Disease Encyclopedia | Physiology VS Pathology

DISEASE ENCYCLOPEDIA

G.I.T Canal

Physiology VS Pathology

Just as physiology is the study of the way in which the body works, pathology is the scientific study of abnormal physiology, i.e. disease. There are many ways in which physiological processes can be upset, and knowledge of the etiology of a disease may give valuable clues to diagnosis and management. The physician will rely on the signs and symptoms, ray images and lab results resulting from the derangement of normal physiology to reach these decisions. In the coming series of articles we will examine how physiological processes common to all body systems are altered by disease.

GASTROINTESTINAL 

The process of digestion begins when food enters the mouth and is chewed and mixed with saliva from the salivary glands; this provides lubrication and begins digestion by salivary enzymes. This bolus of food passes through the pharynx and esophagus via muscular rounded valve called the lower esophageal sphincter (LES) into the stomach for further digestion. The LES closes, preventing reflux (coming back) of the gastric content into the esophagus, where it could cause irritation and digestion continues in the stomach.

The stomach wall contains cells that secrete acid, mucus, enzymes (body digestion tools), and hormones (chemical messengers that orchestrate almost all the body functions) that affect digestion and motility. The bolus enters the small intestine through the pyloric sphincter. Secretions from the intestinal mucosa (wall lining layer of cells) contain additional enzymes and hormones, affecting motility and enhancing digestion. Secretions from the pancreas, liver, and gall bladder increase fluid volume in the small intestine and further enhance digestion and absorption.

Indigestible materials and metabolic waste products pass into the large intestine for elimination.

Digestive problems affect a large number of people and produce a variety of symptoms, including acid indigestion, upset stomach, sour stomach, heartburn, gastroesophageal reflux disease (GERD), nausea, vomiting, bloating, intestinal gas, constipation, and diarrhea. When these symptoms are mild and occur occasionally, self care is appropriate. However, these symptoms also occur in individuals who have peptic ulcer diseases, such as gastric ulcers, duodenal ulcers, chronic gastritis and chronic GERD; treatment of these conditions requires supervision by a physician.

 Many of the OTC self care drugs may be used during treatment of these conditions with prescription medications.

Other symptoms that may occur with the GI symptoms above require immediate referral to a physician, including the presence of blood in the vomit or stools, any difficulty in swallowing or breathing, or the presence of lightheadedness, sweating, or pain in the shoulder, arms, neck, or chest. These symptoms indicate a serious condition that cannot be diagnosed by the individual and are not amenable to self-care. Pregnant women and lactating mothers should consult a physician before using any OTC drugs. OTC drugs should not be administered to children 2 years of age or less unless a physician has been consulted.

Acid indigestion, heartburn, GERD, relief of upset stomach associated with overindulgence in food and drink

1- Antacids

Drug category and indications for use.

Antacids provide relief from occasional heartburn, sour stomach, or acid indigestion, and provide relief of upset stomach from food or drink.

Monograph ingredients

Aluminum hydroxide, calcium carbonate, magaldrate, magnesium hydroxide, magnesium oxide, sodium bicarbonate, and sodium citrate are the most commonly used ingredients in antacid products. 

The neutralizing ability varies among these drugs, with sodium bicarbonate, sodium citrate, and calcium carbonate being the more effective neutralizers, followed by magnesium hydroxide and aluminum hydroxide.

All monograph antacids except sodium bicarbonate are approved for symptoms related to upset stomach from overindulgence of food or drink (hangover symptoms), and their use should be limited to 2 days for this purpose. Sodium bicarbonate releases carbon dioxide, and if any undissolved drug is ingested it can react with gastric acid, causing excessive distension of the stomach and possible rupture.

Mode of action

Antacids chemically neutralize hydrochloric acid, an irritating substance secreted into the stomach from cells in the gastric mucosa.

Warnings and precautions

Too many to worry about while using these O.T.C antacids. 

1- No more than the recommended dose should be taken within any 24 hour period, or for more than 2 weeks without the supervision of a physician. If symptoms are severe, occur frequently, or persist for more than 3 months, referral to a physician is appropriate.

2- If the individual is taking a prescription drug, a physician or pharmacist should be consulted because drug–drug interactions may occur. Many antacids alter absorption of prescription drugs and should be administered

1 hour before or 2 hours after taking prescription drugs.

3- Sodium bicarbonate and sodium citrate antacids exceed (140 mg) of sodium per daily dose and should not be used by individuals on salt-restricted diets (e.g. hypertensive or hepatic patients). Tablets or powders containing sodium bicarbonate must be added to at least 4 ounce (120 mL) of water and be dissolved before ingestion. 

There may be some white residue at the bottom of the glass, but this is not sodium bicarbonate and is safe to ingest. These products produce a vigorous effervescence (bubbling) when carbon dioxide gas is produced; this subsides when all the gas has been released.

4-Aluminum hydroxide has astringent properties and frequently causes constipation on the other hand magnesium compounds are soluble and frequently cause diarrhea.

Manufacturers combine aluminum hydroxide and magnesium hydroxide as a mixture in an effort to balance the bowel effects of these two drugs, with modest success. Magaldrate is a chemical compound of both aluminum and magnesium hydroxides that does not have any particular advantage over products that are physical mixtures. Calcium carbonate may cause constipation and is also combined with magnesium antacids.

5-Individuals with kidney disease should avoid magnesium antacids if they contain more than 50 milliequivalents of magnesium unless under the supervision of a physician.

Recommended doses

Antacids have a short duration of action. They should be administered 1 hour after meals and as frequently as every 2 to 4 hours as needed. Doses vary and depend on the acid-neutralizing capacity of the individual ingredients.