GI: Laxatives Flashcards

(44 cards)

1
Q

Intestinal fluid absorption

A

Majority of water uptake is in small intestine (duodenum, jejunum, ileum)

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2
Q

Causes of Constipation

A
  • Lack of fiber
  • Drugs: anticholinergics, opiates, iron, SSRIs, antiHTNs (nondihydropyridine CCBs – verapamil & diltiazem)
  • Endocrine / metabolic
  • Neurogenic d/o
  • Organic causes
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3
Q

Management of Constipation

A
  • ID & Tx underlying cause
  • Nonpharm methods: ­ increase dietary fiber, fluid, & exercise; respond to the urge to defecate
  • Pharmacologic Tx: individualize
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4
Q

Pregnancy & Constipation: Mgmt

A
  • 1st line: adequate dietary fiber & fluid intake, light physical activity, bulk forming laxative
  • Other safe options: lactulose (chronulac), docusate (colace), polyethylene glycol (Miralax)
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5
Q

Agents to treat constipation

A

bulk forming laxatimes, stool surfactants, osmotic laxatives, stimulant laxatives

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6
Q

Types of bulk forming laxatives

A

Fiber: soluble and insoluble

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7
Q

Significance of fiber in constipation

A

FIber: Resists enzymatic digestion and reaches the colon unchanged

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8
Q

FIber: ADRs

A

Gas, bloating, impaction above colonic strictures

(bulk forming laxatives)

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9
Q

Fiber: dosing considerations

A
  • Start at ½ or less the recommended dose to decrease gas and bloating
  • Take w/8oz water: Risk of choking + help w/constipation

(bulk forming laxatives)

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10
Q

Fiber & colon cancer

A

Hx of colon cancer, don’t recommend fiber first line

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11
Q

Soluble fiber: agents

A

Wheat dextrin (Benefiber) QD

Psyllium (Metamucil) divided doses

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12
Q

Soluble fiber: MOA

A
  • Undergoes fermentation via colonic bacteria resulting in: short chain FA production, increased bacterial mass
  • absorbs water in the intestine to form a viscous liquid which promotes peristalsis and reduces transit time. UTD
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13
Q

Insoluble fiber: agents

A
  • Methylcellulose (Citrucel): 3-6x/day
  • Calcium Polycarbophil (Fibercon) 1-4x/day
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14
Q

Insoluble fiber​: MOA

A

Unfermented fiber that attracts water and increases stool bulk

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15
Q

Stool surfactants: Agents

A

Docusate (Colace) *more common

Mineral oil

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16
Q

Stool Surfactants: MOA

A

Decreases stool surface tension

Softens stool allowing easier defecation

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17
Q

Docusate (Colace): Dosing

A

1-4 divided doses

(stool surfactants)

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18
Q

Docusate (Colace): ADRs

A
  • Diarrhea
  • Abdominal cramping

(stool surfactant)

19
Q

Mineral oil: dosing

A

1-3 divided doses

20
Q

Mineral Oil: ADRs

A
  • Lipid pneumonitis w/aspiration
  • Anal leakage
  • Decreased fat soluble vitamin absorption (A,D,E,K)
  • Diarrhea

Side effects are major limiting factor

(stool surfactants)

21
Q

Osmotic Laxatives: Agents

A

Polyethylene glycol (MiraLax)

Magnesium containing

  • Magnesium sulfate (Epsom salt)
  • Magnesium hydroxide (Milk of magnesia)
  • Magnesium citrate (Citroma)

Phosphate salts: Fleet Enema

Lactulose (Chronulac)

22
Q

Osmotic Laxatives: MOA

A

Nonabsorbable agents that cause colonic osmotic water retention

23
Q

Polyethylene glycol (MiraLax): ADRs

A

Bloating, cramping, flatulence, diarrhea

24
Q

Polyethylene glycol (MiraLax): mixing agents

A

Mix powder w/water, juice, soda, tea

25
Polyethylene glycol (MiraLax): pregnancy & pedi
Safe in pregnancy Pedi: \>6mths
26
Osmotic laxatives: Magnesium containing agents
* Magnesium sulfate (Epsom salt) * Magnesium hydroxide (Milk of magnesia) * Magnesium citrate (Citroma)
27
Osmotic laxatives: Magnesium containing agents ADRs
Abdominal pain, gas, N/V *Caution:* renal insufficiency --\> hypermagnesemia
28
Osmotic Laxatives: phosphate salts Agents
Fleet enema
29
Phosphate salts: ADRs
Electrolyte abnormalities: increased­ (PO4, Na), decreased (Ca, K) (Osmotic laxatives)
30
Phosphate salts: caution in
elderly, renal insufficiency, cardiac dz (Osmotic laxatives)
31
Oral Sodium Phosphate BBW
12/11/2008 FDA safety alert – assoc w/AKI and RF; OTC Fleet Phospho Soda removed from market, Rx products still available (Osmoprep) (Osmotic laxatives)
32
Lactulose (Chronulac): MOA
Colonic bacteria hydrolyze short chain FAs --\> osmotically draws water into the intestinal lumen (Osmotic laxatives)
33
Lactulose (Chronulac): ADRs
Abdominal discomfort, flatulence, diarrhea
34
Stimulant laxatives: Agents
* Anthraquinone derivatives (Sennosides / Senekot) * Diphenylmethane derivatives (Bisacodyl /Dulcolax)
35
Stimulant laxatives​: MOA
Not well understood. Thought to have direct effects on: Enterocytes, enteric neuron, GI smooth muscle Induce limited low-grade inflammation --\> water accumulation & peristalsis
36
Stimulant laxatives​:​ PK
poorly absorbed, undergo colonic hydrolysis to active metabolites
37
Stimulant laxatives​:​​ ADRs
Cramps, nausea, rectal burning, vomiting
38
Anthraquinone derivatives (Sennosides / Senekot): Formulation & Dosing
Tablets, syrup, liquid Daily, divided doses prn (stimulant laxatives)
39
Anthraquinone derivatives (Sennosides / Senekot)​: ADRs
Stimulant laxative ADRs + melanosis coli (senna) – *just* *color*. *goes* *away*
40
Diphenylmethane derivatives (Bisacodyl / Dulcolax): Formulations and dosing
Rectal suppository, tablet Once daily (stimulant laxatives)
41
Assessment question: preferred for constipation w/opiates
rec’d combo of senna and dulcolax
42
Laxatives: Onset of action of 1-3 days which laxatives & stool characteristics
Softened stool * Bulk forming: *psyllium, methylcellulose, calcium polycarbophil * Surfactant/osmotic: *docusate, polyethylene glycol (PEG), lactulose
43
Laxatives: Onset of action of 6-8h which laxatives & stool characteristics
Soft or semifluid stool *Stimulants (irritants): *bisacodyl (PO), Senna (PO)
44
Laxatives: Onset of action of​ 1-3h which laxatives & stool characteristics
watery evacuation * Osmotic (high dose)*: sodium phosphate, magnesium sulfate, milk of magnesia, magnesium citrate * Stimulants: *bisacodyl suppository