Antacids

Magnesium oxide is an effective nonsystemic antacid, ie, it is converted to the hydroxide. It does not neutralize gastric acid excessively nor does it hberate carbon dioxide. The light form is preferable to the heavy for adininistration in Hquids because it is suspended more readily. One gram of magnesium oxide neutralizes 87 mL of 0.1 NUCl in 10 min, and 305 mL in 2 h. 

Magnesium trisihcate is a nonsystemic antacid and an adsorbent. It has a slow onset of activity and is a relatively weak antacid. It may cause diarrhea in large doses owing to soluble magnesium salts. One gram of magnesium trisihcate neutralizes 10 mL of 0.1 NUCl in 10 min, and 15 mL in 2 h. 

Magaldrate is an antacid having somewhat more efficacy than aluminum hydroxide. It does not appear to disturb electrolyte balance or bowel function. 

Sodium bicarbonate is a gastric antacid that may cause systemic alkalosis on overdose and may contribute to edema owing to sodium retention. It is useful for systemic acidosis because both deficient ions are present in the same molecule, and it can be used topically as a moist paste or in solution as an antipmritic. Sodium bicarbonate also is an ingredient of many effervescent mixtures, alkaline solutions, etc. One gram of NaHCO neutralizes 115 mL 0.1 NHCl. 

Hydrogen chloride in air can also be a phytotoxicant (88). Tomatoes, sugar beets, and fmit trees of the Pmnus family are sensitive to HCl in air. Exposure of concentrated hydrochloric acid to the skin can cause chemical bums or dermatitis. Whereas the irritation is noticed readily, the acid can be water flushed from the exposed area. Copious use of miming water is the only recommended safety procedure for any external exposure. Ingestion is seldom a problem because hydrochloric acid is a normal constituent of the stomach juices. If significant quantities are accidentally swallowed, it can be neutrali2ed by antacids. 

USP-grade anhydrous magnesium carbonate is used as a flavor impression intensification vehicle in the processed food industry (see Flavors and spices). Basic magnesium carbonates are used as free flowing agents in the manufacture of table salt, as a hulking agent in powder and tablet pharmaceutical formulations, as an antacid, and in a variety of personal care products (see Pharmaceuticals). 

The principal OTC pharmaceutical products include cold remedies, vitamins and mineral preparations, antacids, analgesics, topical antibiotics, antiftingals and antiseptics, and laxatives. Others include suntan products, ophthalmic solutions, hemorrhoidal products, sleep aids, and dermatological products for treatment of acne, dandmff, insect parasites, bums, dry skin, warts, and foot care products (11). More recent prescription-to-OTC switches have included hydrocortisone, antihistamine and decongestant products, antiftingal agents, and, as of 1995, several histamine H2-receptor antagonists. 

One appHcation patented ia 1989 is the injection of sodium alumiaate into silica-containing formations for enhanced petroleum recovery (39). Additionally, the pharmaceutical industry uses sodium alumiaate as an alkaline source of aluminum for the production of certain antacids (40). 

Sodium sulfate in moderation is used as a diuretic and cathartic for humans and animals (14) (see Gastrointestinal agents). It is also used in consumer products such as laxatives, antacids, and as a natural filler it is used extensively in powdered laundry detergents (see Detergency). 

Sucralfate [54182-58-0] an aluminum salt of sucrose octasulfate, is used as an antacid and antiulcer medication (59). Bis- and tris-platinum complexes of sucrose show promise as antitumor agents (60). Sucrose monoesters are used in some pharmaceutical preparations (21). A sucrose polyester is under evaluation as a contrast agent for magnetic resonance imaging (mri) (61). Oral adrninistration of this substance opacifies the gastrointestinal tract and eliminates the need for purging prior to mri. 

Ketoconazole. For treatment of systemic mycoses with amphotericin B or miconazole, the patient must be admitted to a hospital. This is not always possible, particularly in areas where systemic mycoses occur frequently, nor is it always desirable, because of the expense. For these reasons, it was desirable to find an antimycotic that combined safety and broad-spectmm activity with oral adraiinistration. Ketoconazole (10), which is orally active, met most of these requirements. This inhibitor of the ergosterol biosynthesis is an A/-substituted imidazole, that differs from its precursors by the presence of a dioxolane ring (6,7). Ketoconazole is rapidly absorbed in the digestive system after oral adrninistration. Sufficient gastric acid is required to dissolve the compound and for absorption. Therefore, medication that affects gastric acidity (for example, cimetidine and antacids) should not be combined with ketoconazole. 

Bismuth subcarbonate [5892-10 ] (basic bismuth carbonate) is a white or pale yellow powder that is prepared by interaction of bismuth nitrate and a water-soluble carbonate. The exact composition of this dmg depends on the conditions of precipitation it corresponds approximately to the formula (Bi0)2C02. It has been widely used as an antacid (183). 

Bismuth subnitrate [1304-85-4] (basic bismuth nitrate) can be prepared by the partial hydrolysis of the normal nitrate with boiling water. It has been used as an antacid and in combination with iodoform as a wound dressing (183). Taken internally, the subnitrate may cause fatal nitrite poisoning because of the reduction of the nitrate ion by intestinal bacteria. 

Calcium carbonate is used in food and pharmaceutical appHcations for both its chemical and physical properties. It is used as an antacid, as a calcium supplement in foods, as a mild abrasive in toothpaste, and in chewing gum to name only a few (see EoOD ADDITIVES). 

Ion exchangers are sometimes used on a throwaway basis also. In the laboratoiy, ion exchangers are used to produce deionized water, purify reagents, and prepare inorganic sols. In medicine, they are used as antacid, for sodium reduction, for the sustained release of drugs, in skin-care preparations, and in toxin removal. 

Domestic and phannaceudcal uses of precipitated CaC03 include its direct use as an antacid, a mild abrasive in toothpastes, a source of Ca enrichment in els, a constituent of chewing gum and a filler in cosmetics. 

Stomach acid is approximately 0.020 M HC1. What volume of this add is neutralized by an antacid tablet that weighs 330 mg and contains 41.0% Mg(OH)2, 36.2% NaHCOj, and 22.8% NaCl The reactions involved are... 

The oxides of the Group 1 and Group 2 metals are sometimes referred to as basic anhydrides (bases without water) because of this reaction. The reaction with CaO is referred to as the slaking of lime it gives off 65 kj of heat per mole of Ca(OH)2 formed. A similar reaction with MgO takes place slowly to form Mg(OH)2, the antacid commonly referred to as Milk of Magnesia. ... 

Antacids are neutralizing agents. Examples are magnesium hydroxide, magnesium trisylicate and aluminium hydroxide. Prior to the introduction of histamine-H2 receptor antagonists and proton pump inhibitors, they were the standard drugs for the treatment of duodenal/ peptic ulcers. Today their clinical use is limited to the treatment of dyspepsia and the symptomatic relieve for patients with peptic ulcers. 

Marble. A variety of limestone (CaCOa). It is a hard, very si porous stone, which occurs in nature in many forms and colors. It may be prepd artificially by the recrystn of limestone under great press and at high temp. In powd form it has been used as an antacid ingredient of some Dynamites (see under). Silberrad... 

---