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GI Exam 2
Spears C/D/IBS
| Question | Answer |
|---|---|
| What are the names of the 3 steps of the defecation reflex? | Intrinsic reflex; Spinal reflex; Fecal passage |
| What is the intrinsic reflex (step 1) of the neuronal control of defecation? | when the feces stimulates stretch receptors to become actived. By then being activated, they then go and activate sensory fibers to the spinal cord *feces move inot ad distend the rectum, stimulating stretch receptors there. The receptors transmit signals along afferent fibers to spinal cord neurons |
| What is the spinal reflex (step 2) of the neuronal control of defecation? | Parasymptomatic neurons in the CNS communicate and contract the colon and rectum, causing involuntary relaxation of the internal anal sphincter. *a spinal reflex is intitated in whcih parasymptomatic motor (efferent) fibers stimulate contraction of the rectum and sigmoid colon, and relaxation of the internal anal sphincter |
| What is the fecal passage (step 3) of the neuronal control of defecation? | Voluntary motor neurons are inhibited causing relaxation of the external anal sphincter (allows fecal matter to leave the rectum) |
| What are the 4 major drug classes for constipation? | LOGS 1. Laxatives (BOSS) B-> bulk forming O-> osmotic laxatives S->stimulant laxatives S-> stool softeners (surfactant agents) 2. Opioid receotor antagonists 3. Chloride channel activators (work well on Cl- channel) 4. Guanylate cyclase (GC- Antagonists (work well on Cl-channel) |
| Which meds are the bulk forming laxatives? | 1. Plant derived (Psyllium, methylcellulose_ 2. Synthetic fibers (Polycarbophil) |
| What is the MOA of bulk-forming laxatives (plant-derived and synthetic fibers)? | ingestible and produces a hydrophilic colloid that absorbs water to form a gel, distends colon (activates stretch receptors) -promotes peristalsis (aka the contraction/movement of fecal matter) |
| what are the ADRs of bulk-forming laxatives (plant-derived and synthetic fibers)? | esophageal/GI obstruction (avoid maintaining hydration); bloating, flatulence, abd fullness |
| Can bulk-forming laxatives be used for rapid relief? | No, because they have a slow onset |
| Which medications are the stool surfactant agents (softener or lubricant/emollient)? | Docusate and Mineral Oil |
| Stool surfactant agents (softener or lubricant/emollient): 1. MOA of Docusate; 2. MOA of Mineral Oil; 3. what do they both do? | 1. increases water and lipids to penetrate colon and absorbed by stool 2. lubricates fecal matter; decreases H2O absorption 3. prevents constipation and minimizes straining |
| Which mediation should you avoid long-term use of as it will decreases the absorption of fat-soluble vitamins (A,D, E,K) and why? | Mineral oil; this medication places a lubricant around the stool so if you use for long-term use, it will decrease the absorption of fat-soluble vitamins |
| when is relief seen with docusate? Mineral oil? | within days; within hours |
| Who can docusate NOT be used in? | children < 2 yo |
| What is the risk of using mineral oil? | risk of aspiration (avoid laying down) |
| What are the osmotic laxatives? | MMS PLL Saline Laxatives (Magnesium hydroxide (milk of magnesium), magnesium citrate, sodium phsophate Polyethylene glycol (PEG (Miralax) lactulose Lactitiol |
| What are my osmotic laxatives (Saline Laxatives)? | Magnesium hydroxide (milk of magnesium); Magnesium citrate; Sodium Phosphate |
| My other osmotic agents aside from the Saline Laxatives are? | Polyethylene glycol (PEG), (MIRALAX); Lactulose Lactitiol |
| What is the MOA of the osmotic laxatives? | soluble, but non-absorbable compounds that draws water into the stool = increasing water retention *increases peristalsis |
| What are the ADRs of the osmotic laxatives? | electrolyte disturbance (Mg/Na containing products)--> other complications, caution with CV risk, pregnant, and pts < 2 yo |
| How fast do osmotic laxatives work? | fast acting, bowel purge within hours *Maintain adequate hydration |
| what is the risk of magnesium hydroxide (MOM)? | risk of hypermegnesmia in renal insufficiency pt with long-term use |
| What class engages the nervous system? | stimulant laxatives |
| What are the stimulant laxatives? | Natural stimulants--> Senna; Castor Oil Synthetic--> Bisacodyl |
| What is the MOA of stimulant laxatives? | stimulates enteric nervous system to enhance peristalsis and defecation; -increases water and electrolytes in small intestine fluid; -decreases water absorption in large intestine -get increased motility |
| ______ may diminish therapeutic effects of Bisacodyl (stimulant laxative) | Antacids *bc it prevents bisacodyl from getting to the SOA which decerases the absorption |
| Which medication is a Cl- channel activator? what does it mimic? | Lubiprostone; Prostoglandin |
| What is the MOA of Lubiprostone? | -activates Type-2 Chloride channels (ClC-2) -increases Cl- secretion into the intestine -stimulates motility -shortens transit time to pass stool |
| What is Lubiprostone indicated for? | chronic iodiopathic constipation; Opioid induced Constipation; IBS-C in ADULT WOMEN |
| What meds are Guanylate Cyclase-C agonists? | Linaclotide; Plecantide |
| What is the MOA of Linaclotide and Plecantide? | -Guanylate cylcase-C agonists which increases cGMP; -activates the CFTR (a type of Cl- channel) -increases Cl- secretion into intestine -Accelerates intestinal transit rate |
| What is the BBW of Linaclotide and Plecantide? | Dehydration in PEDIATRIC Pts |
| Who is Linaclotide and Plecantide indicated for? | Chronic iodiopathic constipation; IBS-C in adults |
| Which medications work to increase the amount of Cl- in the intestines which will draw water in? | Cl- channel activator (Lubiprostone) Guanylate cyclase-C agonist (Linaclotide, Plecantide) |
| Which medications are MOR antagonists for opioid-induced constipation/post operative ileus? | MANN Methylnaltrexone; Alvimopan; Naloxegol; Naldemedine |
| What is the MOA of Mu opioid receptor antagonists for OIC/Post operative illeus? | Intestinal opioid receptor antagonists (work peripherally); -decreases water absorption -delays in GI transit time |
| What is the BBW of MOR antagonists for OIC/Post operative illeus? | MI and restricted access |
| Would MOR antagonists increase, decrease, or have no effect on opiod analgesia? | No effect because these medications work peripherally (not centrally acting) |
| What are the 3 effects of peripheral opioid receptor blockers? | -Motility/peristalsis -Fluid reabsorption -anal sphincter function |
| what type of anti-constipation treatment is bisacodyl? -serotonin receptor agonist -bulk-forming laxative -Cl- channel activator -Osmotic stimulant -Stimulant laxative | Stimulant laxative |
| What is the general effect of ACh and serotonin in the enteric nervous system (select all) | increase GI motility and increased CND neurotransmission |
| Opioids can impair gut motility and cause constipation due to? | hyper-polarization of ENS neurons *by giving opitiods-> they would agonize those opioid receptors causing hyper-polarization of those ENS neurons due to opening of the K+ channels causing more K+ influx |
| What are the 4 major drug classes for anti-diarrheals? | COOB Colloidal bismuth components Opioid agonists Octreotide Bile salt-binding resins |
| Which meds are opioid agonists (antimotility)? | LDD E Loperamide Diphenoxylate + atropine Difenoxin + atropine Eluxadoline (mixed MOR/KOR agonist, DOR antagonists) for IBS-D |
| Where do opioid agoniss act? | Peripherally *although, high doses can have CNS effects and prolonged use has potential for addiction |
| How do opioid agonists work? D drugs are paired with atropine what for? | 1. MOR agonist (mild-moderate); -decreases transit time; increases fluid absorption (feces --> intestine); increase tone on anal sphincter 2. anti-cholinergic (paired with an anticholinergic to discourage overdose |
| Which medications are colloid bismuth compounds (antisecretory)? *used in diarrhea | Bismuth subsalicylate; Bismuth subcitrate potassium |
| what is the MOA of colloid bismuth compounds? | inhibits intestinal prostoglandin and chloride secretion -protective layer against acid and pepsin -decreases stool frequency -improves stool consistency |
| ADRs of Bismuth compounds? | harmless blackening of tongue or stool; tinitus |
| What pt should you avoid bismuth compounds in? | pts with renal insufficiency |
| Which meds are antisecretory and what is the effect of being on an antisecretory? | bismuth subsalicylate; Bismuch subcitrate K+; Octreotide effect--> causes less H2O content in the stool |
| MOA of octreotide? | somatostatin analog (remember, this is an inhibitory hormone)--> longer acting than SST; *inhibits intestinal secretion (decreases serotonin, gastrin, motolin, hypothalamic, and pancreatic hormones) *improves stool consistency |
| Octreotide has _______ ______ effects on gut motility. What happens at high doses? | dose-dependent; inhibits Gastric emptying and colonic motility (i.e. used for diarrhea) *at low doses it reduces small bowel motility, delaying transit time |
| What ADRs does Octreotide have? | Steatorrhea (fatty composition within the stool) *fat-soluble vitamin deficiency; GI: abd pain, N, flatulence, gallstones; CV: bradycardia |
| What is the difference in the different 1/2 lives of Octreotide? | For IV--> 1.5 hours SQ--> 6-12 hours Depot IM--> once monthly |
| What can occur with prolonged treatment of Octreotide? | hormone imbalance (i.e glucose, insulin, glucagon, thyroid) |
| Which medications are bile salt-binding resins (aka bile acid sequesterants) in diarrhea? | C drugs: Choelestyramine; Colestipol; Colesevelam |
| What is teheMOA of bile salt-binding resins? | sequestrants trap bile in the intestine via charged (electrostati) interactions ; increases excretion of bile acids to reduce diarrhea effects *normally in the body, bile salts are present, but its when they are reabsorbed in high amounts in which we see diarrhea |
| ADRs of bile salt binding resins? | fecal impaction (hardening of stool in rectum) -bloating, flatulence, constipation |
| what does bile salt-binding resins lower? | serum cholesterol |
| what are the different drug classes for IBS? | Anticholinergics; 5-HTC antagonists; Opioid agonist; Cl-channel activators; GC-C agonists; Na-H Exchanger 3 inhibitor; Reuptake blockers |
| What are the Anticholinergics/Antispasmodics for IBS? What are they specifically used for? | 1. Dicylcomine/Hyoscyamine 2. used to treat abd pain for IBS-C, IBS-D, and IBs-M |
| What is the MOA of othe Anticholinergic/Antispasmodics meds (Dicylcomine/Hyoscyamine? | Muscarinic ACh receptor antagonists in smooth muscle and ENS (smooth muscle relaxation, improves abd pain/bloating -inhibits acid secretion in parietal cells |
| What can high doses of dicylomine and hyoscyamine cause? | ANTi-SLUD (dry mouth, flushing, N/V, tachycardia, urinary retention, dizziness, sedation, blurred vision, confusion |
| What are the 3 GI effects that serotonin has? | Increases motility and pain -activates immune cells causing inflammation in GI system -stimulates gut motility -can activate pain neurons *this is why we use 5-HT blockers to inhibit pain neurons and inhibit gut motility |
| Serotonin synthesis in the GI system occurs through the cell type known as the _________ (EC) cell and can be taken up vie the Serotonin transporter to regulate sertonin's effect in the GI system | Enterochromaffin *not the same as the ECL cell (PUD and GERD)--> secret histamine EC cells secrete/synthesize serotonin |
| Which medication is a 5-HT3 receptor antagonist used to decrease motility and pain? | Alosetron *other 5-HT3 antagonists are only antiemetics -5-HT3 is primarily expressed in the gut |
| What is the MOA of alosetron? | potent, selective 5-HT3 receptor antagonist -inhibits visceral afferent pain sensation (gut to spinal cord/CNS) -inhibits colonic motility -improves stool consistency |
| What is the BBW of alosetron? | GI toxicities, rare but serious |
| Alosetron has _____ affinity and _____ 5-HT3 dissociation | high; slow *so only low doses are needed |
| What is the CI of alosetron? | severe hepatic impairment |
| Which medication is an opioid agonist (antimotility) | Eluxadoline (mixed MOR/KOR agonist, DOR antagonist |
| What is the MOA of Eluxadoline? | MOR/KOR agonist, DOR antagonist -prolongs transit time -reduced abd pain -increases tone of anal sphincter -decreases ACh, 5-HT release and peristalsis |
| What is Eluxadoline used for? | IBS-D in adults and children |
| What is the CI of Eluxadoline? | hepatic or gallbladder impairments; alcohol use disorder |
| T/F: Lubiprostone, Linaclotide and Peclantide can be used for IBs-C | True *remember Lubiprostone can ONLY be used in IBS-C in WOMEN |
| Which medication is a Na/H+ exchanger 3 inhibitor? | Tenapanor |
| What is the MOA of Tenapanor? | NHE3 inhibitor *decreases GI absorption of dietary Na+ increasing Na+ conc. in the gut which water will follow causing an increase in transit time -will get a build up of Na+ conc. in the lumen which will then increase water levels -increases gut (Na+) and water to loosen stool (accelerating transit time) |
| What is Tenapanor used for? | IBS-C in adults |
| What is the BBW of Tenapanor? | Serious dehydration risk in pediatric pts *avoid in pts 6-12 yo |
| T/F: reuptake blockers (antidepressants) are indicated for primary IBS treatment | FALSE *they are not indicated for primary IBS treatment |
| A pt is going to be prescribed an osmotic laxative. Which is an appropriate medication for this class? -bisacodyl -senna -Polyethylene glycol -mineral oil -Polycarbophil | PEG |
| What option best explains Linaclotide's MOA in treating constipation? | Linaclotide increases Cl- secretion and water diffusion via guanyl cyclase receptor activation |
| Which 5-HT3 receptor antagonists can inhibit diarrheal pain and colon motility? | Alosetron |
Created by:
Xander635
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