Antacids, metals used

Aluminium is poorly absorbed from the GI tract, which is just as well since antacid preparations used by dyspeptic patients may contain as much as 500 mg of aluminium per tablet. Aluminium levels in water supplies are variable and may contain from less than 50 to more than I0(K) jg/l. This is a potential hazard to renal dialysis patients when the aluminium can enter the body across the dialysis membrane, thus bypassing intestinal absoiption. The water used in dialysis is now treated to remove contaminating metals. Acute aluminium toxicity is extremely rare. Aluminium toxicity in patients with renal dysfunc-... 

Annealing Heating and cooling a metal, glass, or alloy in a manner that makes it less brittle Anion An atom or group of bonded atoms that has a negative chaise for example, Cl , NO j Anode Electrode at which electrons flow out of an electrochemical cell and oxidation takes place Antacid Base used to neutralize excess hydrochloric acid in the stomach... 

Uydrate of potassa is a most valuable agent to the chemist, and especially in the estimation of the carbon of organic bodies. It is also used to displace metallic oxides from their combinations, ae a solvent for oxides or zino and alumina, also for the decomposition of silicioua minerals by fusion, for drying certain gases, and a variety of ether purposes. In surgery, it is used in the solid stata, cost into sticks, as a most powerful caustie. In medicine, its solution is also frequently employed, especially os an antacid. 

The widely used antacid called milk of magnesia is an aqueous suspension of Mg(OH)2. How would you prepare Mg(OH)2 from magnesium metal ... 

The alkaline earth metal hydroxides M(OH)2 (M = Mg, Ca, Sr, or Ba) are also strong bases ( 100% dissociated), but they give lower OH- concentrations because they are less soluble. Their solubility at room temperature varies from 38 g/L for the relatively soluble Ba(OH)2 to 10-2 g/L for the relatively insoluble Mg(OH)2. Aqueous suspensions of Mg(OH)2, called milk of magnesia, are used as an antacid. The most common and least expensive alkaline earth hydroxide is Ca(OH)2, which is used in making mortars and cements. It is called slaked lime because it is made by treating lime (CaO) with water. Aqueous solutions of the slightly soluble Ca(OH)2 (solubility 1.3g/L) are known as limewater. 

Aluminum compounds are used in many diverse and important industrial applications such as alums in water-treatment and alumina in abrasives and furnace linings. They are found in consumer products such as antacids, astringents, buffered aspirin, food additives, and antiperspirants. Powdered aluminum metal is often used in explosives and fireworks. To learn more about the properties and uses of aluminum, see Chapters 3 and 4. 

We are all exposed to aluminium from the metal utensils we use and also from the occasional use of medicinal preparations such as antacids, but it is poorly absorbed and the risk is probably very small. Dialysis patients with renal disease were found to be at risk of brain damage due to the aluminium derived from the equipment. Realization of this led to a lowering of the exposure of such patients, which decreased the occurrence of toxic effects of aluminium. Patients on dialysis with end stage renal disease, in whom some accumulation of aluminium occurred, showed evidence of metabolic abnormalities and in psychomotor function. 

Antacids are basic substances that reduce gastric acidity by neutralising HCl. The hydroxide is the most common base but trisilicate, carbonate and bicarbonate are also used. Therapeutic efficacy and adverse effects depend also on the metallic ion with which the base is combined, and this is usually aluminium, magnesium or sodium. Calcium and... 

Antacids used in indigestion treatments have differing neutralising capacities, and the degree to which they are absorbed systemically also varies, influencing their duration of action. Soluble salts act quickly but are absorbed rapidly, so have a short duration of action, whereas salts of divalent and trivalent metal ions are insoluble and have a less rapid but more prolonged action. In addition some compounds form a protective layer... 

Problem The popular reaction of sodium or lithium with water often leads students to make the statement that the metal disappears - like a fizzing antacid tablet that dissolves in water . On the one hand, one can see gas as a product and the color change by using an indicator solution. On the other hand, after heating the solution and evaporating the water - it is possible to obtain a white solid, sodium hydroxide. Instead of disappearing , the metals react with water to form a hydroxide solution and the gas hydrogen. 

The analytical measurement of elemental concentrations is important for the analysis of the major and minor constituents of pharmaceutical products. The use of atomic spectroscopy in this regard has been the subject of several reviews (2,3,35,36). Metals are major constituents of several pharmaceuticals such as dialysis solutions, lithium carbonate tablets, antacids, and multivitamin-mineral tablets. For these substances, spectroscopic analysis is an important tool. It is indispensable for the determination of trace-metal impurities in pharmaceutical products and the qualitative and quantitative analysis of metals, essential and toxic, in biological fluids and tissues (37). Beyond this, several drugs which do... 

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