Week 6: Antiemetics and Prokinetics Flashcards
Ondansetron (Zofran) Indications for use and MOA
Indication: ideopathic N/V - non-sedating
5HT3 receptor antagonist: blocks serotonin peripherally on the vagal nerve terminals and centrally in the CTZ
5HT3 Receptor Antagonists (Zofran) ADRs
- serotonin syndrome (from other antidepressant meds combo)
- QT prolongation
meclizine (Dramamine) Indication and MOA
antihistamine & anticholinergic
Indication: Dizziness/spinning
- competes with histamine for H1 receptor sites, blocks the CTZ, and diminishes vestibular stimulation, and depresses labyrinthine functions through its central anticholinergic activity
Dries up the vestibular area - decreases dizziness
Dramamine/Meclizine ADRs
- drowsiness
- dry mouth
- blurred vision
- urinary retention
- paradoxical excitation in children may occur
Dramamine / Antihistamines cautions/ contraindications
- additive CNS depression when combined with CNS depressants
- avoid in patients with BPH, glaucoma, thickened respiratory secretions d/t anticholinergic effects
- Avoid in elderly patients
- ok in pregnancy- avoid in lactation
Scopolamine (Transderm Scop) Indication and MOA
Indication: sea sickness
Anticholinergic drug that blocks the action of acetylcholine at the parasympathetic sites in smooth muscle, CNS and secretory glands
Scopolamine ADRs
- drowsiness, dry mouth, blurred vision, urinary retention, dilated pupils
Scopolamine cautions/ contraindications
- Avoid in pts with glaucoma, BPH, thickened respiratory secretions d/t anticholinergic effects
- Avoid in pregnancy and lactation
- Not for use in pediatrics
- Avoid in elderly pts
Promethazine (Phenergan) and Prochlorper_azine_ (Compazine) [antiemetics] MOA
Blocks dopamine receptors in the CTZ as well as cholinergic, alpha 1 adrenergic, and histamine 1 receptors
Phenothiazines (promethazine (Phenergan) and prochlorperazine (Compazine)) ADRs
- sedation - agranulocytosis - dry mouth - blurred vision - constipations - bradycardia - hypotension
Compazine is a 1st generation antipsycotic - can cause blood dyscrasias
Promethazine - fatal respiratory depression in children < 2 y/o - should be avoided in pediatrics < 5 y/o
Extra parametal side effects (EPS) such as dystonia, akathisia and tardive dyskinesia
Phenothiazines (Phenergan/Compazine) cautions/ contraindications
- additive CNS depression with given with CNS depressants
- avoid in pts with glaucoma, BPH, thickened resp. secretions d/t anticholinergic effects
- NO elderly, pregnancy/lactation
- bradycardia, hypotension (because Alpha 1 receptors are blocked)
Dronabinol (Marinol) MOA
Cannabinoids - synthetic THC
-activates CB1 receptors in the brain, which prevents the pro-emetic effects of endogenous compounds such as dopamine and serotonin
Dronabinol (Marinol) ADRs
- depression
- dizziness
- paranoid thoughts
- somnolence
- palpitations
- tachycardia
- hypotension
Cannabinoids (Dronabinol/Marinol) cautions/ contraindications
- cautions in pts with hx of seizures - decreases the seizure threshold
- monitor pts w/ cardiac dz
- high potential for abuse (drug test will be +)
- not safe in pregnancy/lactation
PROKINETICS: Metoclopramide (Reglan) Indications and MOA
Indication: diabetic gastroparesis, GERD than is not responsive to H2/PPIs
Prokinetic agent - dopamine receptor antagonist in the CNS - stimulates motility in the upper GI tract
