GI Drugs

Question 1

When can aspiration occur?

Answer 1

When barrier pressure (the difference between LES pressure and gastric pressure) decreases

Question 2

What positing puts patients at risk for aspiration?

Answer 2

Lithotomy

Question 3

What are patient risk factors for aspiration?

Answer 3

Intestinal obstruction, non-fasted, delayed gastric emptying, hiatal hernia, GERD, pregnancy, obesity, neuromuscular disease, decreased laryngeal reflexes, male, elderly

Question 4

What is the rule of thumb in prevention of aspiration pneumonitis?

Answer 4

Reduce gastric content acidity pH >2.5

Reduce amount of gastric content

Question 5

What is the mechanism of action for Reglan?

Answer 5

Acts peripherally as a cholinomimetic (facilitates ACh transmission at selective muscarinic receptors) and centrally as dopamine receptor antagonist

Question 6

What type of drug is Reglan?

Answer 6

Prokinetic

Question 7

What are the effects of Reglan use?

Answer 7

Enhances stimulatory effects of ACh on intestinal smooth muscle, increases LES tone, speeds gastric emptying and lowers gastric fluid volume

Question 8

What is the dose of Reglan?

Answer 8

10-20mg PO or IV

Question 9

Why is it important to administer Reglan slowly when given IV?

Answer 9

Intense feeling of anxiety and restlessness, followed by drowsiness, may occur with rapid administration.

Question 10

How is Reglan metabolized and excreted?

Answer 10

Metabolized in the liver and excreted in the urine

Question 11

How is Reglan metabolized and excreted?

Answer 11

Metabolized in the liver and excreted in the urine

Question 12

What type of drugs block Reglan effects?

Answer 12

Anticholinergics

Question 13

What conditions is Reglan contraindicated in?

Answer 13

Bowel obstruction
Parkinson’s disease
Pheochromocytoma (HTN crisis)

Question 14

How do pheothiazines and droperidol interact with Reglan?

Answer 14

Extrapyramidal effects potentiated with concurrent use

Question 15

What are two other medications that can be used as a prokinetic?

Answer 15

Erythromycin

Neostigmine

Question 16

Why isn’t Erythromycin typically used as a prokinetic?

Answer 16

Limited use due to possibility for developing antibiotic resistant bacteria

Question 17

What is the mechanism of action of proton pump inhibitors?

Answer 17

Selective and irreversible bind to the parietal cells in gastric mucosa causing suppression of gastric acid secretion through inhibition of H+ / K+ ATPase enzyme system at the surface of the parietal cells

Question 18

What is the dose of Prilosec?

Answer 18

Dose: 20-40mg PO

Question 19

How is Prilosec metabolized and excreted?

Answer 19

Metabolized by the liver after undergoing extensive first pass effect and excreted in the urine and feces

Question 20

When should PPIs be given prior to surgery?

Answer 20

The night before and morning of surgery

Question 21

When should PPIs be given prior to surgery?

Answer 21

The night before and morning of surgery

Question 22

What kind of drug interactions do PPIs have?

Answer 22

CYP2C19 inducers (St. Johns wart, rifampin), antiretrovirals, clopidogrel (decrease in antiplatelet effects), reduced clearance of diazepam and warfarin

Question 23

What is the mechanism of action of histamine-2 receptor antagonists?

Answer 23

Selective inhibition of histamine at H2 receptors of the gastric parietal cells resulting in reduced gastric acid secretion, gastric volume and hydrogen ion concentration

Question 24

How are H2 antagonists metabolized and excreted?

Answer 24

Metabolized in the liver and excreted in the urine

Question 25

What is the appropriate use of H2 antagonists in an allergic response?

Answer 25

Aids in histamine induced allergic response, but cannot be used for premedication (does NOT prevent histamine release from occurring)

Question 26

What H2 antagonist has lost favor in its use?

Answer 26

Tagamet due to multiple side effects that accompany its use

Question 27

How does Tagamet alter other drugs pharmacokinetics?

Answer 27

Alters absorption of some drugs by increasing gastric fluid pH such as lidocaine, propranolol, diazepam, theophylline, phenobarbital, warfarin, phenytoin

Question 28

How does Tagamet affect the male population?

Answer 28

Can cause gynecomastia and impotence

Question 29

Why are symptoms such as lethargy, hallucinations, and seizures seen with Tagamet use?

Answer 29

It crosses the BBB in high doses, especially in the elderly

Question 30

Why are symptoms such as lethargy, hallucinations, and seizures seen with Tagamet use?

Answer 30

It crosses the BBB in high doses, especially in the elderly

Question 31

What is the mechanism of action of antacids?

Answer 31

Neutralize acidty of gastric contents by providing a base (hydroxide, carbonate, bicarb, citrate) that reacts with H+ ions to form water

Question 32

What type of antacids are used preoperatively?

Answer 32

Only non-particulate used pre-operatively

Question 33

Why aren't particulate antacids used preoperatively?

Answer 33

Aspiration of particulate antacids produces abnormalities in lung function which can result in pulmonary edema, arterial hypoxemia, ARDS

Question 34

What are two non-particulate antacids that can be used preoperatively?

Answer 34

Bicitra | Polycitra

Question 35

How can non-particulate antacids affect other drugs?

Answer 35

Alter gastric and urinary pH: slow absorption of digoxin, cimetidine, ranitidine, speed absorption of phenobarbital Immediate onset

Question 36

When should non-particulate antacids be given preoperatively?

Answer 36

Should give 15-30 minutes prior to induction (Duration of effectiveness: 30-60 minutes)

Question 37

What is the dose of bicitra and what electrolyte does it contain?

Answer 37

15-30 mL PO | Each mL contains 1meq of Na and equals 1meq HCO3

Question 38

What is the dose of polycitra and what electrolyte does it contain?

Answer 38

15-30 mL PO | Each mL contains 1meq of Na, 1meq K, and equals 1meq HCO3

Question 39

Long term use of antacids can have what kind of effects?

Answer 39

``` Alterations in acid base status Infections Acid rebound Milk-Alkali Syndrome Phosphorus depletion Drug interactions ```

Question 40

Long term use of antacids can have what kind of effects?

Answer 40

``` Alterations in acid base status Infections Acid rebound Milk-Alkali Syndrome Phosphorus depletion Drug interactions ```

Question 41

What is milk-alkali syndrome?

Answer 41

Milk-alkali syndrome is caused by the ingestion of large amounts of calcium and absorbable alkali, with resulting hypercalcemia. If unrecognized and untreated, milk-alkali syndrome can lead to metastatic calcification and renal failure.