Gastrointestinal Pharm

mechanisms lang kasi drugs are illegal

Emesis

vomiting

Peptic Ulcer

* ulceration on the mucosal lining of the esophagus, stomach and duodenum
* can also be d/t excess gastric acid

Gastroesophageal Reflux

* indigestion and epigastric pain (dyspepsia) and to heartburn sensations caused by leakage of gastric acid into the distal esophagus.

Antacids

* attempt to chemically neutralize stomach acids.
* Can treat minor cases of dyspepsia that occur from over/eating spicy food, and so forth.
* Can be abused when used as a panacea (a remedy for all ills) for poor eating habits, so other drugs have replaced them in treating major illnesses.
* Can be taken orally, either as tablets or a liquid oral suspension

Adverse Effect of Antacids

* Constipation - most common side effect
* Electrolyte imbalances
* Altered pharmacokinetics
* Side effect of the acid-rebound phenomenon has been disproven in antacids
* Acid-rebound phenomenon - caused by sudden discontinuation of drugs after prolonged use.

H2 Receptor Blocker

* histamine receptor that can stimulate the increase of gastric acid secretion
* Inhibition of such is the long and short term management of peptic ulcer and dyspepsia and GERD.

Adverse effect of H2 Receptor blockers

* headache and dizziness
* mild transient GI problems
* Arthralgia
* Myalgia

Proton Pump Inhibitor

* inhibit the H+, K+ ATPase enzyme that is ultimately responsible for secreting acid from gastric parietal cells into the lumen of the stomach.


* Effective in treating
* H.pylori infection
* Gastric ulcers - decrease morbidity
* Duodenal ulcers
* GERD - decrease risk of esophageal damage and carcinoma

Adverse Effects of PPI

* Usually well tolerated
* Acid-rebound phenomenon
* Increased risk of certain fractures d/t changes in calcium metabolism

H. Pylori

A gram-negative bacterium that is often present in the upper GI in people with gastric ulcer disease.

Combination therapy

Used in treatment for H. Pylori

* Triple therapy - 2 antibacterials + 1 PPI
* Quadruple therapy - 2 antibacterials + 1 bismute compound combined + 1 PPI

Anticholinergics

* Cholinergic stimulation of the gut via vagal efferent fibers produces a general increase in GI motility and secretion.
* Drugs that block the effects of acetylcholine on stomach parietal cells will decrease the release of gastric acid.

Metoclopramide (Reglan)

* Classified as dopamine receptor Enhances peripheral effects of acetylcholine, thus stimulating motility in upper GI tract.
* Useful in moving stomach contents toward the small intestine, thus decreasing risks of gastric acid moving backward into esophagus.

Prostaglandins

* There is little doubt that certain prostaglandins such as PGE2 and PGI2 inhibit gastric secretion and help protect the stomach mucosa by stimulating gastric mucus secretion.

Sucralfate

* Sucralfate is a disaccharide that exerts a cytoprotective effect on the stomach mucosa.
* well tolerated but may cause constipation.

Opioid Derivatives

* Produce a general decrease in GI motility
* May also reduce fluid loss by increasing the absorption of salt and water or by decreasing fluid and electrolyte excretion from the GI tract.
* Adverse Effects:
* Nausea
* Abdominal Discomfort
* Constipation
* Other GI disturbances
* Drowsiness, fatigue, and dizziness have also been reported

Bismuth Salicylate

* May stimulate water and electrolyte absorption \n from the lower GI tract, thus decreasing fecal \n fluid loss
* Bismuth component: may have \n antibacterial effects
* Salicylate component: may inhibit the \n production of prostaglandins that may \n irritate the intestinal lining
* May also decrease acid secretion and \n exerts antacid effect
* Is used to treat mild to moderate diarrhea
* Adverse Effects:
* This drug is relatively free from serious \n side effects \n

Clonidine

* Normally used to treat hypertension.


* Can also stimulate alpha 2 receptors in the GI tract, thereby decreasing secretion, increasing absorption, and normalizing GI movement.

Octreotide

* Inhibits the secretion of serotonin and other peptides that stimulate GI function, and is especially useful in treating diarrhea caused by tumors that secrete these substances into the GI tract

Cholestyramine, colestipol and colesvelam

* Sequester and bind bile acids within the GI tract

Laxatives

Promote the evacuation of the bowel and defecation when normal bowel movements are impaired, but no obstruction exists in the system.

Cathartics

Has the same effect with laxatives, but in a somewhat more rapid fashion.

Bulk-Forming Laxative

* Absorb water and swell within the lower GI tract


* The increased size of the water-laden laxative stretches the bowel, thus stimulating intestinal movement (peristalsis)

Stimulant Laxatives

* May activate peristalsis by a direct irritant effect on the intestinal mucosa or by stimulating the nerve plexus within the gut wall.
* They also work in increasing fluid accumulation within the small intestine.

Hyperosmotic Laxative

* Produces a gradient that draws water into the bowel and small intestine — this increases stoll fluid content and stimulates peristalsis.

Lubricants and Stool Softeners

* Facilitate the entry of water into the fecal mass, thus softening the stoll and permitting easier defaction

Adverse Effect of Laxatives

* Disturbances in the GI system such as nausea and cramps
* With prolonged use, serious lower GI irritation, including spastic colitis may occur
* Excessive loss of water and the concomitant loss of electrolytes may transpire, resulting in dehydration and possible acid base imbalnces
* Laxative dependence

Digestants

* Aid in the digestion of food
* Individuals with cystic fibrosis often use this — this condition leads to a chronic deficiency of pancreatic enzymes and bile salts, therefore patients cannot digest and absorb nutrients from the GI tract, digestants replace the missing compounds, thus improving digestion and nutrient absorption.

Emetics

* Induce vomiting
* Are frequently administered to help empty the stomach of poisons or ingested toxins

Anti-emetic

* Decrease the nausea and vomiting associated with motion sickness, recovery from surgery, or other medical treatments.

Cholelitholytic Agents

* Decrease the cholesterol content of bile and may help dissolve gallstone that are supersaturated with cholesterol.
* Do not appear effective in the treatment of calcified gallstones.