Clinical practice: analgesia in neonates

Intravenous acetaminophen for postoperative pain in the neonatal intensive care unit: A protocol for a pilot randomized controlled trial (IVA POP)

BACKGROUND

In neonates, uncontrolled pain and opioid exposure are both correlated with short- and long-term adverse events. Therefore, managing pain using opioid-sparing approaches is critical in neonatal populations. Multimodal pain control offers the opportunity to manage pain while reducing short- and long-term opioid-related adverse events. Intravenous (IV) acetaminophen may represent an appropriate adjunct to opioid-based postoperative pain control regimes. However, no trials assess this drug in patients less than 36 weeks post-conceptual age or weighing less than 1500 g.

OBJECTIVE

The proposed study aims to determine the feasibility of conducting a randomized control trial to compare IV acetaminophen and fentanyl to a saline placebo and fentanyl for patients admitted to the neonatal intensive care unit (NICU) undergoing major abdominal or thoracic surgery.

METHODS AND DESIGN

This protocol is for a single-centre, external pilot randomized controlled trial (RCT). Infants in the NICU who have undergone major thoracic or abdominal surgery will be enrolled. Sixty participants will undergo 1:1 randomization to receive intravenous acetaminophen and fentanyl or saline placebo and fentanyl. After surgery, IV acetaminophen or placebo will be given routinely for eight days (192 hours). Appropriate dosing will be determined based on the participant's gestational age. Patients will be followed for eight days after surgery and will undergo a chart review at 90 days. Primarily feasibility outcomes include recruitment rate, follow-up rate, compliance, and blinding index. Secondary clinical outcomes will be collected as well.

CONCLUSION

This external pilot RCT will assess the feasibility of performing a multicenter RCT comparing IV acetaminophen and fentanyl to a saline placebo and fentanyl in NICU patients following major abdominal and thoracic surgery. The results will inform the design of a multicenter RCT, which will have the appropriate power to determine the efficacy of this treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05678244, Registered December 6, 2022.

Treatment and outcome data of very low birth weight infants treated with less invasive surfactant administration in comparison to intubation and mechanical ventilation in the clinical setting of a cross-sectional observational multicenter study

The aim of this study was to contribute further to existing randomized controlled trials and meta-analyses showing advantages in the outcome of less invasive surfactant administration (LISA)-treated infants and add new aspects concerning treatment and outcome data collected in the routine clinical setting. Four hundred seven very low birth weight infants who received surfactant via either LISA or intubation methods were enrolled in the observational cross-sectional multicenter study. To compare infants in terms of surfactant administration, we used an exact matching procedure (the same gestational age, severe perinatal depression (pH < 7.10), birth weight < 10th percentile, antenatal steroid treatment, and the same gender). To check for robustness, we performed repeated matching. LISA-treated infants required significantly less mechanical ventilation during hospital stay (p < 0.001) and days with supplemental oxygen (p = 0.03). Analgesics and sedatives were used less often during the stay (p < 0.001). Infants treated with LISA had significantly lower rates of bronchopulmonary dysplasia (p = 0.003). LISA failure infants were identified as more likely to be small for gestational age and more immature.

CONCLUSION

Our study complements former results with advantages for LISA-treated infants in mechanical ventilation and bronchopulmonary dysplasia in the clinical routine.

TRIAL REGISTRATION

DRKS00004589 What is Known: • According to existing literature, LISA-treated infants seem to have some favors in terms of treatment and outcome data. Observational studies in routine clinical setting are missing. What is New: • Data of 407 VLBW infants collected in routine clinical setting showed that LISA-treated infants needed less mechanical ventilation and fewer days with supplemental oxygen and less analgesics and sedatives. A reduced risk of BPD could be showed. SGA infants seem to have higher risks of LISA failure.

Neonatal pain management: still in search for the Holy Grail

Inadequate pain management but also inappropriate use of analgesics in early infancy has negative effects on neurodevelopmental outcome. As a consequence, neonatal pain management is still in search for the Holy Grail. At best, effective pain management is based on prevention, assessment, and treatment followed by a re-assessment of the pain to determine if additional treatment is still necessary. Unfortunately, epidemiological observations suggest that neonates are undergoing painful procedures very frequently, unveiling the need for effective preventive, non-pharmacological strategies. In addition, assessment is still based on validated, multimodal, but subjective pain assessment tools. Finally, in neonatal intensive care units, there is a shift in clinical practices (e.g., shorter intubation and ventilation), and this necessitates the development and validation of new pharmacological treatment modalities. To illustrate this, a shift in the use of opioids to paracetamol has occurred and short-acting agents (remifentanil, propofol) are more commonly administered to neonates. In addition to these new modalities and as part of a more advanced approach of the developmental pharmacology of analgesics, pharmacogenetics also emerged as a tool for precision medicine in neonates. To assure further improvement of neonatal pain management the integration of pharmacogenetics with the usual covariates like weight, age and/or disease characteristics is needed.

Efficacy and safety of intravenous paracetamol in comparison to ibuprofen for the treatment of patent ductus arteriosus in preterm infants: study protocol for a randomized control trial

Background

Patent ductus arteriosus (PDA) is one of most common complications in preterm infants. Although ibuprofen represents the first choice for the closure of PDA, this treatment can cause severe gastrointestinal and adverse renal effects and worsen platelet function. The successful closure of the PDA with paracetamol has been recently reported in several preterm infants, and the safety of paracetamol for this use has been suggested by the available data.

Methods/design

We present the design of a randomized, multicenter, controlled study, whose aim is to assess the effectiveness and safety of intravenous paracetamol in comparison to intravenous ibuprofen for the treatment of PDA in preterm infants. A total of 110 infants born at 25⁺⁰ to 31⁺⁶ weeks of gestational age will be enrolled and randomized to receive paracetamol or ibuprofen (55 patients per group) starting at 24–72 h of life. The primary endpoint of the study is the comparison of the PDA closing rate observed after a 3-day course with paracetamol or ibuprofen. The secondary endpoints include the closure rate of PDA after the second course of treatment with ibuprofen, the re-opening rate of the PDA, the incidence of surgical ligation, and the occurrence of adverse effects.

Discussion

The results of this study will provide new information about the possible use of paracetamol in the treatment of PDA. Paracetamol could offer several important therapeutic advantages over current treatment options, and it could become the treatment of choice for the management of PDA, mainly due to its more favorable side effect profile.

Trial registration

Clinicaltrials.gov NCT02422966.

Eudract no. 2013-003883-30.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1294-4) contains supplementary material, which is available to authorized users.

Neonatal paracetamol treatment reduces long-term nociceptive behaviour after neonatal procedural pain in rats

BACKGROUND

Pain from skin penetrating procedures (procedural pain) during infancy in the neonatal intensive care unit (NICU) may result in changes of nociceptive sensitivity in later life. This supports the need for pain management during such vulnerable periods in life. This study, therefore, analyses the short- and long-term consequences of neonatal paracetamol (acetaminophen) treatment on pain behaviour in an experimental rat model of neonatal procedural pain.

METHODS

A repetitive needle-prick model was used, in which neonatal rats received four needle pricks into the left hind paw per day from postnatal day 0 to day 7 (P0-P7). Paracetamol (50 mg/kg/day s.c.) was administered daily (P0-P7), and sensitivity to mechanical stimuli was compared with a needle-prick/saline-treated group and to a tactile control group. At 8 weeks of age, all animals underwent an ipsilateral paw-incision, modelling postoperative pain, and the duration of hypersensitivity was assessed.

RESULTS

Neonatal paracetamol administration had no effect upon short-term mechanical hypersensitivity during the first postnatal week or upon long-term baseline sensitivity from 3 to 8 weeks. However, neonatal paracetamol administration significantly reduced the postoperative mechanical hypersensitivity in young adults, caused by repetitive needle pricking.

CONCLUSION

Paracetamol administration during neonatal procedural pain does not alter short-term or long-term effects on mechanical sensitivity, but does reduce the duration of increased postoperative mechanical hypersensitivity in a clinically relevant neonatal procedural pain model.

WHAT DOES THIS STUDY ADD

Paracetamol can be used safely in neonatal rats. Neonatal paracetamol treatment had no effect upon short-term mechanical hypersensitivity during the first postnatal week, nor upon long-term baseline sensitivity from 3 to 8 weeks. Paracetamol treatment during the first postnatal week significantly reduced the postoperative mechanical hypersensitivity in young adult rats.

Neurodevelopmental Implications of Neonatal Pain and Morphine Exposure

Neonatal pain management has evolved dramatically in the past few decades. Evidence is clear that neonates experience pain. Furthermore, we are increasingly aware of the detrimental effects of untreated neonatal pain during a critical period of neuronal maturation. Providing safe and effective pain relief is a primary goal of neonatal critical care specialists to ensure good outcomes. However, there are lingering concerns regarding the harmful effects of sedative-analgesics on the developing brain. Thus, striking a fine balance between effective analgesia and avoiding serious short- and long-term adverse effects from pain medications remains a major challenge for caregivers.

[Paracetamol (acetaminophen) use in neonatology: a (re)appreciation of an old drug]

In neonates, paracetamol is mainly used for its analgesic action. This drug is actually preferred by neonatologists because of its broad therapeutic index. Recently, it has been demonstrated that paracetamol is also an anti-cyclooxygenase (COX) medication through its inhibitory action on the peroxidase arm of central and peripheral COX (Boutaud et al., 2002; Toussaint et al., 2010; Graham et al., 2013; Hinz et al., 2008; Hinz and Brune, 2011). As such, this drug interferes with the synthesis of prostaglandins. This inhibition of peroxidase is, however, limited to a low concentration of arachidonic acid (AA) (around 2μM, in vitro) when the plasmatic concentration of paracetamol is experimentally 10μM, actually within the same range as compared to the therapeutic concentrations in vivo. This may partly explain its low anti-inflammatory effect as compared to ibuprofen and indomethacin, which exert their inhibition on COX whatever the AA concentrations are. This new well-demonstrated action of paracetamol on peripheral COX-2 of intact cells could explain recent observations making this drug a potential alternative in treating patent ductus arteriosus. However, the higher dosages that have been claimed by some authors in this indication still remain to be validated. This inhibition that paracetamol shows on the physiological synthesis of prostaglandins E2 (PGE2) could also explain some long-term immune deviations because the physiological concentration of PGE2 is a well-known actor in the genesis of immune homeostasis in the submucosal area. Indeed, recent epidemiology studies have pointed out immune deviations in children repeatedly exposed to paracetamol earlier in life. Consequently, this is actually the new discovery of an old drug. From these new data on paracetamol, a more focused pharmacovigilance on the long-term effects of paracetamol repeatedly given in the early stage should be urgently initiated.

Oral glucose in preterm neonates during oropharyngeal suctioning: a randomized controlled cross-over trial

To investigate whether orally applied glucose reduces pain response during oropharyngeal suctioning in preterm infants with a birth weight >1500 g, we conducted a randomized, double-blind, placebo-controlled cross-over trial on 32 preterm infants undergoing oropharyngeal suctioning while on nasal continuous positive airway pressure (CPAP). The Premature Infant Pain Profile (PIPP) score was assessed and compared in a cross-over design to investigate whether there was a significant difference in the patients' pain response. The mean PIPP score during oropharyngeal suctioning after placebo was 8.6 (KI 7.8-9.4). After glucose administration, the mean PIPP score was 8.0 (KI 7.1-8.9). Comparison of the treatment effects reached no statistic significance (p = 0.23). During the oral study drug administration during nasal CPAP, we observed 47 adverse events, but none necessitated therapeutic intervention and none was classified as serious.

CONCLUSION

In our study, late preterm infants in the first days of life did not benefit significantly from analgesia with glucose during oropharyngeal suctioning. The oral administration of glucose under nasal CPAP led to no serious adverse events.

[Prostaglandins and the immune response at the intestinal submucosal level. A potential site for interference with the repeated use of paracetamol and ibuprofen at a young age?]

Immune deviations have been shown to exponentially increase in young children. As a consequence, research investigating possible environmental reasons for this increase is considered a public health priority. An improved understanding of the immunity of the intestinal submucosal lamina propria has demonstrated the importance of prostaglandins (PGE2s) on its local development with general immune consequences further on. PGE2s appear at this intestinal submucosal level from the metabolism of arachidonic acid mediated by type-2 cyclooxygenases (COX2s) situated in the membranes of many immune cells. The potential risk of repeated inhibition of PGE2 synthesis at a young age has been demonstrated in experiments with animals systemically exposed to a non-steroidal anti-inflammatory drug (NSAID). The repeatedly exposed animal cannot develop tolerance to food antigens and exhibits autoimmune deviations. Acetaminophen (paracetamol) and ibuprofen are analgesic and antipyretic medications given to children either alone or in combination, most often without medical prescription. Recently, it has been demonstrated that paracetamol, like ibuprofen, also carries, besides its central action, a non-selective inhibitory action on peripheral COXs. However, this inhibitory action only relates to physiological concentrations of arachidonic acid and explains the difference in their respective anti-inflammatory effects. Since recently published data have repeatedly reported an increase of immune deviations associated with paracetamol exposure at a young age, it appears important to better understand the possible negative impact of excessive and repetitive inhibitions of the physiological synthesis of prostaglandins by COX2s in childhood during which all immune mechanisms are built up at the intestinal submucosal level. Therefore, a well-designed prospective strategy for pharmacovigilance of these COX inhibitors repeatedly given during childhood is urgently needed.

Development and psychometric properties of the Swedish ALPS-Neo pain and stress assessment scale for newborn infants

AIM

To validate and evaluate the psychometric properties of the ALPS-Neo, a new pain assessment scale created for the continuous evaluation of pain and stress in preterm and sick term infants.

METHODS

A unidimensional scale for continuous pain, Astrid Lindgren Children's Hospital Pain Scale (ALPS 1), was developed further to assess continuous pain and stress in infants treated in the neonatal intensive care unit (NICU). The pain scale includes observations of five behaviours. A manual was created, clarifying the scoring criteria. An internal and an external panel assessed face validity. Psychometric properties were evaluated in three different steps. Inter-rater reliability was estimated from video-based assessments (n = 625) using weighted kappa statistics (test I). Inter-rater reliability was further evaluated in test II (n = 125) and test III (n = 96) by real-time assessments using the intraclass correlation coefficient (ICC) and Cronbach's alpha.

RESULTS

The final inter-rater reliability (test III) was assessed as good with ICC 0.91 for the total score and 0.62-0.81 for the five items. Cronbach's alpha showed 0.95 for the total score.

CONCLUSION

ALPS-Neo is a new assessment tool for optimising the management of pain and stress in newborn infants in the NICU. It has proved easy to implement and user-friendly, permitting fast, reliable observations with high inter-rater reliability.

Use of analgesic and sedative drugs in VLBW infants in German NICUs from 2003-2010

Very low birth weight (VLBW) infants frequently receive analgesia and/or sedation for painful procedures and mechanical ventilation to avoid negative stress. Yet, concerns remain regarding potential adverse long-term effects of these drugs on VLBW infants' neurocognitive outcome. Recent studies have shown that less invasive surfactant application (LISA) and early nasal CPAP treatment reduce the need for mechanical ventilation and painful procedures. Therefore, these measures might also reduce the application of analgesic and/or sedative drugs in VLBW infants. To evaluate this hypothesis and to identify potential changes in analgesic treatment concepts in recent years, we retrospectively analyzed data on analgesia and sedation, respiratory support, and the method of surfactant application in VLBW infants enrolled in the German Neonatal Network (GNN) trial between 2003 and 2009 (period 1) and compared it with data from infants participating in GNN in 2010 (period 2). In both periods, about one third of all infants were treated with analgesic and/or sedative drugs using a wide variety of substances. The administration of novel drugs such as propofol, sufentanil, or intravenous paracetamol was higher in 2010 (6.7 vs. 12.2 %). Infants who were treated with CPAP only received significantly less analgesic/sedative medication than infants who were mechanically ventilated (12 vs. 65 %, p=<0.001). Similarly, infants treated with LISA received less analgesic or sedative drugs as compared to infants who received surfactant via endotracheal intubation (36 vs. 63 %, p=0.001).

CONCLUSION

Although both avoidances of mechanical ventilation and less invasive surfactant application are associated with reduced analgesic or sedative treatment, the percentage of VLBW infants who received analgesia and/or sedation remained unchanged in Germany in recent years.

Successful implementation of a neonatal pain and sedation protocol at 2 NICUs

OBJECTIVE

To evaluate the implementation of a neonatal pain and sedation protocol at 2 ICUs.

METHODS

The intervention started with the evaluation of local practice, problems, and staff satisfaction. We then developed and implemented the Vienna Protocol for Neonatal Pain and Sedation. The protocol included well-defined strategies for both nonpharmacologic and pharmacologic interventions based on regular assessment of a translated version of the Neonatal Pain Agitation and Sedation Scale and titration of analgesic and sedative therapy according to aim scores. Health care staff was trained in the assessment by using a video-based tutorial and bedside teaching. In addition, we performed reevaluation, retraining, and random quality checks. Frequency and quality of assessments, pharmacologic therapy, duration of mechanical ventilation, and outcome were compared between baseline (12 months before implementation) and 12 months after implementation.

RESULTS

Cumulative median (interquartile range) opiate dose (baseline dose of 1.4 [0.5-5.9] mg/kg versus intervention group dose of 2.7 [0.4-57] mg/kg morphine equivalents; P = .002), pharmacologic interventions per episode of continuous sedation/analgesia (4 [2-10] vs 6 [2-13]; P = .005), and overall staff satisfaction (physicians: 31% vs 89%; P < .001; nurses: 17% vs 55%; P < .001) increased after implementation. Time on mechanical ventilation, length of stay at the ICU, and adverse outcomes were similar before and after implementation.

CONCLUSIONS

Implementation of a neonatal pain and sedation protocol at 2 ICUs resulted in an increase in opiate prescription, pharmacologic interventions, and staff satisfaction without affecting time on mechanical ventilation, length of intensive care stay, and adverse outcomes.

Pharmacological treatment of neonatal pain: in search of a new equipoise

Inadequate management of pain in early human life contributes to impaired neurodevelopmental outcome and alters pain thresholds, pain or stress-related behavior and physiological responses. However, there are also emerging animal experimental data on the impact of exposure to analgo-sedatives on the incidence and extent of neuro-apoptosis. Since this association has also been suggested in humans, the pharmacological treatment of neonatal pain is in search of a new equipoise since these 'conflicting' observations are the main drivers to further reconsider our current treatment regimens. This review focuses on new data concerning clinical pharmacology of morphine, followed by data on more recently introduced opioids like remifentanil and tramadol, locoregional anesthesia and minimally invasive techniques in neonates, and finally with data on intravenous paracetamol. Since the available data are still incomplete, priorities for both clinical management and future research will be proposed.

Pharmacokinetics and pharmacodynamics of intravenous acetaminophen in neonates

Effective analgesia in neonates is still hampered owing to a lack of data on pharmacokinetics and pharmacodynamics of analgesics. In this article, the consecutive steps taken to document aspects of disposition (pharmacokinetics and metabolism) and safety (hepatic tolerance, hemodynamic stability and effects on body temperature) during exposure to intravenous acetaminophen in neonates are summarized. Based on these data, dosing suggestions were formulated. However, we have to be aware that such dosing suggestions are - at present - without any validated pharmacodynamic correlates since the applicability of a fixed acetaminophen target concentration (10 mg·l(-1)) in neonates of different subpopulations remains to be documented. In addition, the number of observations in extreme preterm neonates is limited. Finally, epidemiological data suggest a link between perinatal acetaminophen exposure and an increased risk to developing asthma. Consequently, well designed and appropriately powered pharmacodynamic studies in neonates are urgently required, with specific emphasis on extreme preterm neonates.

Neonatal pharmacology: extensive interindividual variability despite limited size

Providing safe and effective drug therapy to neonates requires knowledge of the impact of development on the pharmacokinetics and pharmacodynamics of drugs. Although maturational changes are observed throughout childhood, they are most prominent during the first year of life. Several of these processes overlap, making development an extremely dynamic system in the newborn compared with that in infants, children, or adults. Changes in body composition and porportions, liver mass, metabolic activity, and renal function collectively affect the pharmacokinetic behavior of medications. Instead of simply adapting doses by scaling adult or pediatric doses on the basis of a patient's weight and/or body surface area, integrated knowledge of clinical maturation and developmental pharmacology is critical to the safe and effective use of medications in neonates. Unfortunately, the effects of human ontogeny on both pharmacokinetics and pharmacodynamics have not been well established in these early stages of life, and information regarding the influence of developmental changes on the pharmacodynamics of medications is even more limited. Theoretically, age-dependent variations in receptor number and affinity for drugs have significant potential to influence an individual's response to drug therapy. In this review, some of the relevant covariates of pharmacokinetics and pharmacodynamics in neonates are reviewed and illustrated based on the published literature.

Implementation of a neonatal pain management module in the computerized physician order entry system

BACKGROUND

Despite the recommended guidelines, the neonatal management of pain and discomfort often remains inadequate. The purpose of the present study was to determine whether adding a pain and discomfort module to a computerized physician order entry (CPOE) system would improve pain and discomfort evaluation in premature newborns under invasive ventilation.

METHODS

All newborns <37 weeks gestational age (GA) and requiring invasive ventilation were included in a prospective study during two 6-month periods: before and after the inclusion of the pain and discomfort evaluation module. The main outcome measure was the percentage of patients having at least one assessment of pain and discomfort per day of invasive ventilation using the COMFORT scale.

RESULTS

A total of 122 patients were included: 53 before and 69 after the incorporation of the module. The mean age was 30 (3) weeks GA. After the module was included, the percentage of patients who benefited from at least one pain and discomfort assessment per day increased from 64% to 88% (p < 0.01), and the mean number (SD) of scores recorded per day increased from 1 (1) to 3 (1) (p < 0.01). When the score was not within the established range, the nursing staff adapted analgesia/sedation doses more frequently after module inclusion (53% vs. 34%, p < 0.001). Despite higher mean doses of midazolam after module introduction [47 (45) vs. 31 (18) μg/kg/hr, p < 0.05], the durations of invasive ventilation and hospital stay, and the number of nosocomial infections, were not significantly modified.

CONCLUSIONS

Adding a pain and discomfort tool to the CPOE system was a simple and effective way to improve the systematic evaluation of premature newborns who required ventilatory assistance.

Procedural pain in children: education and management. The approach of an Italian pediatric pain center

Pain management should be warranted for all children in every situation. Italian legislation proposes a model for pain assistance based on specialized tertiary centers which provide direct clinical management for complex cases and assure continuous cooperation with hospitals and family pediatricians for managing painful conditions every day. The Procedural Pain Service of the University of Padua Department of Pediatrics applies such model for procedural pain management. We describe activities of Service since January 1, 2006 on two levels: education and training for territorial services and sedation-analgesia when required for invasive and painful procedures. Since 2006 to date, the Service team produced an internal protocol for procedural sedation, developed two master courses, and organized a training program for procedural pain management in the territorial context. Procedural sedation-analgesia service provided overall 10,832 sedations to perform 14,264 procedures for 3,815 patients, median age of 6 years old. The most frequently performed procedures were lumbar puncture and bone marrow aspiration, followed by gastroscopy and bronchoscopy. Most frequently administered drug combinations were local analgesia + intravenous midazolam alone or midazolam and propofol or midazolam and propofol and ketamine; most frequently used non-pharmacological methods were distraction using cartoons and bubbles. Minor adverse events were recorded in 281 cases (2.5%), the most common being desaturation (2.1%). In conclusion, our model functions on two integrated levels, and it can be considered generally applicable as a solution for pain management.

Perinatal pharmacology: applications for neonatal neurology

The principles of clinical pharmacology also apply to neonates, but their characteristics warrant a tailored approach. We focus on aspects of both developmental pharmacokinetics (concentration/time relationship) and developmental pharmacodynamics (concentration/effect relationship) in neonates. We hereby aimed to link concepts used in clinical pharmacology with compound-specific observations (anti-epileptics, analgosedatives) in the field of neonatal neurology. Although in part anecdotal, we subsequently illustrate the relevance of developmental pharmacology in the field of neonatal neurology by a specific intervention (e.g. whole body cooling), specific clinical presentations (e.g. short and long term outcome following fetal exposure to antidepressive agents, the development of new biomarkers for fetal alcohol syndrome) and specific clinical needs (e.g. analgosedation in neonates, excitocytosis versus neuro-apoptosis/impaired synaptogenesis).

Developmental pharmacology of tramadol during infancy: ontogeny, pharmacogenetics and elimination clearance

AIMS AND OBJECTIVES

To illustrate the complex interaction between ontogeny, i.e., age-dependent maturation, genetic polymorphisms and renal elimination clearance during infancy, based on developmental disposition of intravenous tramadol during infancy.

BACKGROUND

Tramadol (M) is metabolized by O-demethylation (cytochrome P450 [CYP] 2D6) to the pharmacodynamic active metabolite O-demethyl tramadol (M1). This metabolite is subsequently eliminated by renal route while M1 formation will in part depend on ontogeny, i.e., age-dependent activity and CYP2D6 polymorphisms. However, these pathways do not mature simultaneously.

METHODS

A pooled pharmacokinetic analysis of earlier reported time-concentration profiles in neonates and infants was performed with subsequent simulation of the impact of ontogeny, polymorphisms and renal elimination clearance during infancy.

RESULTS

Tramadol plasma time-concentration profile changes with postmenstrual age. The highest metabolite concentrations occur in the 52-week infant, where M1 formation clearance (hepatic, CYP2D6) is already mature but metabolite elimination clearance (through glomerular filtration rate) is immature.

DISCUSSION

The phenotypic observations might in part explain unanticipated (side-)effects of tramadol. In addition to the compound-specific clinical implications, it is important to stress that the maturational trends in the elimination processes described can be considered for other compounds (e.g., codeine) that undergo similar elimination routes.

Haemodynamics of intravenous paracetamol in neonates

INTRODUCTION

Reports on the haemodynamics of intravenous (iv) paracetamol in adult intensive care were recently published. We therefore wanted to explore the haemodynamics of iv paracetamol in neonates.

METHODS

Retrospective, pooled analysis of heart rate (bpm) and blood pressure (mean, systolic, diastolic) observations collected during iv paracetamol pharmacokinetic studies in neonates. Heart rate and blood pressure were recorded just before and 30, 60, 120, 180, 240, 300 and 360 min after iv paracetamol (paired, ANOVA). Clinical characteristics in hypotensive (mean mmHg < gestational age, weeks) cases were compared with controls (Mann-Whitney U test).

RESULTS

Based on observations in 72 neonates, heart rate decreased from 145 (SD 20) to 138 (21), 141 (20), 137 (20), 137 (22), 140 (20), 139 (20) and 140 (21) bpm (paired p < 0.05, ANOVA p = 0.36). There were no changes in systolic and diastolic pressure, but mean arterial pressure decreased from 46 (7) to 43 (8) mmHg at 60 min (paired p < 0.05, ANOVA p = 0.75). Eight neonates developed hypotension. These patients had lower pre-administration arterial pressure (38 vs 47 mmHg, p < 0.05).

CONCLUSIONS

In a setting of open label administration to alleviate (procedural) pain, haemodynamic effects of iv paracetamol in neonates remained modest. We suggest considering impaired haemodynamics to be a relative contra-indication for iv paracetamol in neonates.