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Antiemetics
GI Drugs
| Question | Answer |
|---|---|
| emesis | N/V, protective to expel toxins from GIT, involve central chemoreceptor trigger zone in the mid-brainstem, serotonin, dopamine, muscarinic receptor |
| antiemetics | used for chemotherapy, post radiation therapy, motion sickness, opioids use, postop, CINV (chemo induced N/V) inject 30min prior to chemo and combo w/corticosteroids and NK1 receptor antagonists, well tolerated |
| Serotonin 5HT3 receptor antagonists, CYP metabolized, prolong QT interval | Ondansetron (Zofran), Dolasetron, Granisetron, Palonosetron |
| Ondansetron (Zofran), Dolasetron, Granisetron | Serotonin 5HT3 receptor antagonists, antiemetics, PO/IV, 4-9 hr. half life |
| Palonosetron | antiemetic, serotonin 5HT3 antagonists, potent, longer half life 40 hr, high affinity |
| Antiemetics SE | HA, dizziness, contipation (GI 5HT) |
| Dolasetron | more pronounced QT elongation |
| avoid with other drugs that can alter cardiac conduction? | Class 1C, Class 3 |
| Corticosteriods Dexamethasone (Decadron) | antiemetic properties, enhance efficacy of 5HT3 receptor antagonists for CINV |
| Phenothiazines Prochlorperazine, Chlorpromazine | antiemetic, antihistamine, anticholinergic, good for motion sickeness, antagonize/block dopamine, histamine, cholingeric receptors at trigger zone, lots of SE |
| Phenothiazines SE Prochlorperazine, Chlorpromazine | sedative, anticholinergic effects |
| Antihistamines | diphenhydramine (benedryl) meclizine (bonine) scopolamine |
| diphenhydramine Benedryl | anticholinergic, antihistamine properties |
| Meclizine Bonine | antihistamine, minimal anticholinergic actions = less sadtion |
| scopolamine | antihistamine, potent muscarinic actions = very sedating, best tolerated as transdermal patch (sustained release) for motion sickness |
| What group of drugs have the suffix -setron? | antiemetics |
| Aprepitant (Emend) | highly selective PO substance P neurokinin 1 (NK1) receptor antagonist, used in combo w/antiemetics regimens (5HT3 antagonist+corticosteriod) to prevent CINV, CYP substrate, SE: fatigue, dizziness, diarrhea |
| What does substance P signify? | pain |
| Fosaprepitant | IV, converts to aprepitant within 30 min |
| What is Fos-? | prodrug with an esterase for activation (aprepitant) |
| Triple therapy for emesis? | 5HT3 antagonist dexamethasone NK1 receptor antagonist for 94% prevention |
| Double therapy for emesis? | 5HT3 antagonist dexamethasone for 67% prevention |
| Cannabinoid agonists (Cannabis) Dronabinol | used for nausea, appetite stimulant, pain, emesis, natural-occurring cannabinoid CB1 receptors in brain, SE: high, paranoia, withdrawal, abuse potential |