mcp: gi Flashcards

1
Q

antacids MOA

A

Neutralizes gastric acid in the stomach by raising gastric acid pH

H+ in lumen = gastric acid production

Neutralized by:

  • Al hydroxide
  • Mg2+ hydroxide
  • Na+ bicarbonate
  • Ca2+ carbonate
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2
Q

antacids indications

A

mild, infrequent heartburn

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3
Q

antacids onset of action

A

Rapid relief (5-15 minutes)

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4
Q

antacids duration of action

A

30 minutes – 3 hours

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5
Q

antacids formulations

A

Oral tablet/liquid, sublingual tablet

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6
Q

antacids precaution

A
  • young or advanced age
  • pregnant or breastfeeding women
  • on potentially interacting medications, consider separation of medicines
  • renally impaired
  • pre-disposed to bowel obstruction
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7
Q

antacids precaution, potentially interacting medications

A

thyroid medicines, certain antibiotics, iron supplements

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8
Q

antacids precaution, renally impaired

A

aluminum or magnesium containing antacids

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9
Q

antacids precaution, significant PMH for pre-disposed to bowel obstruction

A

reduced bowel motility, opiate-induced constipation, dehydration, fluid retention (i.e. heart failure)

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10
Q

antacids length of use

A

Not meant for chronic use of longer than 2 weeks

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11
Q

H2RAs MOA

A

-Reversibly binds histamine-2 receptors on parietal cells: decr gastric acid secretion

normal pathway:

  • Upregulation of stimulating G protein (Gs) increases cAMP levels
  • cAMP stimulates the H+/K+ pump, stimulating gastric acid secretion
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12
Q

H2RAs indications

A
  • Short-term treatment of mild-moderate heartburn

- Treatment of GERD and peptic ulcer disease for up to 12 weeks

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13
Q

H2RAs onset of action

A

Quick relief (30 minutes)

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14
Q

H2RAs duration of action

A

5 – 10 hours

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15
Q

H2RAs formulations

A

Oral tablet/capsule, oral liquid, IV solution

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16
Q

Cimetidine

A
  • First prototypical H2RA approved by the FDA in 1979, from which other members of the class were developed
  • Considered the most potent inhibitor of multiple liver enzymes, hepatotoxicity limits use of multiple medications cleared by the liver
  • Other potential drug-disease interactions: mental status changes, renal impairment
  • If you can avoid it, do it!
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17
Q

H2RAs administration

A
  • May take with or without food

- Okay to take with antacids

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18
Q

H2RAs length of use

A

limit self-treatment of OTC product for 2 weeks; up to 12 weeks if prescribed

19
Q

H2RAs side effects

A
  • Headache, dizziness, fatigue, somnolence, constipation, N/V/D
  • Generally well tolerated
20
Q

H2RAs cautions/contraindications

A
  • These medications will decrease activity of medications where acidic pH is required for absorption
  • Pregnancy category B- generally safe
21
Q

H2 receptor blocked by

A

Inhibited by:

  • famotidine
  • cimetidine
  • ranitidine
22
Q

PPI MOA

A

-decreases gastric acid secretion by irreversibly binding to and inhibiting the H+/K+ ATPase on parietal cells

  • Irreversible action: body must generate new proton pumps on parietal cells
  • Targets pumps that are actively secreting gastric acid
23
Q

PPI indications

A
  • persistent heartburn as frequent as >2 days per week or more than 3 months in duration
  • First line treatment for GERD and peptic ulcer disease (PUD)
  • Used in combination with antibiotics to treat H. pylori bacterial infection
24
Q

PPI onset of action

A
  • 2-3 hours initial; up to 4-5 days of therapy for maximum relief
  • NOT for immediate relief of heartburn symptoms!
25
PPI duration of action
12-24 hours
26
H+/K+ ATPase blocked by
``` omeprazole lansoprazole rabeprazole esomeprazole pantoprazole ```
27
PPI administration
-Take PPI 30-60 minutes before a meal OTC products: limit use to 14 day course of therapy -May repeat after 4 months if symptoms appear -Capsules may be sprinkled on applesauce if patient cannot tolerate capsule -Risk of rebound gastric acid hypersecretion if medication stopped abruptly
28
PPI side effects
- Headache, dizziness, constipation, N/D | - Major: fractures (affect pH, affect Ca absorption), hypomagnesemia, C. difficile diarrhea, Vitamin B-12 deficiency
29
Omeprazole/clopidogrel interaction…?
Rule of thumb: - New start patients: consider pantoprazole - Ongoing patients: No adjustment required
30
N/V stimulus
- Stimulus from GI tract triggers release of dopamine and serotonin - Dopamine and Serotonin activate D2 and 5-HT3 receptors in Chemoreceptor trigger zone (CTZ) - CTZ sends an impulse to the vomiting center -> activating the salivation & respiratory centers, pharyngeal, GI, and abdominal muscles – vomiting occurs
31
N/V complications
- Chronic Dehydration-Increased thirst, muscle cramps, darkened urine, dizziness, fatigue - Electrolyte Disturbances (the “Hypos”)- Hypokalemia, Hypomagnesemia, Hypocalcemia, Hyponatremia - Aspiration- Gastric acid penetration and esophageal erosion
32
N/V, when to refer
- REFER when N/V persists for over 48 hours or signs of bleeding are present - Other potential warning signs: AMS, complaints of stiff neck
33
N/V Management Strategy
Environmental-Treatment or prevention of an underlying cause (avoidance of smells/odors) Physiological- Correct the electrolyte imbalance (Pedialyte or diluted electrolyte solution) 1:1 Gatorade/Water Dietary- Easily tolerated high carbs and drinks (“BRAT” diet, ginger ale, water, peppermint) Neurochemical- Target the chemical receptors inducing the N/V stimulus: - Post-operative N/V (PONV): 5-HT3 antagonists - Chemotherapy Induced N/V (CINV): 5-HT3, D2 antagonists
34
N/V pharmacotherapy options
- 5-HT3 Serotonin Receptor Antagonists (ondansetron) | - Phenothiazine Derivatives (promethazine)
35
ondansetron MOA
Selective serotonin subtype-3 receptor antagonist
36
ondansetron indications
``` Prevention of N/V in the following settings: Chemotherapy Post-operative Radiation Hyperemisis Gravidarum (off-label ```
37
ondansetron onset of action
30 minutes
38
ondansetron duration of action
8-12 hours (typically TID dosing)
39
ondansetron formulations
oral tablet, dissolvable tablet, soluble film, IV solution
40
ondansetron administration
Orally Disintegrating Tablet (Zofran® ODT) - Do not remove from blister pack until ready for dose - Wash and dry hands - Peel backing off gently. Do not punch the tablet through the packaging - Place tablet on tongue and allow to completely dissolve before swallowing
41
ondansetron side effects
Headache, dizziness, fatigue, constipation, dry mouth
42
ondansetron serious adverse events
``` Dose dependent QT prolongation: -Affected by other QT prolonging medications Electrolyte abnormalities (decr K+, decr Mg2+) -Other considerations (Female gender, older age) ```
43
ondansetron cautions/considerations
hepatic impairment, increased risk for serotonin syndrome