what 3 classes of drugs type used in antidiarrheals
antimotlity agents, adsorbents, Agents that modify fluid and electrolyte transport
drugs of class Antimotility agents
diphenoxylate
and loperamide
drugs of class Adsorbents
aluminum hydroxide and methylcellulose
drugs of class Agents that modify fluid and electrolyte transport
Bismuth subsalicylate,
which drugs are analogs of meperidine and have opioid-like actions on the gut.
diphenoxylate
and loperamide
which drugs can contribute to toxic megacolon
diphenoxylate
and loperamide
how does diphenoxylate
and loperamide work?
They
activate presynaptic opioid receptors in the enteric nervous system
to inhibit acetylcholine release and decrease peristalsis. At the usual
doses, they lack analgesic effects.
how does aluminum hydroxide and methylcellulose work?
these agents act by adsorbing intestinal toxins or microorganisms
and/or by coating or protecting the intestinal mucosa.
which drug used for traveler’s diarrhea?
Bismuth subsalicylate
how does Bismuth subsalicylate work?
decreases fluid secretion in the bowel. Its action may be due to its salicylate component as well as its coating action.
Adverse effects of Bismuth subsalicylate
Adverse effects may include black
tongue and black stools.
what are laxatives used for?
Laxatives are commonly used for constipation to accelerate the movement of food through the GI tract.
name some Laxatives Irritants and stimulants
Senna, Bisacodyl, Castor oil
Senna: This agent is a widely used stimulant laxative. Its active ingredient is a group of ___________, a natural complex of ______________. Taken orally, senna causes evacuation of the bowels within 8 to 10 hours. It also causes water and electrolyte secretion into the bowel
Senna: This agent is a widely used stimulant laxative. Its active ingredient is a group of sennosides, a natural complex of anthraquinone glycosides. Taken orally, senna causes evacuation of the
bowels within 8 to 10 hours. It also causes water and electrolyte
secretion into the bowel.
senna is used In combination products with what?
a docusate-containing stool softener
what is useful in treating opioid-induced constipation?
senna
bisacodyl is a potent stimulant of the _________.
colon
what acts directly on nerve
fibers in the mucosa of the colon?
bisacodyl
Castor oil is broken down in the small intestine to?
ricinoleic acid (which is very irritating to the stomach and promptly increases peristalsis)
who should avoid castor oil?
Pregnant patients
because it may stimulate uterine contractions.
how does methylcellulose,
psyllium seeds, and bran work?
They form gels in the large intestine,
causing water retention and intestinal distension, thereby increasing
peristaltic activity.
used cautiously in patients
who are? for methylcellulose,
psyllium seeds, and bran.
used cautiously in patients
who are immobile because of their potential for causing intestinal
obstruction.
what is used for the treatment of hepatic encephalopathy? and why?
Lactulose, due to its ability to reduce
ammonia levels.
Saline and osmotic laxative?
Saline and osmotic laxatives
Saline cathartics, such as magnesium citrate and magnesium
hydroxide, are nonabsorbable salts (anions and cations) that hold
water in the intestine by osmosis. This distends the bowel, increasing
intestinal activity and producing defecation in a few hours. Electrolyte
solutions containing polyethylene glycol (PEG) are used as colonic
lavage solutions to prepare the gut for radiologic or endoscopic pro-
cedures. PEG powder for solution is available as a prescription and
also as an over-the-counter laxative and has been shown to cause
less cramping and gas than other laxatives. Lactulose is a semisyn-
thetic disaccharide sugar that acts as an osmotic laxative. It can-
not be hydrolyzed by GI enzymes. Oral doses reach the colon and
are degraded by colonic bacteria into lactic, formic, and acetic acids.
This increases osmotic pressure, causing fluid accumulation, colon
distension, soft stools, and defecation. Lactulose is also used for
the treatment of hepatic encephalopathy, due to its ability to reduce
ammonia levels.
