Droperidol
Dopamine-antagonist antiemetics and prokinetics
Dopamine-antagonist antiemetics and prokinetics
A butyrophenone dopamine blocker given by injection to prevent nausea and vomiting around surgery. It can prolong the QT interval.
Quick facts
- Group
- Dopamine-antagonist antiemetics and prokinetics
- Target
- Dopamine D2 receptor (chemoreceptor trigger zone)
- Used for
- Prevention and treatment of nausea
- Key effects
- Mild to moderate low blood pressure · Restlessness
- Monitor
- Blood pressure and heart rate
- ATC
- N05AD08
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows haloperidol, the butyrophenone closest to droperidol, bound to the human D2 receptor.
Droperidol is a butyrophenone neuroleptic. It blocks dopamine D2 receptors in the chemoreceptor trigger zone, which lowers nausea and vomiting during and after surgery and diagnostic procedures. It also sedates, causes mild alpha-adrenergic blockade with vasodilation and low blood pressure, and potentiates other CNS depressants. Like other butyrophenones it can prolong the QT interval and trigger torsade de pointes.
- Droperidol blocks D2 receptors in the trigger zone
- Less nausea and vomiting around surgery
- Sedation and mild alpha-blockade (low blood pressure)
- Delayed repolarisation can prolong QT
Indications
- Prevention and treatment of nausea and vomiting with surgical and diagnostic procedures, when other treatments fail or are unsuitable
Adverse effects
Common
- Mild to moderate low blood pressure and fast heart rate
- Drowsiness after surgery
- Restlessness, anxiety, dysphoria (often akathisia)
- Dizziness, chills, shivering
Contraindications
- Known or suspected QT prolongation, including congenital long QT syndrome
- Hypersensitivity to droperidol
- Extreme caution with bradycardia, heart disease, low potassium or magnesium, or other QT-prolonging drugs
Key interactions
- Other QT-prolonging drugs (class I and III antiarrhythmics, some antihistamines, antimalarials, antipsychotics, antidepressants)
- Additive QT prolongation and torsade risk; not combined
- Drugs that lower potassium or magnesium (diuretics, laxatives, mineralocorticoid steroids)
- Electrolyte loss makes QT prolongation more likely
- Opioids, benzodiazepines, barbiturates, general anaesthetics
- Additive CNS depression; the doses of both are lowered
- MAO inhibitors
- Listed among risk factors for QT prolongation; extreme caution
What is monitored
- 12-lead ECG before the dose to exclude a prolonged QT
- ECG monitoring for a few hours after the dose when risk is accepted
- Blood pressure and heart rate
- Potassium and magnesium
- Sedation and extrapyramidal signs
Administration and safety
- For IV or IM use only.
- Fluids and other measures to treat low blood pressure must be ready.
- Lower starting doses are used in older, frail and high-risk patients.
- Move and position the patient carefully because of orthostatic hypotension.
- Look-alike risk with other butyrophenones (haloperidol); the name is checked.
Pregnancy and breastfeeding
There are no adequate studies in pregnant women; use in labour and delivery is not recommended.
Nursing care
- Confirm a 12-lead ECG and normal QT before giving it.
- Review the medication list for other QT-prolonging drugs and check potassium and magnesium.
- Watch for palpitations, fainting, low blood pressure and over-sedation after the dose.
- Look for restlessness, dystonia or eye-rolling (extrapyramidal reactions).
- Report fever, rigidity or confusion at once (neuroleptic malignant syndrome).
Pharmacokinetics
- Metabolism
- Liver and kidney function matter for its metabolism and excretion; caution in their impairment
- Half-life
- Sedation usually lasts a few hours; reduced alertness can last up to about half a day
- Onset and duration
- Acts within minutes of an IV or IM dose; peak effect may take up to about half an hour
Test yourself
Think of the answer, then tap the question to see it.
Which ECG check is required before droperidol?
A 12-lead ECG to exclude a prolonged QT interval.
Which receptor does droperidol block to prevent vomiting?
The dopamine D2 receptor in the chemoreceptor trigger zone.
A patient becomes restless and cannot sit still after droperidol. What is it?
Probably akathisia, an extrapyramidal reaction.
Which two electrolyte problems raise its QT risk?
Low potassium and low magnesium.
Connections
← Back to the class: Dopamine-antagonist antiemetics and prokinetics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - DROPERIDOL injection, solution (DailyMed (U.S. National Library of Medicine), 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); RCSB PDB - 6LUQ: Haloperidol bound D2 dopamine receptor structure inspired discovery of subtype selective ligands (RCSB Protein Data Bank, 2026).
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Representative model, for educational purposes only.