GI Flashcards
Which has a higher drug bioavailability: by mouth or by rectum?
Why?
rectum> mouth
Veins of distal rectum drain into pelvic veins and not the portal system so meds reach systemic circulation w/o first pass metabolism.
Meds by mouth–>absorbed in intestines which drain into portal system
Drugs causing Focal to Massive Hepatic Necrosis(4)
“liver HAVAc”
- Halothane
- Amanita phalloides (death cap)
- Valproic Acid
- Acetaminophen
Zone of the liver most susceptible to INJESTED toxins and viral hepatitis?
Function of this zone?
- Zone 1 (periportal)
- Oxygen-intensive metabolism
Zone of the liver most susceptible to Yellow Fever?
Zone II (intermediate)
Which zone of the liver is responsible for cytochrome 450 metabolism?
Zone III
Zone of the liver most susceptible to Ischemia/low O2?
Zone III
Zone of the liver most susceptible to METABOLIC by products?
Name 2 examples of common drugs.
Zone III
Alcohol–>Acetaldehyde
Acetaminophen –>NAPQ1
Antidote to Acetaminophen Toxicity?
N-acetylcystein (replenishes glutathione)
Octreotide:
MOA
Uses(4)
Adverse
Somatostatin analog (in brain inhibits GH release from ant. pituitary)
- Acromegaly
- Carcinoid syndrome
- Variceal bleeding (esp. esophageal)
- VIPoma, gastrinoma, glucaconoma
Adverse: Gallstones and GI upset
Somatostatin: Cell source Actions(4) Increased somatostatin release by? Decrease somatostatin release by?
Dcells (pancreatic islets, GI mucosa)
Inhibits secretion of various hormones-“encourages SOMATO-STAsis
- decrease Gastric Acid/Pepsinogen secretion
- decrease pancreatic and Sm.Intestine fluid secretions
- decrease gallbladder contractions
- decrease insulin and glucagon release
Increase: by Acid (like FAs and AAs)
Decrease by Vagal stimulation
Compare Oral glucose load to IV glucose
Oral glucose load leads to increased insulin compared to IV equivalent due to GIP secretion
GIP: What does GIP stand for? (2) Cell Source Exocrine Actions Endocrine Actions Regulation(3)
- Glucose-dependent Insulinotropic Peptide
- Gastric inhibitory peptide
Kcells (duodenum, jejunum)
Exocrine: decrease Gastric H+ secretion
Endocrine: increase insulin release
increase GIP release via increased FA, AA, oral glucose
Which Abx stimulates the Motilin-R?
Erythromycin
Macrolides: Azithromycin, clarithromycin, erythromycin
MOA
MOResistance
Clinical Use (4)
- Inhib 23S (part of 50S) which blocks translockation (‘macroSLIDES’)
- Methylation of 23S
- Atypical pneumonia: Mycoplasma, Chlamydia, Legionella
- STIs: Chlamydia
- Gram + Cocci: Strep infections in pt allergic to penicillin
- B. pertussis
Macrolides: Azithromycin, clarithromycin, erythromycin
Adverse (5)
“MACRO’
- Motility Issues (GI)
- Arrhythmia (prolonged QT)
- Cholestatic hepatitis
- Rash
- eOsinophilia
Clarithromycin/Erythromycin: inhibit P450–>increase serum concentrations of Theophylline and Oral anticoagulants
How does Atropine affect the stomach?
What does Atropine NOT affect?
- Atropine blocks Vagal stimulation of parietal cells (Ach binding M3)
- Vagal stimulation of G-cells is not affected by atropine b/c the are stimulated by GRP (not Ach)
D-xylose absorption test:
Use
Mechanism
- distinguishes malabsorption from mucosal damage vs. other causes of malabsorption.
- D-xylose doesn’t require pancreatic enzyme processing for absorption
- With pancreatic insuff. : D-xylose would still appear in the blood
- With GI mucosal damage: No D-xylose would appear in the blood
Chagas Disease: infectious agent GI effect (2) Radiographic appearance treatment (2)
T. cruzi
- megacolon, megaesophagus
- “birdbeak”
Treatment: 1. NifurtiMOX 2. Benznidazole
“MOXie people T.ake CRUZes to South America”
Compare treatment of Celiac sprue vs. Tropical sprue
Celiac sprue: gluten free diet
Tropical sprue: Antibiotics
Treatment of Crohn’s disease (5)
- Corticosteroids
- azathioprine
- Abx (ciprofoxacin, metranidazole)
- Infliximab
- Adalimumab
Treatement of Ulcerative Colitis (4)
- 5-aminosalicylic preparation (like melamine)
- 6-mercaptopurine
- infliximab
- colectomy
Schistosoma:
Transmission
Treatment
transmitted by snails and penetrate human skin to form granulomas
tx: Praziquantel
Reye syndrome: Definition Clinical symptoms Cause Mechanism
Fatal childhood hepatic encephalopathy (rare)
- Mitochondrial abnormalities
- Fatty liver (microvesicular fatty change)
- hypoglycemia
- vomitting
- Hepatomegaly
- coma
- viral infection (esp VZV & influenzaB) treated with aspirin
- aspirin decreases B-oxidation by reversible inhib of mitochondrial enzymes
Only childhood illness where it is acceptable to use Aspirin?
Symptoms (6)
Kawasaki disease (asian children desquamating)
- Adenopathy (cervical)
- Strawberry tongue (oral mucositis
- Hand-foot changes (edema, erythema)
- Fever
Treatment of Hepatic encephalopathy(2)
Why?
- lactulose (increase NH4+ generation)
2. Rifaximin or Neomycin (decrease NH4+ producing gut bacteria)
treatment of physiological neonatal jaundice
-phototherapy (non-UV) which isomerizes unconjugated bilirubin to water-soluble form
treatment of Crigler-Najjar Syndrome, type 1 (2)
- plasmapheresis
2. phototherapy
Treatment of Wilson disease (hepatolenticular degeneration)
(3)
chelation w/
- penicillamine
- trientine
- oral zinc
Treatment of hemochromatosis (1, 3)
- repeated phlebotomy
chelation w/
- deferasirox
- deferoxamine
- oral deferiprone
GI drug reaction:
Acute cholestatic hepatitis, jaundice
Erythromycin
GI drug reaction:
Diarrhea(5)
“Might Excite Colon On Accident”
- Metformin
- Erythromycin
- Colchicine
- Orlistat
- Acarbose
GI drug reaction:
Focal to massive hepatic necrosis (4)
“liver HAVAc”
- Halothane
- Amanita phalloides (death cap mushrooms)
- Valproic acid
- Acetaminophen
GI drug reaction:
Hepatitis(5)
- Rifampin
- Isoniazid
- Pyrazinamide
- Statins
- fibrates
GI drug reaction:
Pancreatitis (6)
“Drugs Causing A Violent Abdominal Distress”
- Didanosine
- Corticosteroids
- Alcohol
- Valproic Acid
- Azathioprine
- Diuretics (furosemide, HCTZ)
GI drug reaction: Pseudomembranous Colitis(3)
- Clindamycin
- Ampicillin
- Cephalosporins
- antibiotics predispose to superinfection by resistant C.diff
H2 blockers:
Name (4)
"Take H2 blockers before you '-dine'" "think TABLE FOR 2 to remember H2" 1. Cimetidine 2. ranitidine 3. famotidine 4. nazatidine
H2 blockers:
MOA
Clinical use (3)
Reversible H2-R block–> decrease H+ secretion by parietal cells
- peptic ulcers
- gastritis
- mild esophageal reflux
H2 blockers: Adverse 1. Cimetidine (4) 2. cimetidine and ranitidine (1) 3. others
Cimetidine:
- potent P450 inhib (D-D)
- Antiandrogenic (prolactin release, gynecomastia, impotence, decreased libido)
- CNS effects (Confusion/Dizzy/HA)
- crosses placenta
Both Cimetidine and Ranitidine:
1. decrease renal excretion of creatinine
All other H2 blockers are relatively free of these effects
Proton Pump inhibitors:
Name (5)
- prozole
1. Omeprazole
2. lansoprazole
3. esmeprazole
4. pantoprazole
5. dexlansoprazole
Proton Pump inhibitors:
MOA
Clinical Uses (4)
Adverse (3)
- Irreversible inhib H/K+ ATPase of parietal cells
1. Peptic Ulcers 2. gastritis
3. GERD 4. Zollinger-ellison syndrome
- increase risk of C.diff
- Pneumonia
- decrease Mg+2 (w/ long term use)–>osteoporosis
Triple therapy for H. pylori ulcers
- PPi
- Clarithromycin
- Amoxicillin/Metronidazole
Antacid Use D-D explanation
Affects absorption, bioavailability, or urinary excretion of other drugs by
- altering gastric pH
- altering urinary pH
- delaying gastric emptying
All Antacids can cause what adverse side effect
hypokalemia
Antacids:
Name 3
- Aluminum hypoxide
- Calcium carbonate
- Magnesium hydroxide
Aluminum Hydroxide:
Adverse(6)
- Constipation (“AluMINIMUM feces)
- hypophosphatemia
- prox. muscle weakness
- osteodystrophy
- seizures
Calcium Carbonate:
Adverse (3)
- Hypercalcemia (milk-alkali syndrome)
- Rebound acid increase
- Chelate and decrease effectiveness of other drugs (tetracyclines)
Magnesium Hydroxide:
Adverse(5)
- Diarrhea
- Hyporeflexia
- Hypotension
- cardiac arrest
“Mg+2= Must Go 2 the bathroom”
Which antacid causes constipation?
Diarrhea?
chelation interactions?
hypokalemia?
- Aluminum hydroxide
- Magnesium Hydroxide
- Calcium Carbonate
- All antacids cause hypokalemia
Bismuth, Sulcralfate:
MOA
Clinical Use(2)
“the ‘B’and-aids for the ‘S’tomach”
- Binds ulcer base–>provide physical protection & allows HCO3- secretion –>reestablish pH gradient in Mucous layer
- increase ulcer healing
- traveler’s diarrhea
Misoprostol: MOA Clinical Use Adverse (1) Contra (1)
- PGE1 analog
- increase production/secretion of gastric mucous (decrease acid)
Use: prevention of NSAID-induced peptic ulcers
Adverse: Diarrhea
Contra: women of childbearing potential
Octreotide:
MOA
Clinical Use (4)
Adverse (3)
- Long-acting Somatostatin analog
- Inhib secretion of various splanchnic vasodilatory hormones
- Acromegaly
- Carcinoid syndrome
- Variceal bleeding (esp. esophageal)
- VIPoma, gastrinoma, glucaconoma
Adverse: 1. N/cramp 2. Steatorrhea 3. increase risk of cholelithiasis (CCK inhib)
Osmotic Laxatives:
Name (4)
- Magnesium hydroxide
- Magnesium citrate
- Polyethylene glycol
- Lactulose
Osmotic Laxatives:
MOA
Clinical Use
Adverse(2)
- providee osmotic load to draw water into GI lumen
- Use: constipation
- Adverse: Diarrhea & dehydration
Lactulose:
special use & why
Hepatic encephalopathy
- gut flora degrades lactulose into lactic acid/acetic acid–> this promotes NH4+ excretion
Who typically abuses osmotic laxatives?
Bulimics
Sulfasalazine:
MOA
Clinical Use(2)
-combo of Sulfapyridine +5-aminosalicyclic acid–>activated by colonic bacteria
(antibacterial + anti-inflam)
Use: IBD (both Ulcerative Colitis, Crohn’s colitis)
Sulfasalazine:
Adverse (4)
- Malaise
- Nausea
- Sulfonamide toxicity
- Reversible oligospermia
Classic vignette of Bulemic on laxative
- Female, overweight (increase eating, no weight gain)
- decreased energy
- Met. acidosis
- Electrolyte abnormalities
Loperamide: MOA CNS penetration? Use (1) Adverse (2)
- Agonist at u-R –> slows gut motility
- Poor CNS penetration
Use: Diarrhea
Adverse: Constipation, Nausea
Ondansetron:
MOA (2)
Clinical Use(2)
Adverse (3)
Powerful central-acting Anti-emetic
- 5-HT3 antagonist & decrease vagal stimulation
- post-op vomiting control
- chemo pt nausea control
Adverse: HA, constipation, prolonged QT
Metaclopramide:
MOA
Effect on colon transport time?
Clinical Use (2)
D2-R antagonist
- increase resting tone, LES tone
- increase contractility, motility
* Doesn’t alter Colon transport time - Diabetic & postsurgery
- anti-emetic
Metaclopramide:
Adverse (5)
D-D (2)
- Parkinsonian effects & Tardive dyskinesia
- Restlessness
- Drowsy, Fatigue
- Depression
- Diarrhea
DD: 1. digoxin 2. diabetic agents
Metaclopramide:
Contra (2)
- sm. bowel obstruction
2. Parkinson disease
Orlistat:
MOA
Clinical Use (1)
Adverse (2)
- inhib gastric&pancreatic lipase –> decrease breakdown/absorption of dietary Fats
Use: weight loss
Adverse: Steatorrhea, decrease Fatty-Vitamins
Ursoliol (ursodeoxycholic acid):
MOA(3)
Clinical use(2)
- nontoxic bile acid
- increase bile secretion
- decrease cholesterol secretion and reabsorption
Use:
- Primary Biliary cirrhosis (anti-mitochondrial abs)
- Gallstone preventionor dissolution