GI drugs Flashcards
H2 Receptor Antagonists
Ranitidine
Famotidine
Proton Pump Inhibitor
Omeprazole
Antacids
Mg(OH)2
Al(OH)3
CaCO3
Mucosal Protective Agents
Sucralfate
Bismuth Subsalicylate
Anti-Emetics
Metoclopramide
Ondansetron
Stimulant Laxative
Lubiprostone
Saline Laxative
Mg(OH)2
Antidiarrheal
Loperamide
Alosetron
Mesalamine drug
Sulfasalazine
Corticosteroid GI Drug
Predisone
Thiopurine anti-metabolite
azathioprine
TNF alpha inhibitor
Infliximab
Peptic Acid Disease
Gastroesophageal Reflux Acute - hearburn Chronic - GERD Esophageal damage Risk factors include hiatal hernia, weakened esophageal sphincter, obesity.
Principles of treatment of peptic acid disease
Reduce acid secretion
Neutralize acid
Eradicate H. Pylori
Enhance mucosal defenses
H2 receptor antagonists mechanism of action and pharmacology
Block H2 receptors, stopping histamine-mediated HCl release, Also reduce parietal cell response to ACh and Gastrin.
Low toxicity but reduce dose in renal dysfunction.
NSAIDs and H2 blockers
Famotidine reduces ulcers caused by long term NSAID use.
PPI mechanism of action
IRREVERSABLY inhibit proton pumps (H/K ATPase), inhibiting gastric acid secretion.
PPI pharmacology
Administered as prodrug, accumulates in parietal cell canaliculus. Protonated form binds to the enzyme. Recovery of proton pump function requires synthesis of new pumps, which takes time.
PPI adverse effects
Generally well tolerated, Nausea, diarrhea, and dizziness can occur.
Possible risk of pneumonia, possibly due to increased bacteria in stomach. That’s just based on one study, though.
Indications for PPI use
Ulcers, GERD, 1st line in Zollinger-Ellison Syndrome.
Not great for occasional heartburn.
Antacids - mechanism of action and indication
They are weak bases, neutralize stomach acid. Good for occasional heartburn.
Antacid DDI’s
Changes to pH change absorption and excretion of a lot of different drugs. Increase in urinary pH alters elimination of acidic and basic drugs.
H. Pylori - Treatment
Proton pump inhibitor and several antibitoics.
Sucralfate mechanism of action
Binds to positively charged proteins at low pH. Forms a paste-like gel that adheres to the epithelium of the stomach. This coating protects the cells against acid and pepsin.
Sucralfate problems and DDI’s
Can adsorb other drugs.
Do not co-admin with antacids - needs a low pH to work.
Bismuth Subsalicylate mechanism of action and indication
Binds to ulcers selectively, protects against HCl and pepsin.
Bismuth subsalicylate side effects
Blackens stool and tongue.
Ondansetron (zofran) mechanism of action
Selective 5HT3 receptor antagonist. Little effect on muscarinic or dopaminergic receptors.
Metoclopramide mechanism of action
Complex, seratonin pathway.
5HT4 receptor agonist, 5HT3 receptor antagonist (vagal)
Enhances ACh release in myenteric plexus, increased esophageal clearance.
Metoclopramide indications
chemotherapy induced nausea and vomiting.
Metoclopramide adverse
Dopamine D2 receptor antagonist - Parkinson-like symptoms.
Stimulant laxative
Lubiprostone
Lubiprostone mechanism of action
Cl channel activator - increases intestinal fluid secretion.
Lubiprostone indications
idiopathic chronic constipation
Saline laxative
Mg(OH)2 - works like mannitol for the GI tract, keeping fluids inside by raising osmotic pressure -
Saline laxative indication
Cathartic dose - complete evacuation in less than 3 hours., for colonoscopy prep.
Antidiarrheal agent
Loperamide
Loperamide mechanism of action
Opiod - causes constipation by stimulating mu opiod receptors in intestinal smooth muscle.
Loperamide adverse
Constipation, toxic megacolon
Low abuse potential compared to other opiods because PO absorption is very low.
IBS definition and etiology
Chronic, recurring episodes of abdominal discomfort, pain, distension, and bloating. It is a functional disease, without underlying structural or biochemical abnormalities.
IBS treatment goals
Treat the symptoms. It could be diarrhea or constipation. Think about the psychological-cognitive side too. Treat with antidepressants and psychotherapy if the drugs don’t help.
IBS with dominant diarrhea - Treatment plan
Loperamide
Anticholinergics
Alosetron in treatment resistant women.
Alosetron mechanism of action
5HT3 seratonin receptor antagonist. Decreased colonic motility.
Alosetron limitations and adverse effects
Prescribing physician must be enrolled in a special prescribing program.
Serious, rare side effect of ischemic colitis, can be fatal.
Constipation predominant IBS treatment options
Mg(OH)2 to increase frequency and loosen consistency.
Emergency only - tegasarod, taken off the market by the FDA due to risk of heart attack and stroke. Can request approval for a specific patient in a life threatening emergency.
Inflammatory Bowel Disease
A serious, chronic structural disease, characterized by inflammation, lesions, bleeding, and immune response. Includes Ulcerative colitis and crohn’s disease.
Ulcerative Colitis vs Crohn’s disease
Ulcerative colitis - lesions only in colon, mucosal and submucosal only.
Crohn’s - Lesions along the entire GI tract, involving all 4 layers of bowel wall.
Active IBD treatment
Glucocorticoid (prednisone) - treat inflammation.
Long term IBD therapy
Immunosuppressive therapy
Azathioprine
Azathioprine mechanism of action and adverse
Purine anti-metabolite, reducing conversion of GMP to GDP. Only effective topically on GI wall. Causes bone marrow suppression, rash, fever, nausea.
Ulcerative colitis treatments
5-aminosalicylic acid - Sulfasalazine first line.
Sulfasalazine Adverse
Nausea, Headache, hypersensitivity, bone marrow suppression. Up to 40% of patients can’t tolerate it.
Other treatment options for IBD
Infliximab, antibiotics to alter gut flora
Infliximab mechanism of action
Antibody to TNF-alpha. Blocks its inflammatory effect.
Adverse - immunosuppression - increased infections.
