Deferoxamine and coated charcoal hemoperfusion to remove aluminum in dialysis patients

Encephalopathy after bladder irrigation with alum: case report and literature review

A 70-year-old man with advanced obstructive nephropathy began to hemorrhage from the bladder after decompression with a Foley catheter. Manifestations of encephalopathy appeared after continuous irrigation with 1% alum for 2 days and were associated with elevated serum aluminum concentrations. Repeated treatments with deferoxamine and hemodialysis accomplished some aluminum removal, but the patient succumbed to bronchopneumonia. Brain aluminum content was not excessive at autopsy. A literature review suggests that intact renal function is essential to rapid disposal of a parenteral aluminum load and indicates that most reported instances of encephalopathy after alum irrigation have occurred in patients with compromised renal function. We conclude that alum should not be employed as a bladder irrigant in patients with acute or chronic renal failure.

The importance of bone biopsy in managing renal osteodystrophy

A case is presented in which bone biopsy results helped to resolve not only difficult issues in the clinical management of the patient's renal osteodystrophy but also disruptive psychosocial problems surrounding her clinical course. The outcome was a satisfactory resolution based on rational medical treatment and directed supportive care. The presentation highlights important principles in the procurement, processing, and interpretation of the bone biopsy, while also addressing the importance of accurate diagnosis in facilitating the overall long-term management by the entire renal team.

Aluminum chelation: chemistry, clinical, and experimental studies and the search for alternatives to desferrioxamine

This review focuses on aluminum (Al) chelation, its chemistry and biology. The toxicology and biology of Al in mammalian organisms are briefly reviewed to introduce the problems associated with excessive Al exposure and accumulation and the challenges facing an effective Al chelator. The basics of Al chelation chemistry are considered to help the reader understand the Al chelation chemical literature. The chemical properties of Al enable prediction of effective functional groups for Al chelation. A compilation of distribution coefficients between octanol and aqueous phases (Do/a) for chelators and their complexes with Al shows the effect of complexation on lipophilicity. A compilation of stability constants for Al.chelator complexes illustrates the role of oxygen in ligands that form stable complexes. The history of clinical Al chelation therapy is reviewed, with emphasis on desferrioxamine (DFO), which has been extensively used since 1980. The beneficial and adverse effects and limitations of DFO use in end-stage renal-diseased patients, in patients with neurodegenerative disorders, including Alzheimer's disease, and in animal models of Al intoxication are presented. The methods to evaluate potential Al chelators in vitro, in vivo, and using computer modeling are discussed. The Al chelation literature is reviewed by the chemical class of chelators, including fluoride, carboxylic acids, amino acids, catechols, polyamino carboxylic acids, phenyl carboxylic acids, the hydroxypyridinones, and hydroxamic acids.

Coating charcoal with polyacrylate-polymethacrylate copolymer for haemoperfusion. II. Drug removal and polymer compatibility studies

The newly developed system of polyacrylate-polymethacrylate-coated charcoal, filled in a column has been tested for its efficiency in removing theophylline, as a model drug both from a buffer solution pH 7.4 and human plasma using a closed-circuit apparatus. Preliminary testing determined the capacity of the charcoal column and the effect of circulation rate of the buffer solution on the clearance of theophylline. It was found that the circulation rate does not significantly affect the clearance rate of theophylline, while the concentration of drug in the buffer solution has a considerable effect on the clearance of the drug, presumably due to the saturation of the column. The clearance of the drug from plasma in comparison to buffer solution was also investigated. It was found that more than 70 per cent of the drug was removed from the buffer solution within the first 15 min as compared with 65 per cent from plasma; with 95 per cent removed from buffer after 1 h in comparison to 93 per cent from plasma. The blood compatibility of the polymer was studied by incubating various concentrations (5-25 per cent w/v) of the polymer in blood for 30 min at 25 degrees C. A concentration of 5 per cent polymer was also incubated for a series of incubation times. The results indicated that with polymer concentrations up to 15 per cent there is no significant lysis of RBCs in comparison to a blank.(ABSTRACT TRUNCATED AT 250 WORDS)

Removal of aluminoxamine and ferrioxamine by charcoal hemoperfusion and hemodialysis

We studied the removal of aluminoxamine (AlO) and ferrioxamine (FO) by (i) hemoperfusion/hemodialysis using an AluKart in combination with either a Cuprophan F-120 or a Hemophan FH-160 membrane, or (ii) hemodialysis with a high-flux F-60 polysulfone membrane. The same six dialysis patients underwent in a random order dialysis by the three set-ups after i.v. infusion of 30 mg/kg of desferrioxamine (DFO) during the last half an hour of the preceding dialysis session. The mean +/- SD plasma AlO and FO clearances of the AluKart combined with either a F-120 or FH-160 membrane were 194.3 +/- 25.8 ml/min (AlO) and 164.2 +/- 41.3 ml (FO) at the start of dialysis declining to respectively 76.6 +/- 27.3 and 68.5 +/- 42.6 ml/min at the end of dialysis. With a high-flux dialysis membrane the intra-dialytic plasma clearance remained constant at 81.5 +/- 6.8 ml/min for AlO and 60.0 +/- 2.8 ml/min for FO. In the presence of an AluKart combined with a FH-160 up to 84 +/- 27% and 84 +/- 19% of the available AlO and FO could be removed during a four-hour hemoperfusion/hemodialysis session. During the first hour of dialysis, respectively 59 and 58% of the total amount of AlO and FO extracted by the AluKart was removed compared to only 9 and 16% during the last hour.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and histologic features of iron-related bone disease in dialysis patients

Forty-eight dialysis patients undergoing bone biopsy were analyzed for clinical history, blood biochemical values, bone histologic findings, bone aluminum content (BAC), bone iron content (BIC), bone iron stores, and histochemical staining of bone aluminum and bone iron. Four patients had significant trabecular bone iron staining alone; eight patients had significant bone iron and bone aluminum staining; 13 patients had significant bone aluminum staining alone; and 23 patients showed no significant bone aluminum or iron staining. Patients with significant bone iron staining were younger (37.4 +/- 5.3 years v 53.2 +/- 2.3 years, P less than 0.01, mean +/- SEM) and were more likely to be anephric (P less than 0.001) and to have a history of prior renal transplantation (P less than 0.10). The 12 patients with significant bone iron staining had received more blood transfusions than those without bone iron staining (96 +/- 22.8 U v 22 +/- 5.8 U, P less than 0.005). Patients with bone iron accumulation had higher levels of serum ferritin (3,594 +/- 1,138.4 micrograms/L [ng/mL] v 265 +/- 60.1 micrograms/L, P less than 0.01) and lower levels of immunoreactive parathyroid hormone (iPTH) (349 +/- 150 microLEq/mL v 1,801 +/- 397 microLEq/mL [386 +/- 166 pmol/L v 1,990 +/- 439 pmol/L], P less than 0.005). BIC was also higher in these patients (1,008 +/- 149 micrograms iron/g bone v 300 +/- 46.5 micrograms iron/g bone, P less than 0.001) and higher than normal BIC (256 +/- 44.2 micrograms iron/g bone, eight normals). Bone marrow iron stores were positively related to serum ferritin levels (P less than 0.01) and trabecular bone iron staining (P less than 0.10). All 13 patients with osteomalacia demonstrated significant bone aluminum staining; seven of these patients demonstrated concomitant significant iron staining. Fourteen of 15 patients with severe hyperparathyroidism showed no significant iron or aluminum staining. Our data indicate that iron will probably not accumulate within bone until all other storage sites (eg, bone marrow) are fully saturated. The presence of lower levels of iPTH in iron-overloaded patients raises the possibility that iron overload may induce a state of relative hypoparathyroidism. The most important determinant for the presence of osteomalacia seems to be the presence of significant aluminum staining. No specific bone histologic finding was related to the presence of bone iron staining, but the rarity of isolated significant bone iron staining makes it difficult to evaluate bone histologic diagnoses that might be solely attributable to iron.

Kinetics and efficacy of deferoxamine in iron-overloaded hemodialysis patients

We evaluated the kinetics and efficacy of deferoxamine (DFO) therapy in iron-overloaded hemodialysis patients. Concentrations of DFO and its chelated product, feroxamine (Fx), were assessed following single-dose DFO administration in twelve patients, and during chronic therapy over one year's time in eight, similarly iron-overloaded dialysis patients. A functional assay which relies on measurements of iron and iron binding capacity for the determination of Fx and DFO, respectively, was corroborated with liquid chromatographic techniques. Half-life measurements were also corroborated with tracer doses of 14C-DFO and 59Fe-feroxamine. Intradialytic DFO half-life (2.3 +/- 1.1 h) was considerably less than interdialytic half-life (26 +/- 1 hr). Unbound DFO was found to persist throughout the interdialytic period. Calculation of the percent saturation of the DFO dose indicated that only 30% of a given dose is chelated. The amount of iron removed dialytically was approximately 13.1 +/- 2.7 mg per dialysis session. Chronic DFO administration was also shown to enhance gastrointestinal iron excretion threefold. However, ferritin levels decreased by only 25% after one year of thrice-weekly DFO therapy. We conclude that DFO therapy for iron-overloaded hemodialysis patients is optimized by its administration interdialytically, and results in slow removal of iron, via both dialytic and gastrointestinal routes.