Nausea and labyrinth disorders

Question 1

Treatment of Nausea and labyrinth disorders

Answer 1

• Antiemetics should be prescribed only when the cause of vomiting is known, otherwise they can mask an underlying condition.
• Antihistamines are effective against nausea and vomiting resulting from many underlying conditions. There is no evidence that any antihistamine is superior to another but their duration of action and incidence of adverse effects (drowsiness, etc) differ.

Question 2

Phenothiazines

Answer 2

Phenothiazines (e.g. Prochlorperazine) are dopamine antagonists and act by blocking dopamine receptors in the chemoreceptor trigger zone. They are useful for prophylaxis and treatment of nausea + vomiting in cancer, chemotherapy, radiotherapy and S.E. of opioids, general anaesthetics + cytotoxics.

• Some phenothiazines are available as rectal suppositories which can be useful for patients with severe nausea/persistent vomiting.
• Prochlorperazine can be administered as a buccal tablet which is placed between upper lip and gum.
• Metoclopramide works similarly to Phenothiazines. It also acts on the GI tract and it may be superior to phenothiazines for emesis associated with gastroduodenal, hepatic and biliary disease.
• Domperidone acts on the CTZ. It has the advantage over Metoclopramide and phenothiazines of causing less sedation + dystonic reactions as it does not readily cross the BBB. Domperidone can be used in Parkinson’s for the treatment of nausea caused by dopaminergic drugs

Question 3

Antipsychotic drugs

Answer 3

Antipsychotic drugs including Haloperidol and Levomepromazine are used for relief of nausea and vomiting in terminal illness.

Question 4

Cough/cold medicines containing Promethazine

Answer 4

should not be given OTC to children <6y

Question 5

Postoperative nausea and vomiting treatment

Answer 5

• Drugs used include 5HT3-receptor-antagonists (e.g. Ondansetron), Droperidol, Dexamethasone, some Phenothiazines (e.g. Prochlorperazine) and Antihistamines (e.g. Cyclizine).
• A combination of two or more antiemetic drugs that have different mechanisms of action is often indicated in those with a high risk of post-operative nausea and vomiting.

Question 6

Vomiting during pregnancy

Answer 6

• On rare occasions if vomiting is severe, short-term treatment with an antihistamine such as Promethazine may be required. Prochlorperazine/Metoclopramide are alternatives.
• If symptoms do not settle in 24-48 hours, then specialist advice should be sought.

Question 7

Motion sickness

Answer 7

• The most effective drug for the prevention of motion sickness is Hyoscine Hydrobromide
• Sedating antihistamines are slightly less effective against motion sickness but are better tolerated than Hyoscine.
• If a sedative effect is desired, Promethazine is useful, but a slightly less sedating antihistamine such as Cyclizine or Cinnarizine is preferred.

Question 8

Hyoscine Hydrobromide cautions

Answer 8

May cause central anticholinergic syndrome –> in elderly and children (excitement, ataxia, hallucinations, behavioural abnormalities + drowsiness)

Question 9

Metoclopramide: Side Effects

Answer 9

Can induce acute dystonic reactions involving facial and skeletal muscle spasms & oculogyric crises –> more common in young girls/women & elderly. Usually occur shortly after starting treatment and subside within 24h of stopping it. IV antiparkinsonian drug (e.g. procyclidine) will abort dystonic attacks.

Question 10

Metoclopramide

MHRA Safety Info

Answer 10

MHRA Safety Info: The risk of neurological effects such as Extrapyramidal disorders and Tardive dyskinesia outweigh the benefits of long-term or high dose treatment. To help minimise the risk of unwanted effects:
• In adults >18y, metoclopramide should only be used for prevention of post-operative nausea + vomiting, radiotherapy-induced nausea and vomiting, delayed (but not acute) chemotherapy-induced nausea and vomiting + symptomatic treatment of nausea + vomiting including that associated with migraine
• Only for short-term use up to 5 days
• Usual dose is 10mg repeated up to 3 times daily, max daily dose is 500mcg/kg.
• I.V. dose should be administered slowly over atleast 3 minutes
• Oral liquid formulations should be given via an oral syringe to ensure dose accuracy.

Question 11

Domperidone:

MHRA Safety Info

Answer 11

MHRA Safety Info: As Domperidone is associated with a small increased risk of serious cardiac effects, the following restrictions have been made:

• Domperidone should only be used for the relief of the symptoms of nausea and vomiting
• It should be used at the lowest effective dose for the shortest possible duration (max. 1 week.)
• It is contraindicated for use in conditions where cardiac conduction is, or could be impaired or when there is underlying cardiac disease, when administered with drugs that prolong the QT interval or potent CYP3A4 inhibitors and in severe hepatic impairment
• Recommended dose for adults + adolescents >12y + >35kg is 10mg up to 3 times daily
• Recommended dose for children <35kg is 250mcg/kg up to 3 times daily
• Oral liquid formulations should be given via an oral syringe to ensure dose accuracy.

Question 12

Betahistine

Answer 12

Used for vertigo, tinnitus & hearing loss associated with Menières disease