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GI pharam
UVa med pharmacology block 2
| Question | Answer |
|---|---|
| Al (OH)3 | Antacid - gastric/duodenal ulcers Neutralizes acid in gut lumen, indirectly incr acid secretion, transient alkalosis sidefx: al toxicity, constipation, decr bioavaial of tetracyclines, hypophosphatemia |
| Mg (OH)2 | Antacid - gastric/duodenal ulcers Neutralizes acid in gut lumen, indirectly incr acid secretion, transient alkalosis sidefx: laxation, mixture w/Al Mg prevails |
| Ca2+CO3 | Antacid - gastric/duodenal ulcers Neutralizes acid in gut lumen, indirectly incr acid secretion, transient alkalosis sidefx: Co2 production |
| Cimetidine (tagamet) | H2 antagonist - gastric duodenal ulcer, esoph reflux, reversible compet histamine antag @ parietal cells decr basal acid secretion T1/2 2-3hrs sidefx: anti-androgen, blocks P450, CNS fx. CI impaired renal function |
| Ranitidine | H2 antagonist - gastric duodenal ulcer, esoph reflux, reversible compet histamine antag @ parietal cells decr basal acid secretion T1/2 2-3hrs sidefx: none of cimetidine's |
| Famotidine | H2 antag - gastric duodenal ulcer, esoph reflux, reversible compet histamine antag @ parietal cells decr basal acid secretion T1/2 2-3hrs |
| Sucralfate | Complex of Al(OH)3 & sulfated sucrose protective agent - gastric/duodenal ulcers sidefx: Al toxicity |
| Misoprostil | PGE1 derivative - decr cAMP->decr acid secretion (can replace PGs inhib'd by NSAIDS) T1/2 20-40 mins sidefx: crampy abdom pain, diarrhea CI preganancy |
| Colloidal bismuth | pepto bismol barrier to H+ diffusion to mucosa, bacteriocidal - gastric/duodenal ulcer sidefx: neurotoxicity (rare) |
| Esomeprazole | nexium - isomer of omeprazole, PPI - inhibs H/K ATPase in parietal cells->decr acid secretion, activated by H+, Gas/duod ulcer, esoph reflux, hypersec tumors, ZE syndrome, arthritis T1/2 1hr duration 8-24hrs, met'd liver CYP450 |
| Lansoprazole | PPI - inhibs H/K ATPase in parietal cells->decr acid secretion, activated by H+, Gas/duod ulcer, esoph reflux, hypersec tumors, ZE syndrome, arthritis T1/2 1hr duration 8-24hrs, met'd liver CYP450 |
| Metoclopramide | Prokinetic 5-HT4 agonist HT3 antag dopamine antag, esoph reflux, anti-emetic, incr gastric emptying, motility in SB, LES pressure, sidefx: hyperprolactin, can uncover tardive dysk, extrapyrimidal rxns, cholinergic sxs |
| Domperidone | prokinetic 5HT4 agonist, dopamine antag - esoph reflux (pxs w/parkinsons poor CNS penetration) sidefx: hyperprolactin, dry mouth, diarrhea, cardiac arrhyth |
| Tegaserod | prokinetic 5HT4 selective partial agonist incr gastric emptying, incr motility in SB, IBS sidefx: diarrhea, storke/chest pain/MI |
| Alosetron | 5HT3 antag (more potent than ondansetron) decr motility, decr pain, females w/IBS, pain, diarrhea T1/2 1.5hrs Sidefx ischemic colitis |
| Ondansetron | 5HT3 antag on vagal afferent fibers to GI tract, anti-emetic met'd liver by CYP450 |
| Triple therapy | bismuth, metronidazole, tetracycline |
| Methylcellulose | laxative, bulk forming, softens stool, incr colonic motility8 |
| MgSO4 | saline laxative - exerts osmotic effect in colon empties bowel before procedures, post-chemotherapy T1/2 1-3hrs |
| Bisacodyl | Stimulant laxative - incr fluid/electrolyte accumulation in lumen, decr circular muscular tone, total contractile activity, incr peristaltic mvmnt, decr transit time - generates animal madels of diarrhea sidefx: cathartic colon |
| Diphenoxylate | opiate anti-diarrheal - mild/moderate acute diarrhea, incr circular muscle tone, decr peristaltic mvmnt, transit time, gastric emptying T1/2 12-14hrs sidefx: retained in GI tract does not penetrate CNS, CI infectious/IBD induced diarrhea |
| Bismuth subsalicylate | antibiotic anti-diarrheal - in pepto, traveler's diarrhea |
| Describe the properties of the H2 antagonists from a kinetics standpoint. | reversible, competitive antagonists of the H2 receptor Highly selective action |
| What is the general effect of the protective agents? | To protect the gastic/duodenal mucosal lining form the corrosive effects of acid |
| What are the characteristics of the S isomer of Omeprazole? | The S isomer (esomeprazole) produces higher blood lvls per dose and is thus more effective |
| What is the main use of Misoprostil? | as adjuvant therapy for those using large doses of aspirin or other NSAIDs |
| What are stimulant laxatives used for mostly? What is a major adverse effect of their use? | Generating animal models of diarrhea in the study of anti-diarrhea agents. Therapeutic use is very limited but are OTC. Cathartic Colon may result from prolonged use. |
| Cytotoxic drugs (or radiation) causes what to be released by enterochromaffin cells with what effect? | 5-HT (serotonin) results in vomiting |
| Which H2 receptor antagonist is the most potent | Famotidine |
| What are the three receptors on the parietal cell of the fundic gland mucosa which result in H+/K+ ATPase stimulation? | H2 receptor (PGE2 blocks) Gastrin Muscarinic receptor (results in increase in intracellular Ca2+) |
| Al3+ and Mg2+ can be toxic to which individuals? | Those with poor renal function. |
| ________ stimulates cholecystokinin release and motor function causing laxation. | Mg2+ |
| How is the relapse problem of ulcers solved? | low-dose maintenance therapy along with antibiotics to eradicate H. pylori. |
| What type of laxative is Bisacodyl an how does this type of laxative act? | Stimulant laxative. these promote accumulation of fluid and electrolytes in the lumen and reduce circular muscle tone and reduce contractility. peristaltic pattern is augmented and transit time is reduced. |
| What are the pharmacological actions of meoclopramide? | Stomach increases freq. of antral contractions and inc. gastric emptying Smal bowel-increased motility (not much in colon) NO effect on acid secretion |
| What are the main uses of esomeprazole? | Duodenal ulcer esophageal reflux ZE syndrome and other hypersecretory tumors |
| Name the H+ inhibitors and where they act in the stomach? | Esomeprazole and Iansoprazole They act on the H+/K+ ATPase on the luminal surface of parietal cells |
| What are the actions of metoclopramide? | Cholinergic stimulation Dopamine antagonist (antiemetic in the CNS) 5-HT3 antagonist decreasing emesis (high dose) May block an inhibitory dopamine receptor for cholinergic stimulation (D2 receptor mediated) |
| What drugs are not commonly used in ulcer Tx? | Misoprostil and Sucralfate |
| How is Esophageal reflux treated? | Lower consumption of fat, EtOH, caffeine. Smaller meals Raise head of bed Restrict fluid intake before bedtime Esomeprazole H2 Receptor Antags (2x strength) Pokinetic agents (not many patients) |
| Which H2 receptor antagonist has the highest effect on P450? | Cimetidine |
| PPI's in combination with NSAIDs are useful for treatment of? | Arthritis |
| Prokinetic agents act on what receptors via what general mechanism(s) to produce what effects? | 5-HT3 (afferent) and 5-HT4 (efferent) by antagonism and agonism (respectively) and inhibition of emesis and promotion of GI motility (respectively) |
| What is Diphenoxylate used for? | mild to moderate acute diarrhea of diverse origins where the underlying cause is self-limiting. |
| Which is the best at inhibiting acid secretion...Omeprazole, Cimetidine, or Ranitidine? | Omeprazole |
| What stimulates the emetic center? | Dopamine Agonists |
| 5-HT3 receptors activate what neural pathway? | the afferent fibers from the gut to the NTS (nucleus tractus solitarus) |
| Evidence suggests that antacids can provide a protective effect similar to what drug? | Sucralfate |
| Vagal efferents to the gut release what and promote what? | Acetylcholine they stimulate GI motor function |
| Which agent provides the fastest ulcer healing time | Esomeprazole (3 to 4 weeks) |
| What type of receptors lie on the endocrine cells that release histamine? | Muscarinic (Ach) and Gastrin |
| What causes IBS? | altered enteric nervous activity of the bowel |
| What are the advese effects of metoclopramide? | hyperprolactinemia (from inhib. of dopamine receptors) uncover tardive dyskenisia and parkinson like symptoms (reverse on drug withdrawal) extra pyramidal reactions mild cholinergic symptoms |
| What is the effect of Bisacodyl on feces? | Soft or semifluid over 6 to 8 hrs. |
| The nucleus tractus soltarus is connected to the gut via what nerve? | Vagus |
| What is the anti-diarrheal we are required to know and what are two characteristics of the drug? | Diphenoxylate produce local effects (retained in GI tract) Does not penetrate the CNS |
| Ulcers are effectively treated with: | antacids, H2 receptor antags., esomepraxole or sucralfate |
| What is the consequence of antacids on acid secretion? | While they neutralize acid immediately, the elevation of antrum pH causes increased gastrin secretion and thus more H+ secretion. Small effect in normals, marked in those with duodenal ulcer. |
| What is a typical problem with patients using antacids? | Patient acceptance is poor (multiple doses each day after meals) |
| Where do the H2 antagonists (Cimetidine, Ranitidine, Famotidine) act in the stomach? | Basolateral surface of parietal cells at H2 receptors |
| What are the general guidelines for ulcer Tx? | Withdraw offending agents take a careful history test for H. pylori use triple therapy antibiotic use esomeprazole or H2 antags (rarely) to allow healing Tx for 2 to 4 weeks maintenance doses of PPI's |
| If a patient cannot tolerate PPI's or are refarctory to esomeprazole, what is done at UVa? | use H2 antagonists |
| What has replaced Sucralfate in ICUs? | IV preps of PPIs (proton pump inhibitors) |
| The polymerization of sucralfate is antagnoized by? | Antacids |
| What is the effect of Methylcellulose on feces? | softens over 1 to 3 days |
| What are the actions of the polymerized Sucralfate? | Absorbs enzymes, protein, bile acids, etc. Barrier to H+ for up to 6 hrs May increase PG release to promote an increase in mucous and Bicarbonate. |
| Name some adverse effects of PPI's | interference with liver enzyme function (minor) increased colonization of upper GI Headache Flatulence respiratory infections sinusitis |
| H2 antagonists have their greatest effects on _________ acid secretion. | Basal |
| Describe the solubility properties of the Antacids | Low in neutral pH water. React readily with H+ to neutralize acid to about pH 3.5. |
| How is omeprazole (Esomeprazole) delivered to the Parietal cell pump? | It is a pro drug activated by H+: Coated form taken PO (protects it from stomach acid), abosorbed by the intestine, arrives at the parietal cell via circulation and is activated to the acive form by H+ in the cell. |
| Which drug retards H+ difusion to mucosa and is bactericidal to H. pylori? | Colloidal Bismuth |
| What is the effect of PGE2 in the parietal cell? | It blocks the production of cAMP and thus blocks the effect of histamine on acid secretion. |
| the nucleus tractus solitarus connects to the emetic center in the ___________ in the ___________ | chemotactic trigger zone area postrema |
| What are the CIs of diphenoxylate use? | Not useful or advisable in infectious or inflammatory bowel disease induced diarrhea. Opiates are CI'ed here. Focus on replacement of fluids and electrolytes instead. |
| What is triple therapy and what are some drugs used in triple therapy regimins? | It is the antibiotic therapy used to eradicate H. pylori. Drugs: Bismuth, metronidazole and teracycline (most effective) or Metronidazole, esomeprazole (or lansoprazole), and clariethromycin |
| Complications of treating gastric ulcer: | cyclical nature of the condition high relapse rate (if H. pylori not tx'd) large placebo effect |
| What type of drug is Tegaserod? | A 5-HT4 selective partial agonist |
| What are te adverse effects of Domperidone? | Hyperprolactinemia (pituitary outside BBB) Dry mouth, diarrhea Cardiac arrhythmias (found in one study) |
| Which H2 receptor antagonist has the highest bioavailability (of the ones we have to know)? | Cimetidine |
| Bismuth subsalicylate (Peptobismol) is used for what? | Tx travelers diarrhea. May work as an antibiotic via the Bismuth. |
| What is odansetron used for? | block emesis from cytotoxic agents such as from cancer chemotherapy, irradiation, and anesthetics used in the OR. |
| Why is the half life of omeprazole 1hr, but it inhibits acid secretion for 8 to 24 hrs.? | the parietal cell is thought to concentrate the drug |
| metaclopramide can cause what negative effects? | Dopaminergic responses such as tardive dyskinesia and hyperprolactinemia |
| What are the actions of the prokinetics...name them while you're at it. | they promote gastric emptying and increas tone of the LES. they also have anti-emetic effects. DO NOT effect acid secretion. Metoclopramide Domperidone (also Tegaserod) |
| What was the first marketed 5-HT3 antagonist? | Ondansetron |
| What are the pharmacological actions of domperidone? | Increased antral contractions increased small bowel activity (actions not extended to colon) |
| What is the analogue of esomeprazole (with minimal differences)? | Iansoprazole |
| What is the etiology of esophageal reflux? | excessive number of relaxations of the lower esophageal sphincter Less commonly caused by decreased tone of the LES or delayed gastric emptying. Medications can cause these problems (Ca2+ blockers, antimuscarinics, antacids) as well as diet |
| How do Opiods act as an anti-diarrheal? | increase circular muscle tone and tone of segmenting contractions. Reduce peristaltic pattern and slow transit time (reduce gastric emptying too) |
| What type of drug is alosetron? | A 5-HT3 seletive antagonist (more effective than Odansedron) |
| What is te action of Omeprazole? | To inhibit the H+/K+ ATPase by forming a S-S bridge between the pump and the drug. |
| What is the action of Misoprostil? | inhibits adenylate cyclase complex in parietal cells to inhibit acid secretion. It also acts as a 'replacement' for the PGs whose synthesis is inhibited by NSAIDs |
| What are the pharmacological and adverse effects of alosetron? | inhibits motility and decreases pain high frequency of ischemic colitis...thus it is highly FDA regulated. |
| MgSO4 is what type of laxative? How do these laxatives act? | Saline laxative. These act by osmotic effect. Used to empty the bowel before procedures or to flush out parasites after chemo. |
| What is the effect of antacids on systemic acid-base balance? Pharm effects of Antacids | In normals, the acid that normally there is neutralized by HCO3-. without the acid, the HCO3- can cause alkalosis. |
| Which drug is a 5-HT4 agonist and dopamine D2 receptor antagonist that doesn't enter the CNS well? | Domperidone |
| the cholinergic fibers of the vagus contain what receptors? (Vagal efferents) | 5-HT4 |
Created by:
sam.mrosenfeld
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