Course Instructor: Dr. Rajib Bhattacharjee

Presentation on “Drugs act on git”Antacids

• Prepared By: • Md. Mohabbulla Mohib• Istiaque Hasan • Faisal Bin Kamal • AKM Faisal

Physiology of “GIT”

Physiology of Gastrointestinal System

Gastrointestinal TractUpper GIT

• consists of structures that aid in the ingestion and digestion of food

• includes the mouth, esophagus, stomach, duodenum

Ingestion is the process of consuming something and taking it into the body. Digestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be absorbed

Lower GIT• consists of the small and large intestines

Gastrointestinal TractMouth 1. Salivation 2. Mastication

Major Structures in the Mouth• teeth – to grind the food• salivary glands – moisten food and mucous membranes and

begin carbohydrate digestion• tongue – to push the food to the pharynx to initiate

swallowingEsophagus

the lower esophageal sphincter (LES) prevents reflux of food in the stomach back into the lower esophagus

•

Gastrointestinal Tract

Stomach made up of 5 layers of smooth muscleThe mucus lining of the stomach protects the stomach walls

from the action of stomach acidThe walls of the stomach are lined with parietal cells that

secrete mucus, pepsinogen and hydrochloric acid.

2 types of contractions:1.) tonus contractions – continuous contractions2.) rhythmic contractions – may be slow or fast – responsible for the mixing of food and peristaltic movement

Stomach

Heartburn

What is heartburn?• When excess acid is produced a

condition known as acid indigestion results.

• If excess acid is forced into the esophagus acid reflux or “heart burn” results.

• These conditions are sometimes called gastro-esophageal reflux disease (GERD).

Causes of Acid Indigestion• Excess stomach acid results in a state of

discomfort known as acid indigestion• Acid indigestion may result form a

variety of factors including:• Overeating• Alcohol consumption• Eating certain foods• Anxiety• Smoking• Certain Drugs, i.e. Aspirin

Pathophysiology of Heartburn• If the Lower Esophageal Sphincter (LES) is not

working properly creating a dysfunction – the acid from the stomach can backflow into the esophagus.

Antacids

• What is Antacids?

• Antacids are a form of medicine used (normally in a tablet or liquid form) to help restore the pH balance in your stomach. It is an OTC drug.

• It is mainly weak bases that are used to neutralize excess stomach acid

• Most antacids are weak inorganic bases• Common examples include

• CaCO3

• NaHCO3

• Al(OH)3

• Mg(OH)2

• Alginate Antacids

Ideal Characteristics of Antacidsshould not absorbable or cause systemic alkalosis. should not liberate carbon dioxide &cause

rebound hyperacidity. should not interfere with absorption of food. should not be a laxative or cause constipation. should be quick acting & exert its effect over a

longer period of time.should buffer in the pH range 4-6. should probably inhibit pepsin. should be inexpensive.

Mechanism of Action of Antacids

Mechanism of Action of Antacids• Antacids directly neutralize acidity,

increasing the pH• In addition to neutralizing excess stomach

acid they may be helpful in relieving pain and discomfort, and allowing the mucus layer in the stomach lining to heal.

• They are often used to treat ulcers by preventing the stomach acids from attacking the stomach lining allowing it to heal.

• Although their principle mechanism of action is reduction of intra gastric acidity, they can also promote mucosal defense mechanism by mucosal prostaglandin products.

Mechanism of Action of Antacids

• Reduction of pain associated with acid-related disorders

• 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.

How different Types of Antacids work

CALCIUM CARBONATE

• Calcium Carbonate is a strong and fast-acting antacid.

• Antacids that contain calcium carbonate may work longer than those containing sodium bicarbonate or magnesium.

CaCO3 + 2 HCl CaCl2 + H2O + CO2

ALUMINUM AND MAGNESIUM• Aluminum salts dissolve slowly in the stomach,

gradually relieving heartburn symptoms. But they may cause constipation. Magnesium salts on the other hand, act quickly to neutralize acid but are known to cause diarrhea.

• Because the effects of aluminum and magnesium can balance each other out, using them together is often considered an effective treatment for digestive upset.

Al(OH)3 + 3 HCl AlCl3 + 3 H2O

Mg(OH)2 + 2 HCl MgCl2 + 2 H2O

SODIUM BICARBONATE• Sodium bicarbonate can work quickly to relieve

heartburn symptoms. But it's also quickly eliminated from the stomach so relief may not last long.

NaHCO3 + HCl NaCl + H2O + CO2

• Alginate Antacids• Alginate antacids don't work the way other

antacids do. These antacids contain both calcium carbonate and alginic acid. The alginic acid helps form a barrier that floats on top of the acid in your stomach. This barrier helps prevent stomach acid from moving up into esophagus.

• The calcium carbonate works to neutralize the stomach acid that pushes through the barrier and into your esophagus.

Side Effects

Side Effects of Antacids

•Diarrhea•Loss of appetite

• produce a significant amount of carbon dioxide gas, people often belch

• can cause metabolic alkalosis

• Constipation• Produces

gas and belching

• may results in kidney stones

• Loss of appetite

• Muscle weakness

• Constipation

For Aluminu

m-containi

ng antacids

For calcium-containin

g antacids:

For magnes

ium containi

ng antacid

s:

For sodium

bicarbonate-

containing antacids:

Who cannot take antacidsPatient with kidney failure or heart disease: Sodium bicarbonate has high sodium content and is not appropriate for people who are on salt restricted diets or have congestive heart failure, high blood pressure, or kidney problems.

In pregnancy: If you are pregnant, antacids are safe to use for heartburn symptoms. But do not use antacids that have sodium bicarbonate. They can cause fluid buildup. During pregnancy it is okay to use antacids that have calcium carbonate (such as Tums).

Problem with liver and kidney : If you have a problem with the function of your kidneys or liver, you should be careful with using antacids. All drugs are broken down and removed from the body by the combined action of the liver and kidneys. If your kidneys are not working correctly, it is possible that too much of the drug will build up in your body.

Drug-Drug interactions• When antacids are taken with acidic drugs such as

digoxin , phenytoin , chlorpromazine , isoniazid, they cause the absorption of the acidic drugs to be decreased, which causes low blood concentrations of the drugs, which ultimately results in reduced effects of the drugs.

• Antacids that contain magnesium hydroxide when taken with some other medications (such as tetracycline) will bind to the drug, and reduce its absorption and effects

Adverse EffectConstipation can occur in patients using calcium

carbonate and aluminum containing antacids.Diarrhea is a common adverse effect of

magnesium- and sodium-containing antacids. If diarrhea occurs, the patient may alternate the antacid mixture with aluminum hydroxide.

REFERENCES• The pharmaceutical basis of therapeutics,12

edition; Goodman & Gilman.• http://www.heartburn.com/a-to-z-guides/

nonprescription-medications-and-products-antacids-and-acid-reducers

• http://bodyecology.com/articles/low_stomach_acid_symptoms.php#.UisH6m3-tyM

• http://www.patient.co.uk/health/antacids• http://www.drugbank.ca/drugs/DB01390• https://www.inkling.com/read/pharm-phys-

anesthetic-practice-stoelting-4th/chapter-26/antacids

• http://pharmacy.utah.edu/pharmtox/common_meds/icm15.htm

• http://www.drugbank.ca/drugs/DB06723

Thank you