Drugs as a hidden source of aluminium for chronic renal patients

Chronic aluminium exposure and toxicity related to aluminium absorption continue to be a problem for many patients with renal failure [1]. The two most prevalent sources of aluminium are water used to prepare dialysate and aluminium-containing phosphate binders. However, calcium-based binders, Sevelamer or others, have replaced aluminium phosphate binders and reverse osmosis has been used for water treatment in almost all haemodialysis centres [2–4]. In spite of the reduced exposure of patients to aluminium through these sources, patients on regular renal dialysis present abnormal plasma/serum aluminium levels [5]. In the United Kingdom [6], plasma aluminium was audited over the period of January 2000 to January 2004, resulting in a collection of results for 1626 patients. The range was 1.9–817 mg/l, with a mean value of 12.7mg/l. In the United States, a survey examined retrospectively 1410 measurements of serum aluminium from January 2000 through April 2003 [7]. Although aluminium serum values were satisfactory considering the evolution of the treatment conditions, they cannot be considered within the normal range for all patients, below 15 g/l [7–10]. Patients with renal insufficiency are often on multiple medication. From 80 to 90% of individuals with chronic kidney disease have problems with high blood pressure at some time during the disease. Medicines are used to keep blood pressure in a safe range and to slow the progression of kidney damage caused by this disturbance. Erythropoietin (Epo) and iron supplementation may be used to treat anaemia, which frequently occurs in certain chronic kidney diseases. Specific medications are sometimes needed to treat imbalances of electrolytes, such as high potassium, high phosphate and low calcium levels. Diuretics are also frequently used to treat fluid build-up caused by chronic kidney diseases. Patients on haemodialysis often receive medication for heart failure. Although complying with pharmacopoeias’ prescription related to quality, drugs may have aluminium as impurity and therefore be an extra aluminium source for the patients. Moreover, most formulations contain not only active ingredients but also additives, excipients and vehicles, used to dilute or aggregate the preparation. Certain products can inadvertently contain aluminium in its formulation. Talcum, a common excipient, may present an elevated amount of aluminium, since aluminium oxide can be one of its constituents. In this study we investigated whether the medicines taken by patients on haemodialysis treatment can be an aluminium source. Commercial products, active ingredients and all other substances that comprise these formulations were analysed for their aluminium content.