ANTACIDS

Human Stomach Gastric juices in stomach Contain HCl (aq) Ph 1-3 To suppress growth of bacteria To help in digestion by hydrolysing proteins to amino acids

Indigestion Excess acid production Abdominal discomfort after eating Over eating Stress Certain foods Acid eats away protective mucus layer Painful ulcers

Antacids Remedy for excess stomach acidity Bases Metal oxides, hydroxides Metal carbonates Metal hydrogencarbonates (bicarbonates)

Effect of Antacids Neutralise excess acid and adjust stomach ph to desired level Stomach lining repairs itself Active ingredients Aluminium hydroxide Magnesium hydroxide Sodium hydrogen carbonate

Alginates Combined with antacids Extracted from brown seaweeds Produce a neutralising layer rthat prevents acid reflux E.g. they prevent acid from rising into oesophagus «Heartburn»

Dimethicone Anti-foaming agent Added to reduce surface tension of gas bubbles Causes bubbles to coalesce (come together) Produces defoaming action

Side effects Aluminium hydroxide may cause constipation Can prevent uptake of phosphate ions (precipitation of aluminium phosphate) Large charge to size density leads to binding with other drugs

Side Effects Magnesium hydroxide has laxative properties Calcium carbonate may lead to kidney stones Sodium ions may lead to hypertension

Alkalosis Taking too much antacid leads to alkalosis (a rise in ph of blood) Also can lead to excessive amounts of calcium ions in body

Question Two solid antacid products contain same mass of different active ingredients. One contains sodium bicarbonate, the other calcium carbonate. Which is the better buy and why ?

To Do Look at active ingredients of antacids on page 410 Also look at chemical equations Then try question 3 on page 434