DRUGS FOR GIT DISORDERS.pptx

7/27/2019 DRUGS FOR GIT DISORDERS.pptx

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DRUGSFOR

GASTROINTESTINALDISORDERS



• 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



- 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



• H +/K+-ATPase pump/Proton pump

- stimulated by acetylcholine, histamine,

and gastrin

- inhibited by prostaglandins



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



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)



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



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



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



• 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



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



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)



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)



• 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)



• 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



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

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DRUGS FOR GIT DISORDERS.pptx