Aluminum phosphate binder

The aluminum phosphate binder consists of a combination of orthophosphoric acid (H3PO4) or monoaluminum phosphate [A1(H2P04)3] and aluminum oxide (fused alumina, AI2O3). Upon heating to elevated temperatures the two constituents interact, and aluminum orthophosphate (AIPO4) is formed as the final product of the reaction at temperatures above about 500 °C. This is a cementing process that results in the development of a hardened material. Aluminum phosphate binder is widely employed in refractory concrete applications, and is discussed in more detail in Chapter 23. 

Hollow Fiber with Sorbent Walls. A cellulose sorbent and dialy2ing membrane hoUow fiber was reported in 1977 by Enka Glan2stoff AG (41). This hoUow fiber, with an inside diameter of about 300 p.m, has a double-layer waU. The inner waU consists of Cuprophan ceUulose and is very thin, approximately 8 p.m. The outer waU, which is ca 40-p.m thick, consists mainly of sorbent substance bonded by ceUulose. The advantage of such a fiber is that it combines the principles of hemodialysis with those of hemoperfusion. Two such fibers have been made one with activated carbon in the fiber waU, and one with aluminum oxide, which is a phosphate binder (also see Dialysis). 

Hyperphosphatemia is generally benign and rarely needs aggressive therapy. Dietary restriction of phosphate and protein is effective for most minor elevations. Phosphate binders such as aluminum-based antacids, calcium carbonate, calcium acetate (PhosLo , Nabi), sevelamer (Renagel , Genzyme), and lanthanum carbonate (Fosrenol , Shire) may be necessary for some patients.43 If patients exhibit findings of hypocalcemia (tetany), IV calcium should be administered empirically. 

Progressive encephalopathy was also observed among children with severe renal disease ingesting aluminum-containing phosphate binders (Finberg et al. 1986 Griswold et al. 1983). 

Andrcoli SP, Bergstein JM, Sherrard DJ. 1984. Aluminum intoxication from aluminum-containing phosphate binders in children with azotemia not undergoing dialysis. N Engl J Med 310 1079-1084. 

Chan JCM, Jacob M, Brown S, et al. 1998. Aluminum metabolism in rats Effects of vitamin-D, dihydrotachysterol, 1,25-dihydroxyvitannn-D and phosphate binders. Nephron 48 61-64. 

In addition may medication related to the uremic state lead to important trace element accumulation. In the past this has clearly been established for aluminum resulting from the use of aluminum hydroxide as a phosphate binding agent. As aluminum-based phosphate binders may be contaminated with other elements, e.g. strontium the possibility for a simultaneous accumulation of different elements has been suggested [7]. Strontium is mainly eliminated by the kidney and has been associated with bone mineralization defects when present at high concentrations. In view of this the use of strontium ranelate for the treatment and preven-... 

Aluminum toxicity has also been linked with oral exposure as a result of Al-containing pharmaceutical products such as Al-based phosphate binders or antacid intake. As over-the-counter antacids are an important source for human Al exposure from a quantitative point of view, patient information leaflets in Europe contain warnings of possible Al toxicity. ... 

The trace element with the most established significance in ESKD is aluminum. Central nervous system toxicity is linked to the presence of aluminum in the dialysate or the excessive use of aluminum-containing medications. Consequently, the concentration of aluminum in dialysis solutions has been reduced and aluminum-containing antacids are no longer routinely used as phosphate binders. Aluminum toxicity can be treated with deferoxamine, as discussed in Chap. 44. 

The use of zirconyl chloride octahydrate (ZrOCl2 8H2O) as an intestinal phosphate binder in place of aluminum compounds has also been reported (Graff and Bumel 1995). 

Aluminum intoxication was first implicated in this disorder by Alfrey and associates (Alfrey et al., 1976). The aluminum content of brain gray matter was elevated to eleven times the normal value in patients with dialysis dementia, versus an increase of three times the normal in patients on chronic hemodialysis without dialysis dementia. Aluminum content was also increased in bone and other soft tissue. Oral phosphate binders containing aluminum [AKOHlj and AljlCOj) ] were originally suspected to be the source of the aluminum. 

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