GI Meds COPIED Flashcards
mech of action,
clinical indications,
potential adverse effects
of promethazine
(antihistamine)
H1 Antihistamine
treats nausea and vomiting induced by medications, anesthetics, and a wide range of other stimuli.
Rectal suppository or injection.
What is used primarily for the treatment of motion sickness?
Scopalamine - muscarinic receptor antagonist similar to atropine.
Been used by astronauts.
Skin patch slow 72 hr release.
Treatment of Crohn’s
Control flare-ups
steroids, immunosuppresants (eg. azathioprine)
otherwise biological agents; infliximab (targets TNF)
Surgery
H. Pylori tx
Triple therapy
PPI + two or more antimicrobial agents
eg. amoxicillin + clarithromycin
or metronidazole + clarithromycin
5 days + 5 days treatment programme
mech of action,
clinical indications,
potential adverse effects
of metoclopramide
others; prochlorperazine, domperidone
(acts peripherially - prokinetic drug
and acts centrally - antiemetic)
Blocks dopamine D2 receptors; this prevents the relaxation of GI smooth muscle produced by dopamine. Also increases acetylcholine from cholinergic motor neurons in the enteric nervous system.
>> tone and motility in the oesophagus and stomach. (therefore opioid induced sickness)
Also >> gastric emptying.
NB> also increases resting pressure of lower oesophageal sphincter, therefore << acid reflux.
Indications: GERD, diabetic gastroparesis, intractable hiccup, also antiemetic.
Adverse effects: CNS reactions. CONTRAINDICATED with px with seizures.
mech of action,
clinical indications,
potential adverse effects
of senna, bisacodyl
(stimulant - secretory laxatives )
Alter fluid secretion and stimulates peristalsis
Bisacodyl; used to evacuate the bowel. Can cause cramping and electrolyte/ fluid depletion. SHORT term use only.
mech of action,
clinical indications,
potential adverse effects
of misoprostol,
(cytoprotective drug)
Prostaglandin E1 analogue
expensive. Inhibits gastric acid secretion, promotes mucus and bicarbonate.
Primary indication: prevention of gastric and duodenal ulcers with px who take NSAIDs long term.
contraindicated in PREGNANCY (stimulates uterine contractions)
What hormone stimulates the parietal cells?
Gastrin
mech of action,
clinical indications,
potential adverse effects
of cimetidine, famotidine, ranitidine
(histamine H2-receptor antagonists)
drugs compete with histamine for binding to H2 receptors on gastric parietal cells.
Reduce volume and conc of gastric acid. This also proportionally decreases pepsin. (Gastric acid is the pepsinogen-pepsin catalyst)
cimetidine - weak antiandrogenic activity; can cause gynecomastia in elderly men.
cimetidine - WELL-KNOWN - inhibits P450 enzymes, therefore care with polypharmacy.
mech of action,
clinical indications,
potential adverse effects
of docusate sodium
(stool softener)
facilitate movement of water into fatty intestinal material, thus softening stool.
Indicated for hard, dry stool, prevent aggravation of haemorrhoids, helping px avoid straining.
mech of action,
clinical indications,
potential adverse effects
of omeprazole
(proton pump inhibitor)
inhibitors of proton-pump, Strong inhibitors of gastric acid
Choice drug for peptic ulcers
Choice drug for GERD
Choice drug for Zollinger-Ellison syndrome
Choice drug for long-term NSAID therapy
hypomagnesemia can occur with long-term PPI therapy.
Diagram of vomiting pathways
mech of action,
clinical indications,
potential adverse effects
of dronabinol
(marijuana derivatives)
used for cancer chemotherapy induced emesis when other drugs have failed.
Used as an appetite stimulant for anorexic HIV patients
mech of action,
clinical indications,
potential adverse effects
of sucralfate,
(cytoprotective drug)
this polysaccharide adhers to ulcer craters , inhibits pepsin-catalyzed hydrolysis of mucosal proteins. Helps form a protective barrier.
Used to treat peptic ulcers, but not so effective as H2blockers or PPIs, so only indicated with patients who can’t tolerate the others.
Take 2 hours between other drugs.
mech of action,
clinical indications,
potential adverse effects
of calcium carbonate
(gastric antiacid)
chemically neutralize stomach acid.
Commonly used for acid indigestion and dyspepsia.
Can cause some constipation, can cause rebound acid secretion.
Gastrin and acetylcholine also stimulates the release of ……. from paracrine cells
Histamine
mech of action,
clinical indications,
potential adverse effects
of milk of magnesia
(osmotic laxative)
poorly absorbed salt that osmotically attracts water.
Administer to px to evacuate the bowel in prep for surgery.
Danger> loss of fluids and electrolytes
Summary
peptic ulcer meds
Histamine H2 receptor antagonists, or a proton pump inhibitor, or a cytoprotective agent
+
antibiotics for H.pylori
mech of action,
clinical indications,
potential adverse effects
of psyllium
(bulk forming laxative)
Indigestible hydrophilic drug
absorbs water and increases mass of stool. This stimulates mech peristalsis.
Also used to treat diarrhoea
What is the relationship between histamine and gastric acid production?
histamine stimulates H2 receptors located on parietal cells and provokes acid secretion.
What’s the treatment for GERD?
(causing oesophagitis)
<< gastric acidity (two main groups previously mentioned)
increase the compromised oesophageal sphincter pressure (metoclopramide)
Which cells secrete gastrin?
G cells in the stomach’s antrum
mech of action,
clinical indications,
potential adverse effects
of ondansetron
(phenothiazines)
Selective 5-HT3 receptor antagonist; competitively block 5-HT3 receptors. I.e. blocks stimuli from the chemoreceptor trigger zone.
Acts both peripherally and centrally (vomiting centre)
Indicated for : cancer chemotherapy-induced emesis.
Adverse effects: headache, constipation, and diarrhoa.
ranitidine
H2 histamine receptor antagonist
blocks histamine and thus decreasing the amount of acid released by cells of the stomach.
What is mesalazine used for?
(5-aminosalicyclic acid) 5-ASA
treatment of choice for maintenance of mild-to-moderate ulcerative colitis.
(also reduces risk of colorectal cancer)
Also used inconjunction with antibiotics for the treatment of diverticulitis.
What is Hyosine used for?
(and MOA)
Motion sickness and vesibulocochlear dysfunction.
Targets the vomiting centre and vestibulocochlear nuclei.
How does cyclizine work and indications?
Histamine (H1) receptor antagonist
Targets the vestibulocochlear nuclei
Labyinthine disorder, vertigo, migraine
