Friday, October 3, 2014

D.2 Antacids

D.2.1 State and explain how excess acidity in the stomach can be reduced by the use of different bases.

Antacids - weak bases which neutralizes strong acids
e.g. metal oxides/ hydroxides/ carbonates or hydrogen carbonates
Acid + Metal Oxide --> Salt + Water
Acid + Carbonate --> Salt + Water + Carbon dioxide

Acid indigestion - feeling of discomfort from too much acid in the stomach

Heartburn - acid from the stomach rising into the oesophagus (acid reflux)

Ulcer - damage to the lining of stomach wall, loss of tissue and inflammation

Common antacids:
Mg: faster acting, acts as a laxative
Al: dissolves slower & provide longer-lasting relief, can cause constipation, has been linked with the development of Alzheimer's (but it's not been proven)


Metal carbonates and hydrogen carbonates produce salt, water and carbon dioxide.
- can cause bloating of stomach and flatulence (wind/gas)
- anti-foaming agents (e.g. dimethicone) added to prevent it 

Some antacids contain alginates. They float to the top of the stomach and forms a foam "raft", which acts as a barrier preventing acid reflux.

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Because antacids change pH of the stomach, they can also alter other chemical reactions including absorption of other drugs.
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