Nausea and vomiting Flashcards
Why are antiemetics generally only prescribed when the cause of vomiting is known?
Antiemetics may delay diagnosis, especially in children, when the cause of vomiting is unknown.
What are common antihistamines used as antiemetics?
Cinnarizine, cyclizine, promethazine hydrochloride, and promethazine teoclate.
What is a key side effect of antihistamines used as antiemetics?
Drowsiness and antimuscarinic effects - dry mouth, constipation, blurred vision, urinary retention, and in some cases, confusion or agitation.
What is the action of phenothiazines as antiemetics?
They are dopamine antagonists and act by blocking the chemoreceptor trigger zone in the brain.
What are some potential side effects of phenothiazines?
Severe dystonic reactions, especially in children.
What is metoclopramide’s action as an antiemetic?
It acts on the gastric smooth muscle, stimulating gastric emptying, and is effective for emesis associated with gastrointestinal and biliary disease.
Why is domperidone less likely to cause central side effects?
It does not readily cross the blood-brain barrier.
Which antiemetic drugs are used for chemotherapy-induced nausea and vomiting?
5HT3-receptor antagonists (e.g., granisetron, ondansetron, palonosetron), dexamethasone, and neurokinin 1-receptor antagonists (e.g., aprepitant, fosaprepitant).
5HT3-receptor antagonists (e.g., granisetron, ondansetron, palonosetron), dexamethasone, and neurokinin 1-receptor antagonists (e.g., aprepitant, fosaprepitant).
What is the first-line antiemetic treatment for nausea and vomiting during pregnancy?
Cyclizine or promethazine (antihistamines), prochlorperazine or chlorpromazine (phenothiazines), or doxylamine/pyridoxine combination.
What should be done if first-line antiemetic treatment for pregnancy-induced nausea is ineffective?
Switch to a second-line antiemetic such as oral metoclopramide, domperidone, or ondansetron.
When is oral prednisolone used as an antiemetic in pregnancy?
As third-line treatment when second-line antiemetics are ineffective.
What condition may require regular antiemetic therapy, intravenous fluid, and nutritional support during pregnancy?
Hyperemesis gravidarum.
What is the main treatment for postoperative nausea and vomiting?
A combination of antiemetic drugs from different therapeutic classes, such as 5HT3-receptor antagonists, dexamethasone, droperidol, and haloperidol.
Which drug is licensed to prevent motion sickness?
Hyoscine hydrobromide.
What is the main treatment for acute attacks of Ménière’s disease?
Short courses of antihistamines (e.g., cinnarizine, cyclizine, promethazine teoclate) and phenothiazines (e.g., prochlorperazine).
What is the role of betahistine dihydrochloride in Ménière’s disease?
It can reduce the frequency and severity of hearing loss, tinnitus, and vertigo in recurrent attacks.
