Antiemetic / GI protectant

Question 1

Ondansetron (Zofran) dose, onset, peak, duration?

Answer 1

dose: 4 mg
onset: 30 minutes (i think)
peak: 2 hours
duration: 4 - 24 hours

Question 2

Ondansetron (Zofran) mechanism of action?

Answer 2

• 5-HT3 receptor antagonist or serotonin antagonist
• binds to ligand-gated ion channels in GI tract and the brain, preventing binding of serotonin and the vagal effects that result from stimulation of vomit reflex

Question 3

How is ondansetron (Zofran) metabolized and eliminated?

Answer 3

hepatic metabolism

renal elimination

Question 4

When is ondansetron (Zofran) contraindicated?

Answer 4

with decreased GI motility or decreased lower esophageal sphincter tone

Question 5

Droperidol (Inapsine) dose, onset, peak, duration?

Answer 5

dose: 0.625 - 2.5 mg
onset: 1 - 2 minutes
peak: 30 minutes
duration: 2 - 4 hours

Question 6

Droperidol (Inapsine) mechanism of action?

Answer 6

• dopamine-2 (D2) receptor antagonist

- inhibits D2 receptors in chemoreceptor trigger zone

Question 7

Effects of droperidol (Inapsine) on the body? (and random facts…)

Answer 7

cardiac
- prolongs QT interval => torsades de pointes

• decreases BP (d/t decreases in alpha adrenergic blockade)
• anti-dysrhythmic (0.2 - 0.6 mg/kg for tachydysrhythmias in WPW)

Question 8

How is droperidol (Inapsine) metabolized and eliminated?

Answer 8

hepatic metabolism

renal elimination

Question 9

What are zofran and droperidol categorized as?

Answer 9

both are antiemetics

zofran - serotonin antagonist

droperidol - dopamine antagonist

Question 10

Diphenhydramine (Benadryl) dose and duration?

Answer 10

dose: 50 mg
duration: 3 - 6 hours

(no onset or peak)

Question 11

Diphenhydramine (Benadryl) mechanism of action?

Answer 11

• H1 antagonist

- selectively antagonizes H1 receptors, blocking histamine activation of gastric parietal cell proton pump

Question 12

Effects of diphenhydramine on the body? (and random facts…)

Answer 12

pulmonary - may provide some protection against bronchospasm and opioid induced ventilatory depression (secondary to CO2 response depression)

cardiac - tachycardia is common

neuro - somnolence; impaired cognition

other - dry mouth, blurred vision, urinary retention.

beneficial for PONV and motion sickness/inner ear symptoms

Question 13

Diphenhydramine (Benadryl) is categorized as?

Answer 13

a sedative, antipuretic, antiemetic, and as treatment of anaphylaxis

Question 14

Ranitidine (Zantac) dose, peak, and duration?

Answer 14

dose: 2 - 4 mg/kg
peak: 1 - 3 hours
duration: 1.5 - 2.5 hours

(no onset time)

Question 15

Ranitidine (Zantac) mechanism of action?

Answer 15

• H2 antagonist; proton pump inhibitor

- selectively antagonizes H2 receptors, blocking histamine activation of gastric parietal cell proton pump

Question 16

Effects of ranitidine (Zantac) on the body?

Answer 16

cardiac - rare dysrhythmias (bradycardia, heart block, or hypotension)

neuro - rare mental confusion

other - *minimal CYP-450 interactions; *all side effects are rare

Question 17

Should the ranitidine dose be increased or decreased with advancing age and/or renal dysfunction?

Answer 17

decrease the dose

Question 18

How is ranitidine metabolized and eliminated?

Answer 18

hepatic metabolism

renal elimination

Question 19

How is diphenhydramine metabolized and eliminated?

Answer 19

hepatic metabolism

renal elimination

Question 20

Omeprazole (Prilosec) dose, onset, peak, duration?

Answer 20

dose: 20 mg PO
onset: 2 - 6 hours
peak: 2 - 4 hours (strange, i know)
duration: > 24 hours

Question 21

Omeprazole (Prilosec) mechanism of action?

Answer 21

• proton pump inhibitor

- directly inhibits the H+/K+ ATP-ase proton pump, leading to an increase in gastric pH and a decrease in fluid volume

Question 22

Effects of omeprazole (Prilosec) on the body? (and random facts…)

Answer 22

neuro - may cause headache, agitation, or confusion

other - *should be administered > 3 hours prior to induction; some GI side effects may be seen; no renal or hepatic dosing is necessary

Question 23

How is omeprazole metabolized?

Answer 23

hepatic metabolism

renal elimination

Question 24

Metoclopramide (Reglan) dose, onset, peak, duration?

Answer 24

dose: 10 - 20 mg, given over 3 -5 minutes
onset: 1 - 3 minutes
peak: 5 minutes
duration: 1 - 2 hours

Question 25

Metoclopramide (Reglan) mechanism of action?

Answer 25

• GI prokinetic
• dopamine-2 (D2) receptor antagonist; produces selective cholinergic stimulation of GI tract by:
  1) increasing SM tone in lower esophageal sphincter and stomach
  2) increasing gastric and small intestine motility
  3) relaxes pylorus and duodenum when stomach contracts

Question 26

How is metoclopramide (Reglan) metabolized and eliminated?

Answer 26

hepatic metabolism

renal elimination

Question 27

Effects of metoclopramine on the body? (and random facts…)

Answer 27

neuro - extra-pyramidal effects if on anti-psychotics; *avoid if history of seizures

other - *DO NOT GIVE if GI symptoms; *increases lower esophageal sphincter tone and GI motility; *speeds gastric emptying; *antiemetic action; *decreases gastric fluid volume

• inhibits plasma cholinesterase activity; opioid induced GI stasis and N/V is blunted by this drug