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ANTACIDS
Human Stomach
Gastric juices in stomach
Contain HCl (aq)Ph 1-3To suppress growth of
bacteriaTo help in digestion
by hydrolysing proteins to amino acids
Indigestion
Excess acid production
Abdominal discomfort after eating
Over eatingStressCertain foodsAcid eats away
protective mucus layer
Painful ulcers
Antacids
Remedy for excess stomach acidity
BasesMetal oxides,
hydroxidesMetal carbonatesMetal
hydrogencarbonates(bicarbonates)
Effect of Antacids
Neutralise excess acid and adjust stomach ph to desired level
Stomach lining repairs itself
Active ingredientsAluminium hydroxideMagnesium hydroxideSodium 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 agentAdded 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 equationsThen try question 3 on page 434
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