Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1 Pharmacodynamic properties
Pharmacotherapeutic group: antacids, other combinations ATC code: A02 AX.
Mechanism of action
Rennie is a combination of two antacids, calcium carbonate and magnesium carbonate.
Calcium carbonate and magnesium carbonate have a localised mechanism of action based on the neutralisation of gastric acid which is not dependent on systemic absorption.

Pharmacodynamic effects
Calcium carbonate has a rapid, prolonged and powerful neutralising effect. This effect is increased by the addition of magnesium carbonate which also has a strong neutralising effect. In-vitro studies (with an artificial human stomach model) demonstrate that Rennie increases the pH of the study from 1.5-2.0 to pH 3.0 in 40 seconds and to pH 4.0 in 1 minute and 13 seconds. The maximum pH in this model was pH 5.24.

Clinical efficacy and safety
In healthy volunteers, a significant increase in gastric pH was reached within 2 minutes following the administration of calcium carbonate and magnesium carbonate. The total neutralising capacity of 2 tablets is 29 mEq/H+ (titration to endpoint pH 2.5).

Pharmacokinetic Properties

5.2 Pharmacokinetic properties
Calcium and magnesium:
Calcium carbonate and magnesium carbonates react with gastric acid in the stomach to produce water and soluble mineral salts.
CaCO3 + 2 HCl -> CaCl2 + H2O + CO2
MgCO3 + 2 HCl -> MgCl2 + H2O + CO2

Calcium and magnesium can be absorbed from these soluble salts. However, the extent of absorption is patient and dose dependent. Less than 10% calcium and 15-20% magnesium are absorbed.

In healthy people, the small amounts of absorbed calcium and magnesium are generally rapidly excreted via the kidneys. Serum calcium and magnesium levels may be elevated in patients with impaired kidney function.
Various digestive juices outside the stomach result in conversion of soluble salts in the intestinal tract to insoluble salts which are excreted in the faeces.