Laxatives (bulk-forming, osmotic, stimulant) Flashcards
What are examples of bulk-forming laxatives?
ispaghula husk, methylcellulose, sterculia.
What are examples of osmotic laxatives?
macrogols, lactulose, magnesium hydroxide, sodium acid phosphate.
What are examples of stimulant laxatives?
bisacodyl, senna, co-danthramer, co-danthrusate, glycerol, sodium picosulfate.
What is the first-line subsequent treatment for constipation in adults?
Use a bulk forming laxative as first line treatment in combination with dietary/lifestyle changes. If stools remain hard/difficult to pass add/switch to an osmotic laxative such as a macrogol. If a macrogol is ineffective/not tolerated add lactulose. If stool is soft but remains difficult to pass or sensation of inadequate emptying add a stimulant laxative such as bisacodyl.
What is the first-line and subsequent treatment for constipation in children?
Laxatives should not be used routinely in children. First line laxative treatment should always be an osmotic laxative such as a macrogol (movicol), or lactulose (due to difficulty in administering bulk forming laxatives such as ispaghula husk to children). If problem persists or movicol not tolerated add a stimulant laxative added e.g. bisacodyl.
What are the indications of laxatives?
constipation, constipation | diarrhoea (methylcellulose), chronic constipation (macrogol), faecal impaction and prevention of (macrogol), bowel evacuation before procedures e.g. radiology, endoscopy, surgery (sodium acid phosphate, bisacodyl), constipation in terminally ill patients (co-danthramer, co-danthrusate).
What are the contraindications of bulk-forming laxatives?
Colonic atony, faecal impaction, intestinal obstruction, reduced gut motility, difficulty in swallowing, infective bowel disease.
What are the contraindications of osmotic laxatives?
intestinal obstruction, galactosaemia (lactulose), Chron’s disease, intestinal perforation, paralytic ileus, severe inflammatory conditions of the GI tract, toxic megacolon, ulcerative colitis, acute GI conditions (magnesium hydroxide), conditions associated with increased colonic absorption (sodium acid phosphate), inflammatory bowel disease (sodium acid phosphate).
What are the contraindications of stimulant laxatives?
Intestinal obstruction, acute abdominal conditions, acute inflammatory bowel disease, severe dehydration, undiagnosed abdominal pain.
State the mechanism of action of bulk-forming laxatives.
They are poorly digested fibres that absorb water in the gut to form a mucilaginous mass. This increases faecal mass, softens stool and stimulates peristalsis therefore relieving constipation.
State the mechanism of action of osmotic laxatives.
They are indigestible sugars/magnesium and sodium salts that increase water content retained in the GI tract by osmotic or secretory mechanisms, and loosen dry or impacted stools allowing them to pass easily.
State the mechanism of action of stimulant laxatives.
They stimulate enteric nerves in the colon to cause contractions and promote evacuation of the bowel.
What are the very common/common side effects of bulk-forming laxatives?
abdominal distension, flatulence.
What are the very common/common side effects of osmotic laxatives?
abdominal discomfort, cramps, diarrhoea, flatulence, nausea, vomiting.
What are the very common/common side effects of stimulant laxatives?
abdominal cramps, abdominal pain, diarrhoea, nausea.
