Provided in a phosphate ion adsorbent containing a weakly basic anion exchange resin as an active ingredient which aims at providing preventives and/or remedies for hyperphosphatemia having a high selectivity for the adsorption of phosphate ion and showing an effect of lowering blood phosphorus level and another effect of suppressing phosphorus excretion into the urine.

DISCLOSURE OF THE INVENTION

The invention is accomplished in view of the problems of the above prior art, and is to provide a preventive and/or a remedy for hyperphosphatemia having a high selectivity toward a phosphate ion adsorption action, further having a lowering action of blood phosphorus concentration and a lowering action of urinary phosphorus excretion.

The inventors made extensive researches to solve the above problems and found out that a weakly basic anion exchange resin, which was only used as main uses for removal of hydrochloric acid in an aqueous system and a non-aqueous system, surprisingly has a phosphoric acid adsorption action, a lowering action of blood phosphoric acid concentration and a lowering action of urinary phosphorus excretion, and accomplished the invention.

Namely, the invention relates to a phosphate ion adsorbent comprising as an active ingredient a weakly basic anion exchange resin.

Also, the invention relates to the above phosphate ion adsorbent, characterized in that the weakly basic anion exchange resin is a copolymer containing as monomer components an acrylic acid type compound having a tertiary amino group and divinylbenzene.

Further, the invention relates to the above phosphate ion adsorbent, characterized in that the copolymer further contains as monomer components one or more components selected from the group consisting of acrylonitrile, vinylimidazole, vinylhistidine, vinylpyrazine and diaminodiphenylmethane.

The invention also relates to the above phosphate ion adsorbent, characterized in that the weakly basic anion exchange resin has porous bead structure.

Also, the invention relates to the above phosphate ion adsorbent, characterized in that the weakly basic anion exchange resin is Ionac A-365 (trade name; Sybron Chemicals Co.).

Further, the invention also relates to a preventive and/or a remedy for hyperphosphatemia, characterized in that it contains the above phosphate ion adsorbent.

A phosphate ion adsorbent and a preventive and/or a remedy for hyperphosphatemia according to the invention not only can overcome bad effects shown in usual weakly basic anion exchange resins and the aluminum, calcium and magnesium preparations that have been used as a preventive and/or a remedy for hyperphosphatemia, but also have an extremely high selectivity toward a phosphorus adsorption action compared with oral phosphorus adsorbents reported so far in which anion exchange resins are used.

As described above, considering that in general, a weakly basic anion exchange resin is a resin that has been used up to now at the industrial level for the purpose of decoloring, demineralization or hazardous substance removal for solvent, a supplied water or a waste water, the effect attained by the invention is totally surprising.

Weakly basic anion exchange resins used in the invention typically have as its main backbone copolymers of an acrylic acid type compound, which have a tertiary amino group, for example, such as acrylamide or acrylate, and divinylbenzene, and further may contain as other monomer components acrylonitrile, vinylimidazole, vinylhistidine, vinylpyrazine, diaminodiphenylmethane or the like further in a range that it is pharmaceutically acceptable and does not reduce the effect. Preferably they are weakly basic polyacrylate type resins having porous bead structure.

Although preparation of a weakly basic anion exchange resin used in the invention can be carried out by a conventional method known by publications, etc., specifically it can be carried out by copolymerization of a monovinyl monomer such as acrylic acid or its alkyl ester and divinylbenzene and reaction of this copolymer with polyalkylene polyamine. Additionally, this copolymer can be copolymerized with other monomers such as acrylonitrile, vinylimidazole, vinylhistidine, vinylpyrazine or diaminodiphenylmethane in a range that it is pharmaceutically acceptable and does not lose the effect.

Illustrative of such a weakly basic anion exchange resin is, for example, Ionac A-365 (trade name; Sybron Chemicals Co.) which is being marketed with the main use for removal of, hydrochloric acid in an aqueous system and a non-aqueous system.

The phosphoric acid adsorbent and the preventive and/or the remedy for hyperphosphatemia according to the invention lower blood phosphorus concentration and urinary phosphorus excretion. Therefore, the preventive and/or the remedy for hyperphosphatemia according to the invention are expected to have a preventive and/or therapeutic effect toward a renal function disorder, chronic renal failure, dialysis, hypocalcemia, excess secretion of parathyroid hormone (PTH), suppression of vitamin D activation, ectopic calcification or the like wherein hyperphosphatemia is considered to be the cause of disease. Further, the preventive and/or remedy for hyperphosphatemia of the invention are expected to exert a remarkable preventive effect and/or therapeutic effect toward PTH increase due to hyperphosphatemia, secondary hyperparathyroidism via vitamin D lowering, renal osteodystrophy, uremia, central and peripheral nerve disorders, anemia, myocardial disorders, hyperlipemia, saccharometabolism disorders, itch, dermal ischemic ulcer, tendon rupture, reproductive dysfunction, muscle disorder, growth retardation, cardiac conduction disorders, alveolar diffusion disorders, arteriosclerosis, immunodeficiency, etc.
 

Claim 1 of 3 Claims

1. A method of treating hyperphosphatemia in a patient comprising orally administering to the patient in need of treatment for hyperphosphatemia a therapeutically effective amount of a pharmaceutically acceptable phosphate ion absorbent comprising as an active ingredient a weakly basic anion exchange resin, wherein said resin is a copolymer containing as monomer components divinylbenzene and acrylamide or divinylbenzene and acrylate, wherein the copolymer further contains a tertiary amino group.
 

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