Nausea and labyrinth disorders

Question 1

why should antiemetics only be prescribed when the cause of vomiting is known?

Answer 1

1) may delay diagnosis, particularly in children

2) cause can sometimes be treated e.g. DKA, digoxin or aantiepileptic overdose

Question 2

Phenothiazines are dopamine antagonists and act centrally by blocking the chemoreceptor trigger zone. these drugs are useful in the prophylaxis of N/V associated with what?

Answer 2

1) Diffuse neoplastic disease
2) Radiation sickness
3) Emesis caused by drugs such as opioids, general anaesthetics, and cytotoxics

Question 3

which phenothiazines are sedating?

Answer 3

1) Phlorpromazine hydrochloride

2) Prochlorperazine, perphenazine, and trifluoperazine are less sedating

Question 4

what side effects can occur, especially in children with the use of phenothiazines?

Answer 4

severe dystonic reactions sometimes occur

Question 5

Antipsychotic drugs such as haloperidol and levomepromazine are used for the relief of nausea and vomiting in what condition?

Answer 5

Terminal illness

Question 6

Metoclopramides activity closely resembles that of the phenothiazines. What type of N/V might it be better at treating in comparison to the phenothiazines and why?

Answer 6

1) Metoclopramide also acts directly on the GI tract

2) superior to the phenothiazines for emesis associated with gastroduodenal, hepatic, and biliary disease

Question 7

Domperidone acts at the chemoreceptor trigger zone. What is the advantage of using this drug over metoclopramide or phenothiazines?

Answer 7

less likely to cause central effects such as sedation and dystonic reactions because it does not readily cross the blood-brain barrier

Question 8

Domperidone is particually useful for treating N/V in which condition?

Answer 8

In Parkinson’s disease, it can be used to treat nausea caused by dopaminergic drugs

Question 9

1) Granisetron and ondansetron are useful for N/V in which situations?
2) Palonosetron is licensed for the prevention of nausea and vomiting associated with what?

Answer 9

1) In patients receiving cytotoxics and in postoperative nausea and vomiting
2) Palonosetron : Moderately or highly emetogenic cytotoxic chemotherapy

Question 10

Dexamethasone has antiemetic effects and it is used in vomiting associated with what?

Answer 10

cancer chemotherapy. (It can be used alone or with metoclopramide prochlorperazine, lorazepam etc)

Question 11

list 3 neurokinin 1-receptor antagonists

Answer 11

Aprepitant, fosaprepitant, and rolapitant (these drugs are given with dexamethasone and a 5HT3-receptor antagonist)

Question 12

For each of the following state what they are indicated to treat:

1) Aprepitant
2) Fosaprepitant
3) Rolapitant

Answer 12

1) Aprepitant- prevention of N/V associated with highly and moderately emetogenic chemotherapy
2) Fosaprepitant- prevention of acute and delayed N/V of highly emetogenic cisplatin-based and moderately emetogenic chemotherapy
3) Rolapitant- prevention of delayed N/V associated with highly and moderately emetogenic chemotherapy.

Question 13

Nabilone is a synthetic cannabinoid, when can it be used to treat N/V?

Answer 13

N/V caused by cytotoxic chemotherapy that is unresponsive to conventional antiemetics

Question 14

Nausea in the first trimester of pregnancy is generally mild and does not require drug therapy. If vomiting is severe, which drugs can be prescribed in pregnancy?

Answer 14

1) Short-term antihistamine e.g. promethazine
2) Prochlorperazine or metoclopramide are alternatives
↳ (if does not settle within 24-48h seek advice)

Question 15

what is Hyperemesis gravidarum and how should it be managed?

Answer 15

1) Excessive nausea and vomiting in pregnancy
2) Requires regular antiemetic therapy, IV fluid and electrolyte replacement.
3) Thiamine supplement considered to reduce the risk of Wernicke’s encephalopathy

Question 16

The incidence of postoperative nausea and vomiting depends on many factors including the anaesthetic used, and the type and duration of surgery. List 4 other risk factors

Answer 16

1) Female sex
2) Non-smokers
3) History of postoperative nausea and vomiting or motion sickness
4) Intraoperative and postoperative use of opioids

Question 17

1) which drugs are typically used to manage postoperative nausea and vomiting?
2) when should a combination of two or more antiemetic drugs be used?

Answer 17

1) 5HT3-receptor antagonist, phenothiazines and antihistamines (e.g. cyclizine)
2) in those at high risk of postoperative nausea and vomiting - 2 or more drugs with different MoA’s are often used

Question 18

When a prophylactic antiemetic drug has failed, how should postoperative nausea and vomiting be treated?

Answer 18

treated with one or more drugs from a different class

Question 19

Antiemetics should be given to prevent motion sickness rather than after nausea or vomiting develop. which drug is most effective at treating motion sickness?

Answer 19

Hyoscine hydrobromide (kwells)

Question 20

Discuss the use of antihistamines to treat motion sickness

Answer 20

1) Sedating antihistamines are slightly less effective , but are better tolerated than hyoscine
2) Cyclizine or cinnarizine are usually preferred for motion sickness. But if a sedative effect is desired promethazine is useful

Question 21

Which drugs should not be prescribed in motion sickness as they are ineffective?

Answer 21

1) Domperidone
2) Metoclopramide
3) 5HT3-receptor antagonists
4) Phenothiazines (except antihistamine promethazine)

Question 22

Betahistine is an analogue of histamine and is claimed to reduce endolymphatic pressure by improving the microcirculation. what is this drug licenced to treat?

Answer 22

Vertigo, tinnitus, and hearing loss associated with Ménière’s disease

Question 23

Apart from betahistine, what other drugs may provide some benefit in vertigo associated with Ménière’s disease?

Answer 23

1) A diuretic alone or combined with salt restriction

2) antihistamines (cinnarizine), and phenothiazines (prochlorperazine reserved for the treatment of acute symptoms)