Pharmacokinetics of sufentanil during long-term infusion in critically ill pediatric patients

Opioids: A Review of Pharmacokinetics and Pharmacodynamics in Neonates, Infants, and Children

Pain management in the pediatric population is complex for many reasons. Mild pain is usually managed quite well with oral acetaminophen or ibuprofen. Situations involving more severe pain often require the use of an opioid, which may be administered by many different routes, depending on clinical necessity. Acute and chronic disease states, as well as the constantly changing maturational process, produce unique challenges at every level of pediatrics in dosing and management of all medications, especially with regard to high-risk opioids. Although there has been significant progress in the understanding of opioid pharmacokinetics and pharmacodynamics in neonates, infants, children, and adolescents, somewhat limited data exist from which necessary information, concerning the safe and effective use of these agents, may be drawn. The evidence here provided is intended to be helpful in directing the practitioner to patient-specific reasons for preferring one opioid over another. As our knowledge of opioids and their effects has grown, it has become clear that older medications like codeine and meperidine (pethidine) have very limited use in pediatrics. This review provides pharmacokinetic and pharmacodynamic evidence on the currently available opioids: morphine, fentanyl (and derivatives), codeine, meperidine, oxycodone, hydrocodone, hydromorphone, methadone, buprenorphine, butorphanol, nalbuphine, pentazocin, ketobemidone, tramadol, piritramide, naloxone and naltrexone. Morphine, being the most studied opioid analgesic, is the standard against which all others are compared. Pharmacokinetic parameters of morphine that have been found in neonates, i.e., higher volume of distribution, immature metabolic processes that develop at various rates, elimination that is variable based on age and weight, as well as treated and untreated disease processes, are an example of all opioids in the population discussed in this review. Outside the premature and neonatal population, the use of opioids in infants, children, and adolescents quickly begins to resemble the established values found in adults. As such, the concerns (risks) of these medications become comparable to those seen in adults.

Population pharmacokinetics of intravenous sufentanil in critically ill patients supported with extracorporeal membrane oxygenation therapy

Background

Sufentanil is commonly used for analgesia and sedation during extracorporeal membrane oxygenation (ECMO). Both ECMO and the pathophysiological changes derived from critical illness have significant effects on the pharmacokinetics (PK) of drugs, yet reports of ECMO and sufentanil PK are scarce. Here, we aimed to develop a population PK model of sufentanil in ECMO patients and to suggest dosing recommendations.

Methods

This prospective cohort PK study included 20 patients who received sufentanil during venoarterial ECMO (VA-ECMO). Blood samples were collected for 96 h during infusion and 72 h after cessation of sufentanil. A population PK model was developed using nonlinear mixed effects modelling. Monte Carlo simulations were performed using the final PK parameters with two typical doses.

Results

A two-compartment model best described the PK of sufentanil. In our final model, increased volume of distribution and decreased values for clearance were reported compared with previous PK data from non-ECMO patients. Covariate analysis showed that body temperature and total plasma protein level correlated positively with systemic clearance (CL) and peripheral volume of distribution (V2), respectively, and improved the model. The parameter estimates of the final model were as follows: CL = 37.8 × EXP (0.207 × (temperature − 36.9)) L h⁻¹, central volume of distribution (V1) = 229 L, V2 = 1640 × (total plasma protein/4.5)^2.46 L, and intercompartmental clearance (Q) = 41 L h⁻¹. Based on Monte Carlo simulation results, an infusion of 17.5 μg h⁻¹ seems to reach target sufentanil concentration (0.3–0.6 μg L⁻¹) in most ECMO patients except hypothermic patients (33 °C). In hypothermic patients, over-sedation, which could induce respiratory depression, needs to be monitored especially when their total plasma protein level is low.

Conclusions

This is the first report on a population PK model of sufentanil in ECMO patients. Our results suggest that close monitoring of the body temperature and total plasma protein level is crucial in ECMO patients who receive sufentanil to provide effective analgesia and sedation and promote recovery.

Trial registration

Clinicaltrials.gov NCT02581280, December 1st, 2014.

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.

The optimal bolus dose of sufentanil for satisfactory laryngeal mask airway (LMA) insertion conditions in chinese pediatric patients: A prospective double-blind randomized controlled trial (CONSORT)

BACKGROUND

This study aimed to estimate the optimal dose of sufentanil, coadministered with 2.5 mg/kg propofol, for satisfactory laryngeal mask airway (LMA) insertion conditions in Chinese children and to determine the optimal bolus dose.

METHODS

Seventy-five Chinese children aged 2 to 6 years with the American Society of Anesthesiologists physical status I or II, undergoing elective minor surgery were recruited. They were randomly divided into 5 different dosage groups (0, 0.05, 0.1, 0.15, 0.2 μg/kg). A predetermined sufentanil diluted with 5 mL saline was injected 30 s, 200 s later, followed by 2.5 mg/kg propofol over 10 s. After that the insertion conditions were assessed, using a 6-category score. The duration of apnea was recorded. A Probit analysis was performed to determine the ED50 and ED95 with 95% confidence interval for optimal conditions.

RESULTS

There were less hemodynamic changes in all sufentanil groups than propofol-only group, with 0.2 μg/kg patients showing the most stable cardiovascular responses and best insertion conditions. However, the duration of apnea increased with the increasing dosage of sufentanil. From Probit analysis, the ED50 and ED95 of sufentanil for optimum score were 0.064 μg/kg and 0.177 μg/kg, respectively.

CONCLUSION

In combination with propofol for anesthesia induction in Chinese children, sufentanil 0.2 μg/kg could prevent patients from dramatic hemodynamic change, providing satisfactory LMA insertion conditions.

Sufentanil pharmacokinetics in a full-term neonate treated with extracorporeal membrane oxygenation: a case report

INTRODUCTION

Sufentanil is a potent analgesic drug used for pain management. A few studies describe the pharmacokinetics of sufentanil in neonates; however, no pharmacokinetic data about sufentanil during extracorporeal membrane oxygenation have been published yet.

CASE REPORT

A 1-day-old neonate with moderate hypoxic-ischemic encephalopathy received veno-arterial extracorporeal membrane oxygenation support for refractory respiratory and circulatory failure. Sufentanil plasma concentrations were determined during both extracorporeal membrane oxygenation (n = 14) and non-extracorporeal membrane oxygenation (n = 17) period. Based on these measurements, individual sufentanil pharmacokinetic parameters were calculated.

DISCUSSION

We observed increased sufentanil volume of distribution (11.6 vs 5.6 L/kg) and decreased sufentanil clearance (0.535 vs 0.746 L/h/kg) in extracorporeal membrane oxygenation period. The increment of volume of distribution was attributed to ECMO influence, while difference in clearance was probably due to drug interaction.

CONCLUSIONS

This is the first description of sufentanil pharmacokinetics in neonate treated with extracorporeal membrane oxygenation. We observed considerably larger volume of distribution during extracorporeal membrane oxygenation period in comparison with non-extracorporeal membrane oxygenation period.

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.

Flip-Flop Phenomenon in Epidural Sufentanil Pharmacokinetics: A Population Study in Children and Infants

The aims of this study were to develop a population pharmacokinetic model of sufentanil coadministered with 0.2% ropivacaine as an epidural infusion in infants and describe the sufentanil absorption profile from epidural space. Data from 2 previously published studies were merged for analysis-20 infants aged 3-36 months receiving sufentanil as an epidural infusion and 41 children 0-17 years old receiving sufentanil as a long-term intravenous infusion. A population nonlinear mixed-effects model was built in NONMEM. Sufentanil pharmacokinetics were described by a 2-compartment model with first-order absorption. The effect of body size on all volume and clearance parameters was included in the model according to allometric scaling with theoretical exponents. The maturation process of metabolic clearance was described by the Hill model. During the model-building process the population was divided into 2 fractions with different typical values of metabolic clearance (CL1 and CL2). The typical values of systemic clearance scaled to a 70-kg patient for the 2 subpopulations were CL1 = 52.6 L/h and CL2 = 158 L/h. The parameters of the Hill function were 54.9 weeks for the postmenstrual age of 50% clearance maturation and 0.802 for the Hill coefficient. The typical values of distribution clearance and volumes of the central and peripheral compartments for a patient with a weight of 70 kg were Q = 40.5 L/h, VC = 7.63 L, and VT = 473 L, respectively. The value of the absorption rate constant from the epidural space was 0.0459/h, which suggests flip-flop pharmacokinetics of sufentanil after epidural administration.

The pharmacokinetics of dexmedetomidine during long-term infusion in critically ill pediatric patients. A Bayesian approach with informative priors

The purpose of this study was to assess the pharmacokinetics of dexmedetomidine in the ICU settings during the prolonged infusion and to compare it with the existing literature data using the Bayesian population modeling with literature-based informative priors. Thirty-eight patients were included in the analysis with concentration measurements obtained at two occasions: first from 0 to 24 h after infusion initiation and second from 0 to 8 h after infusion end. Data analysis was conducted using WinBUGS software. The prior information on dexmedetomidine pharmacokinetics was elicited from the literature study pooling results from a relatively large group of 95 children. A two compartment PK model, with allometrically scaled parameters, maturation of clearance and t-student residual distribution on a log-scale was used to describe the data. The incorporation of time-dependent (different between two occasions) PK parameters improved the model. It was observed that volume of distribution is 1.5-fold higher during the second occasion. There was also an evidence of increased (1.3-fold) clearance for the second occasion with posterior probability equal to 62 %. This work demonstrated the usefulness of Bayesian modeling with informative priors in analyzing pharmacokinetic data and comparing it with existing literature knowledge.