Week 11 - Chapter 79 Laxative Flashcards Preview

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Flashcards in Week 11 - Chapter 79 Laxative Deck (28):
1

Bulk-Forming Laxatives

(eg, methylcellulose, psyllium, polycarbophil) have actions and effects much like those of dietary fiber. These agents consist of natural or semisynthetic polysaccharides and celluloses derived from grains and other plant material. The bulk-forming agents belong to our therapeutic group III, producing a soft, formed stool after 1 to 3 days of use.

2

Catharsis

a prompt, fluid evacuation of the bowel.

3

Chloride Channel Activators

By activating (opening) chloride channels in epithelial cells lining the intestine, lubiprostone (1) promotes secretion of chloride-rich fluid into the intestine and (2) enhances motility in the small intestine and colon. The result is spontaneous evacuation of a semisoft stool, usually within 24 hours.

4

Constipation

hard stools, infrequent stools, excessive straining, prolonged effort, a sense of incomplete evacuation, and unsuccessful defecation. determined more by stool consistency (degree of hardness) than by how often bowel movements occur.

5

Laxative Effect

production of a soft, formed stool over a period of 1 or more days

6

Osmotic Laxatives

Osmotic action retains water and thereby softens the feces; fecal swelling promotes peristalsis

7

Stimulant Laxatives

(1) Stimulate peristalsis and (2) soften feces by increasing secretion of water and electrolytes into the intestine and decreasing water and electrolyte absorption

8

Surfactant Laxatives

Surfactant action softens stool by facilitating penetration of water; also cause secretion of water and electrolytes into intestine

9

Methylcellulose category

bulk- forming laxative

10

Docusate Sodium category

Surfactant Laxatives

11

Bisacodyl category

Stimulant Laxatives

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Magnesium Hydroxide Category

Osmotic Laxatives

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Lubiprostone Category

chloride channel activator

14

Methylcellulose Mechanism of Action

have the same impact on bowel function as dietary fiber. Following ingestion, these agents, which are nondigestible and nonabsorbable, swell in water to form a viscous solution or gel, thereby softening the fecal mass and increasing its bulk. Fecal volume may be further enlarged by growth of colonic bacteria, which can utilize these materials as nutrients. Transit through the intestine is hastened because swelling of the fecal mass stretches the intestinal wall, and thereby stimulates peristalsis.

15

Methylcellulose use

temporary treatment of constipation. Also, they are widely used in patients with diverticulosis and irritable bowel syndrome.

16

Methylcellulose adverse effects

effects are minimal. Because the bulk-forming agents are not absorbed, systemic reactions are rare. Esophageal obstruction can occur if they are swallowed in the absence of sufficient fluid. Accordingly, bulk-forming laxatives should be administered with a full glass of water or juice. If their passage through the intestine is impeded, they may produce intestinal obstruction or impaction. Accordingly, they should be avoided if there is narrowing of the intestinal lumen.

17

Docusate Sodium Mechanism of Action

alter stool consistency by lowering surface tension, which facilitates penetration of water into the feces. The surfactants may also act on the intestinal wall to (1) inhibit fluid absorption and (2) stimulate secretion of water and electrolytes into the intestinal lumen.

18

Docusate Sodium Use

Constipation, to Soften stools

19

Docusate Sodium Adverse Effects

-

20

Bisacodyl Mechanism of Action

Stimulates intestinal motility an increases amounts of water and electrolytes in the intestinal lumen

21

Bisacodyl Use

opioid induced constipation for constipation from slow intestinal transit

22

Bisacodyl Adverse Effects

burning sensation and prolonged use can cause proctitis

23

Magnesium Hydroxide Mechanism of Action

poorly absorbed salts whose osmotic action draws water into the intestinal lumen.

24

Magnesium Hydroxide Use

High-dose therapy is employed to empty the bowel in preparation for diagnostic and surgical procedures. High doses are also employed to purge the bowel of ingested poisons, and to evacuate dead parasites following anthelmintic therapy.

25

Magnesium Hydroxide Adverse Effects

substantial loss of water. In patients with renal impairment, magnesium can accumulate to toxic levels.

26

Lubiprostone Mechanism of Action

By activating (opening) chloride channels in epithelial cells lining the intestine, lubiprostone (1) promotes secretion of chloride-rich fluid into the intestine and (2) enhances motility in the small intestine and colon. The result is spontaneous evacuation of a semisoft stool, usually within 24 hours.

27

Lubiprostone Use

(1) chronic idiopathic constipation in adults, (2) irritable bowel syndrome with constipation (IBS-C) in women at least 18 years old, and (3) treatment of opioid-induced constipation in chronic noncancer pain.

28

Lubiprostone Adverse Effects

Nausea is the most common side effect and can be reduced by taking lubiprostone with food and water. Other GI effects include diarrhea, abdominal distention, abdominal pain, gas, vomiting, and loose stools. Headache is the major non-GI effect.

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