Download Hydrochloric acid

ANTACIDS
Selin Palabıyıkoğlu 12-D
What is antacid?
Antacids are medicines that neutralize stomach
acidity.
The stomach secretes:
• Hydrochloric acid: the hydrogen ion concentration of the HCl
normally cause pH to be between 1.5-2.5
• Bicarbonate: helps buffer acidic properties of HCl
• Pepsinogen: a precursor for the enzyme pepsin that breaks down
proteins into peptides.
• Mucus: protective barrier against HCl
These are known collectively as gastric juice.
Factors Affecting the Balance in the
Stomach Mucosa
Aggressive Factors
Protective Factors
Stomach Acidity
Pepsin
Alcohol, nicotine
Anxiety
Helicobacter pylori sytotoxine (bacteria
usually affecting the ulcer)
Drugs ( Aspirin and other analgesics)
Mucus production
Mucosal blood circulation
Cell repairing
Bicarbonate production
Acid related diseases can arise if the stomach lining is damaged or
when too much acid is produced.
Acid Related Diseases
1) Indigestion
2) Peptic Ulcer
3) Gastroesophageal Reflux Disease (GERD)
Indigestion
The discomfort caused by excess acid is known as
indigestion and may result from overeating, alcohol,
smoking, anxiety or in some people from eating
certain types of food.
Peptic Ulcer
• Peptic ulcers are localized wounds in the stomach,
duodenum and lower esophagus mucosa with tissue
destruction.
• “Peptic” reflects a belief (probably misplaced) that
peptic activity is related with pepsin.
• The common symptom is pain occurring before meals
or overnight, relieved by antacids, milk and food.
GERD
• It is defined as present in an individual who
experiences typical symptoms of GERD (heartburn,
acid regurgitation to mouth, belching, globus
sensation, chronic cough and hoarsenes), due to
reflux of stomach contents into esophagus.
• Mucosal injury may present or not.
• It is a very common disorder affecting between 1030% of western population.
• Especially common in pregnant women and obese
people.
Antacids
• Antacids work by neutralizing the acid, preventing
inflammation, relieving pain and discomfort, allowing
the mucus layer and stomach lining to mend.
• When used in the treatment of ulcers, they prevent
acid from attacking the damaged stomach lining and
so allow the ulcer to heal.
• They are most affective if taken between one and
three hours after eating, as food typically remains in
the stomach for up to four hours after a meal.
• Antacids are intended to treat digestive upset by
raising the pH level of the stomach from a highly
acidic 2 to between 3 and 4. This can neutralise up to
99% of the excess acid in the stomach, leading to
substantial relief from symptoms for most people.
• Raising gastric pH from 1.3 to 1.6 neutralizes 50% of
the gastric acid.
• Raising gastric pH 1 point (1.3 to 2.3) neutralizes 90%
of the gastric acid.
• Antacids are bases, usually, metal oxides, hydroxides,
carbonates or hydrogen carbonates (bicarbonates) to
neutralize excess acidity.
• They begin to work within a minute and can provide a
relief that ranges from 10 minutes to more than 90
minutes.
Action of Antacids
• Magnesium Oxide: MgO(s)+ 2HCl(aq)  MgCl2(aq) + H2O(l)
• Magnesium Hydroxide: Mg(OH)2(aq)+2HCl(aq) MgCl2(aq)+ 2H2O(l)
• Aluminum Hydroxide: Al(OH)3(s)+3HCl(aq) AlCl3(aq)+ 3H2O(l)
• Calcium Carbonate: CaCO3(s) + 3HCl (aq)  CaCl2(aq)+H2O(l)+CO2(g)
• Sodium Bicarbonate: NaHCO3(aq)+HCl(aq)NaCl2(aq)+H2O(l)+CO2(g)
• Magnesium Trisilicate:
Mg2Si3O8(s)+4HCl(aq)3SiO2(s)+2H2O(l) +2MgCl2(aq)
• Antacids are combined with chemicals called alginates
that produce a neutralising layer that prevents acid
reflux. They prevent acid in the stomach from rising
into the esophagus and causing “heartburn”.
• Similarly, anti-foaming agents, such as dimethicone or
simethicone are added to reduce the surface tension
of gas bubbles, causing them to come together,
producing a defoaming action.
BRAND NAME
INGREDIENTS
Tums®
CaCO3, MgCO3, MgSi3O8 (magnesium trisilicate)
Rennie®
CaCO3, MgCO3, NaC6H7O (sodium alginate)
Rotaids®
AlNa(OH)2CO3 (dihidroxylaluminum sodium
carbonate
Dank®, Kompensan®
AlNa(OH)2CO3
Maalox®
Asidal®, Mucaine®, Simeco®
Mg(OH)2, Al(OH)3 , simethicone
Di-Gel®
CaCO3
Alca-Seltzer®
NaHCO3, citric acid, aspirin
Milk of Magnesia®
Mg(OH)2
Amphogel®
Al(OH)3
Side Effects
Side effects are very rare. They are more likely when
the medicine is taken large doses or over a long time.
Aluminum
Compounds
 constipation or irregularity
 prevent uptake of phosphate ions causing possible bone damage if
taken in high doses over a long period
Magnesium
Compounds
 diarrhea
Calcium Carbonate
 excessive amount of calcium ions being absorbed into the body
 kidney stones
Sodium Ions
 hypertension
Excessive use of
Sodium Bicarbonate
 alkalosis ( alkaline stomach causes discomfort and is often mistaken
as being due to an acidic stomach so one takes more antacid, making
the stomach still more alkaline, causing more indigestion)
 fluid retention ( bloating)
Precautions
• Antacids should not be given to children under 6
years old.
• Before combining antacids with extra calcium ( dairy
products or calcium supplements) ask for assistance.
• Be careful in low-sodium diet( hypertension cases)
• Occasional use of antacids in small amounts is safe
during pregnancy.
• Magnesium containing antacids should be avoided in
patients with chronic kidney failure.
• Absorbtion of some antibiotics and iron inhibited by
antacids.
Acid “Rebound”
Antacids show the most rapid action but may cause
acid “rebound”: a condition in which the gastric acid
return in greater concentrations after the drug
effect has stopped.
• Remember that;
Antacids DO NOT prevent the
overproduction of acid.
Antacids DO neutralize the acid once it’s in
the stomach.
Questions
1) Which would be the most effective in combating
indigestion- a spoonful of liquid containing 1.00 g of
magnesium hydroxide, or a spoonful of liquid
containing 1.00 g of aluminum hydroxide?
2) One common type of drug taken orally is antacid.
Antacids such as sodium hydrogencarbonate are taken
to reduce stomach acidity.
(i) State the names of two metals, other than sodium,
whose compounds are often used in antacids.
(ii)Give an equation for the neutralization of HCl in the
stomach by sodium hydrogencarbonate.
(iii) Explain how heartburn is caused.
(iv)Explain why dimethicone is added to some antacids.