GI pharmacology Flashcards

1
Q

Name 3 Histamine-2 (H2) receptor antagonists.

A

1) Cimetidine (Tagamet)
2) Ranitidine (Zantac)
3) Famotidine (Pepcid)

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2
Q

What is the MOA of H2 receptor antagonists?

A

antagonism of gastric H2 receptors inhibits hydrochloric acid production and raises gastric pH

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3
Q

What are the drug interaction concerns with Cimetidine (Tagamet)?

A

inhibits CYP450 enzymes found on hepatic microsomes, thereby interfering with its normal function of metabolizing drugs
-prolongs action of drugs that are metabolized by the liver–> theophylline, coumadin, warfarin, aminophylline, phenytoin, halothane, lidocaine, phenobarbital, diazepam, propanolol, labetalol, meperidine, quinidine, TCAs (imipramine and desipramine), and calcium channel blockers

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4
Q

What is special about ranitidine in comparison to cimetidine in regards to side effects?

A

does not traverse the BBB effectively, so it causes less somnolence, lethargy, confusion, hallucinations, and seizures than cimetidine

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5
Q

Why are non-particulate antacids preferred over particulate antacids?

A

b\c they cause less problems than particulate antacids if aspirated

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6
Q

What drug helps to control gastric motility?

A

metoclopramide (reglan)

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7
Q

What are the actions of metoclopramide (Reglan)?

A
  • increase LES tone (prevents reflux into the esophagus)
  • increase gastric motility (promotes gastric emptying)
  • decrease in tone of pyloric sphincter (permits passage of foodstuffs from the stomach to the small intestine)
  • relaxation of the duodenum (this makes room for food coming from the stomach)
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8
Q

How does metoclopramide effects gastric pH?

A

it has No effect on gastric pH

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9
Q

Incidence and severity of aspiration pneumonitis are reduced if:
gastric pH is > ______.
gastric volume is < ______.

A

pH above 2.5

volume < 25mL (0.4ml/kg)

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10
Q

Histamine-2 antagonists reduce ________ ________ ______ secretion, and this action increases gastric pH and decreases gastric volume.

A

gastric hydrochloric acid

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11
Q

________ decreases gastric volume without altering pH.

A

Metoclopramide (reglan)

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12
Q

What 3 drugs are competitive dopamine antagonists?

A

1) droperidol (Inapsine)
2) prochlorperazine (Compazine)
3) metoclopramide (Reglan)

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13
Q

Why should droperidol be avoided in the Parkinsons patient?

A

b\c of its dopamine receptor antagonist activity

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14
Q

Which antimuscarinic is used as an antiemetic?

A

scopolamine

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15
Q

Name a selective serotonin-3 antagonist.

A

ondansetron (Zofran)–> 5HT3 antagonist

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16
Q

What is the most common side effect of zofran?

A

headache