GI Tract Pharmacology Flashcards
what is GERD
movement of gastric contents into esophagus
caused by relaxation of lower esophageal sphincter
what is PUD
peptic ulcer disease
ulcers in upper Gi tract
causes: h. pylori, NSAIDs, stress
Antacid “OIAs”
Use: neutralize gastric activity (primarily for acid reflux)
Dosing: frequent
Side Effects: minimal (constipation from aluminum/calcium, diarrhea from magnesium)
Interactions: binds to other drugs/reduces effectiveness
Histamine-2 Receptor Antagonists “OIAs”
Uses: Inhibit histamine, gastrin, and ACh stimulated acid release; helps with basal and meal-related acids.
Dosing: Usually once to twice a day dosing.
Side Effects: Diarrhea, dizziness, muscle pain, rashes; Cimetidine has multiple drug interactions.
Interactions: Upregulation of receptors may diminish effectiveness with long-term use; cessation may lead to rebound acid secretion.
Proton Pump Inhibitors (PPIs) “OIAs”
Uses: Irreversibly inhibit the H+/K+-ATPase pump on parietal cell membrane, stopping the final step of acid secretion; very effective at healing ulcers and preventing stress ulcer formation.
Dosing: Once daily dosing; need an acidic environment to function.
Side Effects: Similar to H2 Blockers; concerns with long-term use include decreased calcium absorption and increased risk for infection.
concern w/ longterm use causes decrease in calcium absorption/increased risk of infection
neural mechanism for N/V - CTZ
chemoreceptor trigger zone
Senses toxins and drugs in blood and cerebrospinal fluid.
Involves dopamine, serotonin (5HT3), neurokinin, and opioid receptors.
neural mechanism for N/V - vestibular
Responsible for motion sickness.
Involves muscarinic and histamine-1 receptors
how do anticholinergics work for nausea
binds to ACh receptors in vestibular nuclei to block messages in vomiting center
how do neuroleptic drugs work for nausea
similar to antipsychotic agents - blocks dopamine in CTZ
how do antihistamines work for nausea
H1-blocking agents that inhibit vestibular input to the CTZ, blocks Ach binding to H1 in vestbiular nuclei
how do prokinetic drugs work for nausea
block dopamine at CTZ - side use stimulate peristalsis in the stomach
how do serotonin blockers work for nausea
blocks serotonin receptors in GI tract, CTZ, and vomiting center
what is diarrhea
frequent passage of loose stools, either acute or chronic
mostly due to electrolyte imbalances in intestinal tract
chronic diarrhea have underlying GI conditions
how do adsorbents work for diarrhea
coats GI tract, binds to diarrhea causing bacteria and reduces irritation providing relief
how do opiates (lite) work for diarrhea
decreases GI motility and propulsion by increasing absorption of electrolytes and water
reduces pain w/ diarrhea
what is constipation
movement disorder of colon/rectum = infrequent and painful defecation of sense of incomplete evacuation
how do bulk-forming laxatives work for constipation
increases water absorption to soften/bulk up stool and stimulates paristalsis
how do emollient laxatives work for constipation
facilitate water and fat absorption into the stool, reabsorption of water back into the body is blocked
how do hyperosmotic laxatives work for constipation
works in large intestine by drawing fluid into colon
how do saline laxatives work for constipation
increases osmotic pressure by increasing electrolyte and water concentrations in small bowel. increases peristalsis but with watery stools
how do stimulant laxatives work for constipation
stimulates enteric nervous system and peristalsis.
key facts about IBS?
- 3 types - IBS-C, IBS-D, IBS-M (rare)
- idiopathic etiology
- affects women 2:1, often btwn ages 20-30
- 10-15% of population has it, but only 15% of that seek help
symptoms of IBS
- lower abd. pain
- bloating
- diarrhea sx >3 days
- constipation sx >3 weeks (straining, incomplete)
- fatigue, anxiety, depression
what is IBD?
split betwen Crohn’s and Ulcerative Colitis.
chronic inflammatory multisystem condition
