GI Pharm Class Flashcards
What are antacids for?
Short term temporary relief from mild pain and symptoms of PUD/GERD
Also used to promote headline of duodenal ulcers
Are there better drugs for PUD/GERD than antacid
Year with more effective, more convientnt, longer lasting effects
What are the two types of antacids
Low systemic agents
High systemic agents
Name the low systemic agents
Aluminum salts (aluminum hydroxide) Calcium salts(calcium carbonate) Magnesium salts(magnesium hydroxide/carbonate/trisilicate)
What are high systemic agents antacids
Sodium salts (sodium bicarbonate)
What is a supplemental agent for antacids
Simethicone
How do antacids work
They are weak bases that form a salt and water upon reaction with gastric HCl. The net result is to increase the pH and thereby reduce the acidity of the gastric contents. Furthermore, since pepsin is inactivated at pH>4, antacids may also act to decrease the peptic activity of protein breakdown. Also it has been postulated that antacids may increase the mucosal barrier of the gastric lining by stimulating prostagladin synthesis
Side effect aluminum hydroxide
Constipation
Hypophosphatemia (can treat hyperphosphatemia)
Renal osteodystrophy (ESRD) Encephalopathy
Side effect magnesium hydroxide
Diarrhea(stool soft/laxative)
Hypermagnesemia
Side effects calcium carbonate
Hypercalcemia; milk alkali syndrome resulting in nephropathy and metabolic alkalosis
Constipation
Hypophosphatemia (effective treatment for hyperphosphatemia)
Calcium based kidney stones
Side effects sodium bicarbonate
Flatulence, metabolic acidosis
Hypernatremia
Metabolic alkalosis
What is sucralfate
Compound to promote healing of duodenal ulcers. It enhances mucosal barrier through prostagladin synthsis stimulation or by acting as a physical barrier itself and thereby protecting the delicate mucosal lining from the acidic stomach contents. Since sucrlfate requires an acidic environment for activation, it should not be taken with antacids H2 blockers, or protein pump inhibitors
Do antacids reduce acid secretion or production
No
Can get rebound acid production
How do antacids work
Combine with H ions in stomach acid , capturing the loose H atoms
Forming common byproducts that depend on the antacid agent . (Water, carbon dioxide, chloride salts)
At _ doses, antacids increase LES tone
High
Calcium vs magnesium onset
Both rapid
Calcium vs magnesium DOA
Both long
Acid neutralizing capcity of calcium and Magnesium
Both good (calcium a bit better)
Aluminum and sodium
Fair good acid neutralizing and short duration of action
Simethicone
A surfactant-decreases surface tension
AIDS in expulsion of gas GAS RELIEF and given as a supplement with antacids
Why use combinations of antacids
Enhance efficacy and reduce side effects (use of lower doses of each and opposing side effects)
Bc side effects are dose related
How decide which antacid/combination to use
What works best for patient, trial and error, and experience
What are patient factors that we have to take into account what prescribing antacids
Dosage form and palatability
Presence of renal or heart disease
Electrolyte status
Diseases associated with diarrhea and constipation
If on other meds, when should you are antacids
1-2 hours before other medications OR 2-4 hours after other meds
What are anti-ulcer agents
H2 receptor
Proton pump inhibitors
Surface acting agents
PGE1 analogs
Bismuth compounds
Name H2 receptor antagonists
Cimetidine (po/iv)
Famotidine (po/iv)
Nizatidine (po/iv)
Ranitidine (po)
Name proton pump inhibitors
Lansoprazole Dexlansoprazole Omeprazole Esmoprazole Pantoprazole Rabeprazole
Name a surface acting agent
Sucralfate
Name a PGE1 analog
Misoprostol
Name a bismuth compounds
Bismuth subsalicylate
How do H1 blockers work
Reversible block the binding of histamine to the H2 receptor (basolateral membrane of parietal cell) that is present not he parietal cells of the gastric mucosa. By inhibiting stimulation of the H2 receptor, cyclic AMP levels are decreased, which then eventually leads to the decreased activity of the H/K proton pump. The end result is that gastric acid secretion is decreased
Onset Histamine type 2 blockers
.5-2 hours (longer than antacids, shorter than PPI)
QB to BID
Clinical use of histamine type 2 blockers
Treat GERD< peptic ulcer disease, and other diseases associated with gastric ulcers and get ulcer healing in 4-8 weeks
H2 blockers inhibit __% of acid production
20-50
Adverse effects H2 blockers
Headache (CNS)
Nausea/diarrhea/constipatoin (GI)
Gynecomastia
Cimetidine is also associated with decreased hepatic metabolism of certain drugs (warfarin, phenytoin, diazepam)
Cimetidine decreases testosterone binding to androgen receptor (weak anti androgen effects) -gynecomastia in men, galactorrhea in women
Blood dyscrasias-neutropenia, thrombocytopenia
Cimetidine interesting
Prototypical inhibitor of several CYP450 isoenzymes
Lots of drug drug interactions
Ranitidine interesting
Inhibits but 10% of what is with cimetidine
Pregnancy only if necessary!! Contraindicated in preg
Name PPI
Omeprazole po Esomeprazole po/iv Lansoprazole po Dexlansoprazole po Pantoprazole po/iv Rabeprazole po
MOA PPI
Covalently/irreversibly bind sulfhydryl groups of HKATPas at parietal cell secretory sites, thereby inhibiting gastric acid secretion by irreversibly inhibiting functions ase pumps, suppressing gastric secretion
Inhibits pump induced egress of gastric acid
Takes several days to create new steady state of pump activite
Use of PPI
PUD, GERD, zollinger ellison syndrome, and esophagitis, and in regimen for H pylori
why QD dosing PPI
Effects last 24 hours
PPI inhibit _% of acid
50-90
Onset PPI
Days -longer than H2 and ulcerations heal 4-8 weeks
Adverse effects of PPI
CNS-headache
GI-diarrhea, dyspepsia/nausea, *additional risk of Clostridium Difficile Associated Diarrhea
Rash
Rare-generalized myalgia, fatigue, myopathies
Other-kidney disease, bone fractures, MI
Special omeprazole
P450 inhibition many drug drug interactions
Not for preg
Contraindications PPI
Pregnancy, but if 1100% necessary, can try lasoprazole
AVOID omeprazole
Sucralfate
A sulfate polysaccharide-an octasulfate of sucrose and ALOH3 added
MOA sucralfate
Undergoes cross linking from interaction with stomach acid, creating a viscous, sticky polymer which adheres to epithelial cells around ulcer’s crater, preventing acid access to ulcer sites
May also stimulate local prostagladin and mucous productiona nd epidermal growth factor (cytoprotection) but does not affect pH
What use sucralfate for
DU*
But also aphthous ulcers, mucositis/stomatitis
Radiation procitis/ulcers (enema)
Bile reflux gastropathy
Adverse effects sucralfate
Constipation
Contraindication sucralfate
Severe renal failure
Aluminum containing antacids should be avoided
Drug interaction sucralfate
Possible therefore take 2 hours after other meds
QID for active ulcers so plan dosing other meds accordingly if possible
Misoprostol
Prostagladin E1 analog that provides protective prostagladin to gastric mucosa and reduces gastric acid release from parietal cells (providing cytoprotection by increasing mucosal defenses-stimulates bicarbonate and mucous production, increases mucosal blood flow)
Misoprostol and acid output
Reduce basal and nocturnal acid output but lesss than H2 antagonist and PPI
Indication misoprostol
Prevention of NSAID induced gastric ulceration in patients at high risk of ulcerations and complications
Off label uses of misoprostol
With/without mifepristone (pregnancy termination)
Alone for cervical ripening
Post partum hemorrhaging (high dose)
Adverse effects misoprostol
GI-diarrhea with or without N/V and cramping
CNS-related: headache/dizziness
Contraindications misoprostol
Pregnancy
IBD
Bismuth compounds MOA
Not precisely delineated; but as a salicylate derivative can function similar to asprin and inhibit prostagladin synthesis
What was bismuth originally developed as
Antidiarrheal
What is bismuth most well known for
Antimicrobial actions which prevent microbial attachment to mucosa, possible inactivation of enterotoxins, and disruption of bacterial cell wall
OTC bismuth compounds
Alone for reflux (heartburn), indigestion and diarrhea
RX bismuth compounds
In combination with antibiotics and acid suppressant for H pylori
Adverse effects bismuth compounds
Constipation from antidiarrheal
Black/dark stools but regularly formed
Drug interactions bismuth
LOTS take 2 hours after other meds
Contraindications bismuth compounds
Severe renal failure
Antiplatelets and anticoagulatnts (bismuth subsalicylate)
Absolute contraindications bismuth
GI bleeding
Salicylate hypersensitivity
Treat H pylori
Combination therapy-at least 2 antibiotics and an acid reducer (PPI or H blocker)
14 days of triple drug regimen
(PPI, clarithromycin, and either amoxicillin or metronidazole) on BID
Or
10-14 days quadruple therapy PPI BID Metronidazole QID Tetracycline QID Bismuth subsalicylate QID
What drugs may lead to false negative urea breath test with h pylori
Bismuth, antimicrobials, PPI suppress H pylori
Avoid the use of agents known to suppress H pylori
Prevpac for PUD
Amoxicillin
Clarithromycin
Lansoprazole
Omeclamox for PUD
Amoxicillin
Clarithromycin
Omeprazole
Helidac for PUD
Bismuth
Metronidazole
Tetracyclines
Plus additional PPI
Pylera for PUD
Bismuth subcitrate potassium
Metronidazole
Tetracycline
Plus addition of PPI omeprazole
Why consider PPI for a few/several weeks after 10-14 days h pylori combo therapy
For complete healing of ulcers
What do if failure to eradicate h pylori with metronidazole containing triple therapy
Follow up with non metronidazole containing quadruple therapy
H pylori with PCN allergy
No amoxicillin
Substitute metronidazole (consider bismuth quad)
H pyloric ith metronidazole resistance
Substitute tetracycline
Consider quadruple therapy (with clarithromycin and amoxicillin)
H pylori with clarithromycin resistance
Substitute either amoxicillin or tetracycline
Consider bismuth quadruple therapy
Pregnant patient with PUD without h pylori
Short course of antacids or sucralfate
- if moderate symptoms consider ranitidin
- if severe consider iansoprazole
PUD if nsaid at risk
If nsaid not required, consider acetaminophen and D/C NSAID
If NSAID required, consider COX-2 NSAID and/or consider PPI or misoprostol
What are common causes of nausea and vomiting
Chemotherapy/radiation Post op Vestibular dysfunction Gastrointestinal obstruction/dysmotility Metabolic conditions Pregnancy Infections Intracranial lesions Non chemo medications
Receptors of nausea/vomiting
Receptors in Brain and GI stimulate, which we can use antiemetic agents in combinations since have different MOA , espicially for chemo and radiation induced N/V
Categories of emetic potential for chemotherapy
High (90%)
Moderate (30-90%)
Low(10-30%)
Minimal (fewer than 10%)
what are the important receptors for N/V
5-HT3
Neurokinin (NK1)
Histamine (H1)
Dopamine(D2)
Muscarinic (M1)
Cannabinoid
*antagonize them all except agonist cannabinoid
What are commonly used to treat N/V
Glucocorticosteroids
Benzodiazepines
Name serotonin 5HT3 receptor antagonists
Dolasetron
Granisetron
Ondansetron
Palonosetron
Name neurokinin receptor antagonists (NK1)
Aprepitant Fosaprepitant Netupitant Fosnetupitant Rolapitant
Name histamine receptor antagonists
Diphenhydramine Dimenhydrinate Hydroxyzine Promethazine Meclizine Cyclizine
Name dopamine receptor antagonists
Phenothiazines
-chlorpromazine
-perphenazine
Prochlorperazine
Other
- metoclopramide
- haloperidol, olanzapine and trimethobenzamide
Name muscadine M1 receptor antagonists
Scopolamine
Name cannabinoid receptor agonists
Dronabinol
Nabilone
Indication for aldosterone
IBS-D
Serotonin are strong antiemetic agents, what were they developed for
Chemotherapy induced N/V (CINV)
How do serotonin 5-HT3 receptor antagonists work
Block serotonin type-3 receptors at vagal nerve terminals and blocks signal transmission to CTZ
-blocks serotonin receptor activation after serotonin release from intestinal enterochromaffin cells
Uses for serotonin 5-HT2 receptor antagonists
CINV
RINV
Post op NV (PONV)
NV of pregnancy (NVP)
Adverse effects serotonin receptor antagonists
CNS-headache
GI-constipation/diarrhea
—-serotonin syndrome (IF WITH OTHER 5-HT AFFECTING DRUGS)
BUT MOST WORRISOME
-DOSE DEPENDENT QT PROLONGATION AND TORSADES
Dose dependent QT prolongation and torsades with serotonin receptor antagonsits
Extreme caution required when using with other QT-prolonging agents (anti-arrhythmatics ) or in patients with electrolyte imbalances (hypokalemia or hypomagnesmia )
-dolasetron high risk; no longer recommended for CINV prophylaxis
All serotonin 5-HT3 receptor antagonists have short half lives, except which one
Palonosetron and sustained release formulation of grainisetron
Long half life makes palonosetron and 2 branded granisetron agents effective for :
Delayed CINV as a single dose
Drug interactions H2 receptor antagonists
QT prolonging agents
Antiarrhythmics
Name neurokinin NK1 receptor antagonists
Aprepitant Fosaprepitant Netuputitant Fosnetupitant Rolapitant
Fosaprepitant is a prodrug of ___
Aprepitant
Fosnetupitant is a prodrug of __
Netupitant
Netupitant and fosnetupitant are in combo only.. what what
Palonosetron
Neurokinin1 receptor antagonist is a __ antiemetic
Moderate
Blockade of neurokinin receptors (subastant P) in CTZ/VC
Peripheral blockade of NK1 receptors located on vagal terminals in gut an additional hypothesized actio
Therapeutic uses NK1 antagonist
Chemotherapy induced NV
-most effected when used in combo with a glucocoticosteroid and 5HT3 antagonist
Prophylaxis NK1 antagonist
PONV
Only aprepitant given up to 3 hours prior to anesthesia induction
Adverse effects NK1 antagonist
GI-dyspepsia/constipation/diarrhea
CNS-dizzy/fatigue/somnolence
Neutupitant/rolapitant
Moderate major active metabolites
Longer half lives
NK1 cyp450
Mild moderate inhibition
Name H2 receptor antagonists
Diphenhydramine Dimenhydroxyine Promethazine Meclizine Cyclizine
Doxylamine
Initial therapy for NVP
Histamine receptor antagonists are __ antiemetic agents
Weak
Use of histamine receptor antagonist
PONV
MOA histamine receptor antagonist
Block histamine type 1 receptors in VC and vestibular system
-*agents exhibitvarying levels of central anticholinergic properties at level CTZ
Therapeutic uses histamine receptor antagonist
Idiopathic mild NV Post op NV NVP (doxylamine/B6) Motion sickness/vertigo(only indication for meclizine and cyclizine) Chemotherapy-induced NV RINV
Adverse effects histamine->CLASSIC ANTICHOLINERGIC EFFECTS
Drowsiness Dry mouth Constipation Urinary retention Blurred vision Decreased BP
Hydroxyzine pharmacokinetics
Active metabolism=cetirizine
IM route
Promethazine pharmacokinetics
IV administration requires dilution and lower dose (than oral)
Interactions histamine receptor antagonist
Other agents that also induce anticholinergic-related side effects (cumulative)
Name the dopamine receptor antagonists
Phenothiazines
- chlorpromazine
- perphenazine
- prochlorperazine
Other
-metoclopramide
Dopamine receptor antagonists are ___ antiemetic agents
Weak to moderate
How do dopamine receptor antagonists work
Block dopamine type 2 receptors in CTZ
-agents exhibit varying levels of anticholinergic properties; affect other receptors (histamine, muscarinic, adrenergic receptors)
Metoclopramide also stimulates _____ in GI. Doing what
Acetylcholine
Enhancing GI motility (dysmotility use) and increases lower esophageal sphincter tone
-no impact on GI secretions
-also has weak 5HT inhibition
Therapeutic dopamine receptor antagonist
Idiopathic mild NV
Gastroparesis/dysmotility
-specifically metoclopramide
Post operative NV
NV of pregnancy
Chemotherapy induced NV and radiation induced NV
-as single agents only weak moderate antiemetic activity;olanzapine used in combination with other agents for CINV RINV
Adverse effects dopamine effects-classic anticholinergic effects
Drowsy Dry mouth Constipation Urinary retention Blurred vision Hypotension -arrhythmias and extrapyramidal SE are possible;usually seen with larger psychiatric doses
Dopamine receptor antagonists interactions
Other agents that also induce anticholinergic related side effects
Antiarrhythmics, espicially QT prolonging agents
Antihypertensives
Name muscarinic receptor antagonists
Scopolamine
Scopolamine transdermal scop
Worn for 73 Horus
Scopolamine is a _ antiemetic agent
Weak
What is scopolamine used for
Motion sickness
And also in end of life care foe excessive secretions
MOA scopolamine
Block acetylcholine stimulates muscarinic receptors in neural pathways fromt he vestibular nuclei in inner ear to brain stem and from reticular formation to VC
- significant anticholinergic properties
- usually put behind ear
Adverse effects scopolamine -classic anticholinergic effects
Drowsy Dry mouth Constipation Urinary retention Blurred vision
Interactions scopolamine
Other agents that also induce anticholinergic related side effects (cumulative)
Name cannabinoid receptor agonist
Dronabinol
Nabilone
What are cannabinoid
Synthetic preparations of cannabinol (THC)
- synthetic cannabinoids are FDA schedules(controlled) medications
- limits on quantities/refill
Cannabinoids are _ antiemetic agents
Strong
Cannabinoids are reserved for treatment of what
CINV
Stimulation of cannabinoid receptors stimulates what
Central (CB1) and peripheral (CB2) cannabinoid receptors in VC/CTZ
This exerts signal transduction effects through G protein coupled receptors, resulting in decreased excitability of neurons
-minimizing serotonin 5HT3 release from vagal afferent terminals
Therapeutic uses of cannabinoids
CINV
Appetites stimulation in select (anorexic) patients due to severe disease (cancer or AIDS)
Why are cannabinoids commonly reserved for treatment resistant clinical scenarios
FDA scheduling
Can be used in combination with other agents
Adverse effects of cannabinoids
Euphoria/irritability Vertigo Sedation/drowsiness Impaired cognition/memory Alterations in perception of reality Xerostomia Sympathomimetic Appetite stimulation
Pharmacokinetics dronabinol
Large first pass effect and metabolized to one active metabolite
Nabilone pharmacokinetics
Metabolized to several active metabolites
-both have a short time to onset of activity and a long duration of action (34-36 hours) so can use fewer doses a day
Interactions cannabinoids
Caution in use with other CNS depressants and cardiovascular agents and sympathomimetics
Acute CINV
<24 hours after chemo given
Chronic CINV
> 24 hours after chemo given
Anticipatory CINV
Occurs before chemo give, customarily in non treatment naive patients
You should add ___ to antiemetic regimens for adults who receive high emetic risk, antineoplastic agents or who experience breakthrough nausea and vomiting
Olanzapine
High emetogenic regimen for CINV
NK1 receptor antagonist
5HT3 receptor antagonist
Corticosteroid (dexamethasone)
When should the region for CINV be started
Day of (prior to therapy) and 3 days after
What can you add to the high emetogenic regim to make it a four drug regimen
Olanzapine (D2 antagonist)
Cannabinoid in treatment resistance
Also provide therapy for breakthrough NV for all patients and provide therapy for anticipatory NV as needed
Ok
Moderate emetogenic regimen
5HT3 receptor antagonist (palonos/granis SQ)
Corticosteroid (dexamethasone)
When give the moderate emetogenic regimen
Day of (prior) to chemo and for 2 days after
What can you add to the moderate emetogenic regimen
NK1 antagonist or olanzapine
May add cannabinoid in treatment resistsance (make.4 drug after 3)
Provide therapy breakthrough NV for all patients
Provide therapy for anticipatory NV as needed
Ok
Low emetogenic regimen for CINV
Corticosteroid (dexamethasone) Or 5HT3 receptor antagonist Or Metoclopramide Or Prochlorperazine
Same timing thing here
Ok
Minimal emetogenic regimen for CINV
No routine prophylaxis therapy recommended
Breakthrough emesis regimen
Add one agent from a different drug class to the current regimen
Motion sickness
Scopolamine or dimenhydrinate or meclizine
Vertigo
Meclizine or cyclizine
Diabetic gastroparesis
Metoclopramide
Pregnancy induced (stepped therapy)
- Vitamin B6 or histamine antagonist w/B6 or 5 HT2 antagonist
- Dopamine antagonist
- Steroid or different dopamine antagonist
Take home points
Targeted therapy of NV by first determining cause
Multiclass combination therapy appropriate for moderate to high emetogenic chemotherapy regimens
Prevention is more cost effective and clinically accepted than attempting to treat after it develops
What groups of drugs are for diarrhea
Prostagladin inhibitors
Opoid agonists
Serotonin antagonists
Chloride channel inhibitors
Name prostagladin inhibitors
Bismuth