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GI Week 4 - WLB > Laxatives, Antidiarrheals & Treatments for IBS - Fitz > Flashcards

Laxatives, Antidiarrheals & Treatments for IBS - Fitz Flashcards

1
Q

What are the four prokinetic drugs that increase GI motility?

A
  • CISAPRIDE (Propulsid)
  • DOMPERIDONE (Motilium)
  • MACROLIDE ANTIBIOTICS (Erythromycin)
  • METOCLOPRAMIDE (Reglan)
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2
Q

What are the two opiate anti-diarrheal drugs that we need to know?

A
  • DIPHENOXYLATE (Lomotil)
  • LOPERAMIDE (Imodium)
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3
Q

What are the two bile acid binding resin anti-diarrheal drugs that we need to know?

A
  • CHOLESTYRAMINE (Questrin)
  • COLESTIPOL (Colestid, Colestitabs)
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4
Q

What are the two stool softeners that we need to know?

A
  • Docusate
  • Mineral oil
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5
Q

What are the four bulk laxatives that we need to know?

A
  • DIETARY FIBER
  • METHYLCELLULOSE (Celoftel, Citrocel)
  • POLYCARBOPHIL (FiberCon, Fiber Lax, Fibertab)
  • PSYLLIUM (Metamucil)
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6
Q

What are the three stimulant cathartics that we need to know?

A
  • ANTHRAQUINONE DERIVATIVES
    • CASCARA SAGRADA, DANTHRON, SENNA
  • BISACODYL (Alophen, Carter’s Little Pills, Correctol, Dulcolax, Fleet)
  • CASTOR OIL
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7
Q

What are the four osmotic cathartics that we need to know?

A
  • LACTULOSE (Cephulac)
  • MAGNESIUM HYDROXIDE (Milk of magnesia)
  • SODIUM PHOSPHATE
    • Fleet enema, OsmoPrep, Viicol, Wal-phosphate
  • POLYETHYLENE GLYCOL SOLUTION
    • Miralax, GoLytely, GlycoLax, CoLyte, NuLytely
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8
Q

What are the two opiod receptor antagonists that we need to know?

A
  • ALVIMOPAN (Entereg)
  • METHYLNALTREXONE (Relistor)
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9
Q

What four neurotransmitters and two hormones are important regulators of motility and water absorption (from a pharmacologist’s perspective!)?

A
  • Neurotransmitters
    • ACh
    • 5-HT
    • Dopamine
    • Enkephalins
  • Hormones
    • Motilin
    • Somatostatin
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10
Q

What drug classes are used to treat dysfunction of the large intestine by interacting with the afferent neurons of the peristaltic reflex that are stimulated by 5HT release by the enterochromaffin cells?

(Hint: 5 classes)

A
  • SSRIs
  • bulk-forming laxatives
  • contact cathartics
  • 5HT3 antagonists
  • 5HT4 agonists
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11
Q

What three drugs decrease reuptake of 5HT into enterochromaffin cells, which may result in increased 5HT concentrations in the synapse, which consequently increase activity in the afferent limb of the peristaltic reflex?

A
  • Fluoxetine
  • Paroxetine
  • Sertaline
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12
Q

What drugs all increase mass of stool → distension → enteric reflexes → increased GI motility → decreased transit time through the colon?

A
  • DIETARY FIBER
  • METHYLCELLULOSE
  • POLYCARBOPHIL
  • PSYLLIUM
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13
Q

What drugs attract water and can function as “stool stabilizers”?

A
  • POLYCARBOPHIL
  • PSYLLIUM
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14
Q

What two factors limit the use of bulk forming laxatives?

A
  1. enteric reflexes must be functional
    • e.g., many drugs block enteric nervous system receptors, eliminating the peristaltic reflex
  2. unknown cause of the constipation
    • giving these agents if the colon is completely impacted will make the problem worse
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15
Q

What is the mechanism of action of contact cathartics?

A
  • poorly understood but irritation of the mucosa is thought to stimulate gut afferents, leading to increased peristalsis
    • requirement for intact reflex arc????
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16
Q

What two contact cathartic drugs sct on the large intestine and are considered less potent?

A

BISACODYL and ANTHRAQUINONES

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17
Q

What contact cathartic drug acts on both the small and large intestine → has short latency, extremely potent effect, and more significant side effects?

A

Castor Oil

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18
Q

What contact cathartic causes a characteristic, harmless, brown pigmentation of the colonic mucosa (“melanosis coli”)?

A

ANTHRAQUINONES

19
Q

What contact cathartic drug may cause dehydration with electrolyte imbalance and uterine contractions (so it should not be used during pregnancy)?

A

Castor Oil

20
Q

What drug causes inhibition of 5HT3 receptors which modulates visceral afferent pain sensation and (ultimately) reduces GI motility by interfering with the coordination of relaxation and contraction that is critical for peristalsis?

21
Q

What drug binds with higher affinity and dissociates more slowly from the 5HT3 receptor than the agents used as antiemetics, is used in women with severe diarrhea-predominant IBS who have not responded to other therapies, and moves on and off market with some regularity with restricted availability due to side effects?

22
Q

What rare but serious GI toxicities is Alosetron associated with?

A
  • constipation
  • episodes of ischemic colitis
    • some fatal
  • increased side effects with concomitant use of CYP1A2 inhibitors
23
Q

What two drugs act on presynaptic nerve terminals, increasing CGRP release from sensory afferents in the submucosal and myenteric plexuses → causing stimulation of the peristaltic reflex → proximal bowel contraction (via ACh) and distal bowel relaxation (via NO and VIP), therefore promoting gastric emptying and decreasing small and large bowel transit time
(prokinetic rather than laxative)?

A
  • Serotonin 5HT4 Agonists:
    • CISAPRIDE
    • TEGASEROD
24
Q

Even though both drugs should only be used when there are no other options because both drugs have restricted availability (compassionate use only), which 5HT4 agonist is used for diabetic gastroparesis and which one is used for patients with constipation-predominant IBS?

A
  • Cisapride → diabetic gastroparesis
  • Tegaserod → constipation-predominant IBS
25
What serious side effects occur with 5HT4 agonists, with approximately 85% of cases occur when CISAPRIDE is used in patients with known risk factors, particularly co-administration of drugs that inhibit CYP3A4?
Cardiovascular effects including ventricular tachycardia, ventricular fibrillation, torsades de pointes, and QT prolongation
26
What are the actions of enkephalins in the lower GI tract?
* Enkephalins are inhibitory modulators in the myenteric and submucosal plexus. * stimulation of the afferent nerves decreases enkephalin-mediated inhibition of peristalsis (inhibition of inhibition)
27
What two drugs increase phasic colonic segmenting activity by activating κ and μ receptors → causing inhibition of both cholinergic neurons that increase motility and VIP/NO neurons that cause relaxation → increased transit time due to decreases peristaltic reflex (indirectly causes increased water absorption); they also promote constipation by direct inhibition of neurons in the submucosal plexus that promote water excretion?
* Opiates: * DIPHENOXYLATE * LOPERAMIDE
28
Which opiate does not cross the blood-brain barrier and has no analgesic or addictive properties so it is available OTC?
Loperamide
29
Which opiate has no analgesic properties at standard doses, but higher doses have CNS effects thus it is only available by prescription; commercial preparations contain ATROPINE to discourage overuse?
Diphenoxylate
30
What serious GI complications may occur if opiates are administered in patients with severe ulcerative colitis?
Toxic megacolon
31
At high doses, DIPHENOXYLATE causes what adverse side effects?
* euphoria → morphine-like physical dependence can occur with chronic administration * probability of dependence is decreased by adding ATROPINE to the formulation * ATROPINE will also decrease motility (antimuscarinic), and has unpleasant side effects
32
What drug is used to treat constipation caused by acute or chronic opioid therapy and to shorten period of postoperative ileus following small or large bowel resection (short term)?
selective μ receptor antagonist: **Alvimopan**
33
What drug is used to treat constipation caused by acute or chronic opioid therapy and is also administered to patients receiving palliative care for advanced illness (long term)?
selective μ receptor antagonist: **Methylnaltrexone**
34
What two drugs function as cholinomimetics, by inhibiting the dopamine inhibition of ACh-induced contraction, consequently increasing GI motility throughout the entire GI tract, and therefore considered to be prokinetic?
* Dopamine D2 receptor antagonists: * DOMPERIDONE * METOCLOPRAMIDE
35
What drug is used to treat persistent hiccups and impaired gastic emptying, primarily due to postsurgical disorders (esp. vagotomy) and diabetic gastroparesis; crosses the BBB (and therefore also has CNS actions); and causes adverse side effects like dystonia, Parkinsonism, tardive dyskinesia, and increased pituitary prolactin release?
Metoclopramide
36
What D2 receptor antagonist is used to treat impaired gastic emptying, primarily due to postsurgical disorders (esp. vagotomy) and diabetic gastroparesis, does not cross the BBB easily, and is only available via a compassionate use program in the US, but is widely available in other countries, including Canada?
Domperidone
37
What two tricyclic antidepressants have been shown to decrease symptoms in patients with diarrhea-predominant IBS at doses lower than those used to treat depression by altering cholinergic neurotransmission?
Amitryptyline and Desipramine
38
What drugs stimulate motilin receptors directly on GI smooth muscle → causing initiation of migrating motor complex?
Macrolide Antibiotics: Erythromycin
39
What drug is used to treat chronic, idioptathic constipation and constipation-predominant IBS by activating chloride channel ClC-2 → causing more Cl- secretion → and increased water content in stool?
Lubiprostone (class C agent → don't use in pregnant women)
40
What drug is used to treat chronic idioptathic constipation and constipation-predominant IBS by binding/activating guanylyl cyclase-C on the luminal surface of intestinal epithelial cells causing increased intra- and extra-cellular cGMP activates the cystic fibrosis transmembrane conductance regulator (CFTR) → increased Cl- secretion?
Linaclotide (class C agent → don't use in pregnant women, also contraindicated in pediatric patients)
41
What drug is used to treat non-infectious diarrhea caused by anti-HIV drugs (e.g. nucleoside analog reverse transcriptase and protease inhibitors) by voltage-independent blocking of CFTR and anoctamin 1 (calcium-activated chloride channel) causing decreased Cl- secretion → decreased sodium and water excretion → firmer stool?
CROFELEMER
42
What drug is mainly used for inhibition of the effects of carcinoid tumors and VIPomas but has an off-label use for severe diarrhea due to vagotomy or dumping syndrome, short bowel syndrome, AIDS?
Somatostatin analogue: OCTREOTIDE
43

GI Week 4 - WLB (8 decks)

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