Aluminum bioavailability

Yokel RA, McNamara PJ. 1985. Aluminum bioavailability and disposition in adult and immature rabbits. Toxicol Appl Pharmacol 77 344-352. 

Yokel, R.A. and Florence, R.L., Aluminum bioavailability from the approved food additive leavening agent acidic sodium aluminum phosphate, incorporated into a baked good, is lower than from water, Toxicology, 227(1-2), 86, 2006. 

This apparent paradox is resolved if the hypothesis that silicon limits aluminum bioavailability is adopted. Aluminum and silicon concentrations in potable water are inversely related. High aluminum and low silicon levels are found in soft waters from high, well-weathered, acidic catchment areas requiring aluminum coagulation... 

Yatani A, Brown AM (1991) Mechanism of fluoride activation of G protein-gated muscarinic atrial K channels. J Biol Chem 266 22872-222877 Yates CM, Simpson J, Russel D, Gordon A (1980) Cholinergic enzymes in neurofibrillary degeneration produced by aluminium. Brain Res 197 269-274 Yokel RA, McNamara PJ (1985) Aluminum bioavailability and disposition in adult and immature rabbits. Toxicol Appl Pharmacol 77 344-352 Zaman K, Mukhtar M, Siddique H, Miszta H (1992) The effect of aluminum on the stromal cells in vitro on bone marrow in rats. Toxicol Ind Health 8 103-109 Zaman K, Zaman W, Dabrowski Z, Miszta H (1993) Inhibition of delta amino-evulinic acid dehydratase activity by aluminum. Comp Biochem Physiol 104C 269-273... 

When administered with ranitidine, alendronate bioavailability is increased. When calcium supplements or antacids are administered with risedronate or alendronate, absorption of the bisphosphonates is decreased, hi addition, risedronate absorption is inhibited when the drug is administered with magnesium and aluminum. There is an increased risk of gastrointestinal... 

Calcium citrate should not be administered with aluminum-containing compounds. Concomitant administration may increase systemic bioavailability of aluminum and predispose to toxicity... 

In terms of pharmacokinetics, LVX has an excellent profile. With an oral dose of 500 mg, LVX has a bioavailability of >99%, an AUC range of 41.9-47.7 mgh/mL, Cmax of 4.5-6.2 mg/mL, a clearance of 10.5-11.9 L/h, and a volume of distribution (Vd) of 1.3 L/kg (Hurst et al., 2002). In terms of protein bound material, only 24-38% is affected (Fish, 2003). Like other fluoroquinolones, there is a 19-44% AUC reduction when co-administered with an aluminum or magnesium antacid or iron sulfate (Qaqish and Polk, 2003). The major metabolite of levofloxacin arises from glucuronidation (Brysk-ier, 2005). 

In discussing nickel exposure, it is important to consider what form of nickel a person is exposed to and its bioavailability. Such information is not often available. Although high concentrations of nickel may be found in contaminated soil and sediment, it may be embedded in a crystalline matrix or bound to hydrated iron, aluminum, and manganese oxides and, therefore, not bioavailable. 

Azithromycin is rapidly absorbed and well tolerated orally. It should be administered 1 hour before or 2 hours after meals. Aluminum and magnesium antacids do not alter bioavailability but delay absorption and reduce peak serum concentrations. Because it has a 15-member (not 14-member) lactone ring, azithromycin does not inactivate cytochrome P450 enzymes and therefore is free of the drug interactions that occur with erythromycin and clarithromycin. 

Metal bioavailability is generally increased with decreasing pH. This is due to the presence of phosphoric, sulfuric and carbonic acids, which increasingly solubilize organic- and particulate-bound metals. Particulate-bound metals are considered those bound to secondary minerals, for example, clays, iron and aluminum oxides, carbonates and sulfidic and phosphoric minerals. Due to the heterogeneous nature of soils and sediments, wide fluctuations in pH can exist in a given environment. For instance, metals may be more soluble in surface layers where plant exudates, microbial activity, moisture and leaching lower pH. 

Once mineral-bound aluminum is recovered from ores, it forms metal complexes or chelates. Examples of the different forms of aluminum include aluminum oxide, aluminum chlorhydrate, aluminum hydroxide, aluminum chloride, aluminum lactate, aluminum phosphate, and aluminum nitrate. The metal itself is also used. With the exception of aluminum phosphide, the anionic component does not appear to influence toxicity, although it does appear to influence bioavailability. Aluminum phosphide, which is used as a pesticide, is more dangerous than the other forms however, this is because of the evolution of phosphine gas (a potent respiratory tract and systemic toxin) rather than to the exposure to aluminum. 

The influence of some of the aforementioned factors on aluminum absorption is further illustrated by the findings of two animal studies which estimated bioavailability differences by comparing areas under plasma concentration-time curves (AUC) after oral and intravenous dosing (Yokel and McNamara 1988). Using a single oral dose of aluminum chloride, aluminum absorption was estimated to be 0.57% in... 

Gastrointestinal absorption of aluminum is low, generally in the range of 0.1-1 % in humans as discussed in Section 2.3.1.2. Absorption of aluminum compounds is largely determined by its bioavailability in the aqueous conditions of the gut, which is mainly related to pH, the presence of complexing ligands with... 

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