anti-emetics

Question 1

Anti-Cholinergic

Scopolamine

Answer 1

M1 antagonist - blocks parasympathetic impulses –> relaxes smooth muscle and decreases intestinal contractions

Helps motion sickness

AE: dry mouth, drowsiness, vision disturbances

Caution with CNS depressants, liver & renal failure

Question 2

Antihistamines

Diphenhydramine, dimenhydrinate, meclizine, promethazine

Answer 2

H1 antagonist - blocks H1 receptors in vestibular nucleus

Good for motion sickness, weak anti-emetics

AE: sedation/drowsiness, thick bronchial secretions, dry mouth, urinary retention

Question 3

Phenothiazine

Prochlorperazine, chlorpromazine

Answer 3

Inhibit M1 + D2 receptors in chemoreceptor trigger zone (area postrema) & H1 antagonist (sedative)

Use: severe N/V + intractable hiccups

AE: extra-pyramidal (muscle rigidity, spasm, tardive dyskinesia), orthostatic hypotension, increased prolactin –> lactation

Caution with CNS depressants + alcohol

Question 4

Butyrophenone

Droperidol

Answer 4

Central dopamine blockade

Post-op N/V (only given in OR)

AE: black box warning - prolonged QT, extra-pyramidal, drowsiness, dizziness

Question 5

Benzamides

Metoclopramide

Answer 5

Dopamine + serotonin antagonist

Use: N/V, gastroparesis

AE: tardive dyskinesia, restlessness, drowsiness, fatigue, insomnia

CI: hypersensitivity, pheochromocytoma, epilepsy

Caution with opiates, anti-psychotics, anti-cholinergics

Question 6

Serotonin Antagonists

Ondansetron (zofran)
Granisetron
Dolasetron
Palonosetrron

Answer 6

Block serotonin receptors peripherally (intestines) + centrally (chemoreceptor trigger zone)

Use: N/V post chemo, radiation, post-op

AE: headache, dizziness, constipation, prolonged QT (dola)

Question 7

Neurokinin Receptor Blockers

Aprepitant

Answer 7

Substance P + NK1 antagonist

Use: N/V after chemo (use with serotonin antagonists + corticosteroid)

AE: fatigue, drowsiness, decreases coumadin + BC pill effectiveness