MOA
BULK FORMING
Absorbs water. Increases
bulk, therby stimulating
peristalsis
Action: within 24 hrs
EMOLLIENTS
Lubricate intestinal tract
and soften feces, making
hard stools easier to pass.
Does not affect peristalsis
Action: softeners in 72 hr,
lubricates in 8 hr
PROSECRETORY AGENTS
Increases intestinal fluid
secretion through direct
action on epithelial cells,
speeding colonic transit
Action: Usually within 24
hr
Indications
Example
Comments
Acute and chronic
constipation, IBS,
diverticulosis
Methylcellulose (Citrucel),
Psyllium
Contraindicated in patients with abdominal pain, nausea and
vomiting and those suspected of having appendicitis, biliary tract
obstruction, or acute hepatitis. Must be taken with fluids. Best
choice for initial treatment of constipation.
Acute and chronic
constipation, fecal
impaction, anorectal
conditions
Softeners: docusate
Lubricants: Mineral Oil
Can block absorption of fat-soluble vitamins, such as vitamin K,
which increase the risk for bleeding in patients on anticoagulants
Chronic idiopathic
constipation, irritable
bowel syndrome with
constipation (women
only)
linaclotide (Linzess)
lubiprostone (Amitiza)
plecanatide (Trulance)
Contraindicated in patients with history of mechanical GI
obstruction. Can cause nausea and watery diarrhea
magnesium salts
(magnesium citrate, Milk
of Magnesia)
sodium phosphates (Fleet
Enema, Phospho-soda)
polyethylene glycol
(MiraLAX, GoLYTELY)
May cause abdominal distention and diarrhea. Overuse of
magnesium or sodium phosphates in older adults or those with
renal failure can lead to fluid and electrolyte imbalances; least
effective agents in this class
SALINE AND OSMOTIC SOLUTIONS
Cause retention of fluid in Chronic constipation,
intestinal lumen, reducing bowel preparation for
stool consistency and
diagnostic tests and
increasing volume
surgery
Action: Within 15 min–3
lactulose
hr
STIMULANTS
Increases peristalsis and
speeds colonic transit by
irritating colon wall and
stimulating enteric nerves
Action: Usually within 12
hr
Acute constipation, bowel
preparation for diagnostic
tests and surgery
anthraquinones (cascara
sagrada, senna)
phenolphthalein:
sennosides (Ex-Lax),
bisacodyl (Correctol,
Dulcolax)
Cause melanosis coli (brown or black pigmentation of colon).
Most widely abused laxatives. Should not be used in patients with
impaction or obstipation