Acid rebound

Q75 Acid rebound is likely to occur with the chronic use of large doses of which of the following preparations ... 

Antacids containing calcium carbonate have the greatest neutralising capacity but tend to cause acid rebound with long-term use. Calcium carbonate may also lead to hypercalcaemia and the milk-alkali syndrome, which is characterised by nausea, headache and renal damage. 

Acid rebound Antacids may cause dose-related rebound hyperacidity because they may increase gastric secretion or serum gastrin levels. 

The physician is concerned with at least three factors when prescribing antacids (1) Acid rebound (associated with calcium carbonate) (2) milk-alkali syndrome (caused by ingestion of large quantities of alkali) and (3) phosphorus depletion (by aluminum salts). The mechanism of add rebound, especially in the long-term use of caldum carbonate, is poorly understood. It has been established that there is an excessive re-addification of the antrum (pylonc gland area) a number of hours after ingestion of calcium caibonate. 

Hade JE, Spiro HM. Calcium and acid rebound a reappraisal. J Clin Gastroenterol. 1992 15 37-44. 

Antacids are not completely harmless. The HC1 production in the stomach is regulated by the stomach pH. If too much antacid is taken, the pH becomes too high the result will be the so-called acid rebound. This means that ultimately, more HC1 will be produced than was present before taking the antacid pill. 

What does the term acid rebound mean ... 

Antacid Alkalosis Acid Rebound Diarrhea Constipation Other Toxicity... 

Antacids raise the luminal pIT of the stomach. Tliis increases the rale of emptying and so the effect of antacids is short. Gastrin release is increased and, trccausc this stimulates acid release, larger amounts of antacids are needed than would be predicted (acid rebound). Frequent high doses of antacids promote ulcer healing, but such treatment is rarely practical. 

Calcium carbonate is most effective in neutralizing acid, however one third to one half of the dmg can be systemically absorbed resulting in acid rebound. Hypercalcemia and milk-alkah syndrome can result from excessive use of calcium carbonate. Calcium carbonate is intensified if taken with milk products. 

There are no preformulated liquid forms of PPIs, but there are such forms of H2 receptor antagonists. Hence, these are suitable in children who do not wish to swallow tablets and in those whom reasonable acid control can be achieved by H2 receptor antagonists. However, it should not be forgotten that these drugs show tolerance, and what is apparently working early in treatment may not be adequate approximately 7 days after starting the medication. Also, withdrawal of the medication results in acid rebound. 

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