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