Source: Health Products Regulatory Authority (IE) Revision Year: 2022 Publisher: Bayer Limited, 1st Floor, The Grange Offices, The Grange, Brewery Road, Stillorgan, Co. Dublin, A94 H2K7, Ireland
Pharmacotherapeutic group: Antacids, other combinations
ATC code: A02AX
ATC-Code: Calcium carbonate A02AC01, magnesium carbonate: A02AA01
Rennie Peppermint is a combination of two antacids, calcium carbonate and magnesium carbonate. The mode of action of calcium carbonate & magnesium carbonate is local, based on the neutralisation of gastric acid, and is not dependent on systemic absorption. Acting locally in the stomach and oesophagus, they directly neutralise stomach acid and raise both intragastric and oesophageal pH. They protect the gastric and oesophageal mucosa against acid (by neutralisation) and against pepsin (inactivation by an elevated pH). Calcium carbonate has a rapid, long-lasting and powerful neutralising action. This effect is increased by the addition of magnesium carbonate which also has a strong neutralising action. In vitro acid neutralisation studies (artificial stomach model) showed that Rennie increases stomach pH from pH 1.5-2 to pH 3 in 40 seconds and is able to reach pH 4 in 1 minute 13 seconds. The maximum level of pH achieved in the model was pH 5.24. Studies have shown that calcium carbonate antacids have upon-contact (immediate) onset of acid neutralisation, with clinically relevant pH change occurring within minutes.
In the stomach, calcium carbonate and magnesium carbonate react with the acid in the gastric juice, forming water and soluble mineral salts.
CaCO3 + 2HCl => CaCl2 + H2O + CO2
MgCO3 + 2HCl => MgCl2 + H2O + CO2
Calcium and magnesium can be absorbed from these soluble salts. However, the degree of absorption is dependent on the subject and the dose. Less than 10% calcium and 15-20% magnesium is absorbed.
The small quantities of calcium and magnesium absorbed are usually excreted rapidly via the kidneys in healthy individuals. In the case of impaired renal function, plasma concentrations of calcium and magnesium may be increased.
Due to the effects of various digestive juices outside the stomach, the soluble salts are converted to insoluble salts in the intestinal canal and then excreted with the faeces.
Preclinical studies on Rennie are not available. The available preclinical data on calcium carbonate and magnesium carbonate based on conventional studies of repeated dose toxicity, genotoxicity and or carcinogenic potential, and toxicity to reproduction revealed no specific hazard at therapeutic doses for humans.
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