GI MEDs Flashcards
Where is pepsinogen found
Pepsinogen: inactive form of pepsin found in the Chief cells of the gastric glands
What is pepsin
Pepsin: protein splitting enzyme capable of digesting nearly all types of dietary protein and is formed from pepsinogen in the presence of HCl
What is the role of Intirisic Factor
Intrinsic Factor: aids in the absorption of vitamin B12 and is found in the Parietal cells of the gastric glands
What stimulates the production of HCL in the Proptoin Pump
Acetylcholine (parasympathetic)
Histamine
Gastrin
What is the role of prostaglandins in protection of the GI
Inhibit basal and stimulated gastric acid secretion
Diminishes proton pump action
What are the alarm s/s of GERD
Alarm Symptoms: dysphagia, odynophagia, bleeding, weight loss, choking, and epigastric mass
What is the nonpharm approach to GERD
DIet modification
What medications should be avoided in pts w/ GERD
Avoid medications that may reduce LES pressure, delay gastric emptying, or cause direct irritation
Alpha antagonist, anticholinergic, benzodiazepines, CCBs, estrogen, nitrates, opiates, TCAs, theophylline, NSAIDs, and aspirin
What is the pharm approach to moderate GERD
Start with H2 inhibitors in addition with antacids for breakthrough GERD symptoms
If symptoms are not controlled after 4 weeks and max dose of H2 inhibitors switch to a Proton Pump Inhibitor (PPI)
What is the pharm approach to frequent GERD
Start with PPI
should administer 30-60min prior to meal; may increase to BID dosing if needed
What are the causes of PUD
Helicobacter pylori (H.pylori) positive
NSAID induced
Stress Ulcers or Stress-Related Mucosal Damage (SRMD)
SRMD is the preferred term because the mucosal lesions range from superficial gastritis and erosions to deep ulcers
Zollinger-Ellison Syndrome (ZES): gastric acid hypersecretory disease caused by gastrin-secreting tumor and leading to multiple, severe duodenal ulcers
Minor contributor to PUD: inadequate mucosal defense against gastric acid
All pts with PUD should be tested for
H. Pylori
What are the noninvasive and invasive Tests for H. Pylori
Noninvasive:
Fecal antigen assay
Urea-breath testing (UBT)
Serologic testing
Invasive:
Gastric mucosal biopsies by endoscopy
Wha this the Tx for H. Pylori ulcers
Anti-secretory agent: Proton Pump Inhibitor (PPI)
Two antibiotics
1st Line: Triple therapy - clarithromycin + amoxicillin (may replace with metronidazole if allergic to PCN)
2nd Line: Quadruple therapy - for patients that cannot take clarithromycin: tetracycline + metronidazole + bismuth subsalicylate
What is the length of Tx for duodenal ulcers and gastric ulcers
If PUD is present, continue PPI for 4-8 weeks for duodenal and 8-12 weeks for gastric ulcers
How are the urea breath test and the stool antigen test performed
Urea-breath test (UBT) or stool antigen tests are preferred
Must be off PPI for 1-2 weeks prior to the test
Can wait to confirm until after completion of the PPI course
What is standard triple therapy
PPI PO twice daily
Clarithromycin 500 mg PO twice daily
Amoxicillin 1 g orally PO twice daily
(or metronidazole 500 mg PO BID, if PCN allergic)
What is standard Quad therapy
PPI PO twice daily
Bismuth subsalicylate 262mg - two tablets PO four times daily
Tetracycline 500mg PO four times daily
Metronidazole 500mg PO three times daily
What does COX-1 do
Increase blood flow to gastric mucosa and kidneys
Increase platelet aggregation via thromboxane A2 pathway
What does COX-2 do
Increase renal blood flow
Makes PG that activate and sensitize nociceptors (increased pain)
What is the Tx approach to NSAID induced ulcers
DC NSAIDS Or reduce
Switch to Acetominphine or Asprin
Celecoxib (Celebrex):
Should be reserved as last line
Associated with cardiovascular risk
What are the prevention methods for stress ulcers
Proton Pump Inhibitors (PPI)
Histamine-2 Receptor Antagonists (H2RA)
What is the 1st line therapy for intermittent S/s of acid
Antacids
What is the MOA of Sodium Bicarb
Mechanism of Action:
Reacts with HCL to produce carbon dioxide and sodium chloride.
CO2 results in gastric distention and belching
What is the MOA of calcium carbonate
Calcium Carbonate (Tums, Oscal)
Less acid neutralizing capability compared to sodium bicarbonate and other antacids
What is the MOA and clin use of Mag Hydroxide
Mechanism of Action: reacts slowly with HCL to form magnesium chloride and water
Clinical Use: may be used as antacid or laxative (diarrhea)
What is the ADE and caution of Mag Mydroxide
Adverse Effects: osmotic diarrhea caused by unabsorbed magnesium salts
Caution: renal insufficient patients should not take magnesium hydroxide long-term
What is the MOA of aluminum hydroxide
Mechanism of Action: reacts with HCl to form aluminum chloride and water. Antacid
What is the ADE of aluminum hydroxide
Aluminum salts cause constipation
Aluminum is also absorbed and excreted in the kidneys (Renal insufficiency: should not take long-term)
What is the MOA of H2 antagonists
Mechanism of Action:
competitively block the binding of histamine to H2 receptors on the parietal cell, inhibiting gastric acid secretion induced by histamine
Suppress basal and meal-stimulated acid secretion
Reduces acid secretion stimulated by gastrin and cholinometic agents
Which is better in erosive esophagitis, PPI or H2 blocker
PPI
What are the ADE of H2 blockers
CNS effects such as headache, dizziness, fatigue, somnolence, and confusion are most common
Prolonged cimetidine use is associated with rare development of gynecomastia
What is cimetidine
H2 blocker
How is cimetidine cleared
Competes with the medications and creatinine for tubular secretion in the kidney
What is Ranitidine
H2 blocker
Low percentage of side effects and good efficacy
What is Famotidine
Pepcid AC
What are the most effective agents for the Tx of GERD
PPI
Pantoprazole (Protonix) Omeprazole (Prilosec) Omeprazole/Bicarbonate ion (Zegrid) Esomeprazole (Nexium) Rabeprazole (Aciphex) Lansoprazole (Prevacid) Dexlansoprazole (Dexilant)
What is the MOA of PPI
Administered as a prodrug
Irreversibly binds to the H+/K+ ATPase enzyme system (proton pump) of the cells suppressing secretion of hydrogen ions
What is the advantage of PPI over H2RAs
Greater degree of acid suppression achieved and typically longer duration of action than H2RAs
What are the newly learned ADE of PPI
Increase RSK of FX
Hypomagnesemia
C. DIff
CAP
What is the MOA and clin use of Surcralfate
Covers the ulcer site and protects it against acid
Stimulates prostaglandin release
Not absorbed systemically, adverse effects are uncommon
Requires acidic pH for activation
Clinical Use:
Heals peptic ulcers, but not widely used as much because it is not as effective as H2 blockers and PPIs
What is the MOA of misoprostol
Prostaglandin Analog
Synthetic, oral prostaglandin E1 analog that has both antisecretory and mucosal protective properties
Clinical Use:
Approved for the prevention of NSAID-induced ulcers in high-risk patients
Can pregnant pts get misoprostol
NO
Miscarriages
What is the only combination Rx product that contains metronidazole and tetracycline for the treatment of H. pylori
Bismuth, aka petobismol
What is the clin use of Bismuth/ Pepto
Nonspecific treatment of dyspepsia and acute diarrhea
Prevention of traveler’s diarrhea
Used in quadruple drug regimens for H. pylori eradication
What are the ADE of Pepto/ bismuth
Blackening of Stool
Darkening Of tongue
Renal insufficiency
May bind to other drugs
What is the MOA and Clin Use of Metoclopramide
Prokinetic Agent
Dopamine antagonist; stimulates motility of the upper GI track without effecting secretions
Enhances the response to Acetylcholine of tissue in upper GI tract causing enhanced motility and accelerated gastric emptying without stimulating gastric, biliary, or pancreatic secretions
Also block serotonin receptors in the chemoreceptor trigger zone, resulting in the anti-emetic action
Clinical Use: gastroesophageal reflux, prevention of N/V from chemotherapy, impaired gastric emptying (i.e diabetic gastroparesis)
What drug helps N/V in chem pts
Metoclopramide
5HTs Antagonists
What are the MOA and Clin use of Ondansetron/ Granisetron/ Dolasetron/ Palonosetron
5hT3 antagonists
Mechanism of Action: block presynaptic serotonin receptors on sensory vagal fibers in gut wall as well as central blockade in the vomiting center and CTZ
Clinical Use: General medical use Post-operative nausea and vomiting Chemotherapy Induced Nausea and Vomiting (CINV) Radiation-Induced nausea and vomiting
What is the ADE of Ondansetron and other drugs that end in -setron
Well tolerated; most common is headache, dizziness, and constipation
QTc prolongation; small but statistically significant prolongation of QT interval (most pronounced with dolasetron)
Which 5HT3 has the most pronounces QT elongation effects
Dolasetron
What drug class are Meclizine (Antivert,Bonine) Diphenhydramine (Benadryl) Dimenhydrinate (Dramamine) Doxylamine (Unisom) Doxylamine/pyridoxine (Diclegis)
Antihistamines
What is the MOA of antihistamines
Block histamine H1 at the vestibular apparatus preventing vomiting due to motion sickness
All cause some drowsiness and anticholinergic side effects
What drug class are prochloperazine and promethazine
Phenothiazines
What is the MOA and CLin use of Phenothizies: prochloperazine and promethazine
Mechanism of Action:
Block dopamine, muscarinic, and histamine receptors in Chemoreceptor Trigger Zone (CTZ)
Sedation is due to their anti-histamine activity
Clinical Use: effective oral, injectable, and rectal anti-emetics for inpatient and outpatient use
What is promethazine
A 1st gen antihistamine used for the treatment of nausea, vomiting, and motion sickness
DO NOT USE SubQ
IV formulation should be diluted because of tissue necrosis r
What is the MOA and Clin use of scopalamine
Mechanism of Action: cholinergic antagonist with greater central (more lipophilic; blocks muscarinic receptors in the vestibular system) than peripheral effects
Clinical Indication: motion sickness; surgical adjunct (blocks short-term memory and decreases saliva)
What are the important monitoring and ADE of scopalamine
Monitoring: HR, temperature, Urinary Output (UOP)
Adverse Effects: excessive anticholinergic effects (dry mouth: 67%; drowsiness:17%)
What is the MOA and Clin use of Droperidol
Mechanism of Action: blocks dopamine receptors in chemoreceptor trigger zone (CTZ) of the CNS
Clinical Use:
Butyrophenone antipsychotic, no longer used as antipsychotic
Indicated for Postoperative Nausea/Vomiting (PONV)
Most often used for sedation in endoscopy and surgery, in combination with opioids or benzodiazepines
Where is droperidol most often used
Most often used for sedation in endoscopy and surgery, in combination with opioids or benzodiazepines
What are the ADE of Droperidol, a drug used in sedation for endoscopy
EPS, Dystonias, Drowsiness, Agitaton, Confusion
What is the MOA and clin of metoclopramide
Mechanism of Action:
Dopamine antagonist; stimulates motility of the upper GI track without effecting secretions
Enhances the response to Acetylcholine of tissue in upper GI tract causing enhanced motility and accelerated gastric emptying without stimulating gastric, biliary, or pancreatic secretions
Also block serotonin receptors in the chemoreceptor trigger zone, resulting in the anti-emetic action
Dosed several times a day
Clinical Use: gastroesophageal reflux, prevention of N/V from chemotherapy, impaired gastric emptying (i.e diabetic gastroparesis)
What are the ADE of metroclopramide
EPS
What is the MOA and clin use of Trimethobenzamide
Mechanism of Action:
Block emetic impulses in the chemoreceptor trigger zone (CTZ)
Does not cause extrapyramidal symptoms like metoclopramide
Clinical Use:
Used for apomorphine pre-treatment in Parkinson’s patients
Indicated for post-operative N/V and for nausea associated with gastroenteritis
What drug is used in the apomorphine pre-treatment in Parkinson’s patients
Trimethobenzamide
Dexamethasone and Methylprenisone are what drug class
Corticosteroids
What are the clincal use of corticosteroids
Chemotherapy N/V w. 5HT3 Antagonsits (SRAs)
How are BZD used to prevent NV
Clinical Use: used before the initiation of chemotherapy to reduce anticipatory nausea and vomiting caused by anxiety
Products:
Lorazepam (Ativan)
Diazepam (Valium)
What kind of drugs are Dronabinol and Nabilone
Cannaboids used to treat NV in chemo pts
And anorexia with AIDS pts
What drug is used in conjunction with 5-HT3 antagonist and steroid for both the acute and delayed phases of cisplatin-induced emesis
Aprepitant
Drugs that end in –prepitant are used to treat what
Chemo induce NV
What is the Tx approach to mild Diarrhea
rehydration fluids + lactose free diet, avoid caffeine
What is the Anitbiotic therapy for Travelers Diarrhea
Fluoroquinolones
Azithromycin
Rifaximin (Xifaxan) only works in the colon
Rifamixin treats IBS-diarrhea dominant
How do you treat antibiotics C. Diff
Metronidazole or oral vancomycin
How do Opiods agonists stop diarrhea
Activates presynaptic opioid receptors (mu receptors) in the enteric nervous system
Inhibit presynaptic cholinergic nerves in the submucosal and mesenteric plexuses
Lead to increase colonic transit time and fecal water absorption
Decreases mass colonic movement and the gastrocolic reflex
How is the MOA and clin use of Loperamide
Mechanism of Action:
Mu opioid agonist; activates opioid receptors in the enteric system, leading to inhibition of acetylcholine release and decreased peristalsis
Does not cross the BBB
Meperidine derivative
Posses “no” analgesic properties or potential for addiction
Clinical Use:
Control mild to moderate symptoms of non-invasive diarrhea
What is the antidiarheal drug for non invasive diarrhea
Loperamide ( you know this one, its what you always had to have on hand in the field as a medic) ( doc i shit my pants )
What are the common causes of constipation
Altered motility Neurogenic causes (Parkinson disease) Endocrine/metabolic disorders (e.g. hypothyroidism, diabetes, hypokalemia, hypercalcemia, uremia) Pregnancy Psychogenic causes Structural abnormalities or obstruction Nutritional (e.g, reduced fiber and water intake) Medications
What is the MOA and clin use of osmotic Laxatives
Mechanism of Action:
Rapid movement of water into the distal small bowel and colon, leads to high volume of liquid stool
Increase volumes leads to bowel distension and reflex urge to defecate
Followed by rapid relief of constipation
Clinical Use:
Acute or intermittent constipation
Preoperative or pre-procedure bowel preparation
What type of laxative is magnesium based products
Osmotic
What kind of laxative is sodium phosphate
Osmotic
What is the caution with mag sulfate as an osmotic laxative
Caution with in patients with renal impairment due to the risk of magnesium intoxication
Electrolyte Abnml
What is the black box label for sodium phosphate
Nephropathy with oral products
What is the MOA and Clin use of lactulose and 70% sorbitol
Mechanism of Action: metabolize by colonic bacteria, producing increased osmotic pressure causing fluid accumulation, severe flatus, cramps, and defecation
Clinical Use:
Management of acute, intermittent, or chronic constipation
Lactulose:
Preferred in chronic liver disease in the prevention and treatment of overt hepatic encephalopathy (OHE) episodes and portal systemic encephalopathy (PSE)
Reduces ammonia levels
What osmotic laxative is preferred in chronic liver disease
Lactulose
What kind of laxative is polyethylene solutions
Osmotic
Used for preoperative/colon preparation for endoscopic or radiologic procedures
How is Polyethylene taken
Isotonic solution contain an inert non-absorbable, osmotically active sugar
Induce bowel movement/diarrhea to cleanse the bowel usually within 4 hours
Ingest 2-4 Liters over 2-4 hours
What is the 2-4 liters a pt should drink for preoperative/colon preparation for endoscopic or radiologic procedures
Polyethylene Gycol
What is PEG 3350 power approved for
Approved for irritable bowel syndrome constipation dominant (IBS-C)
What are Gylcerin suppository and Mineraol Oil
Lubircating agents
What pts should suppository or mineral oil be used on
Management of acute or intermittent constipation
Pediatric patients
What are psyllium and wheat dextrin
Fiber used to treat constipation
What pts should not receive plant fibers
Celiac pts
What synthetic fiber can be used in celiac pts for constipation
Methyl cellulose
What kind of laxative is docusate
Stool surfactant/ Stool softener
How is ducosate used
Prevention of opioid induced constipation in combination with Senna or prevention of straining (pregnant/post-operative)
Preferred for prophylaxis not acute treatment of constipation
To prevent straining in pregnancy or op pts what stool softener can be used
Docusate
What is the DOC for IBS in women older than 18 yrs old
Lubiprostone
What is the DOC in short term emergency Tx of IBS and Chronic Constipation in women older than 55 years old
Tegaserod
What is Linaclotide used for
IBS and Chronic constipation
What is the DOC for opiod induced constipation
Methyl naltrexone
What is the DOC for postoperative ileus
Alivmopan
What is the DOC for opiod induced constipation in adult pts with chronic non cancer pain
Naloxegol
Define Ulcerative colitis
Superficial, mega colon developing, Risk factor for cancer, that is usually confined to the rectum and terminal colon
Has continuous inflammation
Define chrons
Cobblestone patchy appearance, that rarely leads to cancer, does not develop mega colon, and can be anywhere from mouth to anus in the GI, and can extend deep to the submucosa
What are the 1st line products for IBD
Sulfasalazine and Mesalamine
What do Sulfasalazine and mesalamine treat
IBD: chrons and UC
What TCAs can be used to treat IBS
Amitriptyline, nortriptyline, and imipramine
Can worsen constipation
What SSRIs can be used to treat IBS
Fluoxetine, setraline, citalopram, and paroxetine are all viable options
What is Rifaximin used for
Treats IBS-D
And travelers Diarhhea
What is the caution with Rifaxamin
Caution in liver impairment
What is eluxadoline used for
IBS-D
What pts should eluxamide, a drug for IBS-D be avoided in
should not be used in patients with a history of bile duct obstruction, pancreatitis, severe liver impairment, or severe constipation, and in patients who drink more than three alcoholic beverages per day
What is alosetron used for
Women with IBS-D
What are the black box warnings of alosetron, A 5hT3 antagonist used to treat IBS-D in women
Ischemic colitis and Constipation
