Gastrointestinal Agents PDF

Pharmacology: Drugs Affecting the Gastrointestinal System ANNGEO D. LABOG, RN, MAN HENRY T. BARRIGA JR., RN, MN TRACEY JOY L. DELA CRUZ, RN, MAN MICHAEL FRANCIS H. CAHANDIG, RN, MN  Objectives To understand the drug action, indication, side...

Pharmacology: Drugs Affecting the Gastrointestinal System ANNGEO D. LABOG, RN, MAN HENRY T. BARRIGA JR., RN, MN TRACEY JOY L. DELA CRUZ, RN, MAN MICHAEL FRANCIS H. CAHANDIG, RN, MN  Objectives To understand the drug action, indication, side effects, precautions, and nursing considerations of: common GI medications Review common medical surgical problems related to the same systems. (Gastrointestinal)  MEDICATIONS AFFECTING THE: The system included in GASTROINTESTINAL today’s lesson SYSTEM  COMMON MEDICATIONS AFFECTING THE GASTROINTESTINAL SYSTEM  MEDICATIONS AFFECTING THE GASTROINTESTINAL SYSTEM The primary functions of the gastrointestinal system are digestion, absorption, and excretion. These functions are aided by the motile and secretory properties of the gastrointestinal tract (GIT) and associated accessory organs. Common conditions affecting the GIT include nausea, vomiting, diarrhea, and some conditions associated with the nervous system. MEDICATIONS AFFECTING THE GASTROINTESTINAL SYSTEM  The gastrointestinal system is divided into two sections:  Upper GIT, from the mouth to the stomach. UPPER GI MEDICATIONS  Lower GIT, from the duodenum to the anus. LOWER GI MEDICATIONS UPPER GASTROINTESTINAL MEDICATIONS The most common form of medications used in the upper GIT are antacids or acid-controlling agents since the most common problem involving the stomach is excessive acidity and reflux. Other groups of medications such as anticholinergics, antihistamines and antidepressants may also be used in the treatment of gastric dysfunction. UPPER GASTROINTESTINAL MEDICATIONS UPPER GI MEDICATIONS ANTACIDS & ACID- ANTIEMETICS CONTOLLING AGENTS H2 ANTACID PPI ANTAGONIST ANTACID AND ACID-CONTROLLING AGENTS Acid-related diseases are caused by an imbalance in the gastric glands and their secretions. The most common condition is HYPERACIDITY, and the most harmful is PEPTIC ULCER DISEASE. Other diseases include gastritis, gastroesophageal reflux disease and dyspepsia. The major ingredients in antacids are aluminium hydroxide, calcium carbonate, magnesium salts and sodium bicarbonate. These can be used on their own or in combination w/ antacids.  ANTACID ACTIONS:  Promote the gastric mucosal defence mechanisms, acting as a buffer by neutralising hydrochloric acid in the stomach and reducing pepsin activity.  By increasing the gastric pH, the rate of gastric emptying is increased. The antacid's action is short-lived.  Antacids promote the secretion of:  Mucous, which provides a protective barrier against hydrochloric acid  Bicarbonate, which helps buffer the acidic properties of hydrochloric acid  Prostaglandins, which prevent activation of the proton pump.  Antacids do not prevent the overproduction of acid, but they do neutralise the acid once it is in the stomach.  ANTACID INDICATIONS: Reduction of pain associated with acid- related disorders such as hyperacidity, peptic ulcer, GERD, hiatal hernia, heartburn, indigestion and nervous dyspepsia. Antacid can be taken with medications known to cause gastrointestinal irritation, such as non-steroidal anti-inflammatory drugs (NSAIDs).  ANTACID aluminum salts (AlternaGEL) calcium salts (Oystercal, Tums) EXAMPLES magaldrate (Losopan, Riopan) magnesium salts (Milk of Magnesia, others) sodium bicarbonate(Bell-ans)  ANTACID SIDE EFFECTS: Aluminium hydroxide - constipation, phosphate depletion, fecal impaction, intestinal obstruction and albuminemia (in chronic renal disease), chalky taste. Calcium salts - belching, flatulence, constipation, hypercalcemia, alkalosis, gastrointestinal irritation, renal calculi. Magnesium salts - diarrhea, chalky taste, belching, elevated magnesium levels. Sodium bicarbonate - belching, abdominal distension, systemic alkalosis, hyperventilation, hypokalemia.  ANTACID PRECAUTIONS/CONTRAINDICATIONS: Antacids reduce the absorption of many medications and may combine with tetracyclines, decreasing their absorption. Use with caution with other medications because of interactions. Antacids may cause early dissolving of enteric- coated medications, causing stomach upset.  ANTACID Assess individuals for allergies. Assess individuals for pre-existing conditions that may alter effect of antacids, such as renal disease, fluid NURSING imbalance and gastrointestinal CONSIDERATIONS obstruction. Antacids should preferably be taken two hours before or after other medications. Shake liquids well before administering.  ANTACID Ensure tablets are chewed thoroughly. Administer with at least 240 mL water to enhance absorption. Liquid preparations are more fast-acting than NURSING tablets, but tablets may be sucked to provide CONSIDERATIONS an effect over time. Monitor individuals for side effects such as nausea, vomiting, abdominal pain, diarrhea, constipation and acid rebound. Monitor individuals for therapeutic effect. H2 ANTAGONISTS  H2 ANTAGONIST ACTIONS: Reduce acid secretion from stimuli such as food, histamine and caffeine. They also block histamine at the receptors of acid-producing parietal cells and reduce the production of hydrogen ions, resulting in decreased hydrochloric acid production.  H2 ANTAGONIST INDICATIONS: Treatment of maintenance of gastric and duodenal ulcers, dyspepsia, gastroesophageal reflux disease and upper gastrointestinal bleeding. H2 ANTAGONIST ranitidine Examples: famotidine cimetidine  H2 ANTAGONIST SIDE EFFECTS: Depends on the medication chosen but can include headache, constipation, nausea, diarrhea, rash, dizziness, flatulence, musculoskeletal pain. H2 ANTAGONIST PRECAUTIONS/CONTRAINDICATIONS: Individuals should avoid alcohol, spicy food, smoking and caffeine as gastric acid secretion may be increased and their condition may worsen.  H2 ANTAGONIST Not to be taken with antacid medications or separate them by at least two hours as absorption decreased. Dispersible tablets are dissolved in half a NURSING glass of water before swallowing. CONSIDERATIONS: IV solutions should not be administered rapidly because this may cause dizziness and peripheral vasodilation. Tablets should be protected from light. PROTON PUMP INHIBITOR (PPI)  PROTON PUMP INHIBITOR Proton pump inhibitors reduce the production of gastric acid by blocking the enzyme in the wall of the stomach that produces acid. The reduction of acid prevents ulcers and allows any ulcers that exist in the esophagus, stomach and duodenum to heal. ACTIONS: Reduce gastric acid secretion by inhibiting the action of the proton pump in the parietal cells. When sufficient molecules of the medication bind to the proton pump, they block the final steps of acid production, inhibiting basal and stimulated gastric acid secretion.  PROTON PUMP INHIBITOR INDICATIONS: Treatment of duodenal ulcer, benign gastric acid reflux, esophagitis, gastrinoma and Helicobacter pylori-induced ulcers, and maintenance therapy for gastroesophageal reflux disease. PROTON PUMP INHIBITOR omeprazole EXAMPLES: pantoprazole esomeprazole  PROTON PUMP INHIBITOR SIDE EFFECTS: Depends on the medication chosen but can include rash, urticaria, alopecia, arthralgia, muscle weakness, headache, dizziness, insomnia, abdominal pain, diarrhea.  PROTON PUMP INHIBITOR PRECAUTIONS/CONTRAINDICATIONS: Individuals should be advised not to drive or to operate machinery should dizziness occur. PROTON PUMP INHIBITOR Capsules, tablets and pellets should be swallowed whole NURSING with water and should not be CONSIDERATIONS: chewed or crushed. Powder should be protected from light. ANTIEMETICS ANTIEMETICS Nausea and vomiting have many causes such as gastric irritation, motion sickness, pregnancy, or as a side effect of many medications. Nausea and vomiting are also often a response by the body to remove harmful substances before further absorption occurs.  ANTIEMETICS ACTIONS: These medications can act on various body systems such as the GIT, semi-circular canals of the ear, and the vomiting centre in the brain. They are often prokinetic agents or dopamine antagonists, may stimulate peristalsis and therefore increase the rate of gastric emptying. They may reduce the impulse to the vomiting centre caused by local emetics in the pylorus and duodenum.  ANTIEMETICS INDICATIONS: To relieve nausea and vomiting caused by cytotoxic chemotherapy, gastroesophageal reflux, vertigo, or in the postoperative period.  ANTIEMETICS dolasetron ondansetron EXAMPLES: domperidone prochlorperazine metoclopramide  ANTIEMETICS SIDE EFFECTS: Depends on the medication chosen but can include oculogyric crisis, headache, dizziness, drowsiness, diarrhoea, constipation, pain, pruritis, headache, insomnia, gastroesophageal reflux, hyperkalaemia, extrapyramidal reactions.  ANTIEMETICS PRECAUTIONS/CONTRAINDICATIONS: Hypotension may occur so caution is advised when administering, especially to the elderly. Individuals should be warned not to drive or operate machinery because drowsiness may occur. ANTIEMETICS Do not administer an antiemetic until the underlying cause of the vomiting or nausea has been determined. Monitor the individual's vital signs. NURSING Metoclopramide is compatible with CONSIDERATIONS: morphine or pethidine when mixed in the same syringe. Medication must be protected from light. ANTIEMETICS May be administered orally, intramuscularly, intravenously or by suppository. If administered intravenously, slow administration over one to two minutes NURSING is advised to prevent feelings of CONSIDERATIONS: restlessness, drowsiness and anxiety. Individuals taking phenothiazines for nausea and vomiting should be advised to wear protective clothing when exposed to sunlight.  LOWER GASTROINTESTINAL MEDICATIONS  LOWER GASTROINTESTINAL MEDICATIONS Medications used to treat the lower GIT include those relating to bowel conditions such as diarrhea, constipation, and impaired digestion.  LOWER GASTROINTESTINAL MEDICATIONS LOWER GI MEDICATIONS ANTIDIARRHEALS LAXATIVES INTESTINAL ANTI- BULK- EMOLLIENTS ADSORBENTS FLORA OPIATES STIMULANTS SALINE CHOLINERGIC FORMING MODIFIERS  ANTIDIARRHEALS Acute diarrhea has a sudden onset, is self-limiting and usually resolves without further problems. It is often caused by bacteria, viral or protozoan infection. Causes of chronic diarrhea that may include tumours, DM, Addison's disease and irritable bowel syndrome. Antidiarrheal agents are used to relieve the symptoms of diarrhea and to prevent fluid and electrolyte loss. These agents include adsorbents and anti-motility agents.  ANTIDIARRHEALS: ADSORBENTS ACTIONS: Adsorbents work by coating the intestinal mucosa, by binding to and absorbing the causative bacteria or toxin and passing them out with the stools. INDICATIONS: To relieve the symptoms of diarrhea  ANTIDIARRHEALS: ADSORBENTS EXAMPLE: loperamide  ANTIDIARRHEALS: ADSORBENTS Precautions/Contraindications: Reduces the absorption of certain agents including digoxin, oral iron, hyoscine and atropine. Adsorbents may cause increased bleeding time when given with anticoagulants. Side Effects: Nausea, abdominal cramps, constipation.  Decrease intestinal muscle tone and ACTIONS: peristalsis of the GIT, thereby slowing ANTIDIARRHEALS: the movement of fecal matter. ANTICHOLINERGICS USE: To counteract gastrointestinal muscle spasm  ANTIDIARRHEALS: ANTICHOLINERGICS EXAMPLE: Hyoscine N- butylbromide  ANTIDIARRHEALS: ANTICHOLINERGICS SIDE EFFECTS: May cause urinary retention and hesitancy, impotence, headache, dizziness, confusion, anxiety, drowsiness, tachycardia, impotence, dry skin, rash, flushing, blurred vision, photophobia.  ANTIDIARRHEALS: INTESTINAL FLORA MODIFIERS ACTIONS: Lactobacillus bacterial cultures work by supplying missing beneficial bacteria to the GIT and suppressing the growth of diarrhoea-causing bacteria. INDICATIONS: Gut flora replacement. (Example: Lactobacillus acidophilus, Bacillus clausii)  ANTIDIARRHEALS: INTESTINAL FLORA MODIFIERS Lactobacillus acidophilus EXAMPLE: Bacillus clausii (Erceflora)  ANTIDIARRHEALS: OPIATES ACTIONS: Reduce peristalsis by suppressing intestinal motility, relieve rectal spasms, and decrease the transit time through the bowel, allowing more time for water and electrolytes to be absorbed.  ANTIDIARRHEALS: OPIATES EXAMPLE: Codeine phosphate  ANTIDIARRHEALS: OPIATES SIDE EFFECTS: Depends on the medication chosen but can include nausea and vomiting, dizziness, drowsiness, anorexia, constipation, bradycardia, hypotension, palpitations, urinary retention, rash, urticaria. PRECAUTIONS/CONTRAINDICATIONS: Do not use if pregnant or breastfeeding  ANTIDIARRHEALS: GENERAL NURSING CONSIDERATIONS 1. Obtain a thorough history of the individual's bowel habits, dietary changes, allergies. 2. Some antidiarrheals are not recommended for children under 12 years. 3. Use adsorbents carefully in elderly individuals and those with bleeding disorders. 4. Anticholinergics should not be administered to individuals with glaucoma, urinary retention or cardiac problems.  ANTIDIARRHEALS: GENERAL NURSING CONSIDERATIONS 5. Assess fluid balance and mucous membranes before administering medications. 6. Encourage individuals to take fluids and monitor for hydration. 7. Discontinue antidiarrheals if symptoms persist longer than 48 hours. LAXATIVES  LAXATIVES Laxatives, also known as aperients, purgatives, cathartics and evacuants, are used to improve the transit of food through the intestine and are indicated for use in constipation resulting from poor bowel habits, the use of opioid analgesics and loss of intestinal muscle tone, as well as in individuals on bed rest, and older persons. Types of laxatives: Bulk-forming Stimulants Saline or osmotic laxatives Emollients  LAXATIVES: BULK-FORMING ACTIONS: High in fibre, they increase the volume of feces by absorbing water and thereby increasing peristalsis. INDICATIONS: For constipation, hemorrhoids, pre- operative bowel emptying, control of colostomy, ileostomy and diverticular disease and the symptomatic relief of acute diarrhea.  LAXATIVES: BULK-FORMING EXAMPLES: Psyllium, sterculia, ispaghula. SIDE EFFECTS: Depends on the medication chosen but can include nausea, flatulence and discomfort.  LAXATIVES: STIMULANTS ACTIONS: Increase peristalsis, by stimulating sensory nerves endings in the mucosa. Increase the secretion of water and electrolytes. INDICATIONS: Acute and chronic constipation, bowel preparation before surgery.  LAXATIVES: STIMULANTS EXAMPLES: Bisacodyl and glycerol/glycerin SIDE EFFECTS: Depends on the medication chosen but can include abdominal colic, nutrient malabsorption, excessive loss of water and electrolytes, skin rash, nausea and vomiting  LAXATIVES: SALINE OR OSMOTIC LAXATIVES ACTIONS : Increase osmotic pressure within the bowel, causing more water to enter the intestines; bowel cleanser by inducing diarrhea while maintaining water and electrolyte balance. Cause bowel distension and increased peristalsis and evacuation. INDICATIONS: Constipation, diagnostic bowel preparation and removal of parasites and helminths.  LAXATIVES: SALINE OR OSMOTIC LAXATIVES Lactulose, colon electrolyte EXAMPLES: lavage, sodium phosphate, sorbitol, movicol preparations. Depends on the medication SIDE chosen but can include nausea, abdominal bloating and EFFECTS: cramps, vomiting, rectal irritation.  LAXATIVES: EMOLLIENTS ACTIONS: Act as a stool softener, promoting more water and fat in the stools and lubricating faecal matter and the intestinal walls. USE: In acute and chronic constipation, to allow defaecation without straining, and in painful anorectal disorders.  LAXATIVES: EMOLLIENTS EXAMPLES: Docusate sodium, poloxamer, liquid paraffin, sodium citrate with sodium lauryl sulfoacetate and sorbitol SIDE EFFECTS: Abdominal colic and cramps, skin rashes, decreased absorption of vitamins, diarrhea with excess water and electrolyte loss. LAXATIVES: GENERAL NURSING CONSIDERATION Obtain from the individual a thorough medical history of all presenting symptoms and bowel patterns. Assess fluid and electrolyte balance before commencing therapy. Generous amounts of water should be given with all bulk-forming laxatives. Individuals should not take laxatives if they are experiencing nausea and/or vomiting and abdominal pain and faecal impaction.  LAXATIVES: GENERAL NURSING CONSIDERATION Be aware of the potential for esophageal obstruction with the powdered form. Long-term use of laxatives may result in decreased bowel tone and laxative dependency. Encourage a high-fibre diet and increased fluid intake as an alternative to laxative use. Monitor individuals for therapeutic effect of treatment. Monitor individuals for side effects.