GI Drugs Flashcards
What is reflux esophagitis and what factors contribute?
Heartburn
When esophageal sphincter opens and it shouldnt
Larger meal→More relfux
Factors that decrease esophageal closure:
- Alcohol
- Peppermint
- Chocolate
- Fats
- Acidic beverages
- Red Wine
- Carbonated drinks
-tidine
GI drug
Decrease acid secretion
Mech: H2 receptor blockers
SE:
- Confusion in elderly
- Bradycardia
Cimetidine:
- Inh. P450
- Prevent synth of test.
- Anti-androgenic
- Cause gynecomastia
-prazole
GI drug
Decrease acid formation
Mech: ATPase inhibitor
Known as proton pump inhibitor (PPI) but actually irreversibly inhibit ATPase required to drive H+ pump
Best available class of GI drugs
Prodrug-activated by acid
They are weak bases though→ stay in parietal cell
SE:
- Hypochlorhydria-lack of H+ production
- Decrease Ca absorption→osteoporosis
- Decrease Vit B12 absorption
Systemic vs non-systemic antacids
So, what is the order of cation absorption and why does this matter?
Na>>Ca>Mg>Al
More readily the cation is absorbed the more the anion is absorbed→ systemic alkylation
Particularly important for kidney dysfunction
Sodium Bicarbonate
NaHCO3
Antacid
Speed-rapid
Duration-short
Neutralizing-high
SE:
- CO2 production
- Belching
- Na may compromise low sodium diets
-
Systemic absorption
- Contains Na
- Important in those w/ kidney dysfunction
Calcium carbonate
CaCO3
Antacid
Speed-rapid
Duration-medium
Neutralizing-high
SE:
- Constipating
- Hypercalcemia
Aluminum hydroxide
Al(OH)3
Antacid
Speed-slow
Duration-long
Neutralizing-low
SE:
- Constipation
- Adsorbs drugs
- Loss of phosphate
- Al toxicity
Magnesium hydroxide
Milk of magnesia
Antacid
Speed-slow
Duration-medium
Neutralizing-high
SE:
- Laxative
- Some Mg toxicity
Sucralfate
GI drug-Enhance mucosal defense
Aluminum salt
Tx: Ulcers
Mech: Complex that becomes viscous and binds to damaged mucosa when exposed to acid
SE:
- Constipation
- Excess Al absorption
Contraindication: H+ depleters (PPI or antacids)
SucrALfate=ALuminum salt→Excess Al
Sucralfate=sucrose=sticky…so this sticks to damaged mucosa
Bismuth subsalicylate
GI drug-Enhance mucosal defense
Anti-diarrheal agent–absorbing agent
Mech: Increase mucous production in stomach
Inh. growth of H. pylori
Unpleasant taste+odor
SE:
- Long term use→Darkening of feces, tongue, and teeth
Misoprostole
GI drug-Enhance mucosal defense
Tx: Ulcers
Drop in PGs→Ulcer
Asprin (NSAIDs) and GCs can decrease PGs
Mech: Prostaglandin analog
SE:
- Uterine contractility (abortifacient)
- You eat miso soup when you have a stomach ache because it is prostagrandin anarog (say that w/ a strong asian accent)*
Antibiotic combo for H pylori infection
GI drug-Enhance mucosal defense
Metronidazole
+/-
Amoxicillin
+/-
Clarithromycin
+/-
Tetracycline
Metoclopramide
Tx: Gastroparesis
prokinetic agent–agents that increase stomach emptying rate
Also used for hiccups
Mech: DA and possible 5HT antagonist
Route: Oral or IV
Increase motility w/o secretion (of H or gastrin)
SE:
- Sedation
- Depression
- Parkinson like symptoms
Metoclopramide increases motility
- All that motility→shakes (parkinson like symptoms)*
- All those shakes →sedation *
- All that sedation→depression *
Erythromycin
Tx: Gastroparesis
prokinetic agents–agents that increase stomach emptying rate
Mech: Acts directly on motilin receptor
Route: Oral but IV possible if oral is not
SE:
- ototoxicity
- pseudomemb. colitis
- cardiac arrythmia
- Especially if metabolism is inh by P450
- Remember erythro is a macrolide*
- Motiliy*
- Arrythmias*
- Cholesteric toxicity (liver tox)/Colitis*
- Restricts P450*
- Ototoxicity*
Alvimopan
Tx: Gastroparesis
prokinetic agents–agents that increase stomach emptying rate
Mech: Blocks opiate receptor in gut but not anywhere else
Blocks constipation due to post op opioid use
Dioctal sodium sulfosuccinate
GI Drug
Cathartic–Stool softener
Detergent
Mech: Emulsifies contents of colon
Mineral oil
GI Drug
Cathartic–Stool softener
Mech: Acts like a lubricant
Why mineral oil should NOT be used:
- Prevents fat soluble vitamin absorption
- Aspiration pnemonia →may damage lungs
- May contain carcinogens
What are the bulk adding agents?
Bran
Methylcellulose
Polycarbophil
Psyllium
Bran
GI Drug
Cathartic–Bulk adding agent
Mech: Like eating fiber
Methylcellulose
GI Drug
Cathartic–Bulk adding agent
Mech: Like eating fiber
Polycarbophil
GI Drug
Cathartic–Bulk adding agent
Mech: Like eating fiber
Psyllium
GI Drug
Cathartic–Bulk adding agent
Mech: Like eating fiber
Cascara
GI Drug
Cathartic–Gastric Irritants
Mech: Stimulate gastric nn
Increase motility
Increase electrolyte secretion into gut
SE:
- Nephritis
- Liver damage
Senna
GI Drug
Cathartic–Gastric Irritants
Mech: Stimulate gastric nn
Increase motility
Increase electrolyte secretion into gut
SE:
- Nephritis
- Liver damage
Castor oil
GI Drug
Cathartic–Gastric Irritants
Mech: Stimulate gastric nn
Increase motility
Increase electrolyte secretion into gut
SE:
- Nephritis
- Liver damage
Bisacodyl
GI Drug
Cathartic–Gastric Irritants
Mech: Stimulate gastric nn
Increase motility
Increase electrolyte secretion into gut
SE:
- Nephritis
- Liver damage
MgSO4
GI Drug
Cathartic–Osmotic agent
Mg(OH)2
GI Drug
Cathartic–Osmotic agent
AKA Milk of Magnesia
Polyethylene glycol
GI Drug
Cathartic–Osmotic agent
DOC for colonoscopy
Lubiprostone
GI Drug
Cathartic–Secretion enhancer
Mech: Acts on PGE receptor
PGE1 derivative
Also acts on Cl channel in intestine
Linaclotide
GI Drug
Cathartic–Secretion enhancer
Mech: Activate guanylate cyclase
Increase Cl secretion in stomach
What are the stool softeners?
Dioctal sodium sulfosuccinate
Mineral oil
What are the gastric irritants used as cathartics?
Cascara
Senna
Castor oil
Bisacodyl
What are the osmotic cathartics?
MgSO4
Mg(OH)2
Polyethylene glycol
Adverse effects of cathartics
- Fluid imbalances
- K+ loss, etc
- Mucosal injury
- Malabsorption of nutrients
- Suppress reflex fxns
What is essential to treat diarrhea?
What do we have to be careful about?
Rehydration
Diarrhea is a process to rid bacteria so we must be careful if we are stopping this process
Codeine
Tx: Diarrhea
Narcotic agent
Mech: act a specific receptor
Not generally used for obvious reasons
Diphenoxylate
Tx: Diarrhea
Narcotic agent
Mech: act a specific receptor
Acts primarily in gut
Opiate like effects in CNS though too
Given in comb w/ atropine to avoid abuse
Difenoxin
Tx: Diarrhea
Narcotic agent
Active metabolite of diphenoxylate
Mech: act a specific receptor
Acts primarily in gut
Opiate like effects in CNS though too
Given in comb w/ atropine to avoid abuse
Loperamide
Tx: Diarrhea
Narcotic agent
Narcotic DOC for diarrhea
Mech: act a specific receptor
Acts ONLY in gut–no CNS effects
Atropine
Tx: Diarrhea
Anti-cholinergic agent
Mech: Blocks muscarinic receptor
SE: Many systemic
Scopolamine
Tx: Diarrhea
Anti-cholinergic agent
Mech: Blocks muscarinic receptor
SE: Many systemic
Crofelemer
Tx: Diarrhea
Mech: Blocks Cl channel in gut
Also decreases secretion of Na and H2O
CrofeLemer blocks CL channels
- or *
- CROws block the CLouds*
- CROfelemer blocks CL channels*
Simethicone
Tx: Diarrhea
Mech: Changes gas surface tension of gas pocket in gut
Alpha galactosidase
Tx: Diarrhea
Mech: Increase metab. of oligosacc.→digestible sugars
Oligosacc. produce gas
- Alpha GAlactoSidase inh. GAS production*
- *Be careful there are alpha-glucosidase inh in the diabetes section**
Ulcerative colitis vs Chron’s disease
Ulcerative-mucosal inflammation
Chron’s-mucosa and even into muscle of gut–more severe
-sala-
Sulfasalazine
Mesalamine
Olsalazine
Balsalazide
Tx: IBS–Salicylates
Mech: Decrease PG synth
Online it says mech is unclear–may not be the same as aspirin
Not systemically absorbed-like a topical drug for the stomach
SE:
- Diarrhea
- Take 3-5 weeks to work
Which GCs used for IBS
Prednisone
Budesonide
Infliximab
Tx: IBS
Mech: Binds TNF alpha
Immunosuppressants for IBS
Methotrexate
Cyclosporine
(Apo)morphine
Emetic–central stimulant
Mech: Stimulates DA sites in CTZ
Digoxin
Emetic–central stimulant
Mech: Stimulates DA sites in CTZ
Ipecac
Emetic–reflex stimulant
Mech: Act. receptors in GI mucosa
Instant severe vomiting
SE: Cardiotoxic
Diphenhydramine
or
Dimenhydramine
Anti-emetic–Antihistamine
Mech: Block H1 receptor
SE: Anticholinergic effects
Meclizine
Anti-emetic–Antihistamine
Mech: Block H1 receptor
SE: Anticholinergic effects
Cyclizine
Anti-emetic–Antihistamine
Mech: Block H1 receptor
SE: Anticholinergic effects
Which antihistamines are used as anti-emetics?
Diphenhydramine
Dimenhydramine
Meclizine
Cyclizine
What other drugs mentioned will cause emesis?
NSAIDs
Anti-neoplastic
Iron salts
Scopolamine
Anti-emetic–anti-cholinergic
Mech: Block muscarinic receptor
Route: Patch
SE:
- Dry
- Drowsy
- Etc.
Dronabinol
Anti-emetic–THC derivative
Mech: Bind cannabinoid receptor
SE: Increased appetite
Nabilone
Anti-emetic–THC derivative
Mech: Bind cannabinoid receptor
SE: Increased appetite
Compazine
Anti-emetic
Mech: DA blocker
*Related to anti-psychotic drugs *(phenothiazine)
SE: Extrapyramidal effects
-setron
Ondansetron
Granisetron
Dolasetron
Palonosetron
Anti-emetic (for IBS+chemo)
Mech: 5HT receptor blocker
Affect CTZ +rec. in gut
SE: Constipation
_SE_lective _T_e_R_minators _O_f _N_ausea
-SETRON
-setron blocks serotonin
