Laxatives Flashcards
name 3 bulk laxatives
ispagula husk
methylcellulose
Sterculia
how do bulk laxatives work?
indigestible hydrophilic agents
attract water to stool increasing bulk and stimulating peristalsis
cautions for all laxatives?
don’t use if bowel obstructed or at risk of obstruction
indications for bulk laxative use?
constipation and faecal impaction
viral/bacterial gastritis
mild chronic diarrhoea (eg. assoc with IBS)
side effects of bulk laxatives?
abdo distension and flatulence
rare = faecal impaction and GI obstruction
name 4 osmotic laxatives
lactulose
macrogols
citrate
phosphate enemas
how do osmotic laxatives work?
osmotically active (sugars and alcohol) and not digested or absorbed attract water to stool increasing bulk and stimulating peristalsis
how does lactulose work specifically?
reduces ammonia absorption via deceasing transit time
this acidifies the stool and inhibits proliferation of ammonia producing bacteria which helps liver failure
what are the indications for osmotic laxatives?
constipation and faecal impaction
bowel prep for surgery
hepatic encepahlopathy
what are the side effects of osmotic laxatives?
abdo pain and diarrhoea
phosphate enemas = local irritation and electrolyte disturbance
when must phosphate enemas be used with caution?
heart failure and electrolyte disturbance as they cause fluid shift
name 4 stimulant laxatives
senna
bisocodyl
glycerol suppository
docusate sodium
how do stimulant laxatives work?
increase water and electrolyte secretion from colonic mucosa increasing colon contents and stimulating peristalsis
can directly stimulate peristalsis via action on enteric NS
docusate sodium has stool softening action
indications for stimulant laxatives?
constipation
faecal impaciton
side effects of stimulant laxatives?
abdo pain and cramping
diarrhoea
prolonged use = irreversible atonic colon and reversible melanosis coli
