GI Motility 2

Question 1

Which laxative?

• rapid movement of water into the distal small bowel and colon leads to a high volume of liquid stool followed by rapid relief of constipation
• high doses of osmotically active agents produce prompt bowel evacuation within 1–3 hours
• important that patients maintain adequate hydration by taking increased oral liquids to compensate for fecal fluid loss

Answer 1

Purgatives (Osmotic - nonabsorbably sugars/salts)

• Magnesium citrate
• Sodium phosphate

Question 2

ADEs of which laxative?

• hyperphosphatemia
• hypernatremia
• hypocalcemia
• hypokalemia
• may lead to cardiac arrhythmias
• may lead to acute renal failure due to tubular deposition of calcium phosphate (nephrocalcinosis)

Answer 2

Sodium Phosphate

(Purgative - Osmotic - Nonabsorbable sugars/salts)

Question 3

In which 4 patients should you not prescribe Sodium Phosphate?

(Purgative - Osmotic - Nonabsorbable sugars/salts)

Answer 3

• Frail / elderly
• Renal insufficiency
• Significant cardiac disease
• Unable to maintain adequate hydration during bowel preparation

Question 4

Which laxative?

• complete colonic cleansing before gastrointestinal endoscopic procedures
• balanced, isotonic solutions contain an inert, nonabsorbable, osmotically active sugar with sodium sulfate, sodium chloride, sodium bicarbonate, and potassium chloride
• designed so that no significant intravascular fluid or electrolyte shifts occur

Answer 4

Polyethylene glycol (PEG)

Question 5

Which laxative?

• safe for all patients
• solution should be ingested rapidly (2–4 L over 2–4 hours) to promote bowel cleansing
• treatment or prevention of chronic constipation
• smaller doses of this powder may be mixed with water or juices (17 g/8 oz) and ingested daily
• does not produce significant cramps or flatus

Answer 5

Polyethylene Glycol (PEG)

(MiraLAX)

Question 6

Which laxative?

• Induce bowel movements through direct stimulation of the enteric nervous system and colonic electrolyte and fluid secretion
• may be required on a long-term basis
  
  • Neurologically impaired
  • Bed-bound patients in long-term care facilities

Answer 6

Cathartics (stimulant laxatives)

Question 7

Which laxative?

• Long-term use is controversial
• Newer studies do not report damage to the enteric nervous system like earlier studies
• Nerve damage may be the cause of the constipation rather than the result of using laxatives
• Patients requiring regular use of laxatives may still need to be monitored for these effects

Answer 7

Stimulant laxatives (cathartics)

Question 8

Which laxative?

• Aloe, senna, and cascara
• Occur naturally in plant
• Laxatives are poorly absorbed and after hydrolysis in the colon, produce a bowel movement in 6–12 hours when given orally and within 2 hours when given rectally

Answer 8

Anthraquinone Derivatives

(Laxative Stimulants)

Question 9

Anthraquinone Derivatives (Laxative Stimulant)

• Chronic use causes what?
• There is concern these agents may cause what?

Answer 9

• Characteristic brown pigmentation of the colon (Melanosis Coli)
• Carcinogenic, but epidemiologic studies do NOT suggest a relation to colorectal cancer

Question 10

Which laxative?

• Bisacodyl (Ducolax)
• treatment of acute and chronic constipation
• used in conjunction with PEG solutions for colonic cleansing prior to colonoscopy
• induces a bowel movement within 6–10 hours when given orally and 30–60 minutes when taken rectally
• minimal systemic absorption and appears to be safe for acute and long-term use**

Answer 10

Diphenylmethane Derivative

Question 11

Acute and Chronic therapy w/ opioids may cause constipation due to what mechanism?

Answer 11

Decreasing intestinal motility, which results in prolonged transit time & increased absorption of fecal water

Question 12

Which 3 Opioid Receptor Antagonists (peripherally acting)?

• do not readily cross the blood-brain barrier
• inhibit peripheral μ-opioid receptors without impacting analgesic effects within the central nervous system

Answer 12

• Methylnaltrexone bromide
• Alvinopan
• Naloxegol

Question 13

Which Opioid Receptor Antagonist?

• approved for the treatment of opioid-induced constipation in patients receiving palliative care for advanced illness who have had inadequate response to other agents
• Dosage adjustment with severe renal impairment (CrCl < 30ml/min)

Answer 13

Methylnaltrexone (Relistor)

Question 14

Which Opioid Receptor Antagonist?

• approved for short-term use to shorten the period of postoperative ileus in hospitalized patients who have undergone small or large bowel resection
• no more than 7 days
• possible cardiovascular toxicity

Answer 14

Alvimopan (Entereg)

Question 15

Which Opioid Receptor Antagonist?

• Opioid-induced constipation
• Dosage adjustment with renal impairment (CrCl < 60ml/min)
• Avoid use in severe hepatic impairment (Child-Pugh class C)
• Contraindicated in patients with GI obstruction

Answer 15

Naloxegol (Movantik)

Question 16

Name a few drugs which cause diarrhea

Answer 16

• Laxatives (duh)
• Auranofin (gold salt)
• Antibiotics (Clinda, tetracyclines, Sulfonamides, any broad spectrum)
• Antihypertensives
• Cholinergics
• Cardiac agents (digoxin)
• NSAIDs
• Misoprostol
• PPIs

Question 17

• Acute diarrhea is how many days?
• Chronic diarrhea is how many days?

Answer 17

• Acute: <3 days
• Chronic: >14 days

Question 18

Clinical Controversy

• Withholding food is considered inappropriate in pts w/ no signs of what?
• In osmotic diarrhea, what may control the problem?
• If the mechanism is ____, diarrhea persists

Answer 18

• Severe dehydration
• food
• secretory

Question 19

What type of Antidiarrheal Agent?

• Antimotility

Answer 19

Opioid agonists

Question 20

What type of Antidiarrheal Agent?

• Kaolin-pectin mixture

Answer 20

Absorbents

Question 21

What type of Antidiarrheal Agent?

• Colloidal Bismuth Compounds
• Bile Salt-Binding Resins
• Octrotide

Answer 21

Antisecretory

Question 22

What are the 4 types of Antidiarrheal Agents

Answer 22

• Antimotility
• Adsorbents
• Antisecretory
• Bacterial replacement and enzymes

Question 23

Antidiarrheal Agents

• Safe to use for mild to moderate acute diarrhea
• Should not be used in patients w/ what 3 things?
  
  • Due to risk of worsening the underlying condition?
  • Discontinue in pts whose diarrhea is worsening despite therapy

Answer 23

• Bloody diarrhea
• High fever
• Systemic toxicity

Question 24

Antidiarrheals are used to treat which 2 conditions?

Answer 24

IBS and IBD

Question 25

**Which antidiarrheal agent?** * significant constipating effects * increase colonic phasic segmenting activity through inhibition of presynaptic cholinergic nerves in the submucosal and myenteric plexuses and lead to increased colonic transit time and fecal water absorption * decrease mass colonic movements and the gastrocolic reflex

Answer 25

Opioid Agonists

Question 26

**Which antidiarrheal agent?** * nonprescription opioid agonist * does not cross the blood-brain barrier * no analgesic properties or potential for addiction * tolerance to long-term use has not been reported * administered in doses of 2 mg taken one to four times daily

Answer 26

Loperamide

Question 27

**Which antidiarrheal agent?** * prescription opioid agonist * no analgesic properties in standard doses * higher doses have central nervous system effects * prolonged use can lead to opioid dependence

Answer 27

Diphenoxylate

Question 28

**Which antidiarrheal agent?** * Commercial preparations commonly contain small amounts of atropine to discourage overdosage (2.5 mg diphenoxylate with 0.025 mg atropine) * anticholinergic properties of atropine may contribute to the antidiarrheal action

Answer 28

Diphenoxylate

Question 29

**What type of antidiarrheal agent?** * Kaolin-pectin * Polycarbophil * Attapulgite (removed from market) * Effectiveness unproven * Adsorb nutrients, toxins, drugs, and digestive juices

Answer 29

**Ad**sorbents

Question 30

**Which antidiarrheal agent?** * Mucosal Protective Agents

Answer 30

Colloidal Bismuth Compounds

Question 31

**Bile Salt-Binding Resins** * Conjugated bile salts are normally absorbed where? * Disease of this location (Crohn's Disease) or surgical resection leads to malabsorption of bile salts, which may cause what?

Answer 31

* terminal ileum * colonic secretory diarrhea

Question 32

What are the 3 names of the Bile Salt Binding Resins?

Answer 32

* cholestyramine * colestipol * colesevelam

Question 33

**Which antidiarrheal agent?** * decrease diarrhea caused by excess fecal bile acids * powder and pill formulations that may be taken one to three times daily before meals

Answer 33

**Bile Salt Binding Resins** * Cholestyramine * Colestipol * Colesevelam

Question 34

4 ADEs of Bile Salt Binding Resins

Answer 34

* bloating * flatulence * constipation * fecal impaction

Question 35

**Bile Salt Binding Resins** * Patients w/ diminished circulating bile acid pools, further removal of bile acids may lead to what?

Answer 35

exacerbation of fat malabsorption

Question 36

**Which 2 Bile Salt Binding Resins?** * bind a number of drugs and reduce their absorption * not be given within 2 hours of other drugs

Answer 36

* Cholestyramine * Colestipol

Question 37

**Which Bile Salt Binding Resin?** * does not appear to have significant effects on absorption of other drugs

Answer 37

Colesevelam

Question 38

**Antisecretory : Octreotide** _Which drug?_ * 14-amino-acid peptide released in the gastrointestinal tract and pancreas from paracrine cells, D cells, and enteric nerves as well as from the hypothalamus

Answer 38

Somatostatin

Question 39

What are the **3 key** regulatory peptide physiologic effects of **Somatostatin?**

Answer 39

* inhibits the secretion of numerous hormones and transmitters (gastrin, glucagon. insulin) * reduces intestinal fluid secretion and pancreatic secretion * slows gastrointestinal motility and inhibits gallbladder contraction

Question 40

**Which drug?** * reduces portal and splanchnic blood flow. * inhibits secretion of some anterior pituitary hormones. * clinical usefulness is limited by its short half-life in the circulation (3 minutes) when it is administered by intravenous injection

Answer 40

Somatostatin

Question 41

**Which drug?** * Inhibition of Endocrine Tumor Effects * Two gastrointestinal neuroendocrine tumors (carcinoid, VIPoma) cause _secretory diarrhea_ and systemic symptoms such as _flushing and wheezing_

Answer 41

Somatostatin (Octreotide)

Question 42

**Antisecretory: Octreotide - Somatostatin** * Low doses do what? * Higher doses do what? * Higher doses for the tx of diarrhea due to vagotomy or dumping syndrome as well as for diarrhea caused by what 2 conditions? * Low doses to stimulate small bowel motility in pts w/ small bowel bacterial overgrowth or intestinal pseudo-obstruction secondary to what condition?

Answer 42

* **Low:** stimulate motility * **Higher:** inhibit motility * short bowel syndrome / AIDs * Scleroderma

Question 44

3 "other uses" of Somatostatin (Octreotide - Antisecretory)

Answer 44

* inhibits pancreatic secretion-value in patients with **pancreatic fistula** * treatment of **pituitary tumors** (eg, acromegaly) * **gastrointestinal bleeding** (decreases splanchnic blood flow-vapreotide)

Question 45

**ADEs of which drug?** * Steatorrhea (can lead to fat soluble vitamin deficiency) * sludge or gallstones in over 50% of pts * hyperglycemia / hypoglycemia (less frequent) * Hypothyroidism from long term tx * Bradycardia

Answer 45

**Somatostatin** (Octreotide - Antisecretory)