjusted to around 7 using hydrochloric acid. The reaction mass is filtered using 0.2-micron filter, followed by filtration using 100kd hollow fiber membrane.
The filtered mass, wherein the weight average molecular weight is in the range of 140 to 250 kDa is concentrated to give EIC-O-Fb as a black, amorphous powder.
Yield: 15.0 g
Iron Content: 20.0 to 35.0 % (w/w)

Example 2a: Preparation of EIC-O-Fb
Ferric chloride hexahydrate (14.4 g) is added to the nitrogen purged water for injection (200 ml) at 50 to 550C under nitrogen atmosphere, followed by stirring and addition of ferrous chloride tetrahydrate (10.8 g). The solution containing oxidized icodextrin (EIC-O, prepared following the procedure described in example 1, 10 g in 50 ml water for injection) is added to the mixture with continued stirring. Aqueous ammonia (30 ml) is then gradually added to the stirred mass at 50 to 550C. After 6 to 10 hours, the reaction mass is cooled, pH is adjusted to around 7 using hydrochloric acid. The reaction mass is filtered using 0.2-micron filter, followed by filtration using 100kd hollow fiber membrane.
The filtered mass, wherein the weight average molecular weight is in the range of 140 to 250 kDa is concentrated to give EIC-O-Fb as a light brown to dark brown thick liquid.
Iron Content: 5.0 to 9.0 % (w/w)
Fe(II): NMT 0.2 %.
Yield: 15.0 g

Example 3: Preparation of EIC-O-Fa
The solution containing oxidized icodextrin (EIC-O, prepared following the procedure described in example 1, 30.2 g in 60 ml water for injection) is gradually added to the stirred solution of ferric chloride hexahydrate (88.0 g in 400ml DM water) at 20 to 30°C. The stirring is continued for 30 minutes, followed by addition of aqueous sodium carbonate (15%) till the reaction mixture attained pH of around 6. Aqueous ammonia (around 120 ml) is then gradually added to the stirred mass till the pH is 9.5 to 10. After stirring for 60 to 120 minutes at 20 to 30°C, the reaction mass is heated to 80 to 85°C. After 6 to 10 hours, the reaction mass is cooled, pH is adjusted to around 7 using hydrochloric acid. The reaction mass is filtered using 0.2-micron filter, followed by filtration using 100kd hollow fiber membrane.
The filtered mass, wherein the weight average molecular weight is in the range of 110 to 150 kDa is concentrated to give EIC-O-Fa as a black, amorphous powder.
Yield: 149.7 g
Iron Content: 20.0 to 35.0 % (w/w)

Example 3a: Preparation of EIC-O-Fa
The solution containing oxidized icodextrin (EIC-O, prepared following the procedure described in example 1, 30.2 g in 60 ml water for injection) is gradually added to the stirred solution of ferric chloride hexahydrate (88.0 g in 400ml DM water) at 20 to 30°C. The stirring is continued for 30 minutes, followed by addition of aqueous sodium carbonate (15%) till the reaction mixture attained pH of around 6. Aqueous ammonia (around 120 ml) is then gradually added to the stirred mass till the pH is 9.5 to 10. After stirring for 60 to 120 minutes at 20 to 30°C, the reaction mass is heated to 80 to 85°C. After 6 to 10 hours, the reaction mass is cooled, pH is adjusted to around 7 using hydrochloric acid. The reaction mass is filtered using 0.2-micron filter, followed by filtration using 100kd hollow fiber membrane.
The filtered mass, wherein the weight average molecular weight is in the range of 110 to 150 kDa is concentrated to give EIC-O-Fa as a light brown to dark brown thick liquid.
Yield: 149.7 g
Iron Content: 5.0 to 9.0 % (w/w)

Example 4: Preparation of EIC-R
Aqueous sodium hydroxide (25.0 g in 250 ml DM water) is gradually added to the stirred solution of icodextrin (100.0 g in 400 ml DM water) at 10 to 15°C, followed by a lot-wise addition of sodium borohydride (4 lots, 1.0 g each), with intermittent stirring for about 10 minutes. After about 60 minutes, the reaction mixture is concentrated, followed by addition of methanol and drying at 50 to 60°C.
Yield: 90.2 g

Example 4a: Preparation of EIC-R
Aqueous sodium hydroxide (25.0 g in 250 ml DM water) is gradually added to the stirred solution of icodextrin (100.0 g in 400 ml DM water) at 10 to 15°C, followed by a lot-wise addition of sodium borohydride (4 lots, 1.0 g each), with intermittent stirring for about 10 minutes. After about 60 minutes, the reaction mixture is concentrated, followed by the addition of methanol and drying at 50 to 60°C.
Yield: 90.2 g
Dissolved the above compound in water (300 mL) adjusted the pH 9 to 12 stirred for 30 to 40 mins add bromo alkyl acid at 0 to 5 °C and stirred for room temperature 10 t0 12 hours, neutralized the reaction mass using aqueous hydrochloric acid and concentrated to thick mass and filter to remove inorganic material. The pure product was isolated from the water and alcoholic solvent and isolated using an alcoholic solvent.
Yield: 100 g

Example 5: Preparation of EIC-R-Fa
Aqueous ferric chloride hexahydrate (5.0 g in 25 ml water) is gradually added to the solution of EIC-R (5.0 g in 25 ml water, prepared following the procedure described in example 4A) at 20 to 30°C under nitrogen atmosphere. The stirring is continued for 30 minutes, followed by addition of aqueous sodium carbonate (15%) till the reaction mixture attained pH of around 6. Aqueous ammonia is then gradually added to the stirred mass till the pH is 9.5 to 10. After stirring for 60 to 120 minutes at 20 to 30°C, the reaction mass is heated to 80 to 85°C. After 6 to 10 hours the reaction mass is cooled, pH is adjusted to around 7 using hydrochloric acid. The reaction mass is filtered using 0.2-micron filter, followed by filtration using 100kd hollow fiber membrane.
The filtered mass, wherein the weight average molecular weight is in the range of 170 to 230kDa is concentrated to give EIC-R-Fa as a black, amorphous powder.
Yield: 4.9 g
Iron Content: 20.0 to 35.0 % (w/w)
Fe (II): NMT 0.2 %.

Example 6: Preparation of EIC-R-Fb
EIC-R (20.3 g, prepared following the procedure described in example 5) is dissolved in 50 ml water at 60° C. FeCl3 (22.7 g, 12%) and sodium hydroxide (29.6 g 30%) are gradually added to the mixture, at the same temperature, maintaining a pH of around 11. The reaction mixture is heated to around 100°C, followed by cooling to room temperature. pH of the reaction mass is adjusted to around 8 using aqueous hydrochloric acid. The solution is centrifuged and filtered using an AF-50 filter followed by addition of around 90% aqueous ethanol, till the product is precipitated. The resultant mass is settled for 1-2 hours and isolated.
The crude product is treated with 90% aqueous ethanol, filtered and dried under vacuum to give EIC-R-Fb as a black, amorphous powder.
Yield: 14.2 g
Iron Content: 20.0 to 35.0 % (w/w)
Fe (II): NMT 0.2 %.

Example 7: Preparation of EIC-O
Icodextrin (100 g) was dissolved in water (500 mL) at 20 to 30°C and sodium bromide (1.2 gms) was added. The pH was adjusted between 9.5 and 10.5 using aqueous sodium hydroxide solution (1N) and stirred for 3 hours at room temperature. Sodium hypochlorite solution (92 gms, 9-11% W/V) was added gradually to the reaction mass and maintained at pH 9.5 to 10.5 with sodium hydroxide solution and stirred for 3 to 5 hours. The resultant reaction mixture containing oxidized icodextrin (EIC-O) was cooled and used for the reaction disclosed in Example 8.

Example 8: Preparation of EIC-O-Fa
Ferric chloride (262 gms in 500ml water) was added to the solution containing oxidized icodextrin (EIC-O, prepared according to Example 7) at 20 to 30°C. The mixture was stirred for 120 minutes at a pH of 3 to 5 by intermittent addition of aqueous sodium carbonate solution and stirred further for 8 to 12 hours at 20 to 25°C. The reaction mass was stirred at 95 to 102°C and after completion of reaction based on HPLC, the reaction mass was cooled and filtered to remove low molecular weight and inorganic impurities from the reaction mass. The reaction mixture was distilled, and methanol (2000ml) was added to separate out the product, which was filtered, washed with acetone (100 ml) and dried to give as an EIC-O-Fa as amorphous light brown to brown color powder.
Yield: 140 g
Average molecular weight: 189000 Da
Polydispersity (PD): 1.3
Iron content: 20.0 to 35.0 % (w/w)
Fe (II): NMT 0.2 % w/w.

In a further embodiment, the iron complex obtained from Example 3a (Test compound) was evaluated for acute toxicity (Table 1) and therapeutic activity in terms of hemoglobin levels (Table 2), using diet induced iron deficiency anemia model of Sprague Dawley (SD) rats.

The number of rats surviving the experimental period is given in Table 1. There was no significant difference in the food and water intake of surviving rats during the experimental period.

Table 1: Survival rate of the Rats
Groups No. of Rats No. of Rats survived
Group-I (Normal Control) 8 8
Group-II (Anemic control) 8 8
Group-III Ferrous ascorbate.
(2.2 mg of Fe per kg, p.o.) 8 8
Group-IV (Test compound) (2.2mg of Fe per kg, p.o.) 8 8
Group-V (Ferric carboxymaltose (1.35 mg of Fe per kg, i.v.) 8 8
Group-VI (Test compound) (1.35mg of Fe per kg, i.v.) 8 8
Group-VII (Test compound)
(5 mg of Fe per kg, i.v.) 8 8
i.v.: intravenous p.o.: per oral

Effect on hemoglobin levels:

The effect of iron complex obtained from Example 3a (Test compound) on hemoglobin levels is summarized in Table 2. An iron deficiency diet caused a significant reduction in hemoglobin levels during the experimental period. The decreased hemoglobin levels were significantly improved by the test compound and was found to be equally effective in this regard. The test compound (2.2 mg of Fe per kg, p.o) is equipotent to Ferrous ascorbate (2.2 mg of Fe per kg, p.o.).

The Test compound of 1.35 mg of Fe per kg, i.v. and 5mg of Fe per kg, i.v. was effective and comparable with the Ferric carboxymaltose 1.35mg of Fe per kg, i.v. dose for increasing hemoglobin levels.

Table 2: Effect of test formulations on hemoglobin levels (g/dl)
Event Group-I Group-II Group-III Group-IV Group-V Group-VI Group-VII
Basal 13.69±0.4 13.71±0.5 13.39 ± 0.22 15.68±0.44 12.69± 0.15 13.69± 0.23 12.54± 0.38
I-1 week 13.45±0.15 11.48± 0.45 11.34 ± 0.29 12.49±0.35 13.41± 0.35 11.68± 0.25 11.23± 0.30
I-2 week 13.18±0.33 8.713±0.5 9.025 ± 0.37 6.263±0.33 9.775± 0.37 9.488± 0.23 8.744± 0.45
I-3 week 13.95±0.21 8.738±0.4 9.750 ± 0.55 6.788±0.34 9.413± 0.39 8.988± 0.30 8.778± 0.42
I-4 week 14.48±0.17 8.88± 1.0 8.23 ± 0.35 6.28 ± 0.86 9.18 ± 0.39 8.73 ± 0.32 8.98 ± 0.42
T-1 week 14.63±0.17 9.314±0.6 11.70 ± 0.20 10.13±0.5 11.08± 0.71 10.05± 0.31 13.73± 0.26
T-2 week 14.63±0.19 10.46±0.5 13.08 ± 0.31 12.48±0.23 12.92± 0.39 11.80± 0.47 12.97± 0.27

Group–I: Normal Control
Group-II: Anemic Control
Group–III: Ferrous ascorbate [2.2 mg of Fe per kg, p.o]
Group-IV: Test compound [2.2 mg of Fe per kg, p.o]
Group-V: Ferric carboxymaltose [1.35 mg of Fe per kg, i.v.]
Group-VI: Test compound [1.35 mg of Fe per kg, i.v.]
Group-VII: Test compound [5 mg of Fe per kg, i.v.]
,CLAIMS:Claims:
1) An iron polysaccharide complex comprising a modified icodextrin in association with an iron salt and having weight average molecular weight between 100 - 250 kilodaltons.
2) An iron polysaccharide complex according to claim 1, wherein the iron content of the complex in the liquid form is between 5 and 9% (w/w).
3) An iron polysaccharide complex according to claim 1, wherein the iron content of the complex in the solid form is between 20 and 35% (w/w).
4) An iron polysaccharide complex according to claim 1, wherein the modified icodextrin is oxidized icodextrin.
5) An iron polysaccharide complex according to claim 1, wherein the modified icodextrin is alkylated icodextrin obtained by reduction of icodextrin followed by alkylation of the hydroxy group with a bromoalkyl acid.
6) A process for preparing an iron complex of modified icodextrin by a process comprising of oxidizing icodextrin with sodium hypochlorite solution, optionally in presence of sodium bromide followed by treatment with ferric chloride in presence of an inorganic base, heating to reflux temperature and isolating by filtration of the reaction mass, concentrating the filtrate, and adding an alcohol and isolating the product.
7) A process for preparing an iron complex of modified icodextrin by a process comprising of treating icodextrin with a reducing agent in presence of sodium hydroxide followed by alkylation with a bromoalkyl acid in presence of sodium hydroxide and treating the resulting alkylated compound with ferric chloride in presence of a sodium hydroxide, refluxing the mixture and isolating by cooling and concentrating the mixture, adding an alcohol to the residue to obtain the product.
8) A composition comprising a pharmacologically effective amount of the iron complex of the modified icodextrin according to claim 1 and at least one pharmacologically acceptable carrier.
9) A method of preventing or treating iron deficiency comprises administering parenterally or orally a pharmacological composition of the compound of claim 1 to animal or human subjects in need thereof.