Ultra-Short Acting Opioid Analgesic Pregnancy: SPC §4.6: there are no adequate and well-controlled studies in pregnant women — remifentanil should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus. Lactation: it is not known whether remifentanil is excreted in human milk, but because fentanyl analogues are excreted in human milk, nursing mothers should be advised to discontinue breast feeding for 24 hours following administration. Labour and delivery: safety has not been demonstrated and there are insufficient data to recommend use during labour and Caesarean section; remifentanil crosses the placental barrier and fentanyl analogues can cause respiratory depression in the child.

Remifentanil

Brand names: Ultiva

Remifentanil is an ultra-short-acting opioid given by continuous infusion during anaesthesia to provide intense, rapidly titratable analgesia.

Adult dose

Dose: Induction of anaesthesia: continuous infusion 0.5 to 1 micrograms/kg/MIN, with or without an initial bolus injection of 1 microgram/kg given over not less than 30 seconds. Maintenance of anaesthesia in ventilated patients: bolus 0.5 to 1 micrograms/kg plus continuous infusion — starting rate 0.4 micrograms/kg/min with nitrous oxide 66% (range 0.1 to 2), or 0.25 micrograms/kg/min with isoflurane 0.5 MAC or with propofol 100 micrograms/kg/min (range 0.05 to 2 for each)

Route: Intravenous use ONLY, by calibrated infusion device into a fast-flowing IV line or via a dedicated IV line. Must NOT be administered by epidural or intrathecal injection. Bolus injections must be given over not less than 30 seconds.

Frequency: Continuous infusion titrated to effect — upward in 25% to 100% increments or downward in 25% to 50% decrements every 2 to 5 minutes; in response to light anaesthesia, supplemental bolus injections may be given every 2 to 5 minutes

ALL RATES ARE MICROGRAMS/KG/MINUTE (not per hour). If endotracheal intubation is to occur more than 8 to 10 minutes after the start of the remifentanil infusion, an induction bolus is not necessary. Remifentanil is contraindicated as the sole agent for induction of anaesthesia and must be given with a standard dose of a hypnotic (propofol, thiopental or isoflurane). SPONTANEOUSLY BREATHING ANAESTHETISED PATIENTS WITH A SECURED AIRWAY (e.g. laryngeal mask): recommended starting infusion rate for supplemental analgesia 0.04 micrograms/kg/min, titrated to effect; rates from 0.025 to 0.1 micrograms/kg/min have been studied; bolus injections are NOT recommended in these patients; respiratory depression is likely to occur and ventilatory support and/or urgent intubation may be required. Remifentanil should not be used as an analgesic in procedures where patients remain conscious or do not receive any airway support. IMMEDIATE POST-OPERATIVE PERIOD in patients breathing spontaneously: decrease the infusion rate initially to 0.1 micrograms/kg/min, then increase or decrease by no more than 0.025 micrograms/kg/min every five minutes to balance analgesia and respiratory rate; bolus injections to treat post-operative pain are not recommended in spontaneously breathing patients. TARGET-CONTROLLED INFUSION (TCI, adults, ventilated): target blood remifentanil concentrations of 3 to 8 nanograms/mL generally give adequate analgesia for induction and surgery, with up to 15 nanograms/mL for particularly stimulating procedures; spontaneous respiration is likely to return at calculated concentrations around 1 to 2 nanograms/mL; TCI is not recommended for spontaneous-ventilation anaesthesia or for post-operative analgesia. CARDIAC ANAESTHESIA: after a hypnotic has produced loss of consciousness, remifentanil should be given at an initial infusion rate of 1 microgram/kg/min; bolus injections during induction in cardiac surgical patients are not recommended; endotracheal intubation should not occur until at least 5 minutes after the start of the infusion; high-risk cardiac patients (poor ventricular function, valve surgery) should be given a MAXIMUM bolus dose of 0.5 micrograms/kg; the same recommendations apply during hypothermic cardiopulmonary bypass. CAUTION: the cardiac-anaesthesia dosing TABLE did not extract cleanly from the source text (its bolus and infusion columns are ambiguous in the fetched material) — read that table directly in the SPC before using cardiac maintenance figures. DILUTION: for manually-controlled infusion, dilute to 20 to 250 micrograms/mL (50 micrograms/mL is the recommended dilution for adults); for TCI the recommended dilution is 20 to 50 micrograms/mL. CONCOMITANT MEDICATION: remifentanil significantly reduces the amount of hypnotic required — doses of isoflurane, thiopentone, propofol and temazepam have been reduced by up to 75% when used concurrently. DISCONTINUATION: no residual opioid activity will be present within 5 to 10 minutes after stopping, so longer-acting analgesia must be established before discontinuation; clear IV lines and cannulae to avoid inadvertent administration of residual remifentanil. INTENSIVE CARE: use in mechanically ventilated ICU patients is not recommended for a duration of treatment greater than 3 days. No absolute maximum dose is stated in the SPC, so maxDose is omitted. PROVENANCE NOTE: the interactions listed come from the US label section 7 (openFDA) plus the UK SPC §4.4 statement on concomitant sedatives, because no UK SPC §4.5 was present in the fetched bundle.

Paediatric dose

Dose: 1 microgram/kg

Route: Intravenous bolus injection given over not less than 30 seconds (IV use only; must NOT be given by the epidural or intrathecal route)

Frequency: Bolus given alongside a continuous infusion, for MAINTENANCE of anaesthesia only, in children aged 1 to 12 years — see notes for the infusion rates, which are the central part of the regimen

MAINTENANCE OF ANAESTHESIA ONLY. Induction of anaesthesia with remifentanil is NOT recommended in patients aged 1 to 12 years (no data available), and remifentanil is NOT recommended at all in neonates/infants aged under 1 year (insufficient clinical data). Co-administration of remifentanil with an intravenous anaesthetic agent for induction has not been studied in detail and is not recommended. TCI has not been studied in paediatric patients and is not recommended. CONTINUOUS INFUSION RATES ARE MICROGRAMS/KG/MINUTE. SPC dosing table for paediatric patients 1 to 12 years, each co-administered with nitrous oxide/oxygen in a ratio of 2:1: halothane (starting dose 0.3 MAC) — bolus 1 microgram/kg, infusion starting rate 0.25 micrograms/kg/min, range 0.05 to 1.3; sevoflurane (starting dose 0.3 MAC) — bolus 1 microgram/kg, infusion starting rate 0.25 micrograms/kg/min, range 0.05 to 0.9; isoflurane (starting dose 0.5 MAC) — bolus 1 microgram/kg, infusion starting rate 0.25 micrograms/kg/min, range 0.06 to 0.9. For sole administration of nitrous oxide (70%) with remifentanil, typical maintenance infusion rates should be between 0.4 and 3 micrograms/kg/min; although not specifically studied, adult data suggest 0.4 micrograms/kg/min is an appropriate starting rate. Surgery should not commence until at least 5 minutes after the start of the remifentanil infusion if a simultaneous bolus dose has not been given. Paediatric patients should be monitored and the dose titrated to the depth of analgesia appropriate for the surgical procedure. Recommended dilution for paediatric patients aged 1 year and over is 20 to 25 micrograms/mL. No paediatric maximum dose is stated in this SPC. Verify all under-18 dosing against a children's formulary before administration.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

Contraindicated for epidural and intrathecal use, as glycine is present in the formulation
Hypersensitivity to the active substance, to other fentanyl analogues, or to any of the excipients
Contraindicated for use as the sole agent for induction of anaesthesia

Side effects

Skeletal muscle rigidity (very common)
Hypotension (very common); post-operative hypertension (common)
Nausea and vomiting (very common)
Bradycardia (common); asystole/cardiac arrest usually preceded by bradycardia (rare)
Acute respiratory depression, apnoea and cough (common); hypoxia (uncommon)
Post-operative shivering (common); pruritus (common); drug dependence and withdrawal syndrome (frequency not known)

Interactions

Benzodiazepines and other CNS depressants (sedatives/hypnotics, anxiolytics, tranquillisers, muscle relaxants, general anaesthetics, antipsychotics, other opioids, alcohol) — additive effects increasing the risk of hypotension, respiratory depression, profound sedation, coma and death; use the lowest effective dose for the shortest time and follow patients closely
Inhaled anaesthetics, hypnotics and benzodiazepines — remifentanil decreases the amounts required for anaesthesia; doses of isoflurane, thiopentone, propofol and temazepam have been reduced by up to 75% when used concurrently
Serotonergic drugs (SSRIs, SNRIs and others affecting the serotonergic neurotransmitter system) — risk of serotonin syndrome; discontinue if serotonin syndrome is suspected
Mixed agonist/antagonist and partial agonist opioid analgesics — reduced analgesic effect or potential withdrawal symptoms; consider an alternative

Clinical monograph

How it works

Remifentanil is a potent mu-opioid receptor agonist that is rapidly broken down by non-specific plasma and tissue esterases, giving an extremely short, context-insensitive duration of action.

Prescribing in practice

Profound respiratory depression, apnoea and marked bradycardia or hypotension occur readily, and chest-wall rigidity can impair ventilation — give only by infusion with airway control and full monitoring by an anaesthetist.
Because its effect ceases almost immediately when stopped, plan alternative longer-acting analgesia before emergence to avoid abrupt severe pain.
Administer through a dedicated, carefully primed line as the rapid offset makes infusion errors and dead-space boluses clinically significant; acute opioid tolerance and hyperalgesia may occur.

Monitoring

Continuously monitor ventilation, oxygenation, heart rate and blood pressure throughout the infusion and during the transition to post-operative analgesia.

Counselling the patient

This is a powerful, very short-acting painkiller used during your anaesthetic.
Other pain relief will be arranged for when you wake, as this one wears off almost instantly.

Evidence & guidelines

Remifentanil is a well-established intraoperative opioid valued for its precise, rapidly reversible effect.

Reference: Ultiva SPC; Minto et al. (1997) PK model; AAGBI Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways