`
`3,, 100,20;2
`Patented Aug. 6, 1963
`
`1
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`3,100,202
`PROCESS FOR PREP AruNG AN IRON HYDROXIDE
`POLYiSOMALTOSE COlViPLEX Al"iD THE RE·
`SULTING PRODUCT
`Arthur Millier, §t. Geo:rgenstr. 101lB, and Thecdo:r Rei.:sm,
`Ludwigstr. 19, both of S:mkt Gallen, Switzerland
`No Drawing. Filed lune 17, 1960, §er. No. 36,734
`10 Claims.
`(Cl. 260-209)
`
`The present invention relates :to an improved thera(cid:173)
`peutic composition containing iron and more particularly
`to the process of manufacture of a colloidal iron-poly(cid:173)
`isomaltose complex which is parenterally injectible.
`It is well known that hemoglobin, cytochrome, catalase
`and other prophyrine protein complexes containing iron
`cannot be synthesized by the body tissue unless iron is
`available from an outside source. Blood cells and other
`structures containing kon are constantly destroyed in the
`normal processes of cell metabolism thus :liberating inor(cid:173)
`ganic iron which is in part excreted and has to be re(cid:173)
`placed. While most individuals maintain the requisite
`iron levels through normal food !intake, many individuals
`suffer from <anemia brought about by rron deficiency,
`thus requiring supplemental iron above that in the food
`intake.
`It is recognized that ferrous sulfate, carbonate, citrate,
`soluble double salts and even metallic iron powder, to
`mention a few, have been and are now being used for
`oral iron therapy. It has been found, however, that such
`iron containing compounds, orally given, are incompletely
`absorbed and the metabolism of such is slow in many
`cases. Further, in some cases iron compounds when
`orally taken !TesuHs in severe alimentary disturbances.
`To overcome the obvious defects of the oral administra(cid:173)
`rtion iron containing compounds, saccharated iron oxide
`preparations have been used for intravenous injection with
`limited success, in all probability for the reason that suc(cid:173)
`cessive batches vary in potency. Additionally, these prep(cid:173)
`arations are not suitable for intramuscular or subcutane(cid:173)
`ous injection in that the high osmotic pressure and the
`possible alkalinity of the intravenous injectible prepara(cid:173)
`tions usuaHy result in considerable pain and inflamma(cid:173)
`rtfon at the site of the injection. Further, such prepara(cid:173)
`tions are not appreciably absorbed into the body when
`administered in this manner.
`A known treatment for iron defioiency anemia is a col(cid:173)
`loidal iron preparation prepared from the degradation
`products of dextran complexed with a solution or ;<>uspen(cid:173)
`sion of one or several rtrivalent iron compounds. Dextran
`or gum dextran, as it is sometimes called, is a polysac(cid:173)
`charide having the empirical formula (C6H 100 5)n 1and is
`obtained from the fermentation of a sucrose containing
`material, such as sugar cane, sugar beet, sorghum, molas(cid:173)
`ses and the like. It is preferably fermented under care(cid:173)
`fully controlled conditions by means of bacterium such
`as Leuconostoc mesenteroides, syn. Betacoccus arabi(cid:173)
`nosaceous ( Cienkowski van Tieghem), Bergey's Manual
`of Determinative Bacteriology, fifth edition. The product
`of such a fermentation is called dextran and is a viscous
`mucilaginous substance with high molecular weight often
`reaching 200,000. Because of its high molecular weight,
`dextran is not directly suitable for injection, but :is gen(cid:173)
`erally first hydrolyzed with a dilute mineral acid, filtered
`
`2
`and fractionated to recover simple polymeric forms of
`molecular weight of 30,000 to 80,000 or lower.
`The known colloidal iron dextron complexes have been
`produced by numerous methods, for example by Teacting
`5 dextran degr.adation products in solUJtion or suspension
`with ferric hydroxide or other trivalent iron salts and
`an exceJls of alkali. Other methods employed have been
`to rnact dextran with divalent iron salt to form ferrous
`hydroxide dextran complex which are subsequently con-
`10 verted by oxidation into the corresponding ferric hy(cid:173)
`droxide complex. Complexes prepared by known meth(cid:173)
`ods comprise up <kl about 27% by weight of Fe; however,
`more generally in the rnnge of 16% to 25% and ·are char(cid:173)
`acterized by having a ratio of one mol of Fe to each an-
`15 hydroglucose unit of the dextran. Heretofore attempts to
`increase the iron to anhydroglucose ratio have been un(cid:173)
`successful.
`In accordance with the process of this invention, we
`produce a parenterally injectible iron hydroxide poly-
`20 isomaltose complex which contains 32% Fe by weight
`and has a ·ratio of 2 mols Fe to each anhydmglucose unit
`-0£ ·the polyisomaltose.
`The iron hydroxide polyisomaltose complex prepared
`:in accordance '\.vi•th our process provides a therapeutic
`25 preparation which is more heterogeneous in particle size,
`surprisingly lower toxicity, better pharmacological prop(cid:173)
`erties and of higher therapeutic efficacy than the iron(cid:173)
`dextran complexes hitherto known. >In addition to the
`foregoing advantages, we have di;<>covered that both ~ri-
`30 valent and divalent iron salts may be utilized successfully
`in the process of this invention.
`It has been theorized that ·the therapeutic advantages
`derived from a ferric hydroxide polyisomaltose complex
`prepared in accordance with our process is due •to ithe ratio
`35 of two mols of iron ·to each ruihydrog1ucose unit of the
`polyisomaltose; however, while this theory has been ad(cid:173)
`·vanced as a possible explanation of the advantages de(cid:173)
`rived from our invention, the invention is not limited to
`any particular theory or theories.
`The "iron polyisomaltose" of our invention is a com(cid:173)
`plex compound consisting of iron hydroxide and poly(cid:173)
`asomaltose. Polyisomaltose is a polyhexosan; in other
`words, a polydisaccharide made up of glucose units
`45 (CsH1o0 5)n. For analogy to the nomenclature in Chemi(cid:173)
`cal Abstracts (e.g., polyhexosan-?glucosan-?dextran-7
`polyisomaltose), the compound couJd be designated
`"polyisomaltose ferric hydroxide." While "polyisomal(cid:173)
`rt:ose" is a term used loosely for "dextran" as mentioned
`50 hereinbefore, the latter is a compound of very high mo(cid:173)
`lecular weight, whereas polyisomaltose is a degradation
`product of dextran consisting of polymerized glucose resi(cid:173)
`dues joined predominantly by 1,6 1inkages.
`The molecular range of the partially depolymerized
`55 dextran used as a starting material is selected from the
`standpoint of its mtrinsic viscosity. It is known that the
`term intrinsic viscosity refers to the limiting value of
`specific viscosity divided by concentration at infinite di(cid:173)
`lution measured as follows: llhe "flow time" of solutions
`60 nf different concentrations is determined by a viscometer.
`The flow time of .the solution divided by the flow time
`for water at the same temperature gives the relative vis(cid:173)
`cosity of tihe dextran solution at a given concentration.
`The specific viscosity of the dextran solution at a given
`
`40
`
`Pharmacosmos, Exh. 1010, p. 1
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`3,100,202
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`3
`concentration is obtained :by subtracting 1.0 from the
`value for relative ·viscosity. The specific viscosity of
`each solution is divided by the concentration of that
`solution and the results are plotted against the percentage
`concentration of the solution from whfoh it is obtained.
`By extrapolating the graph obtained to zero concentra(cid:173)
`tion, the limiting value of the specific viscosity divided
`by llhe concentration is obtained. This limiting 'Value
`is the intrinsic 'Viscosity of the material in solution.
`In accordance IWith the process of this 4nvention, a
`solution or suspension of dextran containing predomi(cid:173)
`nantly 1,6 glucose linkage •is mixed with an acidic solu(cid:173)
`tion of an iron compound, in respective amounts of about
`48 to 141 weight parts of said dron compound per 100
`parts of dextran. While it is advantageous to use as a 15
`starting material a dextran having a maximum intrinsic
`viscosity at 25° C. of 0.1, dextran. of hi·gher intrinsic
`viscosity may .be utilized; however, where such is used,
`llhe acidic solution of the iron compound and dextran
`is heated until the intrinsic viscosity of the dextran is 20
`a maximum of 0.1 and without isolating the depolym(cid:173)
`erization products the process is continued. An alkali
`carbonate solution is added to the polyisomaltose-iron
`solution until precipitates formed dissolve with 'Vigorous
`stirring. The 4nitial solution is ochre colGred which upon 25
`completion of the reaction turns brown-red in color.
`All of the carbon dioxide formed during .this reaction
`will have evolved Vlfilen the Teaction is complete. An
`alkali hydroxide is then added to the solution until the
`formed suspension is weM on the alkaline side and then 30
`heated until all suspended iron hydroxide particles are
`in solution.
`The alkaline .ferric hydroxide polyisomaltose complex
`containing solution may be neutralized prior to being
`isolated and pm:Mied. As neutralization reagents, solid, 35
`liquid or gaseous acids may be used, for example cation
`exchange .resins in the H-form, fuming sulfuric acid and
`hydrochloric acid. In order to free llhe solution of elec(cid:173)
`trolytes an alkaline anion exchange resin may be added
`in addition to ·the .cation exchange Tesin, or the solution 40
`may .be dialyzed ·against water.
`Where a divalent iron salt is used initially, the alkaline
`ferrous !hydroxide polyisomaltose solution is dialyzed
`against wen aired, flowing and demineralized water which
`dialysis converts the divalent iron hydroxide to the tri- 45
`valent form while effecting neutralization and removal
`of electrolytes.
`As iron salts, :there may be employed any water solu-
`ble salt suc!h as ferric or ferrous chloride, nitrate, acetate,
`sulfate and the like. Suitable alkaHes include alkali metal 50
`hydroxides, ammonium hydroxide ·and the like. Suitable
`carbonates include sodium and potassium carbonates and
`It is clear that any rwater soluble alkali
`bicarbonates.
`and carbonate may be used with success in the process
`of this invention, the alkali and carbonate chosen being 55
`dictated only by ·the economics of the process.
`Excellent water soluble preparations of our compound
`are obtained by any of the well-known processes for
`example by evaporation of the neutral solutions :under
`reduced pressure or by precipitation with a water solu- 60
`ble organic solvent for example methyl or ethyl alcohol.
`The following examples set out in detail are 4Uustra(cid:173)
`tive of the process of this invention:
`
`NaOH was added. The mixture was maintained at a
`temperature of 70° C. for 30 minutes after which the
`solution was cooled and the pH adjusted to 6.2 with
`90 ml. of a strongly acidic cation exchange resin and
`5 20 ml. of an alkaline exchange resin. The adjusted
`solution was filtered from the exchange resins and mixed
`with 96% ethyl alcohol in a ratio of one part by volume
`solution to 2.5 parts by volume of alcohol. The pre(cid:173)
`cipitated .ferric hydrmcide polyisomaltose complex was
`10 separated from the supernatant solution and dried ·under
`vacuum. The analytically pure complex contained 32%
`iron. The complex was processed into ·an isotonic aque(cid:173)
`ous solution containing 5% iron.
`Example 2
`35 g. of dextran having an intrinsic viscosity at 25° C.
`of 0.05 was dissolved in 75 ml. of water with heat. The
`solution was cooled and to the cooled solution, 50 g.
`FeS04 ·7H20 was added and dissolved. To this solu-
`tion an additional 75 ml. of water was added. N3.:1C03
`was added to the solution until a pH of 2.3 was reached.
`After all of the carbon dioxide formed had evolved, 11
`ml. of 10 N NaOH was added and the reaction was
`allowed to proceed for 30 minutes at a temperature of
`65 ° C. The solution was cooled, centrifuged and di(cid:173)
`alyzed against well-aired, if.lowing and demineralized
`water until there was neutral reaction and no trace of
`sulfate ions. The ferric hydroxide polyiso.maltose solu(cid:173)
`tion was evaporated under reduced pressure at a tem-
`perahlfe of 40° C. until it mad an iron content of 5%.
`The solution was made isotonic by othe addition of NaCl.
`The analytically pure complex contained 32% iron.
`The ferric hydroxide polyisomaltose compound pre(cid:173)
`pared in each of the foregoing examples was analyzed by
`fractionally precipitating the complex from aqueous solu(cid:173)
`tion with methanol to a constant iron content.
`rrhe re(cid:173)
`sults showed in all fractions a ratio of 2 mols of iron for
`each anhydroglucose unit of the polyisomaltose.
`The invention has been described in the foregoing but it
`will be understood that many variations may be introduced
`in details of procedure and conditions without departure
`from the scope of the invention and we intend to be limited
`only by the following claims.
`We claim:
`1. A process of preparing an iron hydroxide poly(cid:173)
`isomaltose complex containing about 32% iron >by weight
`comprising heating an acidic aqueous solution of a water(cid:173)
`soluble dextran, having an intrinsic viscosity greater than
`0.1 at 25° C. and a water-soluble iron compound in re(cid:173)
`spective amounts of about 48 to about 141 weight pants
`of said iron compound per 100 weight parts of dextran
`until the intrinsic 'Viscosity of said solution is not more
`than 0.1 at 25° C., reacting ithe resulting solution with an
`alkali carbonate at 'fill acid pH whereupon carbon dioxide
`is evolved; alkalinizing the resulting solution with an
`alkali metal hydroxide .after completion of the carbon
`dioxide evolution, and thereafter heating the resui.ting
`solution to form said complex.
`2. A process of preparing an iron hydroxide polyiso(cid:173)
`maltose complex containing about 32% iron by weight
`comprising reacting an acidic aqueous solution of a water
`soluble dextran having an intrinsic viscosity of not more
`il:han 0.1 at 25° C. and a water soluble iron compound
`in respective amounts of about 48 to about 141 weight
`parts of said iron compound per 100 weight parts of
`65 dextran with an alkali carbonate at an acid pH whereupon
`carbon dioxide is evolved, arkalinizing the resulting solu(cid:173)
`tion with an alkali metal hydroxide after said carbon di(cid:173)
`oxide has evolved, and thereafter heating the resulting
`solution to form said complex.
`3. The process as claimed in claim 2 wherein said iron
`compound contains trivalent iron.
`4. The process as claimed in claim 2 wherein said iron
`compound contains divalent iron.
`5. The process as claimed in claim 2 wherein said alkali
`75 carbonate is sodium carbonate.
`
`70
`
`Example 1
`A mixture of 50 g. polyisomaltose having an intrinsic
`viscosity of 0.30 at 25° C., 412 ml. water, 80 ml. of
`an aqueous solution containing 30% by weight
`FeC13 ·6H20
`and 8.32 ml. of 37% HOl was boiled under Teflux until
`the intrinsic 'Viscosity at 25° C. decreased to 0.06. The
`solution was cooled and Na2C03 was added to the solu(cid:173)
`tion until the pH reached about 2.4. After all of the
`carbon. dioxide formed had evolved, 45 ml. of 10 N
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`Pharmacosmos, Exh. 1010, p. 2
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`3,ioo,202
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`6. The process as claimed in claim 2 wherein said alkali
`metal hydroxide is sodium hydroxide.
`7. The process as daimed in claim 2 wherein the pH
`of said solution after reaction with alkali carbonate is
`about 2.3 and the pH of said solution after alkalinization 5
`with alkali metal hydroxide is not less than 11.
`8. An iron hydroxide polyisomaltose complex contain(cid:173)
`ing about 3 2 % iron by weight.
`9. A ferric hydroxide polyisomaltose complex contain(cid:173)
`ing about 32% iron >by weight.
`10. A ferrous hydroxide polyisomaltose complex con(cid:173)
`taining about 32% iron by weight.
`
`6
`References Cited in the file of this patent
`UNITED STATES PATENTS
`London et al. ------------ Jan. 21, 1958
`Herb ------------------ May 5, 1959
`Floramo --------------- Feb. 20, 19'62
`
`2,820,740
`2,885,393
`3,022,221
`
`OTHER REFERENCES
`The New England Journal of Medicine, vol. 260, Jan.
`10 22, 1959, paige 180.
`Drug Trade News, vol. 35, No. 10, May 16, 1960,
`pa;ges 1 and 72.
`
`Pharmacosmos, Exh. 1010, p. 3