Antiemetics Flashcards
What are glucocorticoids mentioned?
Dexamethasone and Methylprednisolone.
What is the mechanism of action of Dexamethasone?
May work via inhibition of the nucleus tractus solitarius, serotonin reduction, and prostaglandin synthesis.
What are the uses of Dexamethasone?
Multimodal PONV prophylaxis in moderate to high-risk patients. Combination therapy recommended (e.g., 5-HT3 antagonist + dexamethasone for children at moderate/high risk).
What is the dosage of Dexamethasone?
4 mg IV after induction.
What are the adverse effects of Dexamethasone?
Can increase blood glucose levels.
What are the clinical considerations for Dexamethasone if PONV occurs within 6hrs postop?
If PONV occurs within 6 hours post-op, repeat doses of the same prophylactic antiemetic should be avoided.
What is the use of Methylprednisolone?
Given for PONV.
What is the dosage of Methylprednisolone?
40 mg IV.
What is the mechanism of action of Ondansetron?
Blocks 5-HT3 receptors in the chemoreceptor trigger zone and GI tract.
What are the uses of Ondansetron?
Most widely used antiemetic; more effective for vomiting than nausea.
What is the dosage of Ondansetron?
4 mg IV at the end of the procedure.
What is the duration of Ondansetron’s effect?
4-6 hours.
What are the adverse effects of Ondansetron?
High doses prolong QT interval.
What is the dosage of Granisetron?
Given at the end of surgery.
What is the mechanism of action of Palonosetron?
Longer half-life than other 5-HT3 antagonists (44 hours).
What are the uses of Palonosetron?
Preferred for PDNV (Post-Discharge Nausea and Vomiting).
What are the clinical considerations for Palonosetron?
Efficacy increases when combined with dexamethasone.
What is the dosage of Palonosetron?
Given at induction.
What is the mechanism of action of NK1 Receptor Antagonists?
Blocks NK1 receptors in the nucleus of the solitary tract (NST), where vagal inputs trigger vomiting.
What is the use of Aprepitant?
NK1 Receptor Antagonists, FDA-approved for PONV.
What is the use of Rolapitant?
NK1 Receptor Antagonists, Has a long half-life, making it effective for PDNV.
What is the mechanism of action of Droperidol?
Blocks dopamine receptors in the CNS.
What are the uses of Droperidol?
PONV prophylaxis.
What is the dosage of Droperidol?
0.625 – 1.25 mg IV given at the end of surgery.
What are the adverse effects of Droperidol?
May cause extrapyramidal side effects; contraindicated in Parkinson’s disease.
What is the use of Haloperidol?
Alternative to droperidol.
What is the dosage of Haloperidol?
1 – 2 mg IV.
What are the adverse effects of Haloperidol?
QT prolongation risk.
What is the mechanism of action of Transdermal Scopolamine?
Blocks cholinergic impulses to prevent nausea and vomiting.
What are the uses of Transdermal Scopolamine?
Most effective when used with PCA (patient-controlled analgesia) for postoperative pain.
What is the dosage of Transdermal Scopolamine?
1.5 mg patch applied behind the ear 4 hours before anesthesia.
What is the duration of Transdermal Scopolamine’s effect?
3 days.
What are the adverse effects of Transdermal Scopolamine?
Sedation, dizziness, dry mouth, blurred vision.
What is the mechanism of action of Benzodiazepines (Midazolam)?
Reduces dopamine’s emetic effects and decreases serotonin release.
What are the uses of Midazolam?
Sedation near the end of surgery. May help reduce PONV but can prolong recovery.
What is the mechanism of action of Metoclopramide?
Weak antiemetic with mild dopamine receptor-blocking effects.
What are the uses of Metoclopramide?
PONV prophylaxis.
What is the dosage of Metoclopramide?
Doses >20 mg effective.
When should Metoclopramide be given?
Given at the end of surgery.
What are the adverse effects of Metoclopramide?
Can cause dyskinesia and extrapyramidal effects at high doses. Contraindicated in Parkinson’s disease and bowel obstruction.
What are the final notes on PONV prophylaxis?
Multimodal PONV prophylaxis is recommended for moderate/high-risk patients. Combination therapy (e.g., 5-HT3 antagonist + dexamethasone) is preferred. Rescue therapy should differ from the prophylactic drug used. If PONV occurs within 6 hours post-op, do not repeat the same prophylactic antiemetic.
