GI motility drugs Flashcards
Location of emesis center
Medulla
Afferents of the emesis center
CTZ in area postrema
Vestibular apparatus
Vagal afferents via solitary tract nucleus
Activating receptors on the CTZ
Serotonin
5-HT3
Dopamine D2
Muscarinic M1
Substances released by vestibular apparatus to activate vomiting center
Ach
Histamine
Drug class of Hyoscine
Anticholinergic antiemetic
Drug class of scopolamine
Anticholinergic antiemetic
Drug class of dicyclomine
Anticholinergic antiemetic
Most effective drug for motion sickness
Hyoscine
Side effects of anticholinergic antiemetics
Sedation and dry mouth
Use of anticholinergic antiemetics
Motion sickness
H1 antihistamine with significant antimuscarinic acitivity
Promethazine
Drug class of promethazine
H1 antihistamine and D2 blocker
Drug class of Doxylamine
H1 antihistamine
Drug class of meclizine
H1 antihistamine
H1 antihistamine that is less sedative and has a longer duration of action
Meclizine
Duration of action of meclizine
24 hrs
Antiemetic available in a slow-release patch that lasts 72 hrs
Scopolamine
Drug class of cinnarizine
H1 antihistamine
Use of meclizine
Sea sickness
Uses of cinnarizine
Vertigo
Motion sickness
General uses of H1 antihistamine antiemetics
Motion sickness
General side effects of H1 antihistamine antiemetics
Sedation and dry mouth –> anticholinergic action
Drug class of chlorpromazine
D2 blocker (neuroleptic) antiemetic
Drug class of domperidone
D2 blocker (neuroleptic) antiemetic
Mechanism of D2 blocker antiemetics
D2 receptor antagonist that primarily acts on CTZ, as it does not cross the BBB
Drug class of ondansetron
First generation 5-HT3 antagonist
Drug class of Granisetron
First generation of 5-HT3 antagonist
Drug class of dolasetron
First generation 5-HT3 antagonist
Use and administration of first generation 5-HT3 antagonists
Given 3-5 days after chemotherapy for N/V
Also used for postoperative nausea
Drug class of palonosetron
Second generation 5-HT3 antagonist
5-HT3 antagonist with a longer duration of action
Palonosetron
Antiemetic that may prevent N/V for up to 7 days after chemotherapy, approved for treating both acute and delayed N/V
Palonosetron
Antiemetic drug class that prevents both peripheral and central stimulation of the vomiting center
5-HT3 antagonists
Drug class of aprepitant
NK1 receptor antagonist
Drug that blocks the emetic action of substance P at NK1 receptor
Aprepitant
Drug used for delayed phase vomiting (days 2-5) from cisplatin and for pts undergoing multiple chemotherapy cycles
Aprepitant
Adjuvant antiemetics
Dexamethasone
Cannabinoids
Drug class that is an agonist of CB1 receptor
Cannabinoids
Types of cannabinoids
Dronabinol
Nabilone
Drug class of metoclopramide
Prokinetic
Drug used for gastroparesis or postop emptying delay that speeds up gastric emptying by enhancing coordinated propulsive motility
Metoclopramide
Actions of metoclopramide
D2 antagonism
5-HT3 antagonism
5-HT4 agonism
Drug that increases the release of Ach from cholinergic motor neurons in the enteric nervous system
Metoclopramide
Main side effects of metoclopramide
Sedation
Dizziness
Loose stools
Muscle dystonias (children)
Possible effects of long-term use of metoclopramide
Parkinsonism
Galactorrhea
Gynecomastia
Macrolides used to promote gastric motility by stimulating motilin receptors
Erythromycin
Anticancer drugs with high emetogenic potential
Cisplatin
Cyclophosphamide
Dacarbazine
High emetic risk CINV acute phase treatment regimen
Combination of:
NK1 receptor antagonist
5-HT3 receptor antagonist
Dexamethasone
Moderate and high emetic risk CINV delayed phase treatment
NK1 receptor antagonist
Dexamethasone
Low and moderate emetic risk CINV acute phase treatment regimen
Combination of:
5-HT3 receptor antagonist
Dexamethasone
NT that plays a vital role in promoting GI motility
Serotonin
First line treatment for constipation
Diet and lifestyle modifications:
-Increased fiber intake
-Adequate fluid intake
-Regular exercise
Examples of bulk-forming laxatives
Psyllium
Methylcellulose
Polycarbophil
Preferred drug class for the management of chronic constipation because they can be used for a long time without noticeable side effects
Bulk-forming laxatives
Examples of stool-softening laxatives
Docusate
Glycerin
Mineral oil
Examples of osmotic laxatives
Magnesium oxide
Sorbitol
Lactulose
Magnesium citrate
Sodium phosphate
Polyethylene glycol
Laxative used in hepatic encephalopathy associated with elevated blood ammonia levels
Lactulose
Risk of excessive use of osmotic laxatives
Significant electrolyte and fluid loss
Examples of stimulant/secretory laxatives
Aloe
Senna
Cascara
Castor oil
Bisacodyl
Agent used for evacuating the bowel before surgery or examination that is available as a suppository
Bisacodyl
Adverse effects of stimulant/secretory laxatives
Abdominal cramping
Significant electrolyte and fluid loss (long-term use)
Examples of chloride channel activator laxatives
Lubiprostone
Linaclotide
Example of opioid receptor antagonists used as laxatives
Methylnaltrexone
Alvimopan
Examples of colloidal bulk forming substances used for diarrhea
Psyllium hydrophilic mucilloid
Calcium polycarbophil
Methyl cellulose
Do colloidal bulk forming substances reduce water and electrolyte loss?
No
Uses of colloidal bulk forming substances
Constipation and diarrhea phases of IBS
Drug class of diphenoxylate and its brand name
Antimotility drug
Lomotil
Drug class of loperamide and its brand name
Antimotility drug
Imodium
Synthetic opioid that is chemically related to pethidine and mu opiate receptor agonist. Used exclusively as a constipating agent.
Diphenoxylate
Adjuvant to diphenoxylate to discourage abuse by taking several tablets
Atropine
Rare side effects of diphenoxylate
Respiratory depression
Paralytic ileus
Toxic megacolon (children)
Mu opiate receptor agonist with poor water solubility limiting its intestinal absorption.
Loperamide
Most effective antimotility drug for diarrhea that is available OTC.
Loperamide
Adverse effects of loperamide
Paralytic ileus
Toxic megacolon (children <4 yo)
Drug class contraindicated for use in acute infective diarrheas because they delay the clearance of pathogens from intestine
Antimotility drugs
Drug class of racecadotril
Antisecretory antidiarrheal
Enkephalinase inhibitor that prevents degradation of ENKs, which act as agonists on mu opioid receptors
Racecadotril
Use of racecodotril
Acute secretory diarrheas
Can be used in children
Disease characterized by progressive degeneration of ganglion cells in the myenteric plexus of the esophageal wall causing failure of LES relaxation and loss of peristalsis in distal esophagus
Achalasia
Drugs used for treatment of achalasia
Nitrates
Nifedipine –> Ca channel blocker
Botox into LES
A rare, acquired, premalignant disorder of the stomach characterized by large gastric folds due to overgrowth of mucous cells
Menetrier’s disease
Symptoms of Menetrier’s disease
Epigastric pain
Hypoalbuminemia
Possible associations of Menetrier’s disease
CMV
H pylori infection
Monoclonal antibody used to treat Menetrier’s disease that blocks EGFR
Cetuximab
Treatment options for Menetrier’s disease
PPI or H2 blocker
Albumin transfusion
Cetuximab
Treatment of underlying disease if present
Octreotide
Somatostatin analogue that reduces EGFR signaling, used to treat Menetrier’s disease
Octreotide
Antivirals used for treatment of CMV related Menetrier’s disease
Ganciclovir
Foscarnet
Mechanism of Ganciclovir
Nucleoside analogue that inhibits DNA synthesis via chain termination