Gastrointestinal Pharmacology Flashcards by Alexandra Monica Tan

At least 98% of PUD occurs in which part of the GIT?

Stomach and first portion of the duodenum

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What are other types of antacids aside from MgAlOH3?

Calcium carbonate

Sodium bicarbonate

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What is the MOA of antacids?

React with protons —> neutralize stomach acid

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What are the side effects of sodium bicarbonate?

Fluid retention
Belching
Metabolic alkalosis

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What are the side effects of calcium carbonate?

Hypercalcemia
Renal insufficiency
Milk alkali syndrome (Metabolic alkalosis)

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MgAlOH3 impairs absorption of what drugs?

Fluoroquinolones
Itraconazole
Tetracyclines
Iron

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Why are Aluminum and Magnesium given together?

They cancel out each other’s adverse effects
Mg: diarrhea
Al: constipation

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What are the available H2 recepor antagonists?

F-R-C-N
Famotidine
Ranitidine
Cimetidine
Nizetidine

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H2-receptor agonists are highly effective when?

Highly effective in noctural acid secretion

Modest effect on meal-stimulated secretion

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What are the available proton pump inhibitors

P-R-O-L-E
Pantoprazole
Rabeprazole
Omeprazole
Lansoprazole
Esomeprazole

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What is the MOA of PPIs?

Irreversible blockade of H/K/ATPase in gastric parietal cells -> long-lasting reduction in meal-stimulated and nocturnal acid secretion

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What is a noted adverse effect of chronic PPIs use?

Vitamin B12 deficiency

Malabsorption

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What are the available mucosal protective agents?

Sucralfate
Misprostol
Bismuth salicylate

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What is the MOA of sucralfate?

Binds to injured tissues
Forms a protective covering
Accelerates healing of peptic ulcers
Prevents recurrence

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What is the MOA of Misoprostol?

Binds to EP receptors
Promotes HCO and mucus secretion

Also causes uterine contraction
Prevents NSAID-induced gastric mucosal injury

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What is the MOA of bismuth salicylate?

Protecting coating on ulcerated tissue
Antimicrobial effects
Enterotoxin sequestration
Reduces stool frequency and liquidity in infectious diarrhea

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What are the SE of bismuth salicylate?

Black stool
Darkening of the tongue
Encephalopathy

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What are the available triple regimen therapy for H.pylori infection?

Tetracycline 500mg QID
Metronidazole 250mg QID
Bismuth salicylate 2tabs QID

Ranitidine bismuth citrate 400mg BID
Tetracycline 500mg BID
Clarithromycin/Metronidazole 500mg BID

Clarithromycin 250mg/500mg BID
Omeprazole/Lansoprazole 20mg/30mg BID
Metronidazole 500mg/Amoxicillin 1g BID

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What are the available prokinetic agents for the upper GI?

M-E-D
Metoclopramide
Erythromycin
Domperidone

What is the MOA of prokinetic agents?

Metoclopramide and Domeridone: block D2 receptors

Erythromycin: stimulates motilin receptors

Your prokinetic agents are the drug of choice for what condition?

Diabetic gastroparesis

Which prokinetic agent does not cross the BBB?

Domperidone

What are the mechanisms of action of laxatives?

B-I-L-S
Bulk-forming action —> reflex contraction of the bowel
Irritant/Stimulant on the bowel wall
Lubricating action —> easy passing of stool
Softening action on hard/impacted stool

What are the available bulk-forming laxatives?

Psyllium
Polycarbophil
Maltodextrin
Methylcellulose

What is the MOA of bulk-forming laxatives?

Indigestive, hydrophilic colloids that absorb water Form bulky, emollient gel that distends the colon Promotes peristalsis

What are the available stool softening laxatives?

G-D-M Glycerine suppository Docusate Mineral oil

What are the available stool-softening laxatives?

G-D-M Glycerine suppository Docusate Mineral oil

What are the available osmotic laxatives?

``` MS-PLMS Magnesium oxide Sorbitol Polyethylene glycol Lactulose Magnesium citrate Sodium phosphate ```

What are the available stimulant/cathartic laxatives?

``` ABS-CC Aloe Bisacodyl Senna Cascara Castor oil ```

What is a known side effect of cathartic laxatives?

Melanosis coli | -results from lipofucsin pigment accumulation in macrophages from intake of anthraquinone-containing laxatives

What are the available antidiarrheal agents?

``` CLD DK Diphenoxylate Difenoxin Colloidal bismuth Loperamide Kaolin + Pectin ```

What is the mode of action of antidiarrheal agents?

Activate opioid receptors in the ENS -> slows motility

Why are antidiarrheal agents not given in children less than 4yo? What is used to reverse this SE?

Paralytic ileus | Betanechol to reverse paralytic ileus

What are the available antiemetics?

``` P-A-T-D-O-G Palosetron Alosetron Tropisetron Dolasetron Ondansetron Granisetron ```

Antiemetics belong to what class? | What is its MOA?

5-HT3 receptor antagonist

What are the available immunomodulators for inflammatory bowel disease?

``` M-M-B-O-S Mesalamine Mesalazine Balsalazine Olsalazine Sulfasalazine ```

What is the MOA of immunomodulators

Unknown. Inhibits production of eicosanoid inflammatory mediators Not used for acute flare-ups of disease

What are the available therapy for mild, moderate, and severe IBS?

Mild: Antibiotics, Budesonide, Corticosteroids (topical), 5-aminosalicylates Moderate: Azathioprine/6-mercaptopurine, Methotrexate, TNF antagonist/, Corticosteroids (oral) Severe: Cyclosporine, Natalizumab, Surgery, TNF antagonist, Corticosteroids IV

What are the effects of ursodeoxycholic acid?

- decreases CE secrection -> decreased CE content in bile - dec endogenous BA conc + inhibits immune-mediated hepatocyte destruction -> stabilization of hepatocyte canalicular membranes

What are the uses of UDCA

Nonsurgical therapy for cholelithiasis Prevent gallstone formation in obese patients undergoing rapid weight loss Reduce liver function abnormalities in early stage primary biliary cirrhosis

What is the MOA of rebamipide?

Enhances mucosal defense by scavenging free radicals and temporarily activating COX-2 genes

This is a prokinetic benzamide derivative that inhibits dopamine and acetylcholinesterase

Itopride

What is the MOA of simethicone?

Changes surface tension of gas bubbles -> collapse of foam bubbles -> easier passage of gas and preventing gas pockets in GIT

What is the MOA of racecadotril?

Inhibits enkephalinase -> increases endogenous opioids (enkephalins) -> inhibits adenylate cycles -> increased Cl- absortion Antisecretory effect: reduces secretion of water and electrolytes reducing frequency and duration of acute diarrhea

This probiotic has produces antimicrobial substances that are active against G(+) bacteria. What bacteria?

Bacillus clausii - S.aureus - E.facium - C.difficile

What are uses and MOA of silymarin?

Hepatoprotectant, anti-inflammatory, anti-carcinogenic - Antioxidant, scavenger and regulator of intracellular glutathione - CM stabilizer and permeability regulator - Promote rRNA synthesis - Inhibits transformation of stellate hepatocytes into myofibroblasts

What are the available anorectal preparations available and their corresponding uses?

DAFLON: Diosmin+Hesperidin - potent venotropic drug for venous insufficiency - improves lymph drainage and protects microcirculation - decreases PGE2 and TxA2 synthesis -> dec infammation FAKTU: Policresulen + Cinchocaine - arrests bleeding by coagulation and vascular contraction - antimicrobial action by coagulation properties and acidic pH Cinchocaine: local anesthetic action, relieve pain and itching