GI Motility 1 Flashcards
Drugs stimulating GI motility
- What is the name of the agent that can selectively stimulate gut motor function?
Prokinetic
Submucosal IPANs activate the enteric neurons responsible for what 2 activities?
- Peristaltic & Secretory reflex activity
Stimulation of 5-HT4 receptors on presynaptic terminals of IPANs enhances release of what 2 substances, therefore promoting reflex activity?
- acetylcholine (ACh)
- Calcitonin gene related peptide (CGRP)
What are the 3 types of drugs which stimulate GI motility?
- Cholinomimetic Agents (cholingergic or anticholinesterase)
- Metoclopramide (dopamine & serotonin antagonist)
- Macrolides (erythromycin antibiotic) motilin receptor
What are the 2 Cholinomimetic Agents?
- Bethanechol
- Neostigmine
Which Cholinomimetic Agent?
- Stimulates muscarinic M3 receptors on muscle cells and at myenteric plexus synapses
- History of use in the treatment of GERD and gastroparesis
Bethanechol
Which Cholinomimetic Agent?
- Acetylcholinesterase inhibitor
- enhance gastric, small intestine, and colonic emptying
Neostigmine
What are the 5 ADEs of Cholinomimetic Agents?
(Drugs stimulating GI motility)
(Cholinergic effects)
- Excessive salivation
- Nausea
- Vomiting
- Diarrhea
- Bradycardia
4 uses of Cholinomimetic Agents
- GERD
- Impaired gastric emptying
- Non-ulcer Dyspepsia
- Prevention of vomiting
Which medication is used to tx the following:
- treatment of symptomatic GERD
- not effective in patients with erosive esophagitis
- prokinetic agents are used mainly in combination with antisecretory agents in patients with regurgitation or refractory heartburn
Cholinomimetic Agents
(Bethanechol & Neostigmine)
Which medication is used to tx the following:
Impaired Gastric Emptying
- treatment of delayed gastric emptying due to postsurgical disorders (vagotomy, antrectomy)
- diabetic gastroparesis
- to promote advancement of nasoenteric feeding tubes from the stomach into the duodenum
Cholinomimetic Agents
- Bethanechol
- Neostigmine
Which medication is used to tx the following:
- Symptomatic improvement in a small number of patients with chronic dyspepsia
Cholinomimetic Agents
- Bethanechol
- Neostigmine
Which medication is used for:
- Prevention and tx of emesis?
Metoclopramide
T/F
- Cholinomimetic agents are approved by FDA and available in the US for postpartum lactation stimulation
False
- NOT approved by FDA or available in the US for this purpose
What drug is “sometimes” recommended to promot postpartum lactation? (Canadian source)
Domperidone
Which medication?
- Stimulates GI motility
- Dopamine D2 receptor antagonist
- Prokinetic mechanism
- Inhibits cholinergic smooth muscle stimulation
Metoclopramide
Metoclopramide
(Dopamine receptor antagonist)
- Increases what 3 things?
- Has no effect on what 2 things?
-
Increases:
- Esophageal peristaltic amplitude
- Lower esophageal sphincter pressure
- Gastric empyting
-
No effect:
- small intestine
- colonic motility
Metoclopramide has which 5 ADEs involing the CNS
(especially in what age population?)
- Restlessness
- Anxiety
- Agitation
- Drowsiness
- Insomnia
Age: elderly
(Angry Anxious old ladies get drowsy and restless and cannot fall asleep)
ADEs of which drug?
-
Extrapyramidal effects (dystonias, akathisia, parkinsonian features)
- central dopamine receptor blockade occur acutely in 25% of patients given high doses and in 5% of patients receiving long-term therapy
Metoclopramide
ADE of which drug?
-
Tardive dyskinesia
- sometimes irreversible
- treated for a prolonged period with metoclopramide
Metoclopramide
ADE of which drug?
- Long-term use should be avoided unless absolutely necessary, especially in the elderly
-
Elevated prolactin levels (caused by both metoclopramide) can cause:
- galactorrhea,
- gynecomastia,
- menstrual disorders
- impotence,
Metoclopramide
Which drug?
- Directly stimulate motilin receptors on gastrointestinal smooth muscle and promote the onset of a migrating motor complex
- Beneficial in some patients with gastroparesis
- Tolerance rapidly develops
- Used in patients with acute upper gastrointestinal hemorrhage to promote gastric emptying of blood before endoscopy
Erythromycin
(Cholinomimetic Agents - Macrolides)
4 medications which cause Constipation
- Opiates
- Antacids containing calcium carbonate
- Diuretics (non potassium sparing)
- Iron preparations
Laxatives
- Intermittent constipation is best prevented with what 4 things?
- High fiber diet
- Adequate fluid intake
- Regular exercise
- Pooping when you need to
If the patient suffers from constipation due to a secondary cause/disease, what is first line tx?
Treat the underlying cause
If a patient suffers from constipation and has no underlying diagnosis, how should you treat? (5)
Choose symptomatic therapy
- Dietary modification to increase fiber supplementation (bulk agents)
- Add Osmotic laxative (PEG)
- Add stmulant laxative (Bisacodyl) if no relief/BM in 2 days
- Lubiprostone or Linaclotide trial
- Opioid receptor antagonist (if opioid induced)
What types of laxatives are these?
- Non-absorbable sugars or salts
- Balanced polyethylene glycol
Omsotic Laxatives
What type of laxatives?
- Anthraquinone Derivatives (senna, cascara)
- Diphenylmethane Derivatives (Bisacodyl)
Stimulant Laxatives
What type of Laxative?
- Lubiprostone
Chloride Channel Activator
Which type of laxative?
- Linaclotide
- Plecanatide
Guanylate Cyclase C Agonists
What are the 3 types of Laxatives / Cathartics that cause:
- Softening of Feces in 1 - 3 days
- Bulk-forming agents / osmotic laxatives
- Emollients (softeners)
- Polyethylene glycol 3350 (PEG)
What are the names of the 3 bulking agents?
- Methylcellulose
- Polycarbophil
- Psyllium
What are the names of the 3 Emollients (softeners)?
- Docusate sodium
- Docusate calcium
- Docusate potassium
What are the names of the 2 Polyethylene Glycol 3350? (PEG)
- Lactulose
- Sorbitol
3 laxatives which result in:
- Soft or Semifluid stool in 6 - 12 hours
- Bisacodyl (oral)
- Senna
- Magnesium sulfate (low dose)
What do these agents do?
- Magnesium citrate
- Magnesium hydroxide
- Magnesium sulfate (high dose)
- Sodium phosphates
- Bisacodyl
- Polyethylene glycol-electrolyte preparation
Cause watery evacuation in 1 - 6 hours
Which laxative?
- Indigestible, hydrophilic colloids that absorb water, forming a bulky, emollient gel that distends the colon and promotes peristalsis
Bulk-Forming Laxatives
(Psyllium & Methylcellulose)
What is the name of the bulk forming laxative made w/ synthetic fibers?
Polycarbophil
What are the 2 names of the common preparations of bulk forming laxatives which include natural plant products?
- Psyllium
- Methylcellulose
Bulk Forming Laxatives
- Bacterial digestion of plant fibers within the colon may lead to an increase in what 2 sxs?
- bloating
- flatus
Which laxative?
- mixing of aqueous and fatty materials within the intestinal tract
- administered orally or rectally
- agent include: docusate (oral or enema)
Stool Surfactant Agents (Softeners)
Which laxative?
- clear, viscous oil that lubricates fecal material, retarding water absorption from the stool
- used to prevent and treat fecal impaction in young children and debilitated adults
- not palatable but may be mixed with juices
Mineral Oil
(Stool Surfactant Agents = Softeners)
Which laxative?
- CAUTION–aspiration can result in a severe lipid pneumonitis
- long-term use can impair absorption of fat-soluble vitamins (A, D, E, K)
Mineral Oil
(Stool Surfactant Agents - Softeners)
Which laxative?
- Non-absorbable sugars or salts
- Colon can neither concentrate nor dilute fecal fluid: fecal water is isotonic throughout the colon
- laxatives are soluble but nonabsorbable compounds that result in increased stool liquidity due to an obligate increase in fecal fluid
Osmotic Laxatives
What laxative do you use for acute constipation or prevention of chronic constipation?
Non-absorbable surgars or salts (Osmotic)
Which laxative?
- commonly used osmotic laxative
- not be used for prolonged periods in patients with renal insufficiency due to the risk of hypermagnesemia
Magnesium Hydroxide - (milk of magnesia)
Which 2 laxatives?
- nonabsorbable sugars that can be used to prevent or treat chronic constipation
- sugars are metabolized by colonic bacteria, producing severe flatus and cramps
- Sorbitol
- Lactulose
