DI-071 In vitro comparison of antacid drugs: Application to six marketed formulations

Abstract

BackgroundAntacids are intended to neutralise the gastric H+ ions without interfering with the secretory process. They are generally administered 1 h 30 min after the beginning of a meal.Given the multitude of antacids on the market, it would be interesting to have quantitative techniques to compare these products and to demonstrate their physiological behaviour.PurposeTo evaluate the behaviour of antacids in the presence of an increasing amount of acidity in vitro and to predict their use depending on the importance and periodicity of gastric acidity in vivo.Material and methodsWe studied the in vitro behaviour of six antacid drugs. For this, a therapeutic dose was diluted in 100 ml of distilled water, to which were added increasing amounts of 0.1 N HCl in increments of 0.2 ml every 30 s up to a total acid volume of 25 ml. The variation in pH of the mixture was followed by pH-metry. Each test was repeated three times.The composition of the studied antacids is shown in table 1.Abstract DI-071 Table 1Drug AFor 100 ml of oral suspension:-Aluminium hydroxide (3.49 mg)-Magnesium hydroxide (3.99 mg)Drug BFor a 20 g sachet of oral suspension:-Aluminum phosphate gel at 20% (12.38 g)-Magnesium oxide (152 mg)Drug CFor a 20 g sachet of oral suspension:-Colloidal aluminum phosphate at 17% (14.4 g)Drug DFor a 10 ml sachet of oral suspension:-Aluminium alginate (500 mg)-Sodium bicarbonate (267 mg)Drug EFor one effervescent tablet:-Sodium bicarbonate (170 mg)-Sodium sulfate (285 mg)-Sodium dihydrogen phosphate (195 mg)Drug FFor one suckable tablet:-Calcium carbonate (680 mg)-Magnesium carbonate (80 mg)ResultsThe in vitro behaviour of the six antacid drugs in the presence of increasing amounts of 0.1 N HCl is represented in figure 1.Abstract DI-071 Figure 1ConclusionThe proposed method allowed us to quantitatively compare the studied antacids.According to the results, drug C slightly neutralised stomach acid without an extended effect. It can be prescribed for low and temporary gastric acidity.Drugs A, B and F had an average and extended neutralising action (pH stabilisation around 5). They can be prescribed for moderate and prolonged gastric acidity.Regarding drugs D and E which had a strong neutralising and long acting action that stabilised the pH around 7.5, they can be prescribed for high and prolonged gastric acidity.No conflict of interest.