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End of Chapter Questions

CHAPTER 53
  1. Discuss the aetiology of peptic ulcers.
    Peptic ulcer is the general term used to describe gastric or duodenal ulcers. There are two main causes of peptic ulcer: the use of NSAIDs (except perhaps, the newer COX-2 inhibitors) and the bacterium, Helicobacter pylori. In both cases hydrochloric acid and pepsin production is increased, which can erode the gastric and/or duodenal mucosa. In the case of NSAIDs, it is by prostaglandin inhibition. Gastric prostaglandins increase protective mucus production. The acidity of many of the NSAIDs can also contribute to their enterogastric effects. With H. pylori infections of the stomach, the body tries to defend itself by increasing gastrin production, which in turn increases pepsin and hydrochloric acid production. NSAIDs are more important in causing peptic ulcers whilst H pylori is involved heavily in both. H pylori is present in many NSAID-induced ulcers.
    Smoking is another cause and corticosteroid therapy may be causal. Contrary to popular belief, stress, alcohol and highly spiced food are not thought to be implicated in the aetiology of peptic ulcers.
  2. Explain why proton pump inhibitors are the most effective drugs to use in hyperacidity problems.
    Most of the drugs used to decrease pepsin and acid in the stomach act by inhibiting the control mechanisms. This inhibition is generally competitive and will not suppress these 100%. The PPIs act on the production of protons (hydrogen ions) rather than the controlling factors. They are also non-competitive, e.g. to stop a car at high speed will be slow using the handbrake but very fast if it hits a reinforced concrete wall. The analogy being that the hand brake slows only two wheels (not four), which in turn slow the car whereas the wall affects the car’s forward movement directly.
  3. Discuss the use of triple therapy in the treatment of peptic ulcers.
    In peptic ulcers caused by Helicobacter pylori, eradication of the bacterium is necessary. As this bacterium is prone to become resistant to antibiotics, combination therapy is used with at least two antibiotics. To help prevent resistance developing, hitting the infecting organism/virus by different methods will help to control the infection before resistance can develop, e.g. if you want to stop a car quickly, applying the hand brake and the foot brake will cause the car to stop more quickly than both alone.
    The addition of a proton pump inhibitor and/or an H2 antagonist and/or a cytoprotective expedites the healing process. Hence the term triple therapy, or in some cases, quadruple therapy.
  4. What is the role of histamine in the production of gastric secretions?
    Gastric acid production is mainly controlled by the hormone gastrin. It acts upon the parietal cells, which then produce hydrochloric acid. These cells have H2 histamine receptors on them, which can respond positively to the presence of the amino acid derivative, histamine. Although only about 80% are as potent as gastrin, histamine still plays an important role in gastric acid production.
  5. What are the roles of prostaglandins in the production of gastric secretions?
    Prostaglandin E2 stimulates the secretion of both mucus and bicarbonate from cells in the gastric mucosa, both of which are protective against stomach acid.
  6. Why would diphenhydramine, a H1 antihistamine, be useless in the treatment of a peptic ulcer?
    Diphenhydramine is an antihistamine, which acts on H1 receptors, not H2 receptors that are found in the stomach parietal cells.
  7. Antacids are relatively cheap and have been shown to heal peptic ulcers, but are rarely used as the sole treatment for such ulcers. Why?
    Antacids neutralise hydrochloric acid and to a certain extent inhibit pepsin activity in the stomach. These actions are related to each other as if the pH of the gastric contents rises above 4, pepsin activity is inhibited. Both pepsin and hydrochloric acid are involved in the aetiology of ulcers. Antacids taken for a long time and in large amounts are effective in allowing an ulcer to heal. The problem here is the large amounts that have to be taken. It has been known for patients to take several hundred mLs/day over long periods to promote healing, e.g. six months to a year. Many patients find the taste objectionable, (even butterscotch flavour) and although antacids appear to be cheap, the large amounts consumed counteract this. Since the introduction of the H2 histamine receptor blockers, antacids are rarely, if ever, used to heal ulcers. Nevertheless, they are frequently used to treat acute hyperacidity problems.
  8. Why have gastrectomies and vagotomies been more or less relegated to the past as surgical procedures for peptic ulcers?
    Modern drug treatment for peptic ulcers is usually curative, especially utilising combination therapy of antibiotics and H2 antagonists or proton pump inhibitors. There is now no need for drastic surgical intervention except in cases of perforated ulcers.
  9. Why are magnesium and aluminium hydroxide often combined in antacids preparations?
    Magnesium salts have an osmotic laxative effect, while aluminium salts have the tendency to produce constipation. By combining them, these effects will cancel one another.
  10. What problems could arise from antacids containing calcium carbonate?
    Hypercalcaemia may result. The symptoms of this are: abdominal pain, nausea, vomiting, constipation, polyuria, depression, anorexia, weight loss, polydipsia, tiredness, weakness, sudden cardiac arrest, renal calculi, renal failure and corneal calcification. Obviously not something to treat lightly, but fortunately it is rare due to the relatively infrequent use of calcium containing antacids in large quantities.
  11. What problems could arise from antacids containing sodium bicarbonate?
    Too much sodium in the diet may be one of the causative factors in the aetiology of hypertension and sodium intake should be curtailed in hypertensive patients. Sodium containing antacids, therefore, should be treated with respect and it would be prudent to avoid their use in patients with hypertension or having a family history of hypertension. The use of excess bicarbonate can lead to alkalosis, which can be serious, especially in the aged.
  12. What is Zollinger–Ellison syndrome and why are H2 antagonists or proton pump inhibitors useful in its treatment?
    The Zollinger-Ellison syndrome is the association of a peptic ulcer with a gastrin secreting pancreatic adenoma or simple islet cell hyperplasia. Gastrin excites excessive acid production, which can produce multiple ulcers in the duodenum and stomach. These adenomata can be benign or malignant. The treatment is, therefore, to negate the action of gastrin, which both proton pump inhibitors and H2 antagonists are able to do, the former being the most effective.
  13. Why is bismuth chelate therapy useful in the treatment of some types of gastritis?
    If bismuth is absorbed to a significant extent, encephalopathy and osteodystrophy can occur. Bismuth chelate tends not to be absorbed, so has not the same potential to produce a systemic effect.
  14. Why should Mylanta, an antacid mixture, and ranitidine (Zantac), not be taken at the same time?
    Antacids such as Mylanta can decrease the absorption of ranitidine. Review with clients their medications and try and work out a suitable plan that prevents the antacid, Mylanta, interfering with other medications. Instruct the client to avoid taking Mylanta within one to two hours of ranitidine.
  15. Explain how ranitidine is advantageous over cimetidine as a H2 receptor antagonist.
    There are not as many drug interactions present with ranitidine as there are with cimetidine. Cimetidine slows down the metabolism of several other drugs.
    Ranitidine has no antiandrogenic activity, which would lead to a decrease in libido, sperm count and gynaecomastia.
  16. What non-pharmacological measures can you advise for alleviating manifestations of a peptic ulcer?
    Advise the client to avoid foods that can aggravate ulcers, including caffeine-containing foods, alcohol and spices. Small, frequent meals are also preferable to heavy, infrequent meals.
    Teach the client relaxation techniques and other methods to decrease anxiety and stress.
  17. Rose Goldstein, a 40-year-old client, is ordered colloidal bismuth for gastritis. What client education would you provide?
    • Warn Ms. Goldstein that constipation may occur with the use of this preparation. Advise her on measures to prevent constipation, such as ensuring adequate fibre and fluids in the diet, and maintaining a regular mobilisation routine.
    • Bismuth tablets should be chewed thoroughly before swallowing.
    • Warn Ms. Goldstein that a blackened tongue and faeces may result, which in no way are harmful.
  18. How would you instruct a client to correctly take a chewable antacid tablet?
    Remind the client to chew antacid tablets and follow this with water. Antacid tablets should not be swallowed whole.
  19. Jack Brown, a 56-year-old client, has been prescribed a peptic ulcer treatment regimen consisting of bismuth, metronidazole and tetracycline. How would you advise Mr Brown on ways to prevent problems arising from altered taste, diarrhoea or nausea?
    Altered taste:?
    Metronidazole may cause an altered taste, which can be reduced by taking the medication with, or immediately after, meals. The use of a mouthwash before meals may help remove the metallic taste and improve appetite.
    Diarrhoea:
    Diarrhoea produced by metronidazole can be alleviated by taking the medication with, or immediately after, meals. Bismuth has a slight constipatory effect, which can decrease the incidence of diarrhoea associated with metronidazole and tetracycline.
    Nausea:
    Nausea produced by metronidazole can be prevented by avoiding alcohol consumption during treatment and for 48 hours after the course.
    Advise the client to have small, frequent meals and snacks rather than three large meals during the day.

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CHAPTER 54
  1. Apart from the use of laxatives, what are some of the measures that can be used to help prevent constipation?
    Drink plenty of fluids. Increase fibre in the diet by eating fibrous vegetables and fruit. Exercise also helps. Do not delay bowel movements.
  2. Describe how to obtain a complete bowel washout to enable an unobstructed view during colonoscopy.
    The normal procedure is to use, initially, a stimulant laxative such as bisacodyl in double the normal dose. Once this has caused a bowel movement (usually after about 8 hours) large volumes of an osmotic laxative e.g. polyethylene glycols, by mouth, are used to remove all the remaining contents and wash the bowel walls. Fasting (solids only, liquids are allowed) is concurrent. Other techniques may also be used according to the gastroenterologist’s preference.
  3. Sorbitol is a poorly absorbed sugar alcohol sometimes used to sweeten diabetic jams and jellies. What would be a problem of eating too much of this sugar alcohol?
    Diarrhoea. Sorbitol is not well absorbed from the gut and thus would create a hypertonic fluid in the colon and act as an osmotic laxative. Furthermore, sugar alcohols can be acted upon by the natural flora of the gut to form short chain fatty acids, which can have a laxative effect.
  4. What laxatives can affect the absorption of some vitamins and why? >br>Fat-soluble vitamins can dissolve in liquid paraffin rendering them unavailable to the body. The surfactants such as docusate, can disrupt cell membranes preventing the absorption of vitamins. Laxatives, in general by increasing gastrointestinal transit time, concurrently decrease the time available for absorption of vitamins, especially those that are fat-soluble, which are absorbed slowly under normal circumstances.
  5. In what forms of constipation are laxatives contraindicated?
    a) Intestinal blockage. b) Constipation due to appendicitis should not be treated with laxatives as this can increase the risk of a ruptured appendix.
  6. Why should diarrhoea induced pseudomembranous colitis not be treated with loperamide.
    Pseudomembranous colitis is potentially life-threatening and is due to the release of a toxin by the anaerobic bacterium, Clostridium difficile. Suppressing gastrointestinal motility using an agent such as loperamide will cause the toxin to remain in the intestine for prolonged periods, thus worsening or extending the toxin’s action.
  7. Why are paraffinomas so called?
    Paraffinomas are tumour-like extrusions of the colonic mucosa, which are actually sacs formed by the cell membranes that are filled with liquid paraffin.
  8. Why should liquid paraffin not be taken before lying down?
    Taking liquid paraffin before lying down or retiring at night increases the chance of the drug entering the respiratory tract. If this happens frequently, lipoid pneumonia can result.
  9. What would be a major problem from diphenoxylate overdose?
    Diphenoxylate, being an opioid, would cause respiratory depression in overdose which is potentially life-threatening. Treatment would be with naloxone.
  10. Why is atropine included with diphenoxylate in 'Lomotil'?
    To help prevent abuse. Diphenoxylate can act as a euphoriant and thus has the potential for abuse. The addition of atropine to diphenoxylate preparations causes parasympathetic adverse effects if taken in high quantities, which deters its abuse.
  11. Why can the so called bulk laxatives sometimes be used to treat diarrhoea?
    Bulk laxatives have a high affinity for water and if taken with as little water as possible, will absorb the excess water present in the colon in diarrhoea, thus relieving the symptom.

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CHAPTER 55
  1. What type of antiemetic would be best used in a patient with terminal carcinoma who is on morphine?
    Morphine produces nausea by acting on the CTZ in the brain. Therefore, in treating this kind of nausea, a centrally-acting antiemetic is needed. Metoclopramide, which raises the threshold of the CTZ by decreasing dopaminergic activity, would usually suffice. This drug, or some other antidopaminergic drug, is often given prophylactically when opioids are used in the treatment of pain.
  2. What are the major adverse effects associated with phenothiazine use?
    The major adverse effects, which are relatively common with long-term use (as is usual in the treatment of psychotic symptoms rather than emesis and nausea), are the extrapyramidal symptoms of which there are four varieties. These are:
    • Parkinsonism,
    • Akathisia (restlessness)
    • Acute dystonic reactions: facial grimacing, torticollis (spasm of the neck muscles, twisting the neck), oculogyric crises.
    • Tardive dyskinesia: exaggerated and persistent chewing movements, tongue protrusion.

    This last condition is usually irreversible.
    Phenothiazines depress the CNS principally by being inhibitors of dopamine and serotonin. They are also β-adrenergic blocking agents, have weak anticholinergic and antihistamine activity. The side effects are mostly related to these properties and include: drowsiness, dry mouth, constipation, blurred vision, nasal stuffiness, agitation, excitement, photophobia, postural hypotension, tachycardia, hypothermia, weight gain, urticaria, dermatitis, photosensitivity, jaundice, blood dyscrasias, menstrual irregularities, gynaecomastia, urinary retention, inhibition of ejaculation and hyperglycaemia. You may wish to equate some of these side effects with the pharmacodynamics of these drugs.
  3. Why is domperidone sometimes to be preferred as a dopamine antagonist over prochlorperazine?
    Domperidone does not cross the blood-brain barrier and thus has no action on the basal ganglia to produce extrapyramidal symptoms.
  4. Why is it very unwise for a car driver to take promethazine as a travel sickness prophylactic?
    Promethazine is an antihistamine, which often induces drowsiness, not a desirable attribute when driving.
  5. Explain the three ways whereby the vomiting centre can be stimulated.
    • Irregular movement of fluid within the semicircular canals e.g. seasickness relays messages to the vomiting centre using histaminic and/or anticholinergic pathways.
    • Stimulation of the chemoreceptor trigger zone (CTZ) by poisons relays messages to the vomiting centre using dopaminergic and/or serotonergic pathways.
    • Abnormal stimulation to various parts of the gastrointestinal tract relays messages to the vomiting centre using serotonergic pathways.
  6. Yavuz Olcay, a 60-year-old client in your care, vomits after gastrointestinal surgery. You administer metoclopramide in an attempt to alleviate vomiting. What assessment would you undertake of Mr Olcay?
    • Monitor for manifestations of dehydration if vomiting is severe. These include dry mucous membranes, increased pulse, decreased blood pressure, and decreased urine output.
    • Auscultate bowel sounds for hypoactivity or hyperactivity.
    • Monitor the quantity and character of any vomitus.
    • Examine fluid balance by assessing fluid intake and output.
  7. In a client who is vomiting, what route of administration would you use for the antiemetic given?
    If the client is actively vomiting, the antiemetic should be administered intramuscularly or intravenously.
  8. Alberto Ripaldi, a 50-year-old client, suffers from Ménière’s disease. Why is metoclopramide not the most suitable antiemetic to administer? Which antiemetic would you administer instead? (Ménière’s disease is a disorder of the labyrinth of the inner ear. Common manifestations of this disorder include progressive loss of hearing, headache, vertigo, tinnitus and a heightened sensitivity to loud sounds.)
    • Metoclopramide increases the gastric emptying rate and oesophageal tone. It would therefore have minimal effect in Ménière’s disease.
    • More suitable options include hyoscine and antihistamines (such as dimenhydrinate or promethazine), which act on the vestibular apparatus and vomiting centre in the brain.
  9. What non-pharmacological measures would you provide for a client suffering with nausea? (Refer to chapter 11, table 11.10, for assistance.)
    • Keep the client’s room fresh and clean.
    • Reduce food odours by ensuring meal trays are collected promptly.
    • Ensure the client remains pain free.
    • Encourage the client to avoid ingesting spicy or fatty foods.
  10. Emma Doeline, aged 60 years, is about to take a trip from Melbourne, Australia to Wellington, New Zealand. As she is often affected by motion sickness, she buys an antihistamine preparation at the airport. How would you advise Ms Doeline to take the preparation?
    Suggest to Ms. Doeline that, with travel sickness, the antihistamine preparation should be taken 30 minutes prior to travel. If Ms. Doeline waits until nausea or vomiting occurs, the antihistamine will be ineffective.

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