drugs for git disorders.pptx
TRANSCRIPT
7/27/2019 DRUGS FOR GIT DISORDERS.pptx
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DRUGSFOR
GASTROINTESTINALDISORDERS
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• Peptic ulcer disease
- Due to acid and pepsin
- Most common forms:
1. Helicobacter pylori-associated ulcers
2. NSAID-induced ulcers
3. Stress ulcers
- S/Sx: Epigastric burning pain, nocturnal pain,
relieved by food (duodenal ulcer),worsen with food (gastric ulcer)
- Complications: bleeding, perforation
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- Diagnosis:
Upper GI endoscopy or radiography
HP infection: Endoscopic-mucosalbiopsy for culture, histology or
urease
Non-endoscopic - serologic antibodydetection test, Urea breath test, stool
antigen test
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• H +/K+-ATPase pump/Proton pump
- stimulated by acetylcholine, histamine,
and gastrin
- inhibited by prostaglandins
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1. Antacids
- neutralizes gastric acid
- aluminum hydroxide, magnesium hydroxide (milkof magnesia/ MOM), calcium carbonate,
Sodium bicarbonate (baking soda)
- S/E
Al- constipation; Mg-diarrhea; Ca-kidney stones;
Na-fluid retention; HCO3-alkalosis
Interactions: Al, Mg, Ca + Tetracyclines/Fluroquinolones
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2. H2-receptor antagonists
- cimetidine, ranitidine, famotidine,nizatidine
- histamine congeners
- S/E: well tolerated; headache, dizziness,drowsiness, constipation/ diarrhea
Cimetidine: gynecomastia,
galactorrhea, inhibits metabolism of drugs (theophylline, warfarin,phenytoin)
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3. Proton Pump Inhibitors
- omeprazole, lansoprazole, esomeprazole,
pantoparazole, rabeprazole
- inhibits H+/K+-ATPase pump in gastric
parietal cells
- degraded in acidic environment; formulated
as delayed-release capsules
- S/E: headache, dizziness, drowsiness,
nausea decrease the absorption of
ketoconazole
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4. Prostaglandins
- misoprostol
- PGE, analog
- prevents NSAID-induced ulcer, abortifacient
- S/E: diarrhea
5. Mucosal Protectants
- sucralfate - aluminum salt of sucrose octasulfate
- Colloidal bismuth subcitrate - also anti –H. pylori
-S/E: constipation
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Regimens to Eradicate H.pylori
1. PPI-based 3-drug regimen
PPI + Clarithromycin + amoxicillin or
Metronidazole10-14 days
2. Bismuth-based 4-drug regimen
PPI +Bismuth subsalicylate + Metronidazole+Tetracycline or Amoxicillin or Clarithromycin
7 days
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• Gastroesophageal Reflux Disease (GERD)
– Retrograde movement of gastric contents from
the stomach into the esophagus) – Caused by defective lower esophageal sphincter
pressure and function
– S/Sx: heartburn or pyrosis
– Complications: esophagitis, esophageal CA
– Diagnosis:
• Endoscopy-to assess the mucosa
• 25-hour ambulatory pH monitoring
• Omeprazole trial
• Esophageal manometry-for candidates of antireflux
surgery
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Treatment:
Phase I: lifestyle changes and antacids and/or low dose
H2RAs or PPIs
Phase II: high dose H2RA s or PPIs
Phase III: Surgery
Lifestyle changes:
Elevate the head of the bed
Dietary changes: avoid fatty foods, alcohol, coffee, spicy
foods, orange juice, eat small meals and avoid eating prior tosleeping
Stop smoking
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DIARRHEA
– increased frequency and decreased
consistency of fecal discharge
1. Oral Rehydration Salts/ Oral Glucose-Electrolytesolution (Oresol)
–
prevents dehydration – contains sodium, chloride, potassium, glucose and
citrate (245 mOsm/L)
2. Antimotility agents
- opioids: diphenoxylate (+ atropine),loperamide, paregoric, opium tincture,difenoxin (metabolite of diphenoxylate)
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3. Adsorbents
- kaolin-pectin mixture, polycarbophil, attapulgite
4. Antisecretory
a. bismuth subsalicylate-treatment and preventionof traveler’s diarrhea
b. Enzymes (lactase)
c. Bacterial replacement (Lactobacillus)
5. Octreotide
- analog of somatostatin, blocks the release of serotonin
- for patients with carcinoid tumors (secretesserotonin)
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• CONSTIPATION
1. Bulk-forming laxatives
- fiber (fruits, vegetables, cereals), bran methyl cellulose,psyllium
- increase stool bulk causing peristalsis
2. Osmotic Laxatives
a. saccharides: lactulose, sorbitol
b. saline: magnesium hydroxide/citrates/sulfate (PO, enema)
c. glycerin (suppository)
3. Stimulant Laxatives
- stimulates mucosal nerves in the colon
a. diphenylmethane derivatives: bisacodyl, phenolphthalein
b. anthraquinone derivatives: cascara sagrada,
c. castor oil-active: ricinoleic acid
S/E: dependence on laxatives: daily use is discouraged
4. Stool Softeners/ Emollient Laxatives
-docusate
-surfactant which facilitates mixing of water and oily materials
-used to prevent constipation (post-MI, rectal surgery etc)
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• VOMITING
-triggered by impulse to the vomiting center in themedulla
- Chemoreceptor trigger zone-associated with chemically-induced vomiting (eg. chemotherapy)
1. Dopamine antagonist
a. phenothiazines (e.g. prochlorperazine,
chlorpromazine, promethazine)b. metoclopramine - prokinetic: aids gastric emptying,
accelerates transit through small bowel
-S/E: extrapyramidal effects
2. Selective Serotonin Receptor Inhibitors
- ondansetron, granisetron, dolasetron, palonosetron
- block serotonin receptor on sensory vagal fibers in thegut wall
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3. Antihistaminic-anticholinergic agents
- dimenhydrinate, diphenhydramine, meclizine,scopolamine
4. Cannabinoids -marijuana, nabilone, dronabinol
S/E: mood changes, hyperglycemia
5. Corticosteroids
-dexamethasone- used in chemotherapy induced vomiting
S/E: mood changes, hyperglycemia
6. Benzodiazepines
- lorazepam7. Substance P/Neurokinin 1 Receptor Antagonist
- aprepitant (oral formulation)
8. Pyridoxine