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Home , Aluminium phosphate, Calcium carbonate

A. S YSTEMIC :  They are soluble, readily absorbed and capable of changing the pH of extracellular fluid. Above all, the main criteria of these type of antacids is they produce Systemic .  E.g: bi-. (NaHCO3)  AKA baking soda most available product that is used as an having a rapid on set of action by neutralizing the gastric .  It causes a sharp increase of gastric pH up to or above pH-7 NaHCO3 + HCI -> NaCI + H2O + CO2 1 ADVERSE REACTIONS FOR SODIUM ANTACIDS

 The release of CO2 with resultant belching of flatulence causes gastric distention, posing a risk to people who have gastric ulcers approaching the perforation stage.  Systemic alkalosis may also occur.

2 B.N ON SYSTEMIC ANTACIDS :

 They form insoluble compounds. They have poor absorption capacity. They don’t produce any systemic effects.  Examples:  hydroxide [Mg(OH]2  hydroxide [A1(OH)3  Carbonate [CaCO3]  Combined Antacids.

3 MAGNESIUM CONTAINING ANTACIDS :

There are a large number of officials magnesium containing antacids. They are : I. II. III. IV. Magnesium Trisilicate

4  With the possible exception of Magnesium Trisilicate they all function in the same manner. Among them magnesium Hydroxide available as of Magnesia in the market is one of the best well-known magnesium containing antacid. It is also used as laxative.  Adverse effects :  It has a mild cathartic effect  Magnesium hydroxide has laxative properties.  Magnesium may accumulate in patients with renal failure leading to hypomagnesaemia, with cardiovascular and neurological

complications. 5  Magnesium hydroxide  Magnesium hydroxide is an inorganic compound with

the Mg(OH) 2. As a in , it is often called milk of magnesia because of its milk-like appearance. The form of magnesium hydroxide is known as brucite .  Magnesium hydroxide is a common component of antacids and laxatives ; it interferes with the absorption of folic acid and .[3] Magnesium

hydroxide has low in water, with a Ksp of 1.5×10 −11 meaning it is insoluble in water; all of magnesium hydroxide that does dissolve does dissociate. Since the dissociation of this small amount of dissolved magnesium hydroxide is complete, magnesium hydroxide is considered a strong 6 electrolyte.  History

 In 1829, Sir James Murray used a fluid magnesia preparation of his own design to treat the Lord Lieutenant of Ireland, the Marquis of Anglesey. This was so successful (advertised in and approved by the Royal College of Surgeons in 1838) [4] that he was appointed resident physician to Anglesey and two subsequent Lords Lieutenants, and knighted. His fluid magnesia product was patented two years after his death in 1873. [5]

 The term milk of magnesia was first used for a -colored, aqueous, mildly alkaline suspension of magnesium hydroxide formulated at about 8 %w/v by Charles Henry Phillips in 1880 and sold under the brand name Phillips' Milk of Magnesia for medicinal usage.

 Although the name may at some point have been owned by GlaxoSmithKline , USPTO registrations show "Milk of Magnesia" to be registered to Bayer ,[6] and "Phillips' Milk of Magnesia" to Sterling Drug .[7] In the UK, the non-brand (generic) name of "Milk of Magnesia" and "Phillips' Milk of Magnesia" is "Cream of Magnesia" (Magnesium Hydroxide Mixture, BP).

 Preparation

 Magnesium hydroxide can be precipitated by the metathesis reaction between magnesium and sodium , potassium , or ammonium hydroxide : 2+ −  Mg (aq ) + 2 OH (aq ) → Mg(OH) 2 (s)

 Uses

 Suspensions of magnesium hydroxide in water, often called Milk of Magnesia, are used as an antacid to neutralize stomach acid , and as a laxative. The diarrhea caused by magnesium hydroxide carries away much of the body's supply of potassium , and failure to take extra potassium may to muscle cramps .[8] Magnesium hydroxide is also used as an antiperspirant underarm deodorant .[9] Milk of magnesia is useful against canker sores (aphthous ulcer) when used topically. [10]

 Milk of magnesia is sold for medical use as chewable tablets, capsules, and as liquids having various added flavors. It is primarily used to alleviate constipation , but also to relieve indigestion and heartburn . When taken orally as a laxative, the osmotic force of the magnesia suspension acts to draw fluids from the body and to retain those already within the lumen of the intestine , serving to distend the bowel, thus stimulating nerves within the colon wall, inducing peristalsis and resulting in evacuation of colonic contents. It is also used as an antacid, though more modern formulations such as Maalox combine the antimotility effects of equal 7 concentrations of aluminum hydroxide to avoid unwanted laxative effects.

 Milk of magnesia is also used as a folk remedy, applied and massaged into the scalp a few minutes before washing, to relieve symptoms of seborrhea and dandruff . The mechanisms for its effectiveness in this application, like the causes of seborrhea itself, are unknown. An additional folk use is for the treatment of acne or oily skin by applying topically, allowing to dry, and then washing it off the face (or other body part). It is  Magnesium hydroxide powder is used industrially as a non-hazardous alkali to neutralise acidic wastewaters. [12] It also takes part in the method of building artificial reefs .

 Solid magnesium hydroxide also has smoke suppressing and fire retarding properties. This is due to the endothermic decomposition it undergoes at 332 °C (630 °F) :

 Mg(OH) 2 → MgO + H 2O

 The heat absorbed by the reaction acts as a retardant by delaying ignition of the associated substance. The water released dilutes any combustible gases and inhibits from aiding the combustion. Common uses of magnesium hydroxide as a fire retardant include plastics, roofing, and coatings. Another mineral mixture that is used in similar fire retardant applications are natural mixtures of huntite and hydromagnesite .[13][14]

 Biological metabolism

 When the patient drinks the milk of magnesia, the suspension enters the stomach . Depending on how much was taken, one of two possible outcomes will occur.

 As an antacid, milk of magnesia is dosed at approximately 0.5–1.5g in adults and works by simple + neutralization , where the hydroxide from the Mg(OH) 2 combine with acidic H ions produced in the form of by parietal cells in the stomach to produce water.

 As a laxative, milk of magnesia is dosed at 2–5 g, and works in a number of ways. First, Mg 2+ is poorly absorbed from the intestinal tract, so it draws water from the surrounding tissue by osmosis . Not only does this increase in water content soften the feces, it also increases the volume of feces in the intestine (intraluminal volume) which naturally stimulates intestinal motility. Furthermore, Mg 2+ ions cause the release of cholecystokinin (CCK), which results in intraluminal accumulation of water, electrolytes, and increased intestinal motility. Although it has been stated in some sources, the hydroxide ions themselves do not play a significant role in the laxative effects of milk of magnesia, as basic solutions (i.e. solutions of hydroxide ions) 2+ are not strongly laxative, and non-basic Mg solutions, like MgSO 4, are equally strong laxatives for mole. [15]

 Only a small amount of the magnesium from milk of magnesia is usually absorbed from a person's intestine (unless the person is deficient in magnesium). However, magnesium is mainly excreted by the kidneys so long- term, daily consumption of milk of magnesia by someone suffering from renal failure could lead in theory to hypermagnesemia. 8  As with any other , some people may have adverse reactions to milk of magnesia. These can include weakness, nausea, vomiting, and diarrhea. High doses increase the likelihood of these reactions. Patients with severe are advised to avoid overconsumption of milk of magnesia. Because the kidney functions to excrete magnesium, taking too much would wear out the kidney and lead to toxic levels of magnesium in the blood. Healthy individuals should not use this type of medication continuously for longer : C ACO3  The calcium containing preparations: Specially of CaCO3 are considered by some to be the antacids of choice.  They have rapid action (1 gm, neutralizes 21 meq, of acid) of largely nonsystemic.

CaCO3 + 2HCI -> CaCI2 + H2O + CO2

9  Adverse effects for calcimu carbonate antacids:  It has a tendency to produce constipation which may be reduced in combination with magnesium antacid.  The most serious side effect is Milk alkali syndrome. This can occur during prolonged administration of large doses of CaCO3 together with large amounts of milk.  The other effects are Renal insufficiency, Hypercalcemia, Hyperphospatemia and

Azotemia. 10  Adverse effects of calcium containing antacids  Excess calcium from supplements, fortified food and high-calcium diets, can cause the milk-alkali syndrome, which has serious toxicity and can be fatal. (renal failure, alkalosis, and .  Calcium has been added to over-the-counter products, which contributes to inadvertent excessive intake. The New England Journal of Medicine reported a typical case of a woman who arrived in the emergency department vomiting and in altered mental status, writhing in pain. She had consumed large quantities of chewable antacid tablets containing calcium carbonate. She gradually recovered.  Compounds containing calcium may also increase calcium output in the urine, which might be associated 11 with kidney stones.  Calcium salts may cause constipation.  Other adverse effects from antacids include:  Carbonate : regular high doses may cause alkalosis, which in turn may result in altered excretion of other drugs, and kidney stones.  A chemical reaction between the carbonate and hydrochloric acid may produce gas. This causes gastric distension which may not be well tolerated.  Carbon dioxide formation can also lead to headaches and decreased muscle flexibility.

12 ALUMINUM CONTAINING A NTACIDS They are widely used. They are nonsystemic and also called "Buffer antacids" as they don’t raise the gastric pH above 4.5. Examples are: 1.Alluminium Carbonate  Dried basic aluminum carbonate gel occurs as a white powder. It is insoluble in water and alcohol Al2Co3 is a white creamy thyrotrophic gel and contains equivalents of 4.9–5.3% aluminum oxide and not less than 2.4% Carbon Dioxide . 13 2.Alluminium Hydroxide Al(OH)3 –  Dried al(OH)3 gel occurs as a white odourless,tasteless,amorphases powder and is insoluble in water and alchol.They are found in two dosages forms as, Aluminum hydroxide Gel Dried Aluminum hydroxide Gel . First one is in suspension form and 2nd one is in form. Both of them are popular antacids 14 but the gel has more rapid onset of action than the dried gel. 3. Alluminium Phosphate – • Aluminum Phosphate gel is a white suspension; on standing small amount of water may separate from the suspension. The suspension contains 4-5% aluminum phosphate and may contain preservations. 4. Dihydroxyl Aluminum Aminodcltate –  It occurs as a white odorless powder that has a family sweet and is insoluble in water.  The powder contains 35.5 -38.5% Aluminum Oxide calculated on a dry basis and they contain small amount of aluminum oxide and

Amino . 15 ADVERSE EFFECTS OF ALUMINIUM CONTAINING ANTACIDS  Aluminum salts possess the least amount of neutralizing capability of the antacid ingredients, particularly the aluminum phosphate , and are almost always combined with a magnesium salt.  They are also slower to act than and calcium carbonate.  Although aluminum hydroxide is relatively safe, reports of aluminum accumulation after long-term use suggest that prolonged, indiscriminate use of aluminum-containing antacids carry some risk. 16 As with magnesium salts, aluminum hydroxide should not be used by patients with kidney damage. Aluminum hydroxide may lead to the formation of insoluble aluminium- phosphate-complexes, with a risk for hypophosphatemia and osteomalacia. Although aluminium has a low gastrointestinal absorption, accumulation may occur mainly in the presence of renal insufficiency.

17  Aluminium-containing drugs often cause constipation and are neurotoxic. Aluminium- containing drugs are contraindicated in pregnancy.  It may create Hypophosphatemia by reducing the phosphate in the intestinal tract. To overcome the constipation it sometimes used in combination with Magnesium antacids.

18 COMBINATION ANTACID PREPARATIONS

 Because no single antacid meets all the criteria for an ideal antacid, several products are on the market containing mixtures of antacids.  Most of the combination products are an attempt to use one component to antagonize one or more side effects of another component, e. g.  to balance the constipate effect of Calcium and Aluminum,  the laxative effect of Magnesium is mixed.  Some of the products are also a mixture of an antacid with rapid on set of action & one with19 a supposedly longer duration of action .  The combined antacids are now the most acceptable antacid containing preparations, than that of individual ones. Some of the combined antacid preparations are described below : 1.Aluminum Hydroxide gel-Magnesium Hydroxide preparations: This is available in suspension & tablet dosages forms. Example:  Alumina & Magnesium Oral suspension. U.S.P. XVIII contains 4% aluminum Oxide & 2% Magnesium Hydroxide.  Aluminum Hydroxide Gel Magnesium Trisillicate combinations.  N.F. XIII contains the equivalent of 28- 39% Magnesium oxide (MgO) of 17-25% of Aluminum oxide (AL2O3) 20 2.Calcium Carbonate Aluminum Hydroxide Gel- combinations. ANTACIDS INTERACTION AND WARNINGS

 Sparfloxacin is a broad-spectrum oral fluoroquinolone antimicrobial agent with a long elimination half-life. Concurrent treatment with antacids has demonstrated a reduction in the oral absorption of many quinolones.  Antacids may reduce zinc and iron absorption due to the inhibition of gastric acid secretion.  Inhibition of gastric acid secretion reduces zinc absorption in man Possible effects of antacids and acid-lowering drugs on the pH of the proximal small intestine.

21  Altered pH or complex formation may alter the of other drugs, such as tetracycline and amphetamine.  Urinary excretion of certain drugs may also be affected. Chelation of tetracycline with can cause nausea, vomiting, and phosphate excretion, and cause phosphate deficiency.  Reduced stomach acidity may result in an impaired ability to digest and absorb certain nutrients, such as iron and the B vitamins.  Since the low pH of the stomach normally kills ingested bacteria, antacids increase the vulnerability to infection. It could also result in reduced bioavailability of some drugs. For example, the bioavailability of ketoconazole (antifungal) is reduced at high intragastric 22 pH (low acid content).  Both cimetidine and an antacid containing aluminum and magnesium hydroxide reduced folate absorption from a liquid formula meal.  Although the effects of these drugs on reducing folic acid absorption were relatively small, such reductions could become clinically significant in chronic antacid or H2 receptor antagonist use or intensive antacid or H2 receptor antagonist use by individuals eating diets that are marginal in folate content.  The effect of small doses of four commercially available aluminum-containing antacids on calcium and phosphorus metabolism was investigated in adult males in 20 studies. During the use of these doses of antacids, urinary and fecal calcium increased significantly during a low calcium intake averaging 252 mg/day, and the calcium balances became distinctly 23 more negative. There was a reversal of the normal pattern of phosphorus excretions, namely, the fecal  Following all doses of antacid, a significant increase in 24 h urinary excretion of aluminium was seen. The estimated absorption of aluminium was 8 and 50 times higher when antacids were taken with orange juice or with , respectively, than when taken with water.  Thus, measurable quantities of aluminium are absorbed from single oral doses of antacids. The absorption is substantially enhanced by concomitant ingestion of citric acid.  Two infants presented with growth failure and were found to have generalized osteomalacia (rickets) due to phosphate depletion from prolonged administration of an aluminum-containing antacid given for the symptoms of colic. 24  One of the infants developed bilateral proptosis due to craniosynostosis related to the underlying metabolic bone disease.  The chronic use of aluminum-containing antacids in infants has potential risk for the growing and is not innocuous.  Therefore, antacid therapy should be used in low doses and very cautiously, with routine monitoring of serum calcium and phosphorus in children taking which reduce gastrointestinal phosphate absorption.

25  Special precautions: The use of magnesium-containing antacids in patients with mild to moderate renal impairment should be carefully monitored due to a possible increased danger of hypermagnesaemia. In patients with chronic renal failure, hyperaluminaemia may occur. Encephalopathy and dementia may occur in patients with poor renal function or patients on dialysis, due to an increase in plasma concentration of aluminium. Hypophosphataemia may occur with prolonged administration or large doses of aluminium-containing antacids (except ) especially in patients with an inadequate dietary intake of phosphorus. 26  Laboratory Tests –Serum phosphate levels should be monitored at monthly or bi-monthly intervals in patients on maintenance haemodialysis who are receiving chronic antacid therapy. Use in children –The safety and effectiveness of antacids in children has not been established.

27 DRUG INTERACTIONS  The rate and/or extent of absorption of many medicines may be increased or decreased. Therefore, medication should not be taken within one to two hours of.  An incomplete list of substances for which the above statement has been shown to apply includes: tetracycline, iron salts, isoniazid, ethambutol, some anti -muscarinic drugs, benzodiazepines, phenothiazines ranitidine, indomethacin, phenytoin, nitrofurantoin, Vitamin A, fluoride and phosphate. An increase in the plasma level of quinidine and possible toxicity may result it alkalisation of the urine occurs following antacid therapy.

28  Additional information Heartburn, reflux, indigestion, and sour stomach are a few of the common terms used to describe digestive upset. Self-diagnosis of indigestion does carry some risk because the causes can vary from a minor dietary indiscretion to a peptic ulcer. The pain and symptoms of gastric esophageal reflux disease, GERD or simply "reflux", may mimic those of a heart attack. Misdiagnosis can be fatal. A bleeding ulcer can be life threatening.

29  GERD, and pre-ulcerative conditions in the stomach are treated much more aggressively since both, if untreated, could lead to esophageal or stomach cancer.  It is primarily for this reason that the histamine-2 (H2) blockers including, famotidine, and ranitidine, and the proton pump inhibitors (PPI) omeprazole and its active isomer esomeprazole were made OTC.  (Cimetidine is not a drug of choice now, because of many drug interactions and side effects).  These drugs stop production of stomach acid and provide longer lasting relief but they do not 30 neutralize any stomach acid already present in the stomach. WHY DOES AN ANTACID FIZZ WHEN YOU PUT IT IN WATER

 Antacids contain sodium bicarbonate. That’s right— baking powder. Another important ingredient is citric acid. Both of these chemicals react with each other producing . In its liquid form this carbonic acid decomposes producing water and carbon dioxide. What this means is that the of water is very much like your favourite soda that also contains carbon dioxide in it. The fizz that you see is the carbon dioxide bubbles bubbling to the surface.



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