Antacids

Antacids

Acid Base Chemistry

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Antacids

12.2 Antacids• State and Explain how excess acidity

in the stomach can be reduced by the use of different bases.

• Antacids: bases, metal oxides, hydroxides, carbonates, hydrogen carbonates

• Reacts with stomach acid (excess) to adjust the stomach pH to the desired level

Purpose of HCl in the stomach

• To suppress growth of harmful bacteria

• To help in digestion by hydrolyzing proteins to amino acids

• Normal pH of stomach acid ~

• 1.2 – 0.3 range,

• Stress also produces more acid

Role of antacids

• Neutralizes the excess acids and relives the discomfort

–Excess acid can cause ulcers

Examples: Over the Counter

• Al(OH)3 Mg(OH)2 CaCO3

• NaHCO3

Alginates

• Antacids are combined with

Alginates• extracted from brown sea weeds

• produces neutralizing layer that prevents acid reflux / acid entering into oesophagus

Dimethicone / Antifoaming agent

• Are added to antacids to reduce the surface tension of gas bubbles

• And produce de-foaming action

Silicon Chemistry

• The possibilities offered to the formulation chemist by silicone chemistry are endless and yours to explore.

Active ingredients of some commercial antacids

• Tums: CaCO3 MgCO3 Mg Si3O8

–For the treatment of gastritis and of ulcers• Rolaids : AlNa(OH)2CO3

• Malox : Al(OH)3 Mg(OH)2

• Alka Seltzer : NaHCO3 , citric acid, aspirin

Alka Seltzer : NaHCO3 , citric acid, aspirin

Active ingredients of some commercial antacids

• Milk of Magnesia : Mg(OH)2 or MgO/Mg(OH)2 mixture

• Amphogel Al(OH)3

• Di-Gel : CaCO3

Action of Antacids

• Mg2Si3O8 + 4 HCl 3 SiO2(s)• 2 H2O (l) + 2 MgCl2(aq)

• Write the reactions for rest of the antacids

• Alkalosis: high doses of antacids• basic stomach• Other problems: body produces

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