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47 Cards in this Set
- Front
- Back
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What are the two places in the brain where the regulation of vomiting takes place?
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The chemoreceptor trigger zone in the medulla and the vomiting center in the reticular formation of the medulla
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What is the function of the chemoreceptor triggering zone?
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It has a poor blood-brain barrier and is able to respond to chemical stimuli by inducing vomiting
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What is the function of the vomiting center?
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It integrates the emetic response and receives the excitatory inputs from (1) vagal nerve endings in the GI tract (2) vestibular nuclei (3) higher cortical centers (4) intracranial pressure receptors
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What drugs would be given for emesis due to chemotherapy?
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The most potent are 5-HT3 receptor antagonists such as odansetron and granisetron
phenothiazines, corticosteroids, butyrophenones, cannabinoids - active against mild or moderate emetic chemotherapy antihistamines, muscarinic receptor antagonists, benzos - minimally active |
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What drugs are used for the induction of vomiting?
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1) Ipecac - strong irritant of the stomach
2) apomorphine - actives the chemoreceptor trigger zone directly as well as opiod receptors in the vomiting center 3) L-DOPA - stimulates CTZ 4) Cardiac glycosides 5) Copper sulfate - acts as irritant on the stomach |
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For what are the H1 receptor antagonists used? What are examples?
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They are used for the treatment of motion sickness, but are ineffective against substances acting in the CTZ
1) cinnarizine 2) cyclazine 3) promethazine - severe morning sickness |
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What drugs should be used for vestibular induced nausea and vomiting?
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histamine antagonists (cinnarizine, cyclazine, promethazine, hydroxyzine, ect.) and muscarinic antagonists (hyoscine)
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How do muscarinic antagonists prevent vomiting and what is an example?
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They act on the vestibular nuclei and vomiting center - example is hyoscine
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For what is metoclopramide used and how does it work?
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It is a dopamine receptor antagonist that acts on the CTZ trigger zone and is used in the treatment of vomiting
It has unwanted side effects similar to phenothiazines |
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What is domperidone and for what is it used? How does it work?
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It is a dopamine receptor antagonist that does NOT CROSS THE BBB and is used in treating emesis; it is better than metoclopramide because it does not have the CNS side effects
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For what are odansetron and granisetron used and what is their mechanism of action?
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They are anti-emetics used in the treatment of chemotherapy induced emesis
They are 5-TH3 antagonists and are synergistic with dexamethasone |
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For what is nabilone used and what is it's mechanism of action?
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It is a snythetic cannabinoid that reduces emesis by acting on the CTZ
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What are the goals of therapy in the treatment of peptic ulcer disease?
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1) relieve pain
2) prevent hemorrhage, obstruction and perforation 3) promote healing |
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What are some of the risk factors associated with peptic ulcer disease?
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1) coffee
2) alcohol 3) tobacco 4) salicylates 5) NSAIDS 6) Age 7) stress |
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What is the "gold standard" for the treatment of peptic ulcer disease and how do they work?
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Histamine 2 receptor antagonists block the secretion of acid in the stomach and eliminate the symptoms in up to 50% of patients
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What are some examples of H2 receptor blockers
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1) Cimetidine
2) Ranitidine 3) Fomatidine 4) nizatidine |
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What are some of the uses of H2 receptor antagonists?
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1) promotes healing of ulcers
2) prophylaxis for recurrent ulcers 3) used in patients with reflux esophagitis, bile reflux gastritis 4) useful in Zollinger-Ellison syndrome |
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What are the negative aspects of cimetidine?
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1) It must be taken 4-5 times a day (short half life)
2) causes gynecomastia 3) headache and confusion 4) inhibitor of microsomal enzymes (prolongs half-life on many drugs) 5) impotence in men, prolactin release in women |
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How is ranitidine different from cimetidine?
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1) 5-10 times more potent
2) no anti-androgenic effects 3) does not alter drug metabolism 4) does not bind to testosterone receptors |
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What cholinergic antagonists are used in the treatment of peptic ulcers and how do they work?
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Propantheline
Isopropamide Scopolamine They are not used alone and cause a decreased acetlycholine stimulated secretion of acid and decreased motility along the gastrointestinal tract |
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How do antacids work ? What happens with overdose?
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They are weak bases that neutralize gastric acid and reduce pain while promoting healing
Overdoses can cause alkalosis |
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What is the best antacid to give a patient and why? What are it's side effects?
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Aluminum hydroxide - it is not absorbed from the GI tract
Side effects include constipation and interference with tetracycline; it stimulates mucus secretion* |
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What antacid can cause rebound acid production? What are it's side effects?
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Calcium carbonate stimulates gastrin release; it can also lead to hypercalcemia in overuse and is contraindicated in patients with renal disease
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What can occur in patients using sodium bicarbonate as an antacid?
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It can cause hypertension due to it's sodium componant
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What are the side effects of magnesium hydroxide?
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diarrhea which can lead to hypotension
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What are important interactions to consider with antacids?
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Antacids alter the bioavailability of many drugs by altering the gastric pH
The metal ions can chelate other drugs and prevent absorption (digoxin and tetracyclines) |
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What are the clinical capabilities of proton pump inhibitors?
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They can heal erosive esophagitis, eliminate symptoms, and provide complete mucosal healing of esophagitis in about 6-8 weeks in most cases
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What are the most commonly used proton pump inhibitors?
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Omeprazole
Lansoprazol Esomeprazol |
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What is the mechanism of action of omeprazole? Side effects?
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It inhibits the parietal cell proton pump, reducing basal acid secretions
Side effects include hypertrophy of gastrin producing cells leading to cancer, inhibits microsomal enzymes, causes tumors at high doses |
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What drugs are used to inhibit the formation of proton pumps?
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Urogastrone and Enterogastrone
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What is sulcralfate and how does it work?
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It is a complex polysaccarhide complexed with aluminum hydroxide that fills in the ulcers by forming crosslinks; it requires acidic gastric pH in order to become activated
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What important product of H. pylori is essential for it's colonization of the stoamch?
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Urease is secreted by H. pylori and allows it to have an alkaline microenvironment
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What cause can be most attributed to chronic active, persistent and atrophic gastritis ?
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helicobacter pylori infection
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Infection with H. pylori has been shown to lead to the development of what?
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gastric lymphoma and cancer
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What are the diagnostic tests used to diagnose H. pylori?
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1) serological tests that measure H. pylori antibodies (cannot show current vs. past infection)
2) urease breath test 3) Upper GI scope with biopsy (gold standard)` |
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How is H. pylori treated?
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1) 1-2 weeks of antibiotics (usually double therpay)
2) PPI 3) possibly antacids |
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How do laxatives work?
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They increase the fluid in the bowel, which increases the luminal volume and stimulates peristaltic reflexes
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What are agents that increase fecal bulk?
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Psyllium
carboxymethylcellulose dietary fiber polycarbophil calcium polycarbophil |
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What are the osmotic agents and how do they work?
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Osmotic agents retain water in the bowel and cause peristalsis
1) magnesium salts 2) glycerine 3) lactulose 4) polyethylene glycol |
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How do irritant laxatives work and what are examples?
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They stimulate intestinal secretions and peristalsis
1) diphenylmethane - phenolphthalein |
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How do wetting agents work?
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They facilitate mixing of water and fatty substances to enhance luminal mass
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How do coating agents work as laxatives?
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They coat the feces and reduce water reabsorption; they can also reduce absorption of lipid soluble vitamins
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What opiods are used in the treatment of diarrhea?
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Loperamide
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What anticholinergics are used in the treatment of diarrhea?
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atropine
scopolamine methanthaline propantheline |
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What are the different classes of drugs that can be used to treat diarrhea?
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1) Adsorbents
2) glucocorticoids 3) bismuth subsalicylate 4) loperamide 5) anticholinergic 6) opiod preparations |
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What are the opiod preparations used in the treatment of diarrhea?
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1) opiod tincture
2) codeine 3) diphenoxylate with atropine |
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How do opiod preparations treat diarrhea?
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They act directly on mu receptors in the gut to stimulate segmental contractions and inhibit longitudinal retractions
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