Exam I - GI Drugs Flashcards
Drug List
H2 Receptor Agonist
- Ranitidine
- Famotidine
Drug List
PPIs
-Omeprazole
Drug List
Anatacids
- Mg(OH)2
- Al(OH)3
- CaCO3
Drug List
Mucosal Protective Agents
- Sucralfate
- Bismuth Subsalicylate
Drug List
Anti-emetics
- Metoclopramide
- Ondansetron
Drug List
Stimulant Laxative
-Lubiprostone
Drug List
Saline Laxative
-Mg(OH)2
Drug List
Antidiarrheal
- loperamide
- alosetron (restricted use)
Drug List
Mesalamine
-sulfasalazine
Drug List
Corticosteroid
-Prednisone
Drug List
Thiopurine Anti-metabolite
-azathioprine
TNFa inhibitors
-infliximab
Peptic Acid Dz
Risk Factors
- coffee, EtOH, tobacco
- salicylates/aspirin
- NSAIDs
- Heredity/Age
- H. pylori
- Stress
Peptic Acid Dz
Acute Reflux AKA
-heartburn
Peptic Acid Dz
Chronic Reflux AKA
-GERD
Peptic Acid Dz
Reflux Risk Factors
- hiatal hernia
- weakened esophageal sphincter/pressure
- obesity
- displaced diaphragm
Peptic Acid Dz
Damaging Agents
- Acid
- Pepsin
- H. pylori
Peptic Acid Dz
Protective Agents
- mucous
- bicarbonate
- PgE
Gastric Acid Secretion
Stimulants
- peptides>gastrin release
- gastrin>histamine release (H2 receptors), hcl release
- histamine>hcl release
- vaga>ACh>parietal>HCl
H2 Receptor Antagonists
- low toxicity
- effective for nocturnal secretions
- prophylaxis for NSAID tx duodenal ulcers
PPIs
- irreversible inhibition (long-term effect) of H+/K+ ATPase
- pro-drug; protonation of weak base in parietal cell canaliculus
- P450 metab
- adverse: nausea, diarrhea, dizziness
- more effective than H2 receptor antagonists
Antacids
- weak bases, work in lumen
- Mg(OH)2 produces diarrhea
- Al(OH)3 and CaCO3 produce constipation
- Co-Rx to counteract effects
- use for occasional heartburn
- effective for 2-3 hrs
Antacids
Adverse
- drug-drug interactions
- Al(OH)3 and CaCO3 decrease abx absorption
Muscosal Protection
Sucralfate
- forms paste at low pH
- adheres to pos-charged proteins
- protects cells against acid, pepsin
- take before meal
- adverse: adsorbs drugs; take 2 hrs after admin
- do not co-admin w/ antacid>black stools
Mucosal Protection
Bismuth Subsalicylate
- selectively binds ulcers
- adverse: blackened stool, tongue
Anti-emetics
Ondansetron
- 5HT3 receptor antagonists
- chemotrigger zone
- most effective for cytotox drug (chemotx) emesis
- co-rx for chemtox emesis
- adverse: constipation
Anti-emetics
Metoclopramide
- centrally acting dopamine receptor antags
- also enhances intestinal motility
- chemo/cytoxic drug emesis
- adverse: parkinsonian sx
Laxatives
Contraindications
- cramps
- colic
- nausea
- vomiting
- appendicitis sx
- undiagnosed abdominal pain
Stimulant Laxative
Lubiprostone
Indication
- Indication: idiopathic chronic constipation
- Mech: Activates Cl channels
- Adverse: diarrhea, abdominal pain, distension
Saline Laxative
Mg(OH)2
-Mech: hypertonic sol’n creates osmotic pressure;
incr fluid in GI, stims peristalsis
-Cathartic Dose: complete evac <3 hrs (colonoscopy prep)
Antidiarrheal Agents
Loperamide
- Mech: binds mu opiod receptors in intestinal sm. musc
- Effect: slows intestinal transit time
- Adverse: toxic megacolon, constipation, rare CNS sx
- Contra’d: ulcerative colitis, acute bacill/amoebic dystentery
IBS
Definitions
- chronic, recurring episodes cramps, bloating
- fxn’l dz: no underlying abnormalities
- diarrhea and/or constipation
- 70% women
- tx sx
IBS-D
Diarrhea sub-type
Drugs of choice
1) Loperamide (mu opiod agonist)
2) alosetron (restricted use, 5HT3 receptor antagonist)
- rare ischemic colitis side effects
3) anti-muscarinics (eg atropine; reduce sm musc tone)
IBS-C
Constipation Sub-type
Drugs of Choice
1) Mg(OH)2
2) tegaserod, 5HT4 agonist stims ACh; emergency only
- rish of heart attack, stroke, angina
IBD
Definitions
-chronic, relapsing structural dz w/ inflamm, ulcers, bleeding,
lesions, and immune response
-ulcerative colitis: lesions in colon; mucosal and submucosal
-Chron’s: lesions from mouth to anus, entire bowel wall
Acute IBD
Drugs of Choice
- prednisone:
1) reduce inflammation
2) reduce ulceration
3) initial remission
Chronic IBD
Drugs of Choice
- azathioprine (purine anti-metabolite)
- adverse: bone marrow suppression, rash, fever, nausea
Ulcerative Colitis
Drugs of Choice
-Topical sulfasalazine prodrug (5-ASA mesalamine active drug)
-for lesions in sm and lg instestine
-diff formulations target diff regions of bowel
-interrupts inflammatory pathway
-adverse: 40% intolerance; nausea, headache, hypersens,
bone marrow suppression
Chron’s Disease
Adjunct Therapies
- infliximab, an antibody to TNFa
- binds TNFa, blocking inflammatory effects
- adverse: increased infections
- can also be use for ulcerative colitis
