Investigating the effect of different antacids on neutralizing stomach acid

What is the effect of the type of active ingredients present in antacids on their effectiveness in neutralizing stomach acid?

Personally having experienced the struggles of finding the right medication for acidity, this research is rooted in a desire to contribute to a better understanding of the effectiveness of various antacids, aiming to provide insights that can alleviate the burden faced by individuals grappling with this prevalent health issue. This is therefore not only a very common health problem in Kenya, where about a quarter of the population grapples with it, but one that impinges on individual quality of life. The common acid reflux disease of gastroesophageal reflux (GERD) has doubled worldwide to affect 60 million people and therefore exposes the real need to fight the problems associated with excessive acid (Dirac et al., 2020).

High levels of gastric acid lead to heartburn and indigestion, mostly due to acidity. It can come from common eating habits, stressful conditions, or other health issues. Antacids help reduce the pain associated with acidity and are very commonly used to reduce pain. Antacids work by neutralizing the excess acid in the stomach by increasing the pH level in the stomach to decrease the burning. The most common chemicals in antacids are alkaline compounds like calcium carbonate, magnesium hydroxide and aluminium hydroxide which reacts with the acidic elements in the stomach to produce water and salt, hence neutralizing the acid.

Two common antacids that I will explore are Eno tablets and Relcer gel. Eno tablets contain calcium carbonate and act fast through effervescence after being dissolved in water, thereby making effective the process of the neutralization of acids in the stomach. Relcer gel contains aluminium hydroxide and magnesium hydroxide, thus working through a dual mechanism: neutralization of acid and putting up a protective film over the lining of the stomach against acid. The chemical equation for the neutralization reaction between stomach acid (hydrochloric acid, HCl) and the active ingredient in Eno tablets is-

2HCl(aq) + CaCO₃(s) → CaCl₂(aq) + CO₂(g) + H₂O(l)

As for Rеlcеr gеl which contains thе activе ingrеdiеnts aluminium hydroxidе and magnеsium hydroxidе, thе еquation is as follows-

3HCl(aq) + 3Al(OH)₃(s) + 3Mg(OH)₂(s) → 1AlCl₃(aq) + 3MgCl₂(aq) + 3H₂O(l)

Thе еxpеrimеnt is dеsignеd to dеtеrminе thе еffеctivеnеss of diffеrеnt antacids in nеutralizing stomach acid through a titration mеthod. Titration is chosеn for its prеcision in quantifying thе amount of acid nеutralizеd by antacids, providing accuratе and rеliablе data for comparison. Hydrochloric acid (HCl) of 0.2 mol/dm³ is sеlеctеd as thе titration solution. This concеntration is carеfully chosеn to strikе a balancе bеtwееn sеnsitivity and practicality. A morе concеntratеd acid could lеad to rapid rеactions, making prеcisе mеasurеmеnts challenging. Conversely, a less concentrated acid might result in prolonged titration times, increasing the likelihood of experimental errors. The 0.2 mol/dm³ concentration ensures a controlled and manageable reaction pace while maintaining the sensitivity required for accurate titration. Moreover, this is close to the concentration of hydrochloric acid secreted by parietal cells in the stomach which is between 0.5 and 1.5 mol/dm³ under different physiological conditions (Guyton et.al., 2006).

Slightly increasing that concentration in my experiment allows a simulation of excess stomach acid which forms the basis of the experiment.

The choice of hydrochloric acid is grounded in its relevance to stomach acid, which primarily consists of HCl. By mimicking the acidity of the stomach, the experiment provides insights into how antacids function under conditions similar to those encountered in the digestive system. This physiological relevance enhances the practical significance of the results, offering a closer representation of the real-world effectiveness of antacids. To ensure the reliability of data, each antacid will undergo multiple titrations, and an average will be calculated. This approach minimizes the impact of experimental variability and enhances the reproducibility of results.

Independent variable - Type of active ingredients

•  5 Eno Tablets (containing 500mg of CaCO₃ in each tablet) dissolved in 0.5L of distilled wate
  • Concentration ( g/dm³ )
  • \( \frac{5 \times 500 \, \text{mg}}{0.5 \, \text{dm}3 \times 1000} = 5 \, \text{g/dm}^3 \)

•  2.5ml of Relcer Gel (containing 2500mg of aluminium and magnesium hydroxide) dissolved in 0.5L of distilled water
  • Concentration ( g/dm³ )
  •  \( \frac{2500 \, \text{mg}}{0.5 \, \text{dm} 3 \times 1000} = 5 \, \text{g/dm}^3 \)

Dependant variable - Volume of antacid solution used to neutralize the hydrochloric acid

• The volume of Relcer Gel or Eno solution used to neutralize the HCl will be obtained using titration
• The initial and final volume via titration will be measured in cm³

Environmental considerations-

• HCl is a corrosive chemical, therefore any leftover chemical was disposed of correctly by diluting it with tap water and given to the lab technician to dispose of.

Ethical considerations-

• The antacids used complied with ethical standards and regulations as they were chosen from reputable manufacturers with transparent sourcing practices and adherence to any ethical guidelines.
• There was no use of animals in the experiment.
• Transparent reporting of the experiment and data collected.

• Dissolve the 5 eno tablets (each containing 500mg of CaCo3) in 0.5L of distilled water using a glass stirring rod to stir the solution.
• Dissolve 2.5ml of Relcer Gel (containing 2500mg of aluminium and magnesium hydroxide) in 0.5L of distilled water.
• Set up the 100cm3 burette with the antacid solution (Eno or Relcer Gel).
• Add 25 ml of 0.2 mol/dm3 HCl to a conical flask.
•  Add a few drops of methyl orange indicator.
• Titrate the antacid solution into the flask until the endpoint is reached; the colour changes from yellow to red.
• Record the initial and final volume of antacid solution used for each Eno and Relcer Gel trial.
• Repeat the titration for each antacid at least 3 times.

To calculate the total volume of antacid used in each trial, the following formulas were used: Volume of antacid used = final volume - initial volume

The activity of the ingredients used in antacids on reducing acidity (HCl) was found out. It was calculated based on the volume of antacid solution necessary to neutralize a known volume of HCl solution. More efficiency toward the neutralization of acid can be said to be shown if the volume of antacid solution applied is lessened.

5g/dm³ Eno solution: 25.3 cm³ was required to neutralize the fixed volume of HCl.
5 g/dm³ Relcer gel solution: 66.4 cm³ was required to neutralize the fixed volume of HCl.
With the same concentration of active ingredients, the fact that the Eno solution (Calcium Carbonate) required less volume (25.3 cm³) to neutralize the acid compared to the Relcer gel solution (Aluminium and Magnesium Hydroxide) suggests that Calcium Carbonate reacts more efficiently with stomach acid. This difference in efficiency could be because of the chemical properties of Calcium Carbonate and its direct reaction pathway with hydrochloric acid. Provided there is sufficient reaction between the acid and the Calcium Carbonate to give water and Carbon Dioxide then this can be fairly readily removed. Direct neutralization is probably way faster and more effective towards the drop of stomach acidity in comparison with the mechanism that is occasioned through the combination of Aluminum and Magnesium Hydroxides in Relcer gel. On the other hand, Aluminium and Magnesium Hydroxide work by reacting with stomach acid to form a protective coating on the stomach lining. This coating can neutralize some acid and provide relief from discomfort, but it may take longer to act compared to Calcium Carbonate.

Some of the strengths included-

• Equal concentrations for both antacids thus eliminating discrepancies associated with varied concentration
• Repeated titration for each antacid solution at least 3 times to increase accuracy, remove errors and provide more reliable data.

Some of the weaknesses included

• Using methyl orange the colour change ranges from pH 3.1 to 4.4. While it can show the titration's endpoint, other indicators closer to neutral pH (pH 7) such as phenophthalein and bromothymol blue may provide a more precise assessment of when stomach acid is neutralized.
• Using only 2 antacids. A wider range would provide a better understanding of the effect of different active ingredients.
• The level of uncertainty of the burette was ± 0. 05cm . The uncertainty in volume 3 measurements could affect the precision of endpoint detection particularly if the colour change occurs over a small volume range.

Additional considerations included-

• The speed of neutralization, often known as the rate of acid neutralization, can be a critical component in determining antacid efficacy. Future research should better investigate how long it takes for each antacid to neutralize a fixed volume of acid. This would provide a more complete picture of their efficacy, as some antacids may act faster than others, even if they require the same volume to neutralize the acid entirely. For example, an antacid that neutralizes a big volume of acid slowly may be less effective than one that neutralizes a smaller volume fast, particularly for people who need immediate relief from heartburn or indigestion.

The observed variation in volume required for neutralization could potentially be explained by the active components' dissociation rates. Calcium Carbonate in the Eno solution may dissociate faster than Aluminium and Magnesium Hydroxide in the Relcer gel. This rapid dissociation would allow the Calcium Carbonate molecules to engage with and neutralize the stomach acid molecules more quickly, resulting in a smaller amount required for complete neutralization than Relcer gel. Furthermore, buffering capacity can be an important component in determining total effectiveness. An antacid with a high buffering capacity, such as those containing aluminium and magnesium hydroxide, may provide longer-lasting relief from heartburn and indigestion, even if a larger volume is required for complete neutralization (as observed in Relcer gel). This can be useful for people who have regular attacks of heartburn or who want long-term relief. However, it is important to understand that a high buffering capacity does not always result in speedier relief. While the antacid works to keep the pH neutral and avoid acid rebound, it may take longer to neutralize existing stomach acid than an antacid with a lower buffering capacity but a faster reaction rate.

In conclusion, the experiment found that the Eno solution, containing Calcium Carbonate, needed less volume (25.3 cm³) to neutralize stomach acid than the Relcer gel solution, combining Aluminium and Magnesium Hydroxide (66.4 cm³). This shows that Calcium Carbonate may be a more efficient stomach acid neutralizer at the studied concentration (5g/dm³). However, to fully evaluate antacid effectiveness, additional parameters other than the volume necessary for neutralization must be considered. These are the above-mentioned factors such as buffer region and reaction kinetics. Future studies could investigate them to provide a more complete picture. All in all, with a fixed concentration of both antacids, the data offers strong evidence that Calcium Carbonate in Eno is more effective based on the volume required for neutralization.

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