Osteomalacia and osteitis fibrosa in a man ingesting aluminum hydroxide antacid

Safety Assessment of Alumina and Aluminum Hydroxide as Used in Cosmetics

This is a safety assessment of alumina and aluminum hydroxide as used in cosmetics. Alumina functions as an abrasive, absorbent, anticaking agent, bulking agent, and opacifying agent. Aluminum hydroxide functions as a buffering agent, corrosion inhibitor, and pH adjuster. The Food and Drug Administration (FDA) evaluated the safe use of alumina in several medical devices and aluminum hydroxide in over-the-counter drugs, which included a review of human and animal safety data. The Cosmetic Ingredient Review (CIR) Expert Panel considered the FDA evaluations as part of the basis for determining the safety of these ingredients as used in cosmetics. Alumina used in cosmetics is essentially the same as that used in medical devices. This safety assessment does not include metallic or elemental aluminum as a cosmetic ingredient. The CIR Expert Panel concluded that alumina and aluminum hydroxide are safe in the present practices of use and concentration described in this safety assessment.

Post-renal transplantation hypophosphatemia: a review and novel insights

PURPOSE OF REVIEW

This review intends to elucidate the pathophysiologic mechanism of renal phosphorus loss in the post-renal transplantation population. This review will provide new insight in to the pathophysiologic mechanism(s) responsible for the development of this phenomenon and will also explore the pathogenetic role of persistent phosphorus wasting in the development of post-renal transplantation osteodystrophy.

RECENT FINDINGS

Recently, the phosphaturic hormone, fibroblast growth factor-23, has been ascertain to be increased in the sera of patients with chronic kidney and end-stage renal disease. There is new evidence that a non-PTH humoral factor is persistently present in post-renal transplantation patients that is likely responsible for the observed persistent renal phosphorus loss. We offer that fibroblast growth factor-23 (and/or other phosphatonins) is the culprit factor responsible for the phenomenon of persistent hypophosphatemia in post-renal transplantation patients. Moreover, we believe that the phenomenon of persistent renal phosphorus wasting is an important but overlooked cause of osteodystrophy and increased fracture risk in this patient population.

SUMMARY

The pathophysiology of post-renal transplantation phosphorus wasting is complex and to date is still not fully recognized. Further studies of the regulatory mechanism of fibroblast growth factor-23 and its metabolism may offer additional insights into phosphorus homeostasis and its clinical application in the post-renal transplantation population.

Musculoskeletal manifestations of osteomalacia and rickets

Osteomalacia (OM) is still an important metabolic bone disease with increased prevalence in certain regions of the world as well as in the urban population of elderly confined. The disease presents with a wide variety of clinical, biochemical and radiographic manifestations mimicking other musculoskeletal disorders, including 'osteoporosis'. In this chapter, we provide the basis for its clinical diagnosis and management. There have been significant recent advances in the understanding of vitamin D deficiency and hypophosphataemic osteomalacia, which can now assist clinicians in the precise diagnosis and treatment of this disease. In this chapter we also review the various underlying aetiologies. The successful management of OM depends on the underlying aetiology.

Contemporary understanding and management of reflux and constipation in the general population and pregnancy: a consensus meeting

BACKGROUND

Gastro-oesophageal reflux disease (GERD) and constipation have a major impact on public health; however, the wide variety of treatment options presents difficulties for recommending therapy. Lack of definitive guidelines in pharmacy and general practice medicine further exacerbates the decision dilemma.

AIMS

To address these issues, a panel of experts discussed the principles and practice of treating GERD and constipation in the general population and in pregnancy, with the aim of developing respective treatment guidelines.

RESULTS

The panel recommended antacids 'on-demand' as the first-line over-the-counter treatment in reflux, and as rescue medication for immediate relief when reflux breaks through with proton pump inhibitors. Calcium/magnesium-based antacids were recommended as the treatment of choice for pregnant women because of their good safety profile. In constipation, current data do not distinguish a hierarchy between polyethylene glycol (PEG)-based laxatives and other first-line treatments, although limitations are associated with stimulant- and bulk-forming laxatives. Where data are available, PEG is superior to lactulose in terms of efficacy. In pregnancy, PEG-based laxatives meet the criteria for the ideal treatment.

CONCLUSIONS

The experts developed algorithms that present healthcare professionals with clear treatment options and management strategies for GERD and constipation in pharmacy and general practice medicine.

Aluminum toxicokinetics regarding infant diet and vaccinations

Some vaccines contain aluminum adjuvants to enhance the immunological response, and it has been postulated that this aluminum could contribute to adverse health effects, especially in children who receive a vaccination series starting at birth. The pharmacokinetic properties and end-point toxicities of aluminum are presented. In assessing the relevance of dietary and medical aluminum exposure to public health, we estimated infant body burdens during the first year of life for breast milk and formula diets and for a standard vaccination schedule. We then compared those body burdens with that expected for intake at a level considered safe for intermediate-duration exposure. The methodology blends intake values and uptake fractions with an aluminum retention function derived from a human injection study using radioactive 26Al. The calculated body burden of aluminum from vaccinations exceeds that from dietary sources, however, it is below the minimal risk level equivalent curve after the brief period following injection.

Review article: over-the-counter drugs and the gastrointestinal tract

An increasing number of drugs are becoming available over-the-counter, empowering patients to treat them- selves. Although drugs presently available over-the-counter are generally safe, there are issues of safety and possible delays in diagnosis of serious conditions. Therefore it is vital that patients are made aware of the indications and limitations of over-the-counter drugs through improved communication and education. Pharmacists and drug companies will have an increasingly important role in giving information and advice to patients. This review looks at the present and future of over-the-counter medication, highlighting the safety aspects.

An interesting case of osteomalacia due to antacid use associated with stainable bone aluminum in a patient with normal renal function

Antacids containing aluminum and magnesium hydroxide are widely used nonprescription agents for treatment of gastritis and peptic ulcer disease. One of the side effects of these antacids is that they bind phosphate in the gut, resulting in its malabsorption. Short-term use, consistent with the directions on the manufacturer's label, is safe and effective for most patients. Heavy chronic use, even when within label, can cause serious skeletal impairment. This report concerns the case of a 39-year-old pharmacist who self-mediated for peptic ulcer disease with high doses of a potent antacid containing aluminum and magnesium hydroxide. The patient consumed over 18 kg of elemental aluminum and 15 kg of elemental magnesium over 8 years of antacid use. This treatment resulted in the clinical syndrome of severe osteomalacia due to profound phosphate depletion. Bone biopsy revealed stainable aluminum deposits along 27.6% of the total bone surface, which is a unique observation in a patient with normal renal function. Treatment included withdrawing the antacid and supplementation with phosphate, calcium, and vitamin D. She experienced marked subjective and objective improvement with this regimen. This included a striking increase in her bone mineral density occurring over the 2-year follow-up period. This case documents that long-term antacid therapy, even when used by patients with normal renal function and within the manufacturer's label recommendations, can lead to severe phosphate depletion, osteomalacia, and toxic accumulation of aluminum and magnesium. This clinical syndrome was readily treated by withdrawal of the antacid and with calcium and phosphate supplementation. Physicians recommending treatment with these compounds or learning of their patient's self-medication with them should inform the patient of the potential serious side effects these agents can cause when used chronically at maximally recommended doses.

Osteomalacia

Osteomalacia is a generalized bone disorder characterized by impairment of mineralization, leading to accumulation of unmineralized matrix or osteoid in the skeleton. The classical clinical features of osteomalacia include musculoskeletal pain, skeletal deformity, muscle weakness and symptomatic hypocalcaemia. In childhood the features of osteomalacia are accompanied by rickets, with widening of the epiphyses and impaired skeletal growth. The major cause of osteomalacia is vitamin D deficiency, which is most often due to reduced cutaneous production of vitamin D in housebound elderly people, immigrants to Northern countries and women who adopt strict dress codes which prohibit exposure of uncovered skin. Vitamin D deficiency osteomalacia may also occur with malabsorption, liver disease and anticonvulsant therapy. Less commonly, osteomalacia may result from abnormal vitamin D metabolism, resistance to the action of vitamin D, hypophosphataemia or toxic effects on osteoblast function.

Antacid-induced osteomalacia

The case of a 49-year-old woman suffering from generalized skeletal pain and multiple fractures accompanied by severe hypophosphataemia and low urinary phosphorus excretion is reported. She had been taking large amounts of antacids containing aluminum hydroxide for many years. A diagnosis of antacid-induced osteomalacia was made. It was confirmed by biological work-up, radiographs and bone biopsy. A dramatic biological, osteodensitometric, and clinical improvement was achieved by withdrawal of antacids and phosphorus administration. The literature concerning this unusual condition has been reviewed.

Inhibition of bone resorption by inorganic phosphate is mediated by both reduced osteoclast formation and decreased activity of mature osteoclasts

High concentrations of inorganic phosphate (Pi) are known to inhibit bone resorption, although the mechanism(s) underlying this effect is unclear. To investigate whether Pi can inhibit the formation of osteoclasts we studied the effects of changes in Pi concentration between 1 and 4 mM on osteoclast-like cell formation in 1 week cultures of mouse bone marrow. Osteoclast-like cells were identified by multinuclearity, positive staining for tartrate-resistant acid phosphatase (TRAP), and contraction in response to calcitonin. Increasing concentrations of Pi inhibited formation of these cells in a dose-dependent manner. To study effects of Pi on the bone-resorbing activity of mature osteoclasts we isolated osteoclasts from calcium-deficient egg-laying hens or rat pups and incubated them on sperm whale dentine slices. High Pi concentrations markedly reduced both the number of resorption pits formed per dentine slice and the mean area of each pit in both avian and mammalian systems. These data indicate that high concentrations of Pi act on bone directly, both to inhibit generation of new osteoclasts from their precursor cells and to inhibit bone resorption by mature osteoclasts. These effects of extracellular Pi concentration may play an important modulatory role on bone turnover in vivo and have potential importance in several disease states in which Pi metabolism is perturbed.

Antacid-induced osteomalacia: a case report with a histomorphometric analysis

The case of a 75-year-old woman with severe osteomalacia secondary to ingestion of large amounts of an aluminum-containing antacid is reported. Biochemical analysis revealed signs of phosphate malabsorption and increased levels of bone markers (S-alkaline phosphatase and U-hydroxyproline). A 99mTc-bone scan revealed multiple areas of increased uptake. The patient was normocalcaemic, with normal serum levels of intact parathyroid hormone and 25-hydroxyvitamin D. Serum 1,25-dihydroxyvitamin D was high normal. A transiliac bone biopsy from the patient showed severe osteomalacia. Symptoms, biochemical parameters, bone scan and bone morphology were all normalized 1 year after stoppage of antacid ingestion and treatment with vitamin D2. calcium phosphate and sodium fluoride because of severe osteopeni. The characteristics of this condition and the role of phosphate depletion and aluminum in the pathogenesis of bone lesions are discussed.

Hypophosphatemic rickets with hypocalciuria following long-term treatment with aluminum-containing antacid

We present what we believe is the first case of rickets following prolonged treatment with aluminum containing antacids that bind phosphate, in an 18-year-old mentally retarded boy with cerebral palsy and spastic quadriplegia. As expected, serum calcitriol was increased and urinary phosphate excretion was very low. However, in contrast to all published cases of antacid induced hypophosphatemic osteomalacia in adults, despite a substantial increase in bone resorption reflected by urinary total hydroxyproline excretion, urinary calcium excretion was low rather than high, and significant hypocalcemia occurred after antacids were ceased and a phosphate salt administered. We suggest that the skeleton was so under-mineralized because of growth during prolonged phosphate deficiency, possibly augmented by anticonvulsant administration and immobilization, that increased bone resorption did not release enough calcium to cause hypercalciuria, or to prevent hypocalcemia during resumption of normal mineralization.

Antacid-induced phosphate depletion syndrome presenting as nephrolithiasis

A 29-year-old insulin-dependent diabetic woman developed phosphate depletion, nephrolithiasis and bilateral ureteric obstruction due to antacid abuse. Unlike previous descriptions of chronic phosphate depletion, myalgia, weakness and bone pain were absent. Biochemical features included hypophosphataemia, hypercalciuria, hypophosphaturia, elevated plasma, 1,25-dihydroxyvitamin D and low plasma intact parathyroid hormone. These abnormalities were corrected when antacid ingestion was reduced and phosphate intake supplemented. We propose that phosphate depletion secondary to antacid abuse caused 1 alpha-hydroxylase activation and elevation of the plasma 1,25-dihydroxyvitamin D level, leading to marked hypercalciuria. Once diagnosed, antacid abuse is a readily reversible cause of hypercalciuria and renal stones. Moreover, antacid-induced phosphate depletion may present with nephrolithiasis in the absence of musculoskeletal symptoms. This report is intended to draw attention to this important cause of renal stone disease.

Antacid and sucralfate-induced hypophosphatemic osteomalacia: a case report and review of the literature

A 42-year-old woman presented to our institution with a 2-week history of bone pain in the lower extremities. Her history was remarkable for duodenal ulcer and long-term treatment with a magnesium-aluminum hydroxide antacid (Maalox) and sucralfate. Initial laboratory studies showed severe hypophosphatemia and elevated alkaline phosphatase and serum 1,25-dihydroxyvitamin D levels. Bone scan showed multiple areas of increased uptake consistent with osteomalacia and microfractures. The patient recovered completely following withdrawal of antacids and sucralfate and short-term treatment with phosphate. Although hypophosphatemia induced by aluminum-containing antacids is rare, treatment of peptic ulcer disease with a combination of two aluminum-containing agents may increase the risk of clinically significant hypophosphatemia. Awareness of this condition is important, because early recognition can prevent morbidity and lead to safe and effective treatment.

Aluminum speciation studies in biological fluids. Part 3. Quantitative investigation of aluminum-phosphate complexes and assessment of their potential significance in vivo

Following the discovery that specific health disorders affecting patients with renal disease were due to their excessive body accumulation of aluminum, it was established that aluminum toxicity was mainly due to the ingestion of aluminum-containing phosphate binders. Suspicion of toxicity was thus cast on aluminum-containing antacids, and subsequent tests held on healthy subjects did reveal that aluminum hydroxide gels were also potential oral sources of aluminum, especially in the presence of citric acid. Nevertheless, authors of these tests concluded that there was only marginal absorption of aluminum phosphate. In contrast with these clinical conclusions, it has recently been contended on theoretical grounds that aluminum phosphate represents a serious health hazard. To help elucidate this issue, this paper first deals with a quantitative investigation of aluminum-phosphate equilibria under physiological conditions. Then appropriate computer simulations based on corresponding results are used to assess the actual extent to which phosphate can influence aluminum bioavailability. These simulations confirm that aluminum phosphate is not expected to induce absorption of high amounts of aluminum when administered by itself. Nevertheless, this result may no longer apply in the presence of food, whose various acidic components are likely to modify the involved chemical equilibria. Moreover, it is shown that rising blood plasma phosphate levels should tend to increase aluminum tissue penetration and hence favor its potential toxicity.

Effects of parathyroidectomy on tissue calcium, phosphorus, magnesium, and copper concentrations in aluminum-loaded uremic rats

Rats were subjected to a two-stage 5/6 nephrectomy and treated with Al for 2 and 4 wk with a cumulative dose of 4.2 and 8.4 mg of Al, respectively. Other animals were parathyrectomized (PTx) and loaded with 8.4 mg of Al for 4 wk. Total Al, Ca, P, Mg, and Cu contents were analyzed in the liver, kidney, and bone by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that Al given to growing uremic rats significantly increased the content of Al in the liver, kidney, and bone. Moreover, Al treatment increased the liver and kidney Ca levels and decreased the Ca and P values in bone. Previous parathyroidectomy significantly reduced Al accumulation within organs and changes in the Ca and P levels in the bone, liver, and kidney. The result was not influenced by different degrees of renal failure.

Aluminum speciation studies in biological fluids. Part 2. Quantitative investigation of aluminum-citrate complexes and appraisal of their potential significance in vivo

Because of the recent implications of aluminum in the pathogenesis of various disease states, its in vivo chemistry has been receiving growing attention from bioinorganic chemists over the last few years. In this context, the elucidation of the main factors that govern aluminum bioavailability constitutes an urgent objective. Clearly, prevention measures require that mechanisms of aluminum absorption be definitely characterized, whereas specific sequestering agents are needed to detoxify patients with high-aluminum-body burdens. In particular, speciation studies are necessary to discriminate among the chemical forms under which aluminum predominates in vivo. Low molecular weight (LMW) species, which are the most active in terms of bioavailability, cannot be assessed by analytical techniques, and so computer simulations must be used. In recent clinical studies as well as in preliminary simulations dealing with aluminum distribution in blood plasma, citrate has been recognized as the most important LMW ligand of aluminum. The present paper thus reports a quantitative investigation of aluminum-citrate equilibria, carried out at 37 degrees C in NaCl 0.15 mol dm-3 in accordance with the experimental protocol defined in our previous study on aluminum hydrolysis. The ML, MLH, ML2, M3L3H-4, M2L2H-2, ML2H-1, and ML2H-2 species have been characterized over the whole physiological pH range using as large reactant concentration ratios as possible. Corresponding formation constants have then been used to investigate the role of citrate towards aluminum bioavailability. Blood plasma simulations reveal that citrate can promote aluminum urinary excretion, which substantiates recent clinical observations made on mice. However, the higher plasma aluminum concentrations are, the less effective citrate is to be expected. Gastrointestinal simulations confirm that the electrically neutral ML complex does represent an important risk of aluminum absorption in the upper region of the gastrointestinal tract at usual therapeutic doses. At moderate- and low-aluminum concentrations, citrate is also capable of dissolving the aluminum trihydroxide precipitate, which may combine with the capacity of other ligands to complex Al3+ into absorbable complexes at less acidic pH.

Aluminum and chronic renal failure: sources, absorption, transport, and toxicity

In normal subjects the gastrointestinal tract is a relatively impermeable barrier to aluminum with a low fractional absorption rate for this metal ion. Aluminum absorbed from the gastrointestinal tract is normally excreted by the kidneys; in the presence of impaired renal function aluminum is retained and accumulates in body tissues. Aluminum-containing medications are given, by mouth, to patients with chronic renal failure as phosphate-binding agents for the therapeutic control of hyperphosphatemia. Patients with chronic renal failure are also exposed to aluminum in domestic tap-water supplies used either for drinking or, in those on dialysis treatment, in the preparation of their dialysate. In patients with end-stage chronic renal failure, particularly in those on treatment by hemodialysis, the accumulation of aluminum in bone, brain, and other tissues is associated with toxic sequelae. An increased brain content of aluminum appears to be the major etiological factor in the development of a neurological syndrome called either "dialysis encephalopathy" or "dialysis dementia"; an increased bone content causes a specific form of osteomalacia. An excess of aluminum also appears to be an etiological factor in a microcytic, hypochromic anemia that occurs in some patients with chronic renal failure on long-term treatment with hemodialysis. The various mechanisms involved in the toxic phenomena associated with the accumulation of aluminum in body tissues have not been clearly defined but are the subject of extensive investigations.

Medical reversal of acquired hypophosphatemic osteomalacia

Hypophosphatemic osteomalacia may present as severe disability from bone disease. This report describes a patient with long-standing disease and multiple fractures. Medical management of the phosphate loss may be successful in promoting bone healing when it is not possible to establish the cause of the phosphaturia. Judicious increases in calcium, 1,25-dihydroxyvitamin D, and phosphorus supplements were carefully monitored to avoid failure of therapy or hypercalcemic complications from pharmacologic amounts of these supplements.

Influence of aluminum on mineralization during matrix-induced bone development

A model of de novo mineralization employing matrix-induced endochondral bone formation in rats was used to study the short-term effects of aluminum on the deposition of calcium and phosphate in vivo. In experiments where systemic aluminum concentrations were elevated, the cellular processes associated with bone development appeared to be normal, if somewhat delayed, however precipitation of the mineral phase was prevented. This suggests a primary direct physical chemical effect of aluminum in vivo on calcification, as suggested by in vitro studies which demonstrate that aluminum is a potent inhibitor of calcium phosphate precipitation. Aluminum salts implanted locally with the matrix appeared to be toxic to the cellular processes leading to chondrogenesis and osteogenesis.