The effect of pharmaceutical properties on the acid neutralizing capacity of antacid oral suspensions

Abstract

Acid neutralizing capacity (ANC) of antacids is an important indicator of the efficacy of such products. The purpose of this study is to evaluate the effect of pharmaceutical properties on the ANC of antacid oral suspensions. Fifteen antacid oral suspensions randomly sourced from different manufacturers and coded A1-A15 were assessed using ANC, raft formation, sedimentation profiles, ease of re-dispersibility, density, alkalinity, particle size, viscosity and rheological patterns. The effects of the pharmaceutical properties were discussed on the ANC and conclusions drawn. The results showed that ten (66.67 %) of the samples passed the ANC test among which 5 (83.33 %) were non-sedimenting highly viscous suspensions. One sample (A5) presented raft formation. Sedimentation volume reduces with time, ease of re-dispersibility was in seconds and the density range for all samples was 1.06–1.26 g/mL. The particle sizes of the antacid oral suspensions were within the range for coarse dispersions. The viscosity values ranged from 39.33 ± 1.53 to 2508 ± 24.33 cp. The rheogram of A3 shows a Newtonian flow with a regression coefficient of 0.999 and it had the least ANC. Other samples present non-Newtonian flow in a pseudoplastic pattern. Comparison of the viscosity of samples with ANC shows no direct relationship between the two variables although most samples with low viscosity failed the ANC test. The acid neutralizing capacity of the antacid oral suspensions is influenced by the dynamics of different parameters including type of active pharmaceutical ingredient, sedimentation profile, viscosity and overall rheology of the suspension.