This information is intended for use by health professionals
Dilution:Remifentanil may be further diluted after reconstitution (see sections 6.3 and 6.6). For manually-controlled infusion Remifentanil can be diluted to concentrations of 20 to 250 micrograms/ml (50 micrograms/ml is the recommended dilution for adults and 20 to 25 micrograms/ml for paediatric patients aged 1 year and over). For TCI the recommended dilution of Remifentanil is 20 to 50 micrograms/ml.
General anaesthesiaThe administration of Remifentanil must be individualised based on the patient's response.
Administration by Manually-Controlled Infusion (MCI)Table 1 summarises the starting infusion rates and dose range:Table 1: Dosing Guidelines for Adults
|INDICATION||BOLUS INJECTION (micrograms/kg)||CONTINUOUS INFUSION (micrograms/kg/min)|
|Induction of anaesthesia||1 (give over not less than 30 seconds)||0.5 to 1||_|
|Maintenance of anaesthesia in ventilated patients|
| Nitrous oxide (66%)||0.5 to 1||0.4||0.1 to 2|
| Isoflurane (starting dose 0.5MAC)||0.5 to 1||0.25||0.05 to 2|
| Propofol (Starting dose 100 micrograms/kg/min)||0.5 to 1||0.25||0.05 to 2|
Induction of anaesthesiaRemifentanil should be administered with a standard dose of an hypnotic agent, such as propofol, thiopentone, or isoflurane, for the induction of anaesthesia. Administering Remifentanil after an hypnotic agent will reduce the incidence of muscle rigidity. Remifentanil can be administered at an infusion rate of 0.5 to 1 microgram/kg/min, with or without an initial bolus injection of 1 microgram/kg given over not less than 30 seconds. If endotracheal intubation is to occur more than 8 to 10 minutes after the start of the infusion of Remifentanil, then a bolus injection is not necessary.
Maintenance of anaesthesia in ventilated patientsAfter endotracheal intubation, the infusion rate of Remifentanil should be decreased, according to anaesthetic technique, as indicated in the above table. Due to the fast onset and short duration of action of Remifentanil, the rate of administration during anaesthesia can be titrated upward in 25% to 100% increments or downward in 25% to 50% decrements, every 2 to 5 minutes to attain the desired level of μ (mu)-opioid response. In response to light anaesthesia, supplemental slow bolus injections may be administered every 2 to 5 minutes.
Anaesthesia in spontaneously breathing anaesthetised patients with a secured airway (e.g. laryngeal mask anaesthesia)In spontaneously breathing anaesthetised patients with a secured airway respiratory depression is likely to occur. Special care is needed to adjust the dose to the patient requirements and ventilatory support may be required. The recommended starting infusion rate for supplemental analgesia in spontaneously breathing anaesthetised patients is 0.04 microgram/kg/min with titration to effect. A range of infusion rates from 0.025 to 0.1 microgram/kg/min has been studied. Bolus injections are not recommended in spontaneously breathing anaesthetized patients.Remifentanil should not be used as an analgesic in procedures where patients remain conscious or do not receive any airway support during the procedure.
Concomitant medicationRemifentanil decreases the amounts or doses of inhaled anaesthetics, hypnotics and benzodiazepines required for anaesthesia (see section 4.5). Doses of the following agents used in anaesthesia: isoflurane, thiopentone, propofol and temazepam have been reduced by up to 75% when used concurrently with remifentanil.
Guidelines for discontinuation/continuation into the immediate postoperative periodDue to the very rapid offset of action of Remifentanil no residual opioid activity will be present within 5 to 10 minutes after discontinuation. For those patients undergoing surgical procedures where post-operative pain is anticipated, analgesics should be administered prior to discontinuation of Remifentanil. Sufficient time must be allowed to reach the maximum effect of the longer acting analgesic. The choice of analgesic should be appropriate for the patient's surgical procedure and the level of post-operative care. In the event that longer-acting analgesia has not been established prior to the end of surgery, the administration of Remifentanil can be continued to maintain analgesia during the immediate postoperative period until longer acting analgesia has reached its maximum effect. Guidance on use in mechanically ventilated intensive care patients is provided in section 4.2.3.In patients who are breathing spontaneously, the infusion rate of Remifentanil should initially be decreased to a rate of 0.1 microgram/kg/min. The infusion rate may then be increased or decreased in steps of 0.025 microgram/kg/min every five minutes, to balance the patient's level of analgesia and respiratory rate. Remifentanil should only be used in a setting fully equipped for the monitoring and support of respiratory and cardiovascular function, under the close supervision of persons specifically trained in the recognition and management of the respiratory effects of potent opioids.Furthermore it is recommended that patients should be closely monitored post-operatively for pain, hypotension and bradycardia.In spontaneously breathing patients bolus doses to treat pain are not recommended during postoperative period.
Administration by Target-Controlled Infusion
Induction and maintenance of anaesthesia in ventilated patientsRemifentanil TCI should be used in association with an intravenous or inhalational hypnotic agent during the induction and maintenance of anaesthesia in ventilated adult patients (see table 1 above for manually controlled infusion). In association with these agents, adequate analgesia for induction of anaesthesia and surgery can generally be achieved with target blood remifentanil concentrations ranging from 3 to 8 nanograms/ml. Remifentanil should be titrated to individual patient response. For particularly stimulating surgical procedures target blood concentrations up to 15 nanograms/ml may be required. At the doses recommended above, remifentanil significantly reduces the amount of hypnotic agent required to maintain anaesthesia. Therefore, isoflurane and propofol should be administered as recommended above to avoid an increase of haemodynamic effects such as hypotension and bradycardia (see table 1 above for manually controlled infusion). For information on blood remifentanil concentrations achieved with manually- controlled infusion see section 6.6, Table 11.As there are insufficient data, the administration of Remifentanil by TCI for spontaneous ventilation anaesthesia is not recommended.
Guidelines for discontinuation/continuation into the immediate post-operative periodAt the end of surgery when the TCI infusion is stopped or the target concentration reduced, spontaneous respiration is likely to return at calculated remifentanil concentrations in the region of 1 to 2 nanograms/ml. As with manually-controlled infusion, post-operative analgesia should be established before the end of surgery with longer acting analgesics (see also Guidelines for discontinuation/continuation into the immediate postoperative period in section above for Manually Controlled Infusion ). As there are insufficient data, the administration of Remifentanil by TCI for the management of post-operative analgesia is not recommended.
Paediatric patients (1 to 12 years of age)Co-administration of Remifentanil and an intravenous anaesthetic agent for induction of anaesthesia has not been studied in detail and is therefore not recommended. Remifentanil TCI has not been studied in paediatric patients and therefore administration of Remifentanil by TCI is not recommended in these patients. The following doses of Remifentanil are recommended for maintenance of anaesthesia:
Table2: Dosing guideline for paediatric patients (1 to 12 years of age)
|CONCOMITANT ANAESTHETIC AGENT*||REMIFENTANIL BOLUS INJECTION (microgram/kg)||CONTINUOUS REMIFENTANIL INFUSION (microgram/kg/min)|
|Starting Rate||Maintenance Rate|
|Halothane (starting dose 0.3MAC)||1||0.25||0.05 to 1.3|
|Sevoflurane (starting dose 0.3MAC)||1||0.25||0.05 to 0.9|
|Isoflurane (starting dose 0.5MAC)||1||0.25||0.06 to 0.9|
Concomitant medicationAt the doses recommended above, remifentanil significantly reduces the amount of hypnotic agent required to maintain anaesthesia. Therefore, isoflurane, halothane and sevoflurane should be administered as recommended above to avoid an increase of haemodynamic effects such as hypotension and bradycardia. No data are available for dosage recommendations for simultaneous use of other hypnotics other than those listed in the table with remifentanil (see section Adults-Concomitant medication).
Guidelines for patient management in the immediate post-operative period / Establishment of alternative analgesia prior to discontinuation of RemifentanilDue to the very rapid offset of action of Remifentanil, no residual activity will be present within 5 to 10 minutes after discontinuation. For those patients undergoing surgical procedures where post-operative pain is anticipated, analgesics should be administered prior to discontinuation of Remifentanil. Sufficient time must be allowed to reach the therapeutic effect of the longer acting analgesic. The choice of agent(s), the dose and the time of administration should be planned in advance and individually tailored to be appropriate for the patient's surgical procedure and the level of post-operative care anticipated (see section 4.4).
220.127.116.11 Neonates/infants (aged less than 1 year)There is limited clinical trial experience of remifentanil in neonates and infants (aged under 1 year old; see section 5.1). The pharmacokinetic profile of remifentanil in neonates and infants (aged less than 1 year) is comparable to that seen in adults after correction for body weight differences (see section 5.2). However, because there are insufficient clinical data, the administration of Remifentanil is not recommended for this age group. Use for Total Intravenous anaesthesia (TIVA): There is limited clinical trial experience of remifentanil for TIVA in infants (see section 5.1). However, there are insufficient clinical data to make dosage recommendations.
Special Patient groupsFor dosage recommendations for special patient groups (elderly and obese patients, renally and hepatically impaired patients, patients undergoing neurosurgery and ASA III/IV patients; see section 4.2.4).
Administration by Manually-Controlled Infusion
Table3: Dosing Guidelines for Cardiac Anaesthesia:
|INDICATION||REMIFENTANIL BOLUS INJECTION (micrograms/kg)||CONTINUOUS REMIFENTANIL INFUSION|
|Starting Rate||Typical infusion Rates|
|Induction of anaesthesia||Not recommended||1||_|
|Maintenance of anaesthesia in ventilated patients:|
| Isoflurane (starting dose 0.4 MAC)||0.5 to 1||1||0.003 to 4|
| Propofol (Starting dose 50 micrograms/kg/min)||0.5 to 1||1||0.01 to 4.3|
|Continuation of post-operative analgesia, prior to extubation||Not recommended||1||0 to 1|
Induction period of anaesthesiaAfter administration of hypnotic to achieve loss of consciousness, Remifentanil should be administered at an initial infusion rate of 1 microgram/kg/min. The use of bolus injections of Remifentanil during induction in cardiac surgical patients is not recommended. Endotracheal intubation should not occur until at least 5 minutes after the start of the infusion.
Maintenance period of anaesthesiaAfter endotracheal intubation the infusion rate of Remifentanil should be titrated according to patient need. Supplemental bolus doses may also be given as required. High risk cardiac patients, such as those undergoing valve surgery or with poor ventricular function, should be administered a maximum bolus dose of 0.5 microgram/kg. These dosing recommendations also apply during hypothermic cardiopulmonary bypass (see section 5.2).
Concomitant medicationAt the doses recommended above, remifentanil significantly reduces the amount of hypnotic agent required to maintain anaesthesia. Therefore, isoflurane and propofol should be administered as recommended above to avoid an increase of haemodynamic effects such as hypotension and bradycardia. No data are available for dosage recommendations for simultaneous use of other hypnotics other than those listed in the table with remifentanil (see section Adults - Concomitant medication).
Guidelines for postoperative patient management
Continuation of Remifentanil post-operatively to provide analgesia prior to extubationIt is recommended that the infusion of Remifentanil should be maintained at the final intra-operative rate during transfer of patients to the post-operative care area. Upon arrival into this area, the patient's level of analgesia and sedation should be closely monitored and the Remifentanil infusion rate adjusted to meet the individual patient's requirements (for further information on management of intensive care patients see section 4.2.3).
Establishment of alternative analgesia prior to discontinuation of RemifentanilDue to the very rapid offset of action of Remifentanil, no residual opioid activity will be present within 5 to 10 minutes after discontinuation. Prior to discontinuation of Remifentanil, patients must be given alternative analgesic and sedative agents at a sufficient time in advance to allow the therapeutic effects of these agents to become established. It is therefore recommended that the choice of agent(s), the dose and the time of administration are planned before weaning the patient from the ventilator. Guidelines for discontinuation of RemifentanilDue to the very rapid offset of action of Remifentanil, hypertension, shivering and pain have been reported in cardiac patients immediately following discontinuation of Remifentanil (see section 4.8). To minimise the risk of these occurring, adequate alternative analgesia must be established (as described above), before the Remifentanil infusion is discontinued. The infusion rate should be reduced by 25% decrements in at least 10-minute intervals until the infusion is discontinued. During weaning from the ventilator the Remifentanil infusion should not be increased and only down titration should occur, supplemented as required with alternative analgesics. Haemodynamic changes such as hypertension and tachycardia should be treated with alternative agents as appropriate. When other opioid agents are administered as part of the regimen for transition to alternative analgesia, the patient must be carefully monitored. The benefit of providing adequate post-operative analgesia must always be balanced against the potential risk of respiratory depression with these agents.
Administration by Target-Controlled Infusion
Induction and maintenance of anaesthesiaRemifentanil TCI should be used in association with an intravenous or inhalational hypnotic agent during the induction and maintenance of anaesthesia in ventilated adult patients (see table 3). In association with these agents, adequate analgesia for cardiac surgery is generally achieved at the higher end of the range of target blood remifentanil concentrations used for general surgical procedures. Following titration of remifentanil to individual patient response, blood concentrations as high as 20 nanograms/ml have been used in clinical studies. At the doses recommended above, remifentanil significantly reduces the amount of hypnotic agent required to maintain anaesthesia. Therefore, isoflurane and propofol should be administered as recommended above to avoid an increase of haemodynamic effects such as hypotension and bradycardia (see table 3 and Concomitant medication). For information on blood remifentanil concentrations achieved with manually controlled infusion see section 6.6, table 11).
Guidelines for discontinuation/continuation into the immediate post-operative periodAt the end of surgery when the TCI infusion is stopped or the target concentration reduced, spontaneous respiration is likely to return at calculated remifentanil concentrations in the region of 1 to 2 nanograms/ml. As with manually-controlled infusion, post-operative analgesia should be established before the end of surgery with longer acting analgesics (see Guidelines for discontinuation under Administration by manually-controlled infusion in section 4.2.).As there are insufficient data, the administration of Remifentanil by TCI for the management of post-operative analgesia is not recommended.
Use in Intensive Care
AdultsRemifentanil can be used for the provision of analgesia in mechanically ventilated intensive care patients. If required, additionally sedating drugs should be applied.Remifentanil has been studied in mechanically ventilated intensive care patients in well controlled clinical trials for up to three days. As patients were not studied beyond three days, no evidence of safety and efficacy for longer treatment has been established. Therefore, the use of Remifentanil is not recommended for a duration of treatment greater than three days. Remifentanil TCI has not been studied in intensive care patients and therefore administration of Remifentanil is not recommended in these patients.In adults, it is recommended that Remifentanil is initiated at an infusion rate of 0.1 microgram/kg/min (6 microgram/kg/h) to 0.15 microgram/kg/min (9 microgram/kg/h). The infusion rate should be titrated in increments of 0.025 microgram/kg/min (1.5 microgram/kg/h) to achieve the desired level of sedation and analgesia. A period of at least 5 minutes should be allowed between dose adjustments. The level of sedation and analgesia should be carefully monitored, regularly reassessed and the Remifentanil infusion rate adjusted accordingly. If an infusion rate of 0.2 microgram/kg/min (12 microgram/kg/h) is reached and the desired level of sedation is not achieved, it is recommended that dosing with an appropriate sedative agent is initiated (see below). The dose of sedative agent should be titrated to obtain the desired level of sedation. Further increases to the Remifentanil infusion rate in increments of 0.025 microgram/kg/min (1.5 microgram/kg/h) may be made if additional analgesia is required. Table 4 summarises the starting infusion rates and typical dose range for provision of analgesia in individual patients: Table4: Dosing Guidelines for use within the intensive care setting
|CONTINUOUS INFUSION microgram/kg/min (microgram/kg/h)|
|0.1 (6) to 0.15 (9)||0.006 (0.38) to 0.74 (44.4)|
Table5: Recommended starting dose of sedative agents, if required
|Sedative Agent||Bolus (mg/kg)||Infusion rate (mg/kg/h)|
|Propofol||Up to 0.5||0.5|
|Midazolam||Up to 0.03||0.03|
Establishment of alternative analgesia prior to discontinuation of RemifentanilDue to the very rapid offset of action of Remifentanil, no residual opioid activity will be present within 5 to 10 minutes after discontinuation regardless of the duration of infusion. Following administration of Remifentanil the possibility of tolerance and hyperalgesia should be considered. Therefore, prior to discontinuation of Remifentanil, patients must be given alternative analgesic and sedative agents to prevent hyperalgesia and associated haemodynamic changes. These agents must be given at a sufficient time in advance to allow the therapeutic effects of these agents to become established. The range of options for analgesia includes long acting oral, intravenous, or regional analgesics controlled by the nurse or the patient. These techniques should always be titrated to individual patient needs as the infusion of Remifentanil is reduced. It is recommended that the choice of agent(s), the dose and the time of administration are planned prior to discontinuation of Remifentanil. There is a potential for the development of tolerance with time during prolonged administration of μ -opioid agonists.
Guidelines for extubation and discontinuation of RemifentanilIn order to ensure a smooth emergence from an Remifentanil based regimen it is recommended that the infusion rate of Remifentanil is titrated in stages to 0.1 microgram/kg/min (6 microgram/kg/h) over a period up to 1 hour prior to extubation. Following extubation, the infusion rate should be reduced by 25% decrements in at least 10-minute intervals until the infusion is discontinued. During weaning from the ventilator the Remifentanil infusion should not be increased and only down titration should occur, supplemented as required with alternative analgesics. Upon discontinuation of Remifentanil, the IV cannula should be cleared or removed to prevent subsequent inadvertent administration. When other opioid agents are administered as part of the regimen for transition to alternative analgesia, the patient must be carefully monitored. The benefit of providing adequate analgesia must always be balanced against the potential risk of respiratory depression.
Paediatric intensive care patientsThe use of remifentanil in paediatric intensive care patients cannot be recommended as there are no data available in this patient population.
Renally impaired intensive care patientsNo adjustments to the doses recommended above are necessary in renally-impaired patients, including those undergoing renal replacement therapy, however, the clearance of the carboxylic acid metabolite is reduced in patients with renal impairment (see section 5.2).
Special patients populations
Older people (over 65 years of age)
General anaesthesiaThe initial starting dose of remifentanil administered to patients over 65 should be half the recommended adult dose and then titrated to individual patient's need as an increased sensitivity to the pharmacological effects of remifentanil has been seen in this patient population. This dosage adjustment applies to all phases of anaesthesia including induction, maintenance and immediate post-operative analgesia. Because of the increased sensitivity of elderly patients to Remifentanil, when administering Remifentanil by TCI in this population the initial target concentration should be 1.5 to 4 ng/ml with subsequent titration to response.
Anaesthesia during cardiac surgeryReduction of initial dose is not required (see section 4.2.2).
Intensive CareReduction of initial dose is not required (see section Intensive Care above).
Obese patientsFor manually controlled infusion it is recommended that for obese patients the dosage of Remifentanil should be reduced and based upon ideal body weight as the clearance and volume of distribution of remifentanil are better correlated with ideal body weight than actual body weight. With the calculation of lean body mass (LBM) used in the Minto model, LBM is likely to be underestimated in female patients with a body mass index (BMI) greater than 35 kg/m2 and in male patients with BMI greater than 40 kg/m2. To avoid underdosing in these patients, remifentanil TCI should be titrated carefully to individual response.
Renally impaired patientsOn the basis of investigations carried out to date, a dose adjustment in patients with impaired renal function, including intensive care patients, is not necessary.
Patients with hepatic impairmentStudies carried out with a limited number of patients with impaired liver function, do not justify any special dosage recommendations. However, patients with severe hepatic impairment may be slightly more sensitive to the respiratory depressant effects of remifentanil (see section 4.4). These patients shall be closely monitored and the dose of remifentanil shall be titrated to individual patient need.
NeurosurgeryLimited clinical experience in patients undergoing neurosurgery has shown that no special dosage recommendations are required. ASA III/IV patients
General anaesthesiaAs the haemodynamic effects of potent opioids can be expected to be more pronounced in ASA III/IV patients, caution should be exercised in the administration of Remifentanil in this population. Initial dosage reduction and subsequent titration to effect is therefore recommended. In paediatric patients, there are insufficient data to make a dosage recommendation.For TCI, a lower initial target of 1.5 to 4 ng/ml should be used in ASA III or IV patients and subsequently titrated to response.
Cardiac anaesthesiaNo initial dose reduction is required (see section 4.2.2).
Discontinuation of treatmentSymptoms following withdrawal of Remifentanil including tachycardia, hypertension and agitation have been reported infrequently upon abrupt cessation, particularly after prolonged administration of more than 3 days. Where reported, re-introduction and tapering of the infusion has been beneficial. The use of Remifentanil in mechanically ventilated intensive care patients is not recommended for duration of treatment greater than 3 days.
Muscle rigidity prevention and managementAt the doses recommended muscle rigidity may occur. As with other opioids, the incidence of muscle rigidity is related to the dose and rate of administration. Therefore, bolus injections should be administered over not less than 30 seconds. Muscle rigidity induced by remifentanil must be treated in the context of the patient's clinical condition with appropriate supporting measures including ventilatory support. Excessive muscle rigidity occurring during the induction of anaesthesia should be treated by the administration of a neuromuscular blocking agent and/or additional hypnotic agents. Muscle rigidity seen during the use of remifentanil as an analgesic may be treated by stopping or decreasing the rate of administration of remifentanil. Resolution of muscle rigidity after discontinuing the infusion of remifentanil occurs within minutes. Alternatively an opioid antagonist may be administered; however this may reverse or attenuate the analgesic effect of remifentanil.
Respiratory depression prevention and managementAs with all potent opioids, profound analgesia is accompanied by marked respiratory depression. Therefore, remifentanil should only be used in areas where facilities for monitoring and dealing with respiratory depression are available. Special care should be taken in patients with respiratory dysfunction.The appearance of respiratory depression should be managed appropriately, including decreasing the rate of infusion by 50%, or a temporary discontinuation of the infusion. Unlike other fentanyl analogues, remifentanil has not been shown to cause recurrent respiratory depression, even after prolonged administration. However as many factors may affect post-operative recovery, it is important to ensure that full consciousness and adequate spontaneous ventilation are achieved before the patient is discharged from the recovery area.
Cardiovascular effectsThe risk of cardiovascular effects such as hypotension and bradycardia, which may rarely lead to asystole/ cardiac arrest (see section 4.5 and 4.8) may be reduced by lowering the rate of infusion of Remifentanil or the dose of concurrent anaesthetics or by using IV fluids, vasopressor or anticholinergic agents as appropriate. Debilitated, hypovolaemic, hypotensive and older people may be more sensitive to the cardiovascular effects of remifentanil.
Inadvertent administrationA sufficient amount of Remifentanil may be present in the dead space of the IV line and/or cannula to cause respiratory depression, apnoea and/or muscle rigidity if the line is flushed with IV fluids or other drugs. This may be avoided by administering Remifentanil into a fast flowing IV line or via a dedicated IV line which is removed when Remifentanil is discontinued.
Neonates and infantsThere is limited data available on use in neonates/infants under 1 year of age (see sections 18.104.22.168. and 5.1).
Drug abuseAs with other opioids remifentanil may produce dependency.
|Immune system disorders|
|Rare||Allergic reactions including anaphylaxis have been reported in patients receiving remifentanil in conjunction with other anaesthetic agents|
|Not known||Drug dependence|
|Nervous system disorders|
|Very common||Skeletal muscle rigidity|
|Rare||Sedation (during recovery from general anaesthesia)|
|Rare||Asystole/cardiac arrest, usually preceeded by bradycardia, has been reported in patients receiving remifentanil in conjunction with other anaesthetics|
|Not known||Atrioventricular block|
|Respiratory, thoracic and mediastinal disorders|
|Common||Acute respiratory depression, apnoea|
|Very common||Nausea, vomiting|
|Skin and subcutaneous tissue disorders|
|General disorders and administration site conditions|
|Not known||Drug tolerance|
Discontinuation of treatmentSymptoms following withdrawal of remifentanil including tachycardia, hypertension and agitation have been reported infrequently upon abrupt cessation, particularly after prolonged administration of more than 3 days (see section 4.4).
|Surgical intervention||Age (y), (N)||Study condition (maintenance)||Extubation (min) (mean (SD))|
|Lower abdominal/urological surgery||0.5-16 (120)||TIVA: propofol (5 10 mg/kg/h) + remifentanil (0.125 1.0 micrograms/kg/min)||11.8 (4.2)|
|Inhalation anaesthesia: sevoflurane (1.0 1.5 MAC) and remifentanil (0.125 1.0 micrograms/kg/min)||15.0 (5.6) (p<0.05)|
|ENT-surgery||4-11 (50)||TIVA: propofol (3 mg/kg/h) + remifentanil (0.5 micrograms/kg/min)||11 (3.7)|
|Inhalation anaesthesia: desflurane (1.3 MAC) and N20 mixture||9.4 (2.9) Not significant|
|General or ENT surgery||2-12 (153)||TIVA: remifentanil (0.2 0.5 micrograms/kg/min) + propofol (100 200 micrograms/kg/min)||Comparable extubation times (based on limited data)|
|Inhalation anaesthesia: sevoflurane (1 1.5 MAC) + N20 mixture|
EliminationFollowing administration of the recommended doses of remifentanil, the effective half-life is 3 to 10 minutes.The average clearance of remifentanil in young healthy adults is 40ml/min/kg, the central volume of distribution is 100ml/kg and the steady-state volume of distribution is 350ml/kg.
AbsorptionBlood concentrations of remifentanil are proportional to the dose administered throughout the recommended dose range. For every 0.1 microgram/kg/min increase in infusion rate, the blood concentration of remifentanil will rise 2.5 nanograms/ml. Remifentanil is approximately 70% bound to plasma proteins.
MetabolismRemifentanil is an esterase metabolised opioid that is susceptible to metabolism by non-specific blood and tissue esterases. The metabolism of remifentanil results in the formation of a carboxylic acid metabolite (1/4600th as potent as reminfentanil). Studies in man indicate that all pharmacological activity is associated with the parent compound. The activity of this metabolite is therefore not of any clinical consequence. The half life of the metabolite in healthy adults is 2 hours. After about 7 to 10 hours approximately 95 % of remifentanil as the carboxylic acid metabolite is recovered in the urine in patients with normal renal function. Remifentanil is not a substrate for plasma cholinesterase.
Placental and milk transferPlacental transfer studies in rats and rabbits showed that pups are exposed to remifentanil and/or its metabolites during growth and development. Remifentanil-related material is transferred to the milk of lactating rats.In a human clinical trial, concentration of remifentanil in the foetal blood was about 50% of the concentration of the maternal blood. The foetal arteriovenous ratio of remifentanil concentrations was approximately 30 % suggesting metabolism of remifentanil in the neonate.
Cardiac anaesthesiaThe clearance of remifentanil is reduced by approximately 20% during hypothermic (28°C) cardiopulmonary bypass. A decrease in body temperature lowers elimination clearance by 3% per degree centigrade.
Renal impairmentThe rapid recovery from remifentanil-based sedation and analgesia is unaffected by renal status. The pharmacokinetics of remifentanil are not significantly changed in patients with varying degrees of renal impairment even after administration for up to 3 days in the intensive care setting. The clearance of the carboxylic acid metabolite is reduced in patients with renal impairment. In intensive care patients with moderate/severe renal impairment, the concentration of the carboxylic acid metabolite may exceed 250-fold the level of remifentanil at steady-state in some patients. Clinical data demonstrate that the accumulation of the metabolite does not result in clinically relevant μ -opioid effects even after administration of remifentanil infusions for up to 3 days in these patients.Up to now, data on safety and pharmacokinetic activity of metabolites after infusion of remifentanil for more than 3 days are lacking.There is no evidence that remifentanil is extracted during renal replacement therapy. The carboxylic acid metabolite is extracted during haemodialysis by at least 30%.
Hepatic impairmentThe pharmacokinetics of remifentanil are not changed in patients with severe hepatic impairment awaiting liver transplant, or during the anhepatic phase of liver transplant surgery. Patients with severe hepatic impairment may be slightly more sensitive to the respiratory depressant effects of remifentanil. These patients should be closely monitored and the dose of remifentanil should be titrated to the individual patient need.
Paediatric patientsThe average clearance and steady state volume of distribution of remifentanil are increased in younger children and decline to young healthy adult values by age 17. The elimination half-life of remifentanil in neonates is not significantly different from that of young healthy adults. Changes in analgesic effect after changes in infusion rate of remifentanil should be rapid and similar to those seen in young healthy adults. The pharmacokinetics of the carboxylic acid metabolite in paediatric patients 2 to 17 years of age are similar to those seen in adults after correcting for differences in body weight.
Older peopleThe clearance of remifentanil is slightly reduced in older people ( > 65 years) compared to that in young patients. The pharmacodynamic activity of remifentanil increases with increasing age. Older people have a remifentanil EC50 for formation of delta waves on the electroencephalogram (EEG) that is 50% lower than young patients; therefore, the initial dose of remifentanil should be reduced by 50% in older people and then carefully titrated to meet the individual patient need.
Acute toxicityExpected signs of µ -opioid intoxication were observed in non-ventilated mice, rats and dogs after large single bolus intravenous doses of remifentanil. In these studies, the most sensitive species, i.e. the male rat, survived following administration of 5 mg/kg. Intracranial bleedings in dogs caused by hypoxia declined within 14 days after stopping remifentanil application.
Chronic toxicityBolus doses of remifentanil administered to non-ventilated rats and dogs resulted in respiratory depression in all dose groups, and in reversible intracranial bleedings in dogs. Subsequent investigations showed that the microhaemorrhages resulted from hypoxia and were not specific to remifentanil. Brain microhaemorrhages were not observed in infusion studies in non-ventilated rats and dogs because these studies were conducted at doses that did not cause severe respiratory depression. It is to be derived from preclinical studies that respiratory depression and associated sequelae are the most likely cause of potentially serious adverse events in humans.Intrathecal administration to dogs of the glycine formulation alone (i.e. without remifentanil) caused agitation, pain, and hind limb dysfunction and incoordination. These effects are believed to be secondary to the glycine excipient. Because of the better buffering properties of blood, the more rapid dilution and the low glycine concentrations of the Remifentanil formulation, this finding has no clinical relevance for intravenous administration of Remifentanil
Reproductive toxicity studiesRemifentanil has been shown to reduce fertility in male rats when administered daily by intravenous injection for at least 70 days. This effect was seen at each tested dose. The fertility of female rats was not affected. No teratogenic effects have been observed. Administration of remifentanil to rats throughout late gestation and lactation had no significant effect on the survival, development, or reproductive performance of the F1 generation.
GenotoxicityRemifentanil did not yield positive findings in a series of in vitro and in vivo genotoxicity tests, except in the in vitro mouse lymphoma tk assay, which gave a positive result with metabolic activation. Since the mouse lymphoma results could not be confirmed in further in vitro and in vivo tests, treatment with remifentanil is not considered to pose a genotoxic hazard to patients.
CarcinogenicityLong-term animal carcinogenicity studies have not been performed.
Unopened:Powder for concentrate for solution for injection or infusion: 24 months
Reconstituted solution:Chemical and physical in-use stability of the reconstituted solution has been demonstrated for 24 hours at 25° C.From a microbiological point of view, the product should be used immediately. If not used immediately, in-use storage times and conditions prior to use are the responsibility of the user and would normally not be longer than 24 hours at 2 to 8° C, unless reconstitution has taken place in controlled and validated aseptic conditions.
Diluted solution:All admixtures of Remifentanil with infusion fluids should be used immediately. Any unused diluted solution should be discarded.
1x 4 ml vial, 5x 4 ml vials of powderNot all pack sizes may be marketed.
|Drug Delivery Rate (microgram/kg/min)||Infusion Delivery Rate (ml/kg/h) for Solution Concentrations of|
|20 microgram/ml 1 mg/50 ml||25 microgram/ml 1 mg/40 ml||50 microgram/ml 1 mg/20 ml||250 microgram/ml 10 mg/40 ml|
|Infusion Rate (microgram/kg/min)||Patient Weight (kg)|
|Infusion Rate (microgram/kg/min)||Patient Weight (kg)|
|Infusion Rate (microgram/kg/min)||Patient Weight (kg)|
|Infusion Rate (microgram/kg/min)||Patient Weight (kg)|
|Remifentanil Infusion Rate (microgram/kg/min)||Remifentanil Blood Concentration (nanogram/ml)|