Antacids Acid Base Chemistry
Jan 21, 2016
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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
more acids