GIT pharm Flashcards by Matthew Chang

What are some antacids used

NaHCO3, CaCO3, Mg(OH)2, Al(OH)3

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What are the adverse effects of antacids

Na+ = Fluid retention => HTN, oedema
Ca2+ = Hypercalcemia, rebound acid secretion
Mg2+ = Osmotic diarrhoea
Al3+ = Constipation
Anions = bloating, flatulence
Renal insufficiency

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Name an H2R antagonists

Famotidine

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What is the MOA of H2R antagonists

Inhibit parietal cells H2R => decrease acid secretion

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Which drug is effective in inhibiting nightly HCl secretions

H2R antagonists (famotidine)

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Name a PPI

Omeprazole

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What is the MOA of PPIs

Irreversibly inhibit parietal cells H+/K+ ATPase => decrease HCl

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How long is the course of omeprazole

3-4 days

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What are the adverse effects of PPI

Generally well-tolerated
Headaches, nausea, diarrhoea
CDAD/colitis

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What is the MOA of sucralfate

-ve sucrose sulphate binds with +ve proteins => tenacious gel @ ulcer

Stimulates mucosa PG => increase HCO3- and mucus secretion

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What are the adverse effects of sucralfate

Constipation
Impair absorption of other drugs

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What is the MOA of bismuth

Forms protective layer protecting ulcers from HCl and pepsin

Increase mucus & HCO3- secretion

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What are the precautions of bismuth

Avoid renal insufficiency
Avoid long term use (can cause encephalopathy)

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What is the MOA of misoprostol

PGE1 analogue binds to PGE2R => increase mucus & HCO3 secretion and mucosa blood flow (low dose)

Inhibits HCl secretion (high dose)

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What is the indication of misoprostol

Prevent NSAID induced PUD

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What are the adverse effects of misoprostol

Bone pain
Abdominal pain
Diarrhoea

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What are the contraindications of misoprostol

Pregnancy

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What are the drug classes used for chemotherapy induced n/v

Serotonin 5-HT3 antagonists
Neurokinin R antagonists

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What are the drug classes used for noxious stimulated n/v

Serotonin 5-HT3 antagonists
Antipsychotics
Dopamine R antagonists

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What are the drug classes used to control acute/delayed n/v

Corticosteroids

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What are the drug classes used for anxiety induced n/v

Benzodiazepines

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What are the drug classes used for motion sickness related n/v

Anticholinergics

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Name some serotonin 5-HT3 antagonists

Odansetron
Granisetron

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What enhances serotonin 5-HT3 antagonists action

Corticosteroids
NK1R antagonists

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How are serotonin 5-HT3 antagonists administered

IV 30 mins before Oral 1h before

What are the adverse effects of serotonin 5-HT3 antagonists

Headache, drowsy, GI issues Arrhythmias => prolong QT

What are the contraindications of ondansetron

Avoid 1st trimester Avoid CYP450 inhibitors

What are some corticosteroids used for n/v

Dexamethasone

Name a dopamine R antagonist

Metoclopramide

What is the MOA of dopamine R antagonist

Antagonise D2R at trigger zone Prokinetic effect => increase GI motility

What are the adverse effects of dopamine R antagonist

Parkinsonian symptoms (elderly) Irreversible tardive dyskinesia (long term) Increase prolactin => menstrual disorders, gynaecomastia

What are some NK1R antagonists

Aprepitant Fosaprepitant

How are NK1R antagonists administered

Aprepitant = oral Fosaprepitant = IV

What is the drug-drug interaction for NK1R antagonists

Metabolised by CYP3A4

What are the adverse effects of NK1R antagonists

Common = fatigue, hiccups, GI issues Severe = peripheral neuropathy, blood dyscrasia

What are some antipsychotics

Promethazine Droperidol

What is the MOA of antipsychotics

Antihistamine => Dopamine/Muscarinic antagonism

What are the adverse effects of antipsychotics

Sedation Hypotension Parkinsonism Dropiderol => arrhythmias

What are some benzodiazepines

Lorazepam Diazepam

What is the MOA of benzodiazepines

Bind to allosteric site on GABA(A) receptors => increase Cl- conductance

What are the contraindications of benzodiazepines

Avoid CNS depressants and pregnancy

What are the adverse effects of benzodiazepines

Sedative

Name an anticholinergic used for n/v

Hyoscine

What is the MOA of anticholinergics

M1R antagonist at vestibular & vomitting centre

What are the adverse effects of anticholinergics

Urinary retention Dry mouth

What are some dietary changes to cope with n/v

Ginger Avoid overeating Avoid going on empty stomach Avoid coffee, high fat, acidic, v sweet food Take high protein and bland foods

What is the pharmacotherapy for pregnancy related n/v

Pyridoxine/ Doxylamine (Vit B6)

What are the pharmacotherapies for n/v in children

Gastroparesis = metocloperamide Post-op/ chemo = 5-HT3/ NK1R antagonists

Name a bulk forming laxative

Psyllium

What is the MOA of bulk forming laxatives

Indigestible, hydrophilic colloids - Absorb H2O => form bulk - Emollient gel => increase stool mass & distends colon => increase peristalsis

What are the adverse effects of bulk forming laxatives

Abdominal pain Bloating, flatulence

What do stool surfactant laxatives comprise of

Glycerin NaCl mineral oil

What is the MOA of stool surfactant laxatives

Decrease surface tension => increase H2O lipid penetration Mineral oil lubricates and decrease colon H2O absorption

What are the adverse effects of stool surfactant laxatives

Mineral oil => aspiration Decrease lipid soluble vit absorption (Vit A, D, E, K)

Name some osmotic laxatives

Sorbitol Lactulose Mg(OH)2 Na3PO4

What is the MOA of osmotic laxatives

Stimulate osmosis => increase stool liquid and volume => increase peristalsis

What are the adverse effects of osmotic laxatives

Severe flatus and abdominal cramps Na3PO4 => Hypernatremia/ phosphetemia and Hypocalcemia/kalemia

What are some stimulant laxatives

Aloe Senna Bisacodyl

What is the MOA of stimulant laxatives

Simulate - Migrating colonic contractions - ENS - Colonic secretions

What are the adverse effects of stimulant laxatives

Aloe, Senna = melanosis coli Bisacodyl = cardiac toxicity

What is the indication of stimulant laxatives

Neurologically impaired/ bed bound patients

Name a Cl- channel activator

Lubiprostone

What is the MOA of Cl- channel activators

Stimulates type 2 Cl- channels => increase Cl- secretions Decrease intestinal transit time

What are the adverse effects of Cl- channel activators

Rebound constipation after discontinuation Nausea

What are the contraindications of Cl- channel activators

Avoid pregnancy

Name an opioid antagonists

Methylnatrexone bromide

What is the MOA of opioid antagonists

Blocks M-receptors

What is the indication of opioid antagonists

Opoid-induced constipation

What are the adverse effects of opioid antagonists

Stomach pain Nausea and diarrhoea

Explain if opioid antagonists will affect the analgesic effect of pre-administered opoids

No Methylnaltrexone does not cross BBB

What re some 5-HT4 agonists

Cisapride Prucalopride

What is the MOA of 5-HT4 agonists

Increase neurotransmitter release and SM motor activity => Increase GI motility

What are the advantages of prucalopride

Increased affinity and no CVS effects

What are the adverse effects of 5-HT4 agonists

Stomach pain Nausea and diarrhoea

Name some opioid agonists

Loperamide Diphenoxylate

What is prescribed w diphenoxylate

Atropine - discourages overdose - contributes to antidiarrhoea

What are the adverse effects of opioid agonists

Loperamide => constipation Diphenoxylate high dose => CNS effects, dependance

What are some bismuth compounds

Bismuth subcitrate Bismuth subsalicylate

What is the MOA of bismuth compounds

Rapid dissociation in stomach => salicylate absorption => inhibits PG production and Cl- secretion => decrease stool freq and liquidity

What are some intestinal adsorbents used

Kaolin Diomectite

What is the MOA of intestinal adsorbents

Absorbs bacteria and toxins Decrease stool liquidity and no.

What are the adverse effects of intestinal adsorbents

Constipation

What is the MOA of lacteal fort

Lyophilizate of killed lactobacillus acidophilus => adheres to intestinal cell surface => competitive exclusion => prevents over colonisation of microbes

What is the MOA of resins

Bind bile acids to salts => alleviates diarrhoea caused by excess bile salts

What are the adverse effects of resins

Constipation and flatulence Fat malabsorption

Name a somatostatin-like peptide

Octreotide

What is the MOA of somatostatin-like peptides

Mimic somatostatin => inhibit neurotransmitter release - Decrease intestinal/pancreatic secretions - Decrease GI motility - Inhibit GB contraction

What is the indication of charcoal

Emergency treatment for poisoning

What are the adverse effects of somatostatin-like peptides

Gallstones Hypothyroidism Steatorrhoea

What are the adverse effects of charcoal

n/v Aspiration => empyema, ARDS

Which drug should be used for effective and rapid control of diarrhoea

Loperamide

What combination of drugs should be used to prep for colonoscopy

Stool surfactant laxatives Stimulant laxatives

GIT pharm Flashcards

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