Effectiveness of Antacid Tablets

by Trisha Dwivdi, 2002

Abstract

The purpose of this project was to figure out if antacid tablets are effective in neutralizing the human stomach. Effective was defined to mean that the tablet did not neutralize too much of the solution or too little of the solution compared to other brands. I titrated a solution that had a pH that was similar to the human stomach and tested four brands of popular antacid tablets. The four brands were Pepcid AC®, Zantac 75®, Rolaids®, and Alka Seltzer®. Rolaids® was the only brand that did not neutralize the solution. The other three antacid tablets did work and I decided that antacid tablets are effective in neutralizing the human stomach since they did not neutralize all of the stomach solution or they did not just neutralize a small amount of it. This experiment was all relative to the other tablets, because I had no background information on what defines an antacid tablet to be effective so I had to base it on the results of the other tablets. Rolaids® took an irregular amount of stomach solution compared to the other tablets to neutralize, so I based my results on this observation.

Introduction

The purpose of doing this project was to figure out if antacid tablets work effectively since there are many tablets out there on the market. I predicted that the antacid tablets will neutralize the stomach solution I made and therefore be effective. I worked in the Breck School Science Lab under the supervision of Ms. Lois Fruen, Ms. Johnson, and Ms. Gilbert.

Purpose

By titrating with a solution that is similar in acidity to the human stomach, I figured out which antacid tablet works best without neutralizing too much or too little of the solution.

Materials

10.0 mL Pipette
1000 mL Volumetric flask
1000 mL 1.0 M HCL
4 Different brands of antacid tablets
Stirring rod, plate, and bar
1.0 L Storage bottle
Mortar and Pestle
250 mL Erlenmeyer flask
Burette
Color Indicator

Procedure

Making the Stomach Solution
1. I took 1.0 mL of 1.0 M HCl and poured it into a 1 L volumetric flask.
2. I filled the flask to the inscribed line with distilled water.
3. Then, I poured the solution into a large storage bottle and labeled it.

Antacid Tablet Set-up
1. I obtained 1 dose of an antacid tablet and recorded the brand used.
2. Then, I measured and recorded the mass of one dose, and used a mortar and pestle to grind it into a powder.
3. I then transferred the powder into an erlenmeyer.
4. If more distilled water was needed, I added more into the flask.
5. I placed an indicator, preferably bromthymol blue and a stirring bar into the base.
6. Then I placed the flask onto a magnetic stirrer.

Titrating the Solution
1. I obtained 25.0 mL of the 1.0 M HCl solution poured it into a beaker and transferred it into a burette. I recorded the initial volume.
2. I slowly opened the nozzle of the burette and let it drip into the beaker with the antacid tablet mixture.
3. I let it drip until the indicator turned the desired color. If the indicator, when placed in was blue or yellow, then the desired color should be green. If, instead, methyl red was used and the color when it was placed in the solution was red or yellow, then titrate the solution until it turns orange. If phenolphthalein was used and the solution turned white or red when it was placed in, then the solution should have been titrated until it turned pink.
4. I recorded the amount of 1.0 M HCl used in the titration and I repeated this process over again with a different antacid tablet.

Helpful Hints

1. Titrate each brand of antacid tablet at least three times.
2. Choose an indicator that is not the same color as the solution.

Background
"Heartburn, or acid indigestion, develops when something causes irritation or inflammation to the lining of the stomach or the esophagus. This is usually due to some chemical, biological or physical injury. Once the lining has been injured or irritated even water or regular foods, not to mention stomach acid, can be irritating. In medicine, inflammation or irritation is generally designated by the suffix "itis". Hence, the terms gastritis, esophagitis, or duodenitis describe irritation to these organs of the upper digestive tract. Gastritis (inflammation of the stomach lining) is most often caused by chemical or infectious agents. Aspirin, anti-inflammatory pain killers, alcohol, coffee and tea can cause gastritis. Some prescription medications, such as arthritis drugs, prednisone, and certain antibiotics can also irritate the stomach. Often, the avoidance of known irritants resolves this problem” (1). Something else that can help stomach irritation are antacids.

Antacids are any group of drugs that neutralize acid in the digestive system. They help relieve or prevent pain associated with peptic ulcers by neutralizing acid. This relieves symptoms of excess acid, like heartburn, but does not correct the problem that caused it, which could just be too much highly seasoned food or could be an ulcer, a stomach inflammation or even cancer” (2). Hydrochloric acid (HCl), the acid that is produced in the stomach, is important to digestion. "It combines with weak bases, such as an antacid tablet, to form a salt and water. (HCl + NaOH ( NaCl + H2O) Antacids reduce gastric acidity and thereby reduce the activity of pepsin. They differ in their reaction time, neutralizing capacity, side-effects, complications and price. Over-the-counter antacids vary as much as seven fold in neutralizing capacity in laboratory tests. Tablets are more efficient than their liquid counterparts because liquid antacids may interfere with the absorption of certain heart medicines and antibiotics when taken together” (3). Many antacid products contain compounds of aluminum, magnesium, or, often, both. These chemicals react with acids to form more neutral compounds that do not irritate peptic ulcers. Aluminum hydroxide (Al(OH3)) and other aluminum compounds are weak though effective antacids but can cause constipation. The reaction between aluminum hydroxide and stomach solution is represented by 3HCl + Al(OH)3 (3H2O + AlCl3. They are frequently sold in combination with magnesium compounds, which are stronger antacids that can cause diarrhea. Sodium bicarbonate (NaHCO3), available as baking soda, is a potent neutralizer of stomach acid. It can even upset the balance between acids and bases in the blood and the sodium can contribute to high blood pressure. Magnesium compounds are less strong than sodium bicarbonate but act quickly. They may cause diarrhea. Calcium carbonate (CaCO3) is strong and fast acting, but the can cause the formation of kidney stones and can cause constipation. Calcium antacids may also cause "acid rebound"—an increase in stomach acid after the drug's effects have worn off” (2). Antacids came in tablet, capsule, and liquid form. Commonly used antacids include such brand-name products as Pepcid AC®, Rolaid®, and Tums®, another common antacid containing a compound of calcium that is helpful for digestion but not recommended for ulcer treatment. Pharmacist, Larry Dearth of Kmart®, said that, "The most popular brands of antacid tablets bought by many customers was Rolaids®, Alka Seltzer®, Tums®, and Pepcid AC®. These antacid tablets seem to be very effective because their sales are pretty stable and they attract a lot of consumer attention" (4). There are many ingredients in these tablets. Calcium carbonate (CaCO3) is a very effective antacid and reacts more slowly than sodium bicarbonate (NaHCO3) and is an active ingredient in Tums®. These drugs ordinarily do not cause harmful side effects, and a doctor's prescription is not needed to purchase them. However, antacids that contain magnesium, hydroxide can cause diarrhea, while those with aluminum hydroxide (Al(OH3)) can cause constipation. Problems also may develop when antacids are used for long periods. For example, extensive use of antacids that contain calcium carbonate (CaCO3) can cause too much calcium to accumulate in the body. High calcium levels can lead to kidney damage and other problems.

The type of antacid medicine you get, could have an affect on the how effectively you recuperate. "Liquid antacids may interfere with the absorption of certain heart medicines and antibiotics when taken together. Long-term use of antacids containing aluminum is discouraged as aluminum may accumulate in the human body. Antacids containing calcium ion may be beneficial to women with osteoporosis but should only be used intermittently for treating stomach acid. If you are being treated for certain medical conditions or take prescription medications, check with our physician or pharmacist regarding the effects of antacids in your particular situation” (1).

"To avoid heartburn, stay away from food that you know causes it. Eat smaller meals and try no to eat when under stress. Do not lie down after eating or eat within two or three hours of bedtime. Sleep with your head raised. If your doctor thinks it is appropriate, get rid of excess body weight. Do not wear clothing that is too tight around the waist or abdomen” (2).

Results

The average mass of one dose, which is three tablets, as seen in Figure 1, of Rolaids® was 4.389 g and the average volume it neutralized was 584.0 mL of the stomach solution. Zantac 75® had an average mass of one dose, which is one tablet, of 0.5767 g and it neutralized an average of 28.67 mL of the stomach solution, which is shown in Figure 1. Figure 1 also shows that Pepcid AC® neutralized an average of 5.763 mL of stomach solution and its average mass of one dose, which is one tablet, was 0.2063 g. Alka Seltzer® had an average mass of one dose, which is two tablets, of 6.431 g and it neutralized 17.22 mL of the stomach solution which is shown in Figure 1.

[pic]

Table 1.
Brand: Ave. Mass of 1 Dose (g): Ave. Final Volume of Stomach Solution (mL)
Pepcid AC® 0.2063 5.763
Zantac 75® 0.5767 28.67
Rolaids® 4.389 584.0
Alka Seltzer® 17.22 17.22

Conclusion
The object of this project was to determine if the different brands of antacid tablets were effective, meaning that they did not neutralize too much or too little of the stomach solution. By titrating a stomach solution with a pH of 3, as the human stomach normally is, each brand of antacid tablet was tested to figure out their effectiveness Effectiveness was determined after the project was over. As seen in Table 1, the antacid tablet that took the most stomach solution to neutralize was Rolaids®. This amount was such an extreme as can be seen in Figure 1, where the other brands took a much smaller amount to neutralize, that I concluded that the amount of stomach solution Rolaids® took to neutralize was way too much, compared to the other brands. The other brands can then be called effective, since the amount of stomach solution they took to neutralize were all around the same amount and the chances for them all to not neutralize the stomach solution, are pretty slim (Refer to Figure 1 to see this correlation. The other three brands are all near each other on the graph, whereas Rolaids is up high on the graph.)

These results show that most antacid tablets are effective, which means that they all neutralized an amount of stomach acid that directly correlated to their mass and this proves my hypothesis. I also discovered that when the mass was small, such as the mass of one dose of Pepcid AC®, which is 1 tablet, then the amount of stomach solution it neutralizes was also small compared to that of Alka Seltzer®, whose mass of one dose, which is two tablets, neutralizes more stomach acid than Pepcid AC®. Another way of deciding that Rolaids® is very ineffective as far as being able to neutralize the stomach, is that it has a slightly smaller mass than Alka Seltzer, but it takes thirty-five times more the stomach solution to neutralize than Alka Seltzer®.

Another experiment to do with antacids is to figure out which antacid tablet leaves the most residue behind. I noticed while doing this experiment that some tablets would never dissolve all the way. This could be because I did not take enough time to stir it, but it would be interesting to figure out, which antacid tablet brand is the best in terms of how hazardous the materials in the tablet are.

Bibliography

1. Sansum-Santa Barbara Medical Foundation Clinic (2002); see www.sansum.com/newspress/heartburn.html.
2. The New York Times Learning Network Student Connections (1999); see www.nytimes.com/learning/students/scienceqa/archive/990717.html.
3. Altruis Biomedical Network (2000-02): see www.e-antacid.com/.
4. L. Dearth, personal communication.