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43 Cards in this Set

  • Front
  • Back
Which 2 substances are used to induce vomiting following ingestion of a toxic substance?
Ipecac & Charcoal (safer & more effective)
What are the contraindications for using ipecac syrup?
1. following ingestion of a caustic agent (acid or alkali)
2. in pt w/dec level of consiousness or impaired gag reflex
3. cases in which toxin is expected to cause loss of consciousness or impairment of gag reflex w/in short time period
4. following ingestion of liquid hydrocarbon w/ low viscosity.
How do they think ipecac works and how long does it take to vomit?
Takes 30 min. Mechanism involves activation of vagal afferents in abdomen.
Which structures are impt for maintaining balance when stationary?
Utricle & saccule. Have hair cells covered w/ cilia & dense statoconia crystals. Head moves & weight of statoconia causes cilia to bend-->hair cells get dopolarized or hyperpolarized. Vestibular nerves synapse w/ hair cells & relay position to brain stem and cerebellum.
Which structure is impt for detecting changes in position?
Semicircular canals.
Why do you get motion sickness?
Input from vestibular apparatus regarding position or movement differs from what would be expected based on experience.
What are the inhibitory receptors in the vestibular nuclei?
GABAA, GABAB, 5-HT1A, serotonergic, and mu and delta opioid receptors.
What are the stimulatory receptors in the vestibular neuclei?
D2 dopaminergic, 5-HT2 serotonergic, muscarinic Ach, and H2 and H1 histamine receptors.
Which drugs can inhibit motion sickness but initially induce vomiting due to action on area postrema?
Opioids, ex. morphine
What are the most effective drugs for tx of motion sickness?
Muscarinic Ach receptor antagonists, ex. hyoscine.
What are the most commonly used drugs for tx of motion sickness and have a duration of 24 hrs?
H1 receptor antagonists.
Describe the emetic pathway for motion sickness.
Nucleus tractus solitarus-->nerve impulses-->antiperistalsis-->Upper GI sphincter opens and epiglottis closes-->contraction of diaphragm and ab muscles-->inc intragastric P-->LES relaxes
Which chemo drug is highly emetogenic?
Which chemo drugs are moderately emetogenic?
Combo or one of doxorubicin, cyclophosphamide, epirubicin, carboplatin.
Whats the difference b/w acute and delated emesis?
Acute-->w/in 24 hrs of chemo
Delayed-->more than 24 hrs most chemo.
What is the standard anti-emetic therapy for acute emesis from moderately and highly emetogenic chemo?
5-HT3 receptor antanogist (ondansetron, granisetron, dolsetron, tropisetron) in combo w/ corticosteroids (dexamethasone)
Cytotoxic drugs cause the release of what from enterochromaffin cells of the stomach?
5-HT -->acts on 5-HT3 receptors on vagal afferents-->vagal afferents synapse @ dendrites of nucleus tractus solitarus.
What is the area postrema?
Area adjacent to CSF-containing ventricles. Doesnt have a BBB to large polar molecules, so can detect toxins in blood & CSF. Delayed emesis may involve this area b/c there is a projection form area postrema to NTS.
What prevents delayed emesis after cisplatin chemo?
Antagonists of substance P receptor, neurokinin-1. (NOT 5-HT3 receptor antagonists!)
What combo is currently given to prevent delayed emesis due to highly and moderately emetogenic chemo agents?
Metoclopramide & Corticosteroid.
Once anticipatory chemo emesis occurs, what tx should be given?
Anxiolytic meds (BZD's)
What receptors are found in the vomiting center (medulla)?
Muscarinic (5-HT3) and histamine (H1)
What receptors are found at the vestibular nuclei?
Muscarinic, H1 (so can you H1 and muscarinic Ach antagonists)
What are the 5 groups of drugs that can be used as antiemetics?
1. Serotonin 5-HT3 antagonists
2. Dopamine D2 antagonists
3. Anticholinergics
4. H1 Antihistamines
5. Cannabinoids
What are the indications for serotonin 5-HT3 antagonists?
(ondansetron, granisetron, dolasetron, palonosetron, ramostron)
-chemo induced nausea & vomiting--given 30 minu before chemo.
-postop & postradiation nausea and vomiting
What are the SE of Serotonin 5;HT3 antagonists?
HA & constipation, prolongation of QT interval, excellent safety profile
Which antiemetic drug has the most pronounced prolongation of the QT interval and thus greatest effect on the heart?
When would you give a dose reduction w/ serotonin 5 HT-3 meds?
w/ hepatic insufficiency and NOT renal insufficiency (even though excreted by both organs)
D2 antagonists antagonize receptors where?
Which of the D2 antagonists cannot cross the BBB?
Domperidone CAN, Metoclopramide CANNOT
Which drugs are prokinetic agents b/c of their 5-HT4 agonist activity?
D2 antagonists
Which D2 antagonist can only be given orally?
domperidone. Metoclopramide also has an IV form
Which antiemetic drug causes extrapyramidal side effects?
Metoclopramide as it crosses the BBB, so domperidone is better tolerated.
Which antiemetic drug is used for postop nausea & vomiting, causes QT prolongation, is very potent and sedative, is used for schizophrenia, and is stronger than haloperidol?
Droperidol (D2 antagonist)
Which drugs are antipsychotics w/ potent antiemetic property due to D2 antagonism?
Which antiemetic drug is used in pregnancy and used by NASA for space motion sickness?
Promethazine (H1 antihistamine)
What are the most effective drugs for motion sickness?
H1 antihistamines.
(Meclizine, Cyclizine, Dimenhydrinate, Diphenydramine, Promethazine)
Which drug is an NK1 receptor antagonist? It can be combined w/ serotonin antagonist & corticosteroid for prevention of acute or delayed N & V. SE: Fatigue, dizziness, diarrhea.
Which drug is used as a transdermal patch for motion sickness?
Scopolamine (anticholinergic)
What are 2 cannabinoids used as an antiemetic?
Dronabinol and Nabilone.
During which weeks does vomiting during pregnancy occur?
starts in 4th-7th week after LMP and resolves by 20th week of gestation
What is the best tx for morning sickness?
try to avoid pharmaceutical tx-->start w/ dietary changes including small, frequent bland meals, low fat, hi carb, salty, sour.
Which drugs have been found to be better than a placebo for pregnancy emesis?
pyridoxine (B6), phenothiazines, trimethobenzamide or ondansetron, antihistamines, anticholinergics.