Remifentanil

Indications

Remifentanil is a very short-acting opioid painkiller used in hospitals during general anaesthesia, to provide strong pain relief and help keep the patient comfortable during surgery. It is also used for pain relief and sedation in patients on breathing machines in intensive care, and sometimes for pain relief during labour under close specialist supervision.

How It Works

Remifentanil attaches to opioid receptors (mu receptors) in the brain and spinal cord, which block the passage of pain signals. It is broken down very quickly by enzymes in the blood and tissues, so its effect starts within about a minute and wears off within minutes once the infusion is stopped. This allows the anaesthetist to adjust pain relief precisely.

Dosage and Administration

Remifentanil is given only by an anaesthetist or trained critical care team, by injection or continuous infusion into a vein using a controlled pump. The dose is as prescribed and is adjusted to body weight, the type of surgery and the patient's response. Because the effect ends quickly, other longer-acting painkillers are usually given before the infusion is stopped so that pain does not return suddenly after the operation.

Interactions

• Other anaesthetics, sedatives, sleeping medicines and benzodiazepines such as Midazolam: increase drowsiness and the risk of slowed breathing.
• Other opioids and alcohol: add to the effects on breathing.
• Beta blockers and calcium channel blockers: may increase the fall in heart rate and blood pressure.
• MAO inhibitors: should be stopped beforehand as advised by the doctor.

Tell the medical team about every medicine you take.

Contraindications

Remifentanil should not be used in people allergic to it or to other fentanyl-type medicines, and it is not given by injection into the spine (epidural or intrathecal) because the product contains glycine. It is used only where full breathing support and monitoring are available.

Side Effects

Common effects include slowed or shallow breathing, low blood pressure, slow heart rate, nausea and vomiting, shivering after surgery, itching and muscle stiffness, especially of the chest wall. Pain can return quickly when the infusion stops.

The medical team monitors breathing, heart rate and blood pressure throughout. After you go home, get urgent medical help if you have difficulty breathing, severe drowsiness, chest pain, or signs of an allergic reaction such as swelling of the face or a widespread rash.

Pregnancy and Lactation

Remifentanil crosses the placenta and can affect the baby's breathing, so it is used in pregnancy and labour only when the doctor judges the benefit outweighs the risk, with the baby monitored. Small amounts may pass into breast milk; mothers are usually advised to wait about 24 hours after receiving it before breastfeeding, or as advised by the doctor.

Precautions and Warnings

Used only by trained staff with resuscitation equipment ready. Elderly, weak or very unwell patients often need lower doses. Long infusions can lead to tolerance or withdrawal symptoms if stopped suddenly. Do not drive, operate machines or drink alcohol for at least 24 hours after anaesthesia.

Overdose

Too much Remifentanil causes severe breathing slowdown, muscle rigidity, very low blood pressure and slow heart rate. The infusion is stopped, breathing is supported and an opioid reversal medicine such as Naloxone may be given by the team.

Therapeutic Class

Opioid analgesic used in anaesthesia (controlled medicine).

Storage

Store as directed on the pack, usually below 25°C, in a secure controlled-drug cupboard in the hospital, out of the reach of children.