the present invention relates to a calcium formate composition for oral administration to an individual . the composition is useful in reducing phosphorus absorption in the gastrointestinal tract . calcium formate is shown below to be effective in inhibiting phosphorus absorption when administered orally in in vivo tests and has been shown to prevent the absorption of ingested phosphorus at a lower dose than other calcium - containing binders . as a result of these discoveries , calcium formate , alone or in combination with other materials , can be used to bind phosphorus in the gastrointestinal tract , thus reducing the percentage of an amount of phosphorus consumed ( i . e ., of a given “ dose ” of phosphorus ) which is absorbed . preferably , this dose would be 0 . 5 - 10 . 0 grams when adjusted to doses intended for human patients . the present invention also relates to a method of inhibiting gastrointestinal phosphorus absorption . the method of the present invention is based on the demonstration that calcium formate is an effective binder of phosphorus when administered orally to an individual . the method comprises orally administering a quantity of calcium formate sufficient to bind with phosphorus in the gastrointestinal tract . preferably , this dose is between 10 - 200 milliequivalents of calcium and is preferably present in either tablet or gelatin capsule form . in a most preferable form of the present invention , the oral dose is ingested at mealtimes . as a result of the present invention it is possible to administer calcium formate to reduce absorption of dietary phosphorus , which has the net effect of reducing the risks of adverse effects ( e . g ., bone disease and secondary hyperparathyroidism ) observed in individuals ( e . g ., chronic renal patients ) in whom the ability to excrete phosphorus in the urine is impaired . as used herein , the term “ phosphorus ” includes phosphorus and phosphate in its various forms ( e . g . hpo 4 − , po 4 − 3 , etc .). according to the method of the present invention , calcium formate is administered , alone or in combination with other substances ( e . g ., in a hard gelatin capsule ; along with materials necessary to form a tablet or caplet as a delivery vehicle for the calcium formate ; or along with a second phosphorus binder or other pharmaceutically useful substance ) in sufficient quantities to reduce phosphorus absorption in the gastrointestinal tract . the calcium formate is administered orally , preferably close in time to food and beverage consumption . by “ at mealtimes ” we mean within 30 minutes of a meal . in one embodiment , 0 . 5 - 10 . 0 grams of anhydrous calcium formate ( 10 - 200 milliequivalents calcium ) is taken prior to food consumption ( e . g ., meal time ) and a second dose of 0 . 5 - 10 . 0 grams of anhydrous calcium formate is taken after food consumption . the dose or quantity to be taken at a given time varies on an individual - by - individual basis and can be adjusted as needed ( e . g ., by monitoring serum concentration of phosphorus and calcium ). in another embodiment of the present invention , calcium formate is administered , alone or in combination with other substances , in sufficient quantities to supplement an individual &# 39 ; s calcium intake . the examples below indicate that calcium formate in quantities between 0 . 5 and 3 . 0 g / day are sufficient to improve calcium balance , bone density and calcium retention . the present invention is also a pharmaceutical composition comprising calcium formate in a pharmaceutically acceptable carrier , wherein the calcium formate is present in an amount between 0 . 5 - 1 . 0 grams . in another embodiment , the pharmaceutical composition comprises calcium formate in amount suitable to inhibit gastrointestinal absorption of phosphorus , provides between 11 and 44 milliequivalents of calcium , and is 10 % lighter than the corresponding calcium acetate dose and is the richest form of calcium available . by “ corresponding ” or “ therapeutically equivalent ,” we mean a dose that is equally effective . in another embodiment of the present invention , the pharmaceutical composition essentially comprises only calcium formate and at least one pharmaceutically carrier , wherein the calcium formate is present in an amount sufficient to produce between 11 and 44 milliequivalents of calcium . by “ essentially comprises ” we mean that calcium formate is the only active ingredient in the pharmaceutical composition . the present invention is also a pharmaceutical composition comprising calcium formate in a pharmaceutically acceptable carrier combined with other therapeutic agents , preferably a vitamin d compound . most preferably , the calcium formate is combined with vitamin d is cholecalciferol in a range of 125 iu to 400 iu in a tablet or capsule . [ 0033 ] table 1 serum ( mg %) serum ca ( mg %) group % ca formate ( mean ± sem ) weight ( mean ± sem ) 1 week on diet 1 0 4 . 96 ± . 48 209 ± 5 . 5 nd 2 1 3 . 25 ± 31 229 ± 5 . 5 nd 3 2 2 . 50 ± 32 211 ± 6 . 3 nd 4 3 2 . 5 ± 20 194 ± 6 . 5 nd 2 weeks on diet 1 0 5 . 98 ± 39 295 ± 4 . 8 11 . 4 ± . 20 2 1 4 . 70 ± . 62 211 ± 3 . 8 14 . 0 ± . 51 3 2 2 . 7 ± 24 198 ± 5 . 2 12 . 8 ± . 94 4 3 2 . 9 ± 0 . 8 150 ± 8 . 0 12 . 9 ± 1 . 3 five - week - old sprague dawley rats were given a synthetic diet containing 0 . 47 % ca and 0 . 2 % phosphorus for two weeks prior to the addition of calcium formate to the diet . body weights were measured and blood serum was collected after one or two weeks on calcium formate . the results of this experiment are tabulated in table 1 . all rats supplied with calcium formate had less serum phosphorus than control rats . there seemed to be little difference in serum phosphorus between rats on 2 % or 3 % calcium formate , thus indicating that a saturation binding point had been reached . twenty 15 - day - old weanling rats from holzmann company were placed on a an adequate synthetic diet called “ diet 11 ” ( suda , t ., et al ., j . nutr . 100 : 1049 - 1052 , 1970 ). this diet is supplemented with vitamins a , d , e and k as described in that paper . therefore , these are vitamin d - sufficient animals . the animals were then placed on a basal diet that contains 0 . 02 % calcium , i . e . an extremely low calcium diet . these animals served as controls . another group were placed on the same diet containing calcium formate , providing calcium at 0 . 25 % of the diet . another group was supplied calcium formate at 0 . 47 % calcium in the diet , and another group was provided 0 . 47 % calcium in the form of calcium carbonate . growth of the animals reflects the ability of the animals to utilize calcium . using a growth assay of this type to illustrate the effectiveness of the calcium salt is supported by steenbock , h . and d . c . herting , j . nutr . 57 : 449 - 468 , 1955 . table 2 , below , tabulates the results . referring to table 2 , we conclude that calcium formate is at least equal to calcium carbonate in ability to supply calcium to experimental rats . in fact , there is a slightly better growth obtain with 0 . 25 % calcium as the formate in comparison to other treatment groups . calcium formate can therefore be used as a dietary supplement to provide dietary calcium .
a calcium formate composition for oral administration to an individual for the purpose of supplementary dietary calcium is disclosed .