Evaluation of Acid Neutralizing and Buffering Capacities of Selected Antacids in Ghana

Introduction: The ability of an antacid to have a high Acid Neutralizing Capacity (ANC) and to resist significant changes in pH by demonstrating a longer Buffering Capacity (BC) is crucial in assuring quality and efficacy of the brand. This study has evaluated the acid neutralizing and buffering capacities of nine selected antacid brands coded “L1-L9” (each having a different retail price) in Ghana.

Methodology: The active acid neutralizing ingredients were recorded and the preliminary antacid test (PAT) determined with 0.5 N HCl after 10 minutes. The acid neutralising capacity (ANC) was evaluated with 1 N HCl by neutralizing the excess with 0.5 N NaOH after 15 minutes stirring (USP 32 NF 27). Buffering capacity (BC) was estimated with 0.1 N HCl and titrated with 0.1 N NaOH at 5 minutes interval up to 50 minutes. All determinations were at 37±3 °C using a pH meter.

Results and Discussion: All brands had as part of their active ingredients dried aluminum hydroxide and magnesium hydroxide, with 67% containing simethicone as antifoam. The PAT confirmed all sampled brands to be antacids with pH range of 4.38±0.21-6.43±0.06. The ANC of all brands were in the range 13.16 ± 0.55 – 20.70 ± 0.18 mEq/g with “L4” and “L9” having the lowest and highest respectively. “L9” further demonstrated a considerably higher BC up to 40 minutes whiles “L6” had the least BC up to 15 minutes. Brand “L9”, with dried aluminum hydroxide gel showed superior ANC and BC values.

Conclusion: The current work has shown that antacids exert their effects by the combined action of their acid neutralization and buffering capacities however, cost does not translate to quality as both expensive and low cost brands were found within acceptable limits of antacid action. It is highly recommended for manufacturers to state ANC and BC values on labels to assure medicine quality, efficacy and value for money.