Antiemetics in EM



Indications

Licensed indications for different anti-emetic agents:

Drug N & V Motion sickness Vertigo Chemotherapy N&V Meniere’s dis. Post-op N&V Migraine
Betahistine     X        
Cinnarizine   X          
Cyclizine X X X X (Radiotherapy) X X  
Domperidone X            
Metoclopramide X     X     X
Ondansetron       X   X  
Prochlorperazine X   X   X   X
Promethazine X            

Cautions / interactions

The information in the tables should be used in conjunction with the BNF or the SPC (medicines.ie)

Drug Contra-indications Cautions Side Effects Interactions
Betahistine Phaeochromocytoma

Asthma

Hx of peptic ulcer

Not recommended <18 yrs old

Nausea

Dyspepsia

Headache

Antihistamines

Caution with MAOIs

Cinnarizine

Porphyria

Children <5 yrs

GI obstruction

Parkinson’s

Hepatic or renal insufficiency

Nausea

Dyspepsia

Somnolence

↑ weight

Antimuscarinic S/Es

Alcohol

CNS depressants

TCAs

Cyclizine

Porphyria

Acute alcohol intoxication (↑ toxicity of alcohol)

Not recommended in children <6yrs

Severe heart failure

Acute MI

Prostatic hypertrophy

Urinary retention

Glaucoma

GI obstruction

Epilepsy

Hypertension

Nausea

Dyspepsia

Antimuscarinic S/Es

Loss of appetite

Additive effects with alcohol & other CNS depressants e.g hypnotics, tranquillisers, anaesthetics.

NB: Reports of abuse of cyclizine for its euphoric or hallucinatory effects

Domperidone

Prolactinoma, cond. where ↑ gastric motility is harmful e.g. GI haemorrhage

Impaired cardiac conduction

Concomitant drugs that prolong QT interval

Hepatic impairment

Concomitant CYP3A4 inhibitors

Not recommended if <12 yrs or >60yrs

May prolong QT interval

Use lowest dose for shortest duration

Dry mouth

GI disturbance

Galactorrhoea

Drugs that prolong QT e.g. erythromycin, citalopram, haloperidol & amiodarone

Potent CYP3A4 inhibitors e.g. systemic azole antifungals & some macrolides erythromycin & clarithromycin

Metoclopramide

GI obstruction, perforation or haemorrhage

Phaeochromocytoma

Children <1yr

Eepilepsy

Parkinson’s Disease

Elderly

Those <20yrs

Cardiac disorders

Electrolyte imbalance

Bradycardia

Renal & hepatic impairment

Methaemo-globinaemia

Diarrhoea

Somnolence

Hypotension (post IV doses)

Extrapyramidal S/Es (esp in <20 yrs or in high doses)

Hyperpro-lactinaemia

Ciclosporin

Alcohol (enhanced sedation)

CNS depressants

SSRIs (risk serotonin syndrome)

Levodopa or dopaminergic agonists

Ondansetron

Congenital long QT syndrome

Concomitant use with apomorphine

Risk of QT prolongation

GI obstruction

Adenotonsillar surgery (may mask occult bleeding)

Electrolyte abnormalities

CCF

Correct hypokalaemia & hypomagnesaemia prior to administration

Constipation

Headache

Flushing

Phenytoin

Carbamazepine & rifampicin alter effectiveness of ondansetron

Erythromycin, domperidone, citalopram & other drugs that prolong QT interval

SSRIs & SNRIs (risk of serotonin syndrome)

Apomorphine C/I

Tramadol

Prochlorperazine

Avoid in kids <10kg or 1 yr.,

Impaired liver function

Hypothyroidism

Elderly

Cardiac failure

Prostate hypertrophy

Epileptic patient (lower seizure threshold)

Parkinson’s

CV disease or family Hx of QT prolongation

S/Es occur at low frequency

Extrapyramidal S/Es

QT prolongation & cardiac arrhythmias (usually dose related)

µ blockers (hypotensive effect)

Antacids (absorption)

Drugs that can prolong QT

Abrupt cessation can lead to acute withdrawal symptoms incl. nausea, vomiting, sweating & insomnia

Adrenaline mustn’t be used in patients overdosed with prochlorperazine

Promethazine

Kids <2yrs due to potential for fatal resp depression

Avoid in pts taking MAOI up to 14 days previously

Pts with blood dyscrasias

CNS depression of any cause

Asthma

Bronchitis

Bronchiectasis

Bladder neck or pyloroduodenal obstruction

Severe coronary artery disease

Narrow angle glaucoma

Epilepsy

Hepatic & renal insufficiency

Children with signs & symptoms of Reye’s Syndrome

Drowsiness

Dizziness

Restlessness

Headaches

Nightmares

Tiredness

Disorientation

Action of anticholinergic agents, TCAs, Sedatives or hypnotics is enhanced

Alcohol should be avoided

Promethazine may interfere with urine pregnancy tests

Promethazine may lower seizure threshold, may need to dose adjust AEDs

Antihypertensives



Content by Fiona Ahern, Dr Íomhar O' Sullivan. Last review Dr ÍOS 24/09/24.