LECTURES 61 & 62 - gastrointestinal protectant Flashcards by Margaret Whitmer

Q

List systemically absorbed antacids

A

NaHCO3
CaCO3

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Q

List minimally absorbed antacids

A

Al(OH)3
Mg(OH)2

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Q

List antacid salts with high neutralizing capacity

A

NaHCO3
Al(OH)3
Mg(OH)2

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Q

List antacid salts with moderate neutralizing capacity

A

CaCO3

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Q

List the adverse effects of NaHCO3 as an antacid salt

A

Systemic alkalosis
Fluid retention
Excess gas (CO2)

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Q

List the adverse effects of CaCO3 as an antacid salt

A

Hypercalcemia
Kidney stones
Metabolic alkalosis
(CO2)

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Q

List the adverse effects of Al(OH)3 as an antacid salt

A

Constipation
Hypophosphatemia

If absorbed - encephalopathy

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Q

List the adverse effects of Mg(OH)3 as an antacid salt

A

Diarrhea

If absorbed - CNS toxicity

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Q

Describe the types of acid secretion that PPI’s are able to neutralize

A

PPI’s effectively block both nocturnal acid secretion && acid secretion stimulated by meals

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Q

Describe the types of acid secretion that H2RA’s are able to neutralize

A

H2 antagonists are&raquo_space; at suppressing nocturnal acid secretion
vs. acid secretion stimulated by meals

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Q

Describe the MOA of PPI’s

A

absorbed in the stomach & taken up by parietal cells (slow onset, ~1 hr)
activated by acidic pH in parietal cells (prodrugs)
Irreversibly inhibit H+/K+ ATPase
Long DOA (> 24 hr) due to covalent inhibition & slow turnover of proton pumps

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Q

Name a potential ADR of PPI’s

A

When hypergastrinemia occurs, it may result in rebound hypersecretion of gastric acid upon drug withdrawal

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Q

List examples of PPI’s

A

Benzimidazoles:

Esomeprazole (Nexium) → pursued S-enantiomer - more potent
Omeprazole (Prilosec) → racemic mixture - less potent
Lansoprazole (Prevacid)
Rabeprazole (Aciphex)
Pantoprazole (Protonix)
Dexlansoprazole (Dexilant)

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Q

Describe the dosing regimen of Benzimidazoles

A

Dosed PO BID

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Q

What class of drug is Esomeprazole (Nexium)?

A

Benzimidazoles - Proton Pump Inhibitors (PPI’s)

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Q

What class of drug is Omeprazole (Prilosec)?

A

Benzimidazoles - Proton Pump Inhibitors (PPI’s)

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Q

What class of drug is Lansoprazole (Prevacid)?

A

Benzimidazoles - Proton Pump Inhibitors (PPI’s)

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Q

What class of drug is Rabeprazole (Aciphex)?

A

Benzimidazoles - Proton Pump Inhibitors (PPI’s)

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Q

What class of drug is Pantoprazole (Protonix)?

A

Benzimidazoles - Proton Pump Inhibitors (PPI’s)

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Q

What class of drug is Dexlansoprazole (Dexilant)?

A

Benzimidazoles - Proton Pump Inhibitors (PPI’s)

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Q

What class of drug is Vonoprazan (Voquenza)?

A

K+-competitive acid blocker (P-CAB)

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Q

Describe the binding of Vonoprazan (Voquenza)

A

reversible binding

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Q

List advantages of Vonoprazan (Voquenza)

A

Faster acid suppression
Not a prodrug

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Q

List potential ADRs of Vonoprazan (Voquenza)

A

Acute tubulointerstitial nephritis
Skin reactions

(others are similar to PPI’s)

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List medications that act as mucosal protective agents

Sucralfate (Carafate) Misoprostol (Cytotec)

Describe the dosing of Misoprostol (Cytotec)

Dosed PO QID (used in combination with chronic NSAIDs)

Describe the dosing of Sucralfate (Carafate)

Dosed PO QID

Describe the MOA of Sucralfate (Carafate)

- Polymerizes & forms protective barrier at ulcer site - Acidic pH activates complex

Describe the MOA of Misoprostol (Cytotec)

- Reduced acid secretion (parietal cell) - Cytoprotectant effects (enhanced mucus & bicarbonate secretion)

List ways to detect an H. pylori infection associated with peptic ulcers

- 13/14C-labelled urea - H2N-CO-NH2 - PCR of stool sample

Describe why antibiotics may be considered for treatment of peptic ulcers

Many peptic ulcers are associated with infection of the gastric mucosa by Helicobacter pylori (gram-negative bacilli)

Name a medication that can be used to treat peptic ulcers caused by an H. pylori infection

Bismuth subsalicylate (pepto-bismol) -- as part of multi-drug therapy --

Describe the activity of Bismuth subsalicylate (pepto-bismol)

Antibacterial, antiviral & antisecretory activity

Describe the MOA of Bismuth subsalicylate (pepto-bismol)

Converted to bismuth salts & salicylic acid in the GI tract

Describe the uses of Bismuth subsalicylate (pepto-bismol)

Nausea, heartburn, indigestion, upset stomach, diarrhea Part of multi-drug therapy for H. pylori eradication

Describe the action of prokinetic drugs

increase GI motility

List examples of prokinetic drugs

- Metoclopramide (Reglan) - Prucalopride (Motegrity) - Tegaserod (Zelnorm) - Lubiprostone (Amatiza) - Linaclotide (Linzess) - Plecanatide (Trulance) - Tenapoanor (Ibrelsa)

Describe Metoclopramide (Reglan)

D2 dopamine receptor antagonist

Describe the MOA of Metoclopramide (Reglan)

- Blockade of D2 receptors in the myenteric plexus leads to increased ACh release - D2 receptor blockade also produces anti-emetic effects

List the clinical uses of Metoclopramide (Reglan)

- Promotes gastric emptying to facilitate small bowel intubation - Post-op & diabetic gastroparesis - GERD

List potential SE's of Metoclopramide (Reglan)

Can lead to acute dystonic (muscle contraction) reactions

Describe the MOA of 5HT4 receptor agonists

Activation leads to increased cAMP, PKA activation & release of ACh

List examples of 5HT4 receptor agonists

- Prucalopride (Motegrity) - Tegaserod (Zelnorm)

Describe the dosing for Prucalopride (Motegrity)

PO QD

Describe the dosing for Tegaserod (Zelnorm)

PO BID

Describe the indication for Prucalopride (Motegrity)

tx of chronic idiopathic constipation (CIC) in adults

Describe the indication for Tegaserod (Zelnorm)

treatment of IBS with constipation in women under 65

Describe the indication for Chloride Channel Activators

treatment of IBS + constipation

List examples of chloride channel activators

- Lubiprostone (Amatiza) - Linaclotide (Linzess) - Plecanatide (Trulance)

Describe the MOA for Lubiprostone (Amatiza)

Stimulation of type 2 chloride channel (CIC-2) activator in small intestine

Describe the dosing for Lubiprostone (Amatiza)

PO BID

Describe the MOA for Linaclotide (Linzess) & Plecanatide (Trulance)

Peptide activator of guanylate cyclase C (GC-C)

Describe the dosing for Linaclotide (Linzess) & Plecanatide (Trulance)

PO QD

Describe the MOA for Tenapoanor (Ibrelsa)

Na+/H+ exchanger inhibition: - The sodium/hydrogen exchanger (NHE3) is expressed on the luminal side of small bowel & colonic epithelial cells - NHE3 functions to absorb sodium from the luminal contents - Increased Na+ in the gut → increased water in the gut, which accelerates transit of intestinal contents

Describe the dosing for Tenapoanor (Ibrelsa)

PO BID

Describe the indications for Tenapoanor (Ibrelsa)

For IBS with constipation

Give examples of drug classes that reduce GI motility (antidiarrheals)

Opiates 5HT3 receptor antagonists

Describe the MOA for Opiates

Inhibition of presynaptic cholinergic nerves

Describe the MOA for 5HT3 receptor antagonists

- Blocks visceral afferent pain sensation & decreases colon motility - 5HT3 receptors are ion channels → activation is excitatory

List examples of opiates that act as antidiarrheals

Diphenoxylate -- active in the CNS Loperamide (Imodium) -- Poorly traverse the blood brain barrier -- Act locally to delay gastric emptying

Which nervous system affects the intrinsic primary afferent neuron for 5HT3 receptors

Enteric Nervous System (ENS) signaling

List effects caused by the extrinsic primary afferent (5HT3 receptors) & the nervous system that is associated

Nausea, vomiting, pain CNS signaling

List the effects of interneuron & motor neurons in the ENS for the 5HT3 receptors

Increased peristalsis

Given an example of a 5HT3 receptor antagonist

Alsosetron (Lotronex)

Name the indication of Alsosetron (Lotronex)

IBS with diarrhea

What is the dosing for Alsosetron (Lotronex)?

PO BID