Week 11 - Chapter 79 Laxative

Question 1

Bulk-Forming Laxatives

Answer 1

(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.

Question 2

Catharsis

Answer 2

a prompt, fluid evacuation of the bowel.

Question 3

Chloride Channel Activators

Answer 3

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.

Question 4

Constipation

Answer 4

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.

Question 5

Laxative Effect

Answer 5

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

Question 6

Osmotic Laxatives

Answer 6

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

Question 7

Stimulant Laxatives

Answer 7

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

Question 8

Surfactant Laxatives

Answer 8

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

Question 9

Methylcellulose category

Answer 9

bulk- forming laxative

Question 10

Docusate Sodium category

Answer 10

Surfactant Laxatives

Question 11

Bisacodyl category

Answer 11

Stimulant Laxatives

Question 12

Magnesium Hydroxide Category

Answer 12

Osmotic Laxatives

Question 13

Lubiprostone Category

Answer 13

chloride channel activator

Question 14

Methylcellulose Mechanism of Action

Answer 14

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.

Question 15

Methylcellulose use

Answer 15

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

Question 16

Methylcellulose adverse effects

Answer 16

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.

Question 17

Docusate Sodium Mechanism of Action

Answer 17

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.

Question 18

Docusate Sodium Use

Answer 18

Constipation, to Soften stools

Question 19

Docusate Sodium Adverse Effects

Answer 19

-

Question 20

Bisacodyl Mechanism of Action

Answer 20

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

Question 21

Bisacodyl Use

Answer 21

opioid induced constipation for constipation from slow intestinal transit

Question 22

Bisacodyl Adverse Effects

Answer 22

burning sensation and prolonged use can cause proctitis

Question 23

Magnesium Hydroxide Mechanism of Action

Answer 23

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

Question 24

Magnesium Hydroxide Use

Answer 24

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.

Question 25

Magnesium Hydroxide Adverse Effects

Answer 25

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

Question 26

Lubiprostone Mechanism of Action

Answer 26

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.

Question 27

Lubiprostone Use

Answer 27

(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.

Question 28

Lubiprostone Adverse Effects

Answer 28

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.