Reliability of sufentanil plasma level assays in patients

Pharmacokinetics of Fentanyl and Its Derivatives in Children: A Comprehensive Review

Fentanyl and its derivatives sufentanil, alfentanil, and remifentanil are potent opioids. A comprehensive review of the use of fentanyl and its derivatives in the pediatric population was performed using the National Library of Medicine PubMed. Studies were included if they contained original pharmacokinetic parameters or models using established routes of administration in patients younger than 18 years of age. Of 372 retrieved articles, 44 eligible pharmacokinetic studies contained data of 821 patients younger than 18 years of age, including more than 46 preterm infants, 64 full-term neonates, 115 infants/toddlers, 188 children, and 28 adolescents. Underlying diagnoses included congenital heart and pulmonary disease and abdominal disorders. Routes of drug administration were intravenous, epidural, oral-transmucosal, intranasal, and transdermal. Despite extensive use in daily clinical practice, few studies have been performed. Preterm and term infants have lower clearance and protein binding. Pharmacokinetics was not altered by chronic renal or hepatic disease. Analyses of the pooled individual patients' data revealed that clearance maturation relating to body weight could be best described by the Hill function for sufentanil (R ² = 0.71, B _max 876 mL/min, K ₅₀ 16.3 kg) and alfentanil (R ² = 0.70, B _{max (fixed)} 420 mL/min, K ₅₀ 28 kg). The allometric exponent for estimation of clearance of sufentanil was 0.99 and 0.75 for alfentanil clearance. Maturation of remifentanil clearance was described by linear regression to bodyweight (R ² = 0.69). The allometric exponent for estimation of remifentanil clearance was 0.76. For fentanyl, linear regression showed only a weak correlation between clearance and bodyweight in preterm and term neonates (R ² = 0.22) owing to a lack of data in older age groups. A large heterogeneity regarding study design, clinical setting, drug administration, laboratory assays, and pharmacokinetic estimation was observed between studies introducing bias into the analyses performed in this review. A limitation of this review is that pharmacokinetic data, based on different modes of administration, dosing schemes, and parameter estimation methods, were combined.

Correction to: Pharmacokinetics of Fentanyl and Its Derivatives in Children: A Comprehensive Review

Fentanyl and its derivatives sufentanil, alfentanil, and remifentanil are potent opioids. A comprehensive review of the use of fentanyl and its derivatives in the pediatric population was performed using the National Library of Medicine PubMed. Studies were included if they contained original pharmacokinetic parameters or models using established routes of administration in patients younger than 18 years of age. Of 372 retrieved articles, 44 eligible pharmacokinetic studies contained data of 821 patients younger than 18 years of age, including more than 46 preterm infants, 64 full-term neonates, 115 infants/toddlers, 188 children, and 28 adolescents. Underlying diagnoses included congenital heart and pulmonary disease and abdominal disorders. Routes of drug administration were intravenous, epidural, oral-transmucosal, intranasal, and transdermal. Despite extensive use in daily clinical practice, few studies have been performed. Preterm and term infants have lower clearance and protein binding. Pharmacokinetics was not altered by chronic renal or hepatic disease. Analyses of the pooled individual patients' data revealed that clearance maturation relating to body weight could be best described by the Hill function for sufentanil (R ² = 0.71, B _max 876 mL/min, K ₅₀ 16.3 kg) and alfentanil (R ² = 0.70, B _{max (fixed)} 420 mL/min, K ₅₀ 28 kg). The allometric exponent for estimation of clearance of sufentanil was 0.99 and 0.75 for alfentanil clearance. Maturation of remifentanil clearance was described by linear regression to bodyweight (R ² = 0.69). The allometric exponent for estimation of remifentanil clearance was 0.76. For fentanyl, linear regression showed only a weak correlation between clearance and bodyweight in preterm and term neonates (R ² = 0.22) owing to a lack of data in older age groups. A large heterogeneity regarding study design, clinical setting, drug administration, laboratory assays, and pharmacokinetic estimation was observed between studies introducing bias into the analyses performed in this review. A limitation of this review is that pharmacokinetic data, based on different modes of administration, dosing schemes, and parameter estimation methods, were combined.

Very sensitive and specific determination of sufentanil in human serum applying liquid chromatography-two stage mass spectrometry

Sufentanil is the most potent synthetic opioid currently in use. Extremely low serum concentrations have to be determined for therapeutic drug monitoring and to support brain death diagnosis by excluding opioid induced coma. The described method utilizes a HPLC-MS-MS system with an electrospray ion source and an ion-trap mass spectrometer. The serum samples were extracted under basic conditions with toluene-2-propanol (10:1, v/v). Chromatographic separation was achieved on a RP-18 70x2 mm column with a 0.02% trifluoroacetic acid in a water-acetonitrile gradient as mobile phase. The limits of detection and quantification are 3 and 10 pg/ml, respectively. At the limit of quantification, the intra-day relative standard deviation of the assay is 12.6% and the inter-day relative standard deviation is 14%.

Sufentanil plasma concentrations following lower extremity tourniquet release

STUDY OBJECTIVE

To investigate whether release of a tourniquet on the lower extremity affects plasma concentrations of sufentanil, as previously demonstrated with fentanyl and midazolam.

DESIGN

Prospective.

SETTING

University tertiary-care institution with residency program.

PATIENTS

20 ASA status I, II, and III patients undergoing total knee arthroplasty under a tourniquet using a sufentanil, nitrous oxide, relaxant regimen.

INTERVENTIONS

Each patient received sufentanil 1 to 2 micrograms/kg at induction of anesthesia and in 12.5 to 25 microgram increments as needed thereafter, until 15 minutes prior to tourniquet release.

MEASUREMENTS AND MAIN RESULTS

Plasma sufentanil concentrations were determined before tourniquet inflation, immediately before tourniquet deflation, and 1, 2, 5, 10, 20, 30, and 40 minutes following deflation. A 15% elevation of plasma sufentanil concentration above that predicted by elimination pharmacokinetics defined a secondary peak. Although the aggregate data did not indicate an overall statistically significant rise in plasma concentrations after deflation, 9 (45%) patients exhibited a secondary peak in sufentanil plasma concentration following tourniquet deflation (range of secondary peaks, 16% to 89% above predicted values). No patient experienced clinically significant respiratory depression.

CONCLUSION

Release of a tourniquet on the lower extremity may yield a detectable rise in plasma sufentanil concentration.

The effects of intravenous and epidural sufentanil in the chronic maternal-fetal sheep preparation

This study examines the placental transfer and hemodynamic and acid-base changes after intravenous (i.v.) and epidural administration of sufentanil in the chronically instrumented maternal-fetal sheep preparation. A dose of 50 micrograms sufentanil was injected either i.v. or epidurally into seven ewes. Neither i.v. nor epidural injection of sufentanil affected maternal mean arterial pressure (MMAP), uterine blood flow (UBF), maternal heart rate (MHR), fetal mean arterial pressure (FMAP), fetal heart rate (FHR), or blood gases and acid-base status in mother and fetus, After i.v. administration, a peak sufentanil level of 1.28 ng/mL +/- 0.285 (SD) was detected in maternal plasma. A peak plasma level of 0.037 ng/mL +/- 0.041 (SD) was attained in the fetus. A constant maternal-fetal concentration ratio of 5.5 from 15-60 min after the i.v. injection was found. After epidural injection a mean peak plasma level of 0.059 ng/mL +/- 0.042 (SD) was reached in the mother 25 min after injection. Sufentanil levels were undetectable in fetal plasma after epidural injection into the mother. Because placental transfer of sufentanil is small, the maternal and fetal cardiovascular and acid-base effects are minimal in the pregnant ewe.

[Peroperative perfusion of fentanyl or sufentanil: plasma concentrations and postoperative respiratory changes]

This study was designed to assess postoperatively the time course of respiratory depression due to fentanyl (F) or sufentanil (S), as well as the plasma concentrations. Seventy patients scheduled for orthopaedic surgery lasting more than 3 hours were randomly assigned to two groups, F (n = 8) or S (n = 9). Anaesthesia was induced with etomidate (0.3 mg.kg-1), droperidol (0.15 mg.kg-1), vercuronium (0.1 mg.kg-1), a loading dose of either F (10 micrograms.kg-1) or S (1 microgram.kg-1), and maintained with 60% nitrous oxide in oxygen, and an infusion of F (6 micrograms.kg-1.h-1) or S (0.6 microgram.kg-1.h-1). Mechanical ventilation was maintained postoperatively in the recovery room until the patient could be extubated. PetCO2, SpO2, fR and F and S plasma concentrations were assessed at the end of the opioid infusion, at extubation, every hour for the first 6 hours, and thereafter every 2 h for a further 10 and 18 h. Time to extubation was the same in both groups (301 +/- 141 and 307 +/- 148 min). At the time, plasma concentrations of F and S were 1.35 +/- 0.9 ng.ml-1 and 0.14 +/- 0.07 ng.ml-1 respectively. Secondary peaks in plasma concentration (78% mean increase in comparison to the previous figure) were observed in 6 patients in group F. No similar peaks occurred in group S. Mean elimination half-life was shorter with sufentanil (457 +/- 130 min) than with fentanyl (325 +/- 132 min) (not significant). The results of this study suggest that sufentanil results less frequently in postoperative secondary peaks than fentanyl.

Maternal and neonatal effects of adding epidural sufentanil to 0.5% bupivacaine for cesarean delivery

STUDY OBJECTIVE

To determine the maternal and fetal effects of the addition of epidural sufentanil to 0.5% bupivacaine for cesarean delivery.

DESIGN

Randomized, double-blind, prospective study.

SETTING

University Hospitals, Katholieke Universiteit Leuven, Leuven, Belgium.

PATIENTS

Sixty women at term scheduled for elective cesarean section, all of whom had elected epidural anesthesia.

INTERVENTIONS

The 60 women were divided into three groups of 20, with each group receiving a different 1 ml study solution: saline (control) or sufentanil 20 micrograms or sufentanil 30 micrograms added to 0.5% bupivacaine and epinephrine (1:200,000).

MEASUREMENTS AND MAIN RESULTS

In the mother, the quality of anesthesia, the duration of postoperative analgesia, the volume of anesthetic, and the frequency of side effects were examined. The neonates were evaluated at 5 and 10 minutes after birth by Apgar scores and between 60 and 120 minutes after birth by both the screening test developed by Prechtl and the Neurological and Adaptive Capacity Scoring System. Immediately after delivery, maternal and umbilical vein blood were drawn and assayed for sufentanil levels. Adding sufentanil significantly improved the quality of anesthesia without depressing the neurobehavioral status of the baby.

CONCLUSION

The epidural injection of sufentanil added to 0.5% bupivacaine with epinephrine improved the quality of anesthesia during elective cesarean section without jeopardizing the safety of the baby.

Sufentanil. A review of its pharmacological properties and therapeutic use

Sufentanil, an opioid analgesic, is an analogue of fentanyl, and has been used for the induction and maintenance of anaesthesia, and for postsurgical analgesia. It has shorter distribution and elimination half-lives, and is a more potent analgesic than fentanyl. In clinical practice, however, intravenously administered sufentanil produces essentially equivalent anaesthesia to fentanyl and is a better anaesthetic than morphine or pethidine (meperidine) for major surgery. It would appear to maintain haemodynamic stability during surgery better than other opioids or inhalational anaesthetics. Postoperative respiratory depression has been reported in a few patients. For outpatient surgery, intravenous sufentanil produces equivalent anaesthesia to isoflurane or fentanyl. Recovery tends to be more rapid after sufentanil and the requirement for postoperative analgesia is less. Initial clinical trials with sufentanil administered epidurally to relieve pain during labour have produced encouraging results, but further studies are required to establish the drug's role in this indication. Epidural sufentanil produces a more rapid onset and better initial quality of analgesia than morphine, buprenorphine or hydromorphine when administered postoperatively, but the duration of analgesia is shorter. Thus, sufentanil's primary place in therapy at this time would appear to be as high dose anaesthesia for major surgery such as cardiac surgery, and as low dose supplement to balanced anaesthesia in general surgery. In addition, low doses administered epidurally seem to have a potential role for analgesia during labour or after surgery although further studies are required to clarify this situation.