INTRODUCTION 

 

The project is aimed at analyzing some of commercially available antacids to determine their ability to neutralize HCL & hence determine the best brands which has the highest ability to neutralize acids.The project can provide important information about the various antacids available commercially.We all know that the food we eat undergoes various biochemical reactions resulting in digestion. In this process various enzyme working at different condition are required. The enzymes of stomach require an acidic pH to function, hence dil.HCl is produced in the stomach. However, sometimes the stomach starts producing excess of HCL. This condition is called gastric hyperacidity & is usually caused by overeating highly spiced food. In an uncontrolled condition this HCL can also destroy the mucous lining of the stomach & result in peptic ulcer.            

Hydrochloric acidGaseous hydrogen chloride is colorless and has a pungent, irritating odor. The water solution is yellow in color because of impurities, usually dissolved iron. Hydrogen chloride gas is soluble in some organic solvents. Hydrochloric acid reacts with many metals to form salts known as chlorides. Hydrochloric acid is secreted in gastric juices by glands in the walls of the stomach, where the acid aids in the digestion of foods.  

      Antacids

        

Antacids are the commercially available product which neutralizes the excess HCl secreted in the stomach.The action of antacids is based on the fact that base can neutralize an acid forming salt and water.The antacid should not contain excess of alkali that may lead to an alkaline medium in the stomach and make the enzyme inactive. Thus some additional compounds are added to the antacid to keep the pH optimum.The action of an antacid is for a short time, irrespective of the dose; hence it is required to take an antacid at frequent intervals. Antacids are of two types- 

1. Absorbable 

1. Non Absorbable 

1 Absorbable antacids: NaHCO3 mixture is commonly used for giving relief from indigestion. It has a moderate neutralizing power. It is inexpensive and easily available. However, it releases carbon dioxide gas in the stomach and causes swelling of deep ulcers and hence it is not generally used. 2 Non Absorbable antacids: these are available in three broad groups:1 Aluminum salts: all these drugs have a common buffering action and reduce acidity in the stomach. eg. ,Al(OH)3,AlPO4,Al2(CO3)3 and dihydroxy aluminiumamino acetate. 2 Magnesium salts: their action is slow. These cause a purgative action. eg. , MgCO3, MgO.etc. 3  Calcium salts: these are powerful antacids. They have no buffering action and can therefore neutralize the acid completely in the stomach.    

   Terms and Facts 

Acidosis 

Condition characterized by normally high levels of acidity, or low levels of alkalinity (bicarbonate content), in body tissues and fluids, especially in blood; caused by excess retention of carbon dioxide because of faulty oxygen-carbon dioxide exchange in lungs, constriction of air passages, or inability of diseased kidneys to excrete acids: condition may accompany diabetes mellitus, severe diarrhea, emphysema, severe pneumonia, or starvation: condition may also be brought on by drugs or anesthesia: symptoms include headache, weakness, rapid breathing, and fruity odor on breath: treatment depends on diagnosing underlying cause and then correcting acid-base imbalance; often compared with opposite condition, alkalosis.   

Alkanosis 

Abnormally low level of acidity, or high level of alkanity (bicarbonate content) in body tissues and fluids, especially in blood; metabolic alkanosis (alkalemia) caused by overuse of antacids (drugs used to treat ulcers), by use of potent diuretics (substances that promote production of urine), or by depletion of body fluid volume (through severe vomiting, for example); respiratory alkanosis caused by hyperventilation as result of anxiety, asthma, congestive heart failure, pulmonary embolism (obstruction), or pneumonia; treatment depends on diagnosing underlying cause and then correcting acid-base imbalance; often compared with opposite condition, acidosis.  

   Ulcers 

A potentially serious condition, an ulcer is a break in the skin or mucous membrane with a loss of surface tissue and the disintegration and sloughing off of the epithelial tissue, leaving an open sore. Ulcers can occur in any tissue or organ as the result of injury, disease, or chronic irritation or inflammation. The most common type in humans is the peptic ulcer, found in the gastrointestinal tract.

Peptic ulcers occur most frequently at the beginning of the duodenum, in the lower stomach, and in the lower end of he esophagus (see digestive system). Normally these organs are protected by mucous membranes that provide a barrier against gastric acids and digestive enzymes and by alkaline secretions from the small intestine and pancreas that neutralize gastric juices. A peptic ulcer results when either too much acid or pepsin (a digestive enzyme of gastric juice) are secreted or when the mucosal barrier is weakened and becomes unable to protect against the acid-pepsin complex. Most duodenal ulcers are thought to be caused by excessive secretion of acid and pepsin. Gastric ulcers, on the other hand, occur in patients who have a normal or even slightly lower secretion of gastric acid but whose stomach mucosa have a reduced resistance to digestion.

Heredity plays a strong role in the development of ulcers. Offspring of people who secrete excessive amounts of gastric acid or who have diminished mucosal protection are also likely to show the same symptoms. Chronic stress and anxiety can stimulate the body to produce excessive amounts of stomach acid, which, in susceptible individuals, can lead to duodenal

and esophageal ulcers. Some gastric and duodenal ulcers may also be caused by the bacterium helicobacter pylori, which produces a toxin that harms the stomach lining and then elevates acid levels in the stomach.  

 

Lining of helicobacter pylori with stomach 

 

Medical treatment for ulcers is generally a combination of stress reduction and the use of antacid or antimicrobial drugs, along with prohibition of cigarette smoking and avoidance of the use of alcohol, aspirin, and other substances that can break down the mucosal barrier. 

                    digestive system 

 

The Human Stomach    

 

The human stomach is roughly J-shaped and is locates in the upper left side of the abdomen. The stomach of an adult is about 10 inches (25 centimeters) long and can easily expand to hold as much as 1 quart (0.9 liter) of food. The wall of the stomach is composed of four different layers. The innermost layer, called the mucosa, is honey combed with millions of glands that secrete mucus, acid, and enzymes. The mucus forms a mucous lining that protects the stomach from the corrosive action of the gastric juices, which break down food. The second layer of the stomach, called the submucosa, is composed of connective and elastic tissue containing nerves and blood and lymph vessels. The third layer contains longitudinal, circular, and oblique sets of smooth muscles that enable the stomach to churn, mix, and move food. The fourth layer, known as the serosa, connects the muscles to the peritoneum, the outer covering of the stomach. The stomach is subdivided into four regions: the cardia (so named because it is nearest the heart), an opening leading down from the esophagus; the fundus, an expanded area curving up above the cardiac opening; the body, or intermediate, region, which is the central and largest portion of the stomach; and the pylorus, a narrowing where the stomach joins the small intestine.

Circular muscles, or sphinters, close off the openings at the esophagus and small intestine, except when food is passing through. In this manner food is enclosed by the stomach until it is ready for final digestion. (see also digestive system. ) 

The wavelike pumping action that moves food from the esophagus through the rest of the digestive system is called peristalsis. Periodic contractions of the stomach muscles occur about three times a minute and churn and knead the food into a semiliquid mixture of food and gastric juice called chime.The secretions and movements are controlled by the vagus nerve and the sympathetic nervous system ). After the stomach empties, the contractions persist and increase with time and may cause hunger pangs.  

Disorders of stomach 

The stomach is subject to a number of disorders, including hyperacidity (excessive acid secretion), gastritis (inflammation of the stomach lining), peptic ulcer (a lesson of the mucous membrane), and cancer. Medications can be used to regulate the production of acid, but surgery may be needed to correct other conditions. Persons who have had their stomachs removed are still able to live by ingesting small quantities of special foods times a day.    

   Acids and Bases 

 

An acid is defined as a substance containing hydrogen that dissociates (break up) in water to produce hydrogen ions. An acid may also be defined as a compound in which the hydrogen can be replaced by a metal. The other part of the compound is called the acid radical. For example, in sulphuric acid (H2SO4) one atom of sulphur and four of oxygen form the acid radical that is joined to two atoms of hydrogen. A typical metal-acid reaction occurs when zinc is placed in a solution of sulphuric acid. Hydrogen is released as a gas, and zinc unites with the acid radical to form zinc sulphate: 

H2SO4 + Zn  -> ZnSO4 + H2 

The strongest acids are the mineral, or inorganic, acids. These include sulphuric acid, nitric acid, and hydrochloric acid. More important to life are hundreds of weaker organic acids. These include acetic acid (in vinegar), citric acid (in lemons), lactic acid (in sour milk), and the amino acids (in proteins). A base is a substance the hydroxide ion, OH-, or the hydroxyl group, OH, which dissociates in water as the hydroxide ion, OH-. Basic solutions have a characteristic brackish taste. The hydroxides of metals are metal compounds that have the hydroxyl group, and they are bases. Hydroxides of the metals lithium, sodium, potassium, rubidium, and cesium have the special name of alkalies. The oxides of beryllium, magnesium, calcium, strontium, and barium are called alkaline earths. A basic solution is also called an alkaline solution.These descriptions help explain why acids and bases react so readily with each other. An acid has hydrogen to exchange for a metal, and a base has a metal to exchange for hydrogen. When the two metal react, the exchange takes place. These reactions or exchanges are sometimes violent. Acids and bases react to form compounds that are called salts. The reaction of sodium hydroxide and sulphuric acid produces a salt, sodium sulphate (Na2SO4), and water: 2NaOH + H2SO4 -> Na2SO4 + 3H2O    Acids and bases react freely in aqueous (water) solutions. It is said that when an acid dissociates, it forms an acid radical and a hydrogen ion. Actually, the hydrogen ion (H+) does not exist in large concentrations in the aqueous solution. Instead, the hydrogen ion attaches itself to a water molecule to form the hydronium ion, H3O+. It is customary, however, to simplify reaction equations by using the symbol for the hydrogen ion, H+. When a base dissociates, it produces a hydroxide ion (OH-) with a negative charge and a metal ion with a positive charge. The hydrogen ion and the hydroxide ion combine to form a molecule of water. The negative acid radical and the positive metal ion can then form a salt. Acids and bases can cause many organic substances to change color. For example, if lemon juice is added to tea, the tea becomes lighter in color. This occurs because the acid in the lemon juice changes the color of a substance in the tea from dark brown to light brown. The reaction can be reversed by adding an alkaline substance, such as baking soda (NaHCO3),

to the tea. This addition restores the original color. A substance that changes color when an acid or base is added to it is called an indicator.          

   Volumetric analysis 

 

Quantitative chemical analysis in which the amount of a substance is determined by measuring the volume that it occupies is called volumetric analysis. This method most commonly uses a second substance of known concentration, called the titrating reagent that is allowed to combine with the substance whose concentration is unknown. This process is usually carried out by gradually adding a standard solution-that is, a solution of known concentration-of titrating reagent from a burette, which is essentially a long, graduated measuring tube with a stopcock and a delivery tube at its lower end. The addition of the titrating reagent is stopped when the equivalence point is reached. The equivalence point is the point at which all the component in the sample has reacted with the titrating reagent added to the sample. The experimental point at which the reaction is complete is marked by some signal, which is called the end point. This signal can be the color change of a chemical indicator or a change in some electrical property that is measured during the titration.           

EXPERIMENT 

 

Aim:   a comparative study of effectiveness of different commercially available antacids.  

Apparatus:   burette, pipette, conical flask, glass rod, mortar & pestle.  Chemicals:   HCl solution (0.1N), NaOH solution (0.1N), phenopthalein, methyl orange, commercial antacids.  

Procedure: 

1. Take 50ml of 0.1N of NaOH solution in the burette.2. Take 50ml of 0.1N of HCl solution in conical flask.3. Add 2-3 drops of phenolphthalein / methyl orange to

the conical flask, which serves as indicator.4. Add 1gm of finely powdered antacid to the conical

flask.5. Shake well and now titrate the solution and observe

the end point-a pink / yellow solution.6. Repeat this with other antacids and note the

readings.       

  Results    

Antacid Cost per gm Strength ml/gm Cost per ml HCl neutralized

Eno 0.8 4.2 0.8

Digene 1.2 2.2 1.2

Gelusil 1.2 2.4 1.2

 

Observations    

   

Antacid Volume of HCl used (x)

Volume of NaOH (50-x)

HCl neutralized by antacid (50-x)

Strength of antacid ml/gm

Eno(4gm) 50ml 33.2 16.8 4.2

Digene(4gm) 50ml 41.2 8.8 2.2

Gelusil(4gm) 50ml 40.4 9.6 2.4

  

Precautions- 

 

1. The weighing should be accurate. 

1. Powdering should be fine to promote maximum dissolution.  

1. The amount of HCl should sufficiently in excess so as to neutralize every bit of the antacid.  

Inference    

 

Digene is prescribed frequently as it contains Mg(OH)2 which acts as buffer and purgative. On the other hand antacids having calcium carbonate may have high acid neutralizing

capacity but produce CO2 in the stomach resulting in swelling of deep ulcers. A part from being best the most effective ENO is the best.       

Uses of antacids: 

1. It gives immediate relief from gastric hyperacidity. 

1. Controlled use of antacids can prevent ulcers in stomach.  

Harmful effects of antacids: 

1. Excess use of antacids can cause alkalosis. 

1. Use of antacids containing CaCO3 can cause swelling of deep ulcers.