Nausea And Labyrinth

Question 1

When do we prescribe antiemetics?

Answer 1

Prescribe antiemetics only when cause of vomitting is known, especially in children

Question 2

What’s one thing to remember about anti emetics

Answer 2

They are unnecessary and harmful when the cause the cause can be treated eg. Diabetic ketoacidosis and digoxin overdose

• we chose drug according to aetiology of vomitting
• antihistamines (cyclizine, promethazone cinnarizine) are effective for n.v from many underlying conditions (similar efficacies but different side effects eg.drowsiness and antimuscarinic side effects. These are good for vertigo and motion sickness
• pheonthiazines (chlorpromazine, prochlorperazine, perphenazone and trifluorperazine) are dopamine antagonists and block the chemoreceptor trigger zone, severe dystonic reactions occur especially in children. Prochlorperazine can be used for chemo induced and radiation induced n/v side effects

Question 3

The different antiemetics

Answer 3

• prochlorperazine- is less sedating and baccalaureate tablets can be used in severe nausea or persistent vomitting
• levopromazine and haloperidol - used in nausea and vommiting in terminal patients and end of life palliative care
• domperidone - acts at the chemoreceptor trigger zone (doesn’t cross BBB so less sedating side effect and less dystonic side effects compared to metoclopramide). Low dose can be used in Parkinson’s disease
• 5ht3 antagonists - granisetron and ondansetron - n and vommiting following cytotoxic, chemo and postoperative nausea
• Dexamethasone - vomitting in chemotherapy induced nausea and vomitting, alone or with 5HT3 antagonists
• Aprepitant - n and v associated with chemo. Given with sexamethasone and 5HT3 antagonists
  Nabilone - synthetic cannaboid - add on for chemo induced nausea and vomitting as last option

Question 4

NAUSEA and Vomiting during pregnancy

Answer 4

1) self care advice - ( rest,oral hydration, dietary changes)
2) non pharmacological - eg. Ginger (mild-moderate nausea)

Question 5

Pharmacological interventions

Answer 5

Chlorpromazine
Cyclizine
Metoclopramine
Prochlorperazine
Promethazine hydrochloride
Promethazine teoclate
Ondansetron

Question 6

What is hyperemesis gravidarum - more serious nausea during pregnancy

Answer 6

Requires regular antiemetic therapy
IV fluid and electrolytes replacement
Thiamine to reduce the risk of wernickes encephalopathy

Question 7

Motion sickness

Answer 7

Give antiemetics to prevent motion sickness, before n and v develops -

• hyoscine hydro bromide
• Promethazine - if sedative effect required, if not then give less sedating like cyclizine or cinnarizine

Avoid - domperidone, 5ht3 antagonists, metoclopramide, phenothiazines (except Promethazine) are ineffective in motion sickness

Question 8

Post of N/V

Answer 8

Normally a combo of two are given

5HT3 -eg.ondansetron
- dexamethasone
- droperidol and haloperidol
- prochlorperazine (licensed for the prevention and treatment of n/v)
- cyclizine (prevention and treatment of post op n/v caused by opioids and general anaesthesia)

Question 9

Ménière’s disease

Answer 9

Inner ear disorder, vertigo

Take:

Betahistine - licensed for vertigo, tinnitus and hearing loss associated with Ménière’s disease

• antihistamines (cinnarizine) and phenothiaiznes eg. Prochlorperazine are also used
• prochloroperazine should be reserved for acute symptoms where possible

Question 10

Antiemetics safety advice

Answer 10

• Domperidone - risk of cardiac side ffects - report symptoms of arrhythmia develop (palpitation or syncope) MHRA - max treatment duration should not be exceeded - usually 7 days
• Metoclopramide - risk of neurological adverse effects - prescribe only short term = 5 days
• promethazone - children less than 6 y/o should not be given OTC cough and cold meds containing Promethazine