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Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
Gi system pharmacology
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Gi system pharmacology

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  • 1. Pharmacology
  • 2. General Guidelines for GI Meds
      • Administration Principles:
      • List current medications (including OTC drugs and herbal products) and history of allergies to identify any potential risks to client
      • Administer doses on time
      • Do not break or allow client to chew sustained release or enteric coated preparations (some meds i.e. antacids are supposed to be chewed)
      • Provide verbal and written instructions to client
  • 3. Client Teaching
    • Understand medication actions, side effects, signs of toxicity, importance of follow-up with prescriber and complying with follow-up lab tests and how to self administer
    • Do not take OTC drugs or herbal products without consulting prescriber
    • Take exactly as prescribed and do not miss or double doses
    • Report adverse effects promptly
    • Do not discontinue drug without consulting provider
    • Do not drink alcohol while taking prescription medications
  • 4. Chapter 24
    • Agents Used To Treat Hyperacidity and Gastroesophageal Reflux Disease
  • 5. Antacids
    • Alkaline chemical agents used for relief of symptoms associated with hyperactivity and PUD
    • Primary goal of antacid therapy is the relief of pain
    • Pain-reducing effect believed to be due to:
      • Acid neutralizing capacity (the higher the better)
      • Inhibition of the protein-digesting ability of pepsin
      • Increase in the resistance of the stomach lining to irritation
      • Increase in tone of the lower esophageal sphincter
  • 6. Antacids (cont)
    • Systemically absorbed
      • i.e. sodium bicarbonate, evervescent solutions
      • Highly soluble in gastric fluids; once dissolved, they are absorbed readily
      • Rapid onset and short duration of action—must take frequently
      • May cause acid-base (metabolic alkalosis) and electrolyte disturbance
      • May cause rebound hyperacidity
      • Prolonged use causes stress on kidneys
  • 7. Antacids (cont)
    • Nonsystemic antacids
      • Most useful for long-term therapy
      • Stays in GI tract
      • Does not alter systemic acid-base balance or electrolytes
      • Most cause either constipation or diarrhea (can combine agents to cancel these side effects out)
  • 8. Antacids (cont)
    • 3 basic forms: aluminum, magnesium, and calcium based
    • Aluminum hydroxide—prolonged use may cause phosphate depletion
      • Maalox, Mylanta
      • constipation
    • Magnesium—caution if impaired renal function; may accumulate and cause toxicity
      • Milk of magnesia
      • diarrhea
    • Calcium carbonate—may cause kidney stones and increased gastric acid secretion
      • Tums
      • constipation
    • Table 24.1 p. 567-568
  • 9. Antacids (cont)
    • Many antacid preparations contain the antiflatulent simethicone, which reduces gas and bloating
    • Administration :
      • Antacids generally taken about 1 hour after eating, and their neutralizing action lasts for about 3-4 hours (ineffective if taken on an empty stomach)
  • 10. Antacids (cont)
    • Interactions
      • Capable of causing several drug interactions when administered with other drugs
        • Adsorption (binding) of other drugs to antacids—reduces ability of the other drug to be absorbed
        • Chemical inactivation—produces insoluble complexes
        • Increased stomach pH—increases absorption of basic drugs and decreases absorption of acidic drugs
        • Increased urinary pH—increases excretion of acidic drugs and decreases excretion of basic drugs
  • 11. Antacids (cont)
    • ***Clients should be advised NOT to take other oral medications within 1-2 hours from the time they are taking antacids
    • Do not administer within 1-2 hours of any enteric-coated drug product
  • 12. Histam INE H2 Receptor Antagonists
    • Cime tidine (Tagamet), famo tidine (Pepcid), niza tidine (Axid), and rani tidine (Zantac)
    • Used to treat duodenal ulcers, gastric ulcers, and excessive secretion of hydrochloric gastric acid
    • Prevent stress ulcers in critically ill clients
    • Inhibit action of histamine at parietal cells in stomach—decreased hydrogen ion production= increased pH in the stomach
    • Reduce but do not eliminate acid secretion
  • 13. H2 antagonists
    • Use caution in clients with impaired renal or hepatic function—dosages usually reduced
    • Low incidence of side effects
    • Occasionally: diarrhea, muscle pain, rash, drowsiness, dizziness, and/or confusion
    • Not recommended for nursing mothers or children <16 y/o
    • Client teaching:
      • Avoid smoking which causes gastric stimulation
      • Avoid antacid use within 1 hour of dose
      • Once-a-day dosage should be taken at bedtime; if prescribed more than daily, take before meals
      • Avoid gastric irritants such as alcohol, aspirin, and NSAIDS
  • 14.
    • Cimetidine (Tagamet)
      • May cause impotence, gynecomastia, and central nervous system effects (i.e. confusion )
      • May increase pharmacological effects and toxicity of many drugs
      • Cigarette smoking may diminish effectiveness
      • Use of antacids may reduce the absorption of cimetidine
      • Administer with or immediately following a meal
  • 15. PR oton Pump Inhibitors
    • Esome prazole magnesium (Nexium), lanso prazole (Prevacid), ome prazole (Prilosec), rabe prazole (Aciphex)
    • Used to treat hyperacidity, GERD, esophagitis
    • Suppress gastric acid secretion by blocking final step in gastric acid production through inhibition of H+, K+ATPase (proton pump) in the gastric parietal class
    • Hydrogen ions unable to move out of parietal cell into the stomach
    • Block all acid secretion
  • 16. Proton Pump Inhibitors
    • Used to treat erosive or ulcerative GERD or duodenal ulcers, active benign gastric ulcers, and NSAID associated gastric ulcers
    • Generally for Short term therapy (4-8 weeks)
    • Used for healing and to reduce relapse rates of heartburn in erosive or ulcerative GERD (maintenance therapy)
  • 17. Administration Considerations
    • May give with antacids
    • If unable to swallow capsules, lansoprazole and esomeprazole capsules may be opened and sprinkled on applesauce before taking
    • To give per NG tube, dilute capsule contents in 40ml juice
    • Omeprazole(Prilosec), pantoprazole (Protonix), and rabeprazole (Aciphex), must be swallowed whole
    • Should be taken 30-60 min before breakfast
  • 18. Proton Pump Inhibitors
    • Side/adverse effects
      • Headache, diarrhea, constipation, abd pain, nausea, flatulence
      • Rash, hyperglycemia, dizziness, pruritis, dry mouth
      • May increase liver enzymes
  • 19. Proton Pump Inhibitors (cont)
    • Esomeprazole (Nexium)—highest healing effect on esophagus
      • Action decreased by food; should be taken on an empty stomach
      • In combination with clarithromycin and amoxicillin has been approved for treatment (and cure) of pts with Helicobacter pylori infection and duodenal ulcer
      • SE: diarrhea, abdominal pain, nausea
      • 20-40mg daily X 4-8 weeks
  • 20. Proton Pump Inhibitors
    • Lansoprazole (Prevacid)
      • In combination with clarithromycin and amoxicillin has been approved for treatment (and cure) of pts with Helicobacter pylori infection and duodenal ulcer
      • 15-30mg daily X4-8 weeks
      • Not recommended for use in children
  • 21. Proton Pump Inhibitors (cont)
    • Omeprazole (Prilosec)
      • GERD and esophagitis
      • 20-40mg daily X 4-8 weeks
      • In combination with clarithromycin and amoxicillin has been approved for treatment (and cure) of pts with Helicobacter pylori infection
  • 22. Sucralfate (Carafate)
    • Treatment of ulcers and chronic PUD
    • Binds to the base of ulcers and erosions, forming a protective barrier over the base of this area
    • Limits access of pepsin
    • Protects ulcer from further attack by acid, pepsin, and bile salts
    • Does little to neutralize gastric acid
    • Short term treatment (up to 8 weeks) or at a reduced dose for maintenance therapy
    • 1 gram 4Xdaily on an empty stomach: 1 hour before each meal and at bedtime
  • 23. Misoprostol (Cytotec)
    • Synthetic prostaglandin analog
    • Decrease gastric acid secretion and exert a protective effect on the mucosal surface of the stomach
    • Prevention of gastric ulcers in patients taking NSAIDS (i.e. aspirin)
    • SE: diarrhea, abdominal pain, uterine contractions and cause miscarriage—contraindicated for use by pregnant women
  • 24. Misoprostol
    • Reinforce client teaching:
      • Avoid gastric irritants such as caffeine, alcohol, smoking, and spicy foods
      • Follow contraceptive practices while on misoprostol
      • Report abnormal vaginal bleeding
      • Increase fluids and fiber to decrease constipation
  • 25. Metoclopramide (Reglan)
    • Stimulates motility of upper GI tract without stimulating the production of gastric, biliary, or pancreatic secretions
    • Increases force of gastric contractions, relaxes pyloric sphincter, increases LES pressure (decreasing GERD), and increases peristalsis in small intestine
    • Accelerates gastric emptying and passage of gastrointestinal contents
    • Adverse effects: CNS depression, gastrointestinal upset, parkinsonism-like reactions
    • 10mg 4X daily, 30 minutes before each meal and at bedtime
  • 26. Gastrointestinal Enzymes
    • Congenital abnormality, disease, advancing age, or surgery may cause a deficiency in gastrointestinal enzymes that normally assist in food digestion
    • Many of these enzymes may be provided orally using commercially available products
    • Pancreatic enzymes i.e. pancrelipase, pancreatin
    • Enzymes that help digest lactose i.e. lactase
  • 27. Pancreatic Enzymes
    • Deficiencies: Pancreatitis, pancreatic cancer, cystic fibrosis, GI surgery
    • Enzymes: Pancrealipase and Pancreatin
    • Required for proper digestion of fats, proteins, and complex carbohydrates
    • Most derived from pigs or cows (monitor for sensitivity)
    • Usually enteric coated tablets or capsules containing enteric coated enzyme beads
    • Should be taken in conjunction with every meal and snack
  • 28. Lactase Enzyme
    • Lactose intolerance due to inadequate production of lactase enzyme
    • S/S lactose intolerance: diarrhea, flatulence, bloating shortly after milk consumption
    • LactAid, Lactrase, Dairy Ease
  • 29. Emetics and Antiemetics
  • 30. Antiemetics
    • Given to prevent and treat nausea and vomiting due to motion sickness, CNS disorders, administration of certain drugs, radiation therapy
    • Vomiting center (VC) in the brain that is responsible for initiating the necessary physiologic events that lead to nausea and eventually vomiting (along with the chemoreceptor trigger zone--CTZ)
      • Stimulated by neurotransmitters
  • 31. Antihistamines and Anticholinergics
    • Anticholinergics
      • i.e. scopalamine
      • Bind to and block acetylcholine receptors—preventing nauseous stimuli from being transmitted
      • Limit stimulation of the emetic center
    • Antihistamines
      • i.e. meclizine (Antivert), diphenhydramine (Benadryl), promethazine (Phenergan)
      • Block histamine H2 receptors, preventing cholinergic stimulation
  • 32. Antihistamines and Anticholinergics
    • Anticholinergic side effects
      • Dry mouth, urinary retention, blurred vision
      • Use with caution in clients with benign prostatic hypertrophy and narrow-angle glaucoma
  • 33. Neuroleptic agents
    • i.e. chlorpromazine (Thorazine), droperidol (Inapsine), perphenazine, and prochlorperazine (compazine)
    • Prevent nausea and vomiting by blocking dopamine receptors on the CTZ
    • Many of the neuroleptics also have anticholinergic actions
    • Adverse effects: orthostatic hypotension, sedation, tardive dyskinesia
  • 34. Prokinetic Agents
    • i.e. metoclopramide (Reglan), cisapride
    • Block dopamine, but also stimulate acetylcholine to increase gastric emptying
  • 35. Serotonin-Blocking Agents
    • (serotonin antagonists)
    • Initially used for treatment of chemotherapy-related n/v
    • i.e. ondansetron (Zofran), granisetron(Kytril), dolasetron mesylate (Anzemet), and palonosetron HCl (Aloxi)
    • Prevent transmission of triggers that cause nausea and vomiting
  • 36. Aprepitant (Emend)
    • Used in conjunction with serotonin antagonists and a corticosteroid, such as dexamethasone (Decadron) for the treatment of chemo related delayed n/v
  • 37. Emetics
    • Substances that induce vomiting—becoming less common
    • Treatment of oral drug overdose and poisoning
    • Not used with acid or corrosive poisonings
    • Assess risk for aspiration
    • Ipecac syrup
    • Do not use with charcoal
  • 38. Laxatives and Antidiarrheals
  • 39. Laxative Classifications
    • Stimulant
    • Saline
    • Bulk-forming
    • Lubricant
      • Stool softeners
      • Suppositories
    • Lactulose
    • Enemas
  • 40. Stimulant Laxatives
    • i.e. bisacodyl (Dulcolax), cascara sagrada, senna (Senokot)
    • Increase motility of the GI tract by chemical irritation of the intestinal mucosa or by a more selective action on specific nerves in the intestinal wall
    • Increase secretion of water into both the small and large intestines
    • Produce a watery, often diarrheal stool
    • Many absorbed into systemic circulation (side effects i.e. rash, discoloration of urine)
    • May cause dependence
  • 41. Saline Laxatives
    • Magnesium citrate, magnesim hydroxide (MOM), magnesium sulfate (epsom salts), sod
    • Draw water through the intestinal wall by osmotic action and increase fluidity of stool and stimulate greater intestinal motility
      • Result in: bowel distention, increased peristalsis, and evacuation
    • Unpleasant taste, may be absorbed systemically
    • Prolonged use may cause dehydration
    • Short term. Used in preps for diagnostic procedures
  • 42. Saline Laxatives
    • Contain salt
    • Unpleasant taste
    • Systemically absorbed
    • Result in:
      • Poor client compliance
      • Risk for dehydration
      • Risk for congestive heart failure
  • 43. Bulk Forming Laxatives
    • Citrucel, fibercon, metamucil
    • Safest form
    • Absorb fluid and swell in the intestine, stimulating peristaltic action
    • Slow effect, 12-72 hours to produce response
    • Normally formed stools
    • Not systemically absorbed
    • Should always be taken with a large volume of fluid
    • Can cause esophageal obstruction, fecal impaction if chewed or taken in dry powder form
  • 44. Lubricant Laxatives
    • Liquid petrolatum (Mineral oil)
      • Not digestible or absorbable
      • No systemic effects
      • Administer oral or rectal
    • Oils that act as lubricants to facilitate passage of fecal mass through intestine
  • 45. Stool Softeners
    • i.e. docusate sodium (Colace)
    • Detergent like drugs that permit easier penetration and mixing of fats and fluids with the fecal mass
    • Softer, more easily passed stool
    • Not systemically absorbed
    • Do not irritate the intestine or stimulate peristalsis
  • 46. Suppositories
    • Usually in a wax base
    • Administered rectally
    • Absorbed systemically
    • Available containing stimulant drugs
      • Glycerin
        • Absorbs water from tissues, creating more mass
      • Bisacodyl
        • Induces peristaltic contraction by direct stimulation of sensory nerves
    • May be overused
  • 47. Long-Term Use
    • Long-term use of laxatives often results in decreased bowel tone and may lead to dependency.
    • Encourage
      • A healthy, high-fiber diet
      • Increased fluid intake
  • 48. Lactulose
    • Sugar (two monosaccharides )—not digested or absorbed in the stomach or small intestine and passes to the colon unchanged
    • Digested by colon bacteria—forms acidic substances that draw water into the colon
    • Also causes ammonia from the blood to pass into the colon
    • May mix with fruit juice, water or milk to improve taste
  • 49. Polyethylene Glycol Electrolyte Solution
    • (CoLyte, GoLYTELY)
    • Oral administration rapidly causes large volume of water to be retained in the colon
    • Results in induction of diarrheal state within 30-60 minutes; administration continued over 3 hours—complete evacuation and cleansing of bowel w/in 4 hours
    • Consume 4 liters of solution within 3 hours at a rate of 240ml every 10 minutes
    • Mixture of salts—Little change in water or electrolyte balance
  • 50. Enemas
    • Administration of liquids directly into lower colon
    • Hyperosmotics
      • Solutions contain salts (e.g., Fleet enema)
    • Solutions containing salts act by osmotically drawing fluid into the colon to initiate the defecation reflex
    • Soap, glycerin, and mineral oil also used
  • 51. AntiDiarrheal Agents
    • Proper diagnosis before symptomatic treatment begun
    • Drug therapy
      • Reduce motility of the GI tract, permitting normal dehydration of intestinal contents
      • Remove irritants from the GI tract
      • Replace microorganisms that normally inhabit the intestine, but may have been destroyed by antibiotics
  • 52. Reduce GI Motility
    • Opium powder, tincture of opium, paregoric
    • Opiates that contain morphine reduce propulsive movement of the small intestine and colon and permit dehydration of intestinal contents
    • May lead to dependence with prolonged use and CNS depression with even occasional use
    • Monitor closely
    • Lomotil and Imodium, although not opium derivatives, are chemically related to meperidine, another narcotic
    • Anticholinergic drugs also used—reduce intestinal motility
  • 53. Adsorbents
    • Kaolin, bismuth salts, attapulgite, aluminum hydroxide
    • Most commonly used antidiarrheal agents
    • Claylike materials administered in a tablet or liquid suspension form after each loose bowel movement
    • Can bind drugs, digestive enzymes, toxins, bacteria, and other noxious substances that may be the cause of the diarrheal condition
    • Should not be used w/in several hours of other oral drugs
    • Little scientific proof that they work
  • 54. Lactobacillus
    • Lactobacillus acidophilus—normal flora of GI tract
    • Treatment of diarrhea associated with antibiotic therapy
    • Must be kept refrigerated

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