Breast milk oxycodone concentrations in mothers given oxycodone for post-Caesarean delivery pain management.

AIMS: Both effective analgesia and early breastfeeding play an important role in maternal and neonatal well-being after Caesarean delivery. We studied controlled-release oxycodone tablet treatment for postoperative pain management and determined the excretion of oxycodone into breast milk. METHODS: Controlled-release oxycodone/naloxone 10/5-mg tablets (n = 21) or controlled-release oxycodone 10-mg tablets (n = 22) were administered to mothers twice a day for the first 3 days after elective Caesarean delivery as a part of multimodal analgesia. Maternal plasma and breast milk samples were collected daily. Oxycodone, noroxycodone, oxymorphone and noroxymorphone concentrations were analysed with ultra-performance liquid chromatography-mass spectrometry. Maternal pain intensity was recorded with an 11-point Numeric Rating Scale (0-10). Neonatal oxycodone exposure was estimated by simulating five different exposure scenarios, including the highest possible exposure through breast milk. RESULTS: The mean oxycodone and noroxycodone milk-to-maternal plasma ratios were 3.2 and 3.0, respectively. A strong correlation was found between plasma and breast milk oxycodone (R2 = 0.87) and noroxycodone concentrations (R2 = 0.91). In the simulated highest neonatal exposure scenario, the neonate's maximum plasma concentration was estimated to be 5.4 ng/mL and the estimated weight-adjusted infant oxycodone dose was less than 10% of the maternal dose. Pain intensities were similarly low between the two treatment groups. CONCLUSIONS: The oxycodone dose received from colostrum and breast milk during the first three postoperative days after Caesarean delivery is assumed safe for healthy, term neonates, but in extreme cases it is possible for the neonate to receive a dose through breast milk that may elicit opioid effects.

Buprenorphine plasma and cerebrospinal fluid concentrations in osteoarthritis patients during low-dose transdermal patch dosing.

METHODS: Fifty-six (56) patients scheduled for arthroplasty, received 7-day extended-release buprenorphine transdermal patches (5 µg/h) for five consecutive weeks, starting two weeks prior to the surgery. Simultaneous plasma and cerebrospinal fluid (CSF) samples were collected during spinal anesthesia. RESULTS: Median buprenorphine plasma and CSF concentrations at steady-state were 54 pg/mL (range 8.6 - 167 pg/mL) and 1.6 pg/mL (0.30 - 7.3 pg/mL), respectively. The median CSF/plasma -ratio was 3% (range 0.35 - 16%). Large between-subject variability was observed in the measured buprenorphine concentrations within the study population.

Oxycodone does not affect placental circulatory physiology during the early first stage of labor-A randomized trial.

INTRODUCTION: Opioids are used for pain relief during the first stage of labor. Oxycodone can cause maternal hypotension that may modify utero- and fetoplacental circulatory physiology. We hypothesized that maternal intravenous (i.v.) oxycodone has no detrimental effect on utero- and fetoplacental hemodynamics during the early first stage of labor. MATERIAL AND METHODS: Twenty-two parturients requiring pain relief during the first stage of labor were randomized in a double-blinded and placebo-controlled study. By Doppler ultrasonography, both uterine artery (Ut) and umbilical vein (UV) volume blood flows (Q), Ut pulsatility index (PI), and Ut vascular resistance (RUt) were calculated. Blood flow velocity waveforms were obtained between uterine contractions. After baseline measurements, women received oxycodone 0.05 mg/kg or a placebo intravenous. Doppler ultrasonography was repeated up to 120 min after the first drug administration. The second dose of oxycodone 0.05 mg/kg was allowed at 60 min to all parturients with contraction pain ≥5/10. Maternal plasma samples were collected at each study phase and after delivery with umbilical cord plasma samples, to measure oxycodone concentrations. CLINICALTRIALS: gov identifier (NCT no. NCT02573831). RESULTS: At baseline, mean QUt and QUV did not differ significantly between the placebo-first (478 mL/min and 57 mL/min/kg) and the oxycodone-first (561 mL/min and 71 mL/min/kg) groups. In addition, RUt and Ut PI were comparable between the groups. Following oxycodone at 60 min, mean QUt and QUV (714 mL/min and 52 mL/min/kg) were similar to the placebo-first (520 mL/min and 55 mL/min/kg) group. Furthermore, all the measured parameters were comparable to the baseline values. At 60 min after the first study drug administration, all the parturients in the placebo-first group needed intravenous oxycodone 0.05 mg/kg. At 120 min, we found no statistically significant change in any of the measured parameters. No significant correlation was found between maternal oxycodone concentration and QUt or QUV. Furthermore, newborn oxycodone concentration did not correlate with QUV. CONCLUSIONS: Oxycodone did not have any detrimental effect on either utero- or fetoplacental circulatory physiology during the early first stage of labor. Maternal plasma oxycodone did not correlate with utero- and fetoplacental hemodynamics. No correlation was found between newborn oxycodone concentration and fetoplacental hemodynamics.

Postoperative pain in a prospectively assessed surgical short-stay cohort: A subgroup analysis.

BACKGROUND: There is sparse information about postoperative pain after short stay surgery. We explored the incidence of immediate postoperative pain and its relationship with persistent pain or opioid use 2 weeks after surgery. METHODS: This was a subgroup analysis of prospective and controlled data from adult patients (n = 931) who underwent short-stay surgery in a tertiary care hospital. Data comprised patient demographics, surgical category, pain scores and analgesic management during the recovery unit stay, before discharge on the postoperative morning after surgery and again 2 weeks after surgery. RESULTS: Half of the patients had severe dynamic pain in the recovery unit. It was commonest after orthopaedic (70% of patients), followed by gynaecological (54%), gastrointestinal (51%) and spine surgery (49%). Multimodal pain management was used for most patients (n = 811, 87%) with opioid use predominant. The median oxycodone dose during short-stay was the highest after orthopaedic surgery (39 mg). The first individual dynamic pain score after surgery was associated with follow-up pain score at rest (OR = 1.37), dynamic pain (OR = 1.35) and pain interference (OR = 1.34) at 2 weeks after surgery. Maximum dynamic pain reported in the recovery unit was associated with pain at rest (OR = 1.56), dynamic pain (OR = 1.65) and pain interference (OR = 1.45) at 2 weeks after surgery. Pain scores at 2 weeks were highest and analgesic use greatest in those patients who underwent spinal surgery. CONCLUSIONS: Intense postoperative pain remains common after short-stay surgery in some surgical categories including orthopaedic surgery and is associated with a greater likelihood of pain at 2 weeks.

Resilience, pain, and health-related quality of life in gynecological patients undergoing surgery for benign and malignant conditions: a 12-month follow-up study.

BACKGROUND: Gynecological surgery has many impacts on women's physical and mental health, and efforts to improve recovery from surgery are constantly under evaluation. Resilience is an ability to overcome stressors and adversities, such as traumas and surgeries. This study aimed to explore patients' resilience and psychological symptoms in relation to recovery, health-related quality of life (HRQoL), and pain one year after gynecological surgery. METHODS: In a prospective cohort study, we enrolled consecutive elective gynecologic surgery patients who completed questionnaires before and at one year after surgery: the Resilience Scale-25, the 15D instrument of HRQoL (15D), the Life Satisfaction Scale-4, and the Hospital Anxiety and Depression Scale. Their mean 15D scores were compared to those of an age-matched sample of women from the general Finnish population (n = 2743). RESULTS: We enrolled 271 women who underwent gynecological surgery due to benign (n = 190) and malignant (n = 81) diagnoses. Resilience was equally high in women with benign and malignant diagnoses at both time points. Higher resilience associated with less pain, analgesic use, and better pain relief from the use of pain medication at 12 months after surgery. Pain intensity was similar in the two groups, but patients with benign diseases had less pain at 12 months than before surgery. Before surgery, patients' HRQoL was worse than that of the general population, but at 12 months the mean HRQoL of patients with benign diseases had improved to the same level as that in the general population but had decreased further in patients with malignant diseases. Anxiety was higher and life satisfaction was lower in patients with malignant diseases before surgery. At 12 months, anxiety had decreased in both groups, and life satisfaction had increased in patients with malignant diseases. Depression was similarly low in both groups and time points. CONCLUSIONS: Resilience correlated with less pain one year after surgery. After surgery, HRQoL improved in patients with benign diseases but deteriorated in patients with malignant diseases. Patients with low resilience should be identified during preoperative evaluation, and health care professionals should give these patients psychological support to enhance their resilience. Trial Registration ClinicalTrials.gov; registered October 29, 2019; identifier: NCT04142203; retrospectively registered.

Patient functional recovery after a 23-h surgery - a prospective, follow-up study.

PURPOSE: We evaluated patients' functional outcomes 2 weeks after a 23-h surgery model in a tertiary care hospital. METHODS: This prospective study comprised data on 993 consecutive adult patients who underwent a 23-h surgery. Patients were interviewed before surgery and at 14 days after surgery by telephone with a multidimensional structural survey including closed- and open-ended questions. Regarding functional outcomes, the patients were asked to assess their general wellbeing, energy levels and activities of daily living on a 5-point numeric rating scale (1 = poor to 5 = excellent). Data on patient characteristics, medical history, alcohol use, smoking status and pre-, peri- and postoperative pain and satisfaction with the care received were collected and analysed to determine whether these factors contributed to their recovery. The primary outcome measure was patient functional recovery at 14 days after surgery. RESULTS: Most patients reported moderate to excellent functional outcomes: 93.6% (95% CI, 92.1--95.1) of the patients showed a score ≥ 3 on the 5-point numeric scale. One out of four patients (23%) scored all three domains as excellent. A weak inverse correlation was noted between functional recovery and most pain in the 23-h postanaesthesia care unit as well as pain at 2 weeks after surgery. A weak positive correlation was noted between functional recovery and patient satisfaction with the instructions at discharge. CONCLUSIONS: Most patients showed ample functional recovery at 14 days after the 23-h surgery. Higher pain scores in the postanaesthesia care unit and 2 weeks after surgery predicted poor functional outcomes, and satisfaction with postoperative counselling predicted better outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT04142203.

Psychiatric Symptoms, Posttraumatic Growth, and Life Satisfaction Among Parents of Seriously Ill Infants: A Prospective Case-Controlled Study.

We evaluated psychiatric symptoms, posttraumatic growth, and life satisfaction among the parents (n = 34) of newborns (n = 17) requiring therapeutic hypothermia or urgent surgery (interest group). Our control group included 60 parents of healthy newborns (n = 30). The first surveys were completed soon after diagnosis or delivery and the follow-up surveys 1 year later (participation rate 88% in the interest group and 70% in the control group). General stress was common in both groups but was more prevalent in the interest group as were depressive symptoms, too. Anxiety was more common in the interest group, although it showed a decrease from the baseline in both groups. Life satisfaction had an inverse correlation with all measures of psychiatric symptoms, and it was lower in the interest group in the early stage, but similar at 12 months due to the slight decline in the control group. Mothers in the interest group had more anxiety and depressive symptoms than fathers in the early stage. Mothers had more traumatic distress than fathers at both time points. Half of the parents experienced substantial posttraumatic growth at 12 months. In conclusion, the serious illness of an infant substantially affects the well-being of the parents in the early stages of illness and one year after the illness.

Nifedipine disturbs fetal cardiac function during hypoxemia in a chronic sheep model at near term gestation.

BACKGROUND: Nifedipine is a widely used drug in pregnancies complicated by maternal hypertensive disorders that can be associated with placental insufficiency and fetal hypoxemia. The evidence regarding fetal myocardial responses to nifedipine in hypoxemia is limited. OBJECTIVE: We hypothesized that nifedipine would not impair fetal sheep cardiac function under hypoxemic environment. In particular, we investigated the effects of nifedipine on fetal ventricular functional parameters and cardiac output. STUDY DESIGN: A total of 21 chronically instrumented fetal sheep at 122 to 134 gestational days (term, 145 days) were included in this study. Fetal cardiac function was evaluated by measuring global longitudinal strain, indices describing ventricular systolic and diastolic function, and cardiac outputs using two-dimensional speckle tracking and tissue and spectral pulsed-wave Doppler echocardiography. Fetal carotid artery blood pressure and blood gas values were invasively monitored. After baseline data collection, fetal hypoxemia was induced by maternal hyperoxygenation. After hypoxemia phase data collection, 9 fetuses received nifedipine infusion, and 12 fetuses received saline infusion. Data were collected 30 and 120 minutes after the infusion was started. After 120 minutes of data collection, maternal and fetal oxygenation were normalized, and normoxemia phase data were collected, while infusion was continued. RESULTS: Hypoxemia decreased fetal carotid artery mean arterial pressure from 40 (8) mm Hg to 35 (8) mm Hg (P<.007), and left ventricular global longitudinal strain showed less deformation than at baseline (P=.001). Under hypoxemia, nifedipine caused a reduction in right ventricular global longitudinal strain (P<.05), a decrease in right ventricular isovolumic relaxation velocity and its deceleration (P<.01) indicating diastolic dysfunction, and a drop in right ventricular cardiac output (P<.05). Nifedipine did not alter fetal left ventricular functional parameters or cardiac output. When normoxemia was restored, fetal right ventricular functional parameters and cardiac output returned to baseline level. CONCLUSION: In hypoxemic fetus, nifedipine impaired right ventricular function and reduced its cardiac output. The detrimental effects of nifedipine on fetal right ventricular function were abolished, when normoxemia was restored. Our findings suggest that in a hypoxemic environment nifedipine triggers detrimental effects on fetal right ventricular function.

Resilience and health-related quality of life in patients with pulmonary diseases receiving ambulatory oxygen therapy.

BACKGROUND: Pulmonary diseases affect health-related quality of life (HRQoL), but there are few data on patients' adaptation to a serious illness. This study assessed resilience and its associations with HRQoL, life satisfaction, anxiety and depression in patients with pulmonary diseases receiving ambulatory oxygen therapy. METHODS: In this prospective cohort study, we enrolled 42 patients with pulmonary diseases receiving ambulatory oxygen therapy. The patients completed the following questionnaires at baseline and after one and three months; the Resilience Scale-25, the Life Satisfaction Scale-4, the 15D instrument of HRQoL, the Hospital Anxiety and Depression Scale (HADS) and the Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST 2.0). To compare HRQoL, we recruited age- and gender-matched controls from the general population (n = 3574). The primary outcome was the proportion of patients with low resilience. RESULTS: Half (42-48%) of the patients had low resilience, which was correlated with low HRQoL, low levels of life satisfaction and higher levels of anxiety and depression. Patients had very low HRQoL compared to controls. Dissatisfaction with life increased during the 3-months follow-up, but only a few patients had anxiety or depression. Patient satisfaction with assistive technology was high; the median QUEST 2.0 score (scale 1-5) was 4.00 at baseline, 3.92 at one month and 3.88 at three months. CONCLUSIONS: Resilience was low in half of the patients with pulmonary diseases receiving ambulatory oxygen therapy. Higher resilience was positively correlated with HRQoL and life satisfaction and negatively correlated with anxiety and depression. TRIAL REGISTRATION: ClinicalTrials.gov Protocol Record 507A023. Registered 17 September 2020-Retrospectively registered, https://clinicaltrials.gov/ct2/results?cond=&term=NCT04554225&cntry=&state=&city=&dist= .

Population pharmacokinetics of oxycodone: Premature neonates to adults.

BACKGROUND: Oxycodone is used in children and adults for the control of acute postoperative pain. Covariate influences such as age, size, and fat mass on oxycodone pharmacokinetic parameters over the human lifespan are poorly quantified. METHODS: Pooled oxycodone time-concentration profiles were available from preterm neonates to adults. Data from intravenous, intramuscular, buccal, and epidural formulations were analyzed using nonlinear mixed-effects models. Normal fat mass was used to determine the influence of fat on oxycodone pharmacokinetics. Theory-based allometry was used to scale pharmacokinetic parameters to a 70 kg individual. A maturation function described the increase in clearance in neonates and infants. RESULTS: There were 237 subjects (24 weeks postmenstrual age to 75 years; 0.44-110 kg) providing 1317 plasma concentrations. A three-compartment model with first-order elimination best described oxycodone disposition. Population parameter estimates were clearance (CL) 48.6 L.h-1 .70 kg-1 (CV 71%); intercompartmental clearances (Q2) 220 L.h-1 .70 kg-1 (CV 64%); Q3 1.45 L.h-1 .70 kg-1 ; volume of distribution in the central compartment (V1) 98.2 L.70 kg-1 (CV 76%); rapidly equilibrating peripheral compartment (V2) 90.1 L. 70 kg-1 (CV 76%); slow equilibrating peripheral compartment (V3) 28.9 L.70 kg-1 . Total body weight was the best size descriptor for clearances and volumes. Absorption halftimes (TABS ) were: 1.1 minutes for intramuscular, 70 minutes for epidural, 82 minutes for nasogastric, and 159.6 minutes for buccal administration routes. The relative bioavailability after nasogastric administration was 0.673 with a lag time of 8.7 minutes. CONCLUSIONS: Clearance matured with age; 8% of the typical adult value at 24 weeks postmenstrual age, 33% in a term neonate and reached 90% of the adult clearance value by the end of the first year of life. Allometric scaling using total body weight was the better size descriptor of oxycodone clearance than fat-free mass.

Oxycodone target concentration dosing for acute pain in children.

BACKGROUND: Oxycodone pharmacokinetics have been described in premature neonates through to obese adults. Covariate influences have been accounted for using allometry (size) and maturation of oxycodone clearance with age. The target concentration is dependent on pain intensity that may differ over pain duration or between individuals. METHODS: We assumed a target concentration of 35 mcg.L-1 (acceptable range ±20%) to be associated with adequate analgesia without increased risk of adverse effects from respiratory depression. Pharmacokinetic simulation was used to estimate dose in neonates through to obese adults given intravenous or parenteral oxycodone. RESULTS: There were 84% of simulated oxycodone concentrations within the acceptable range during maintenance dosing. Variability around the simulated target concentration decreased with age. The maturation of oxycodone clearance is reflected in changes to context-sensitive halftime where clearance is immature in neonates compared with older children and adults. The intravenous loading and maintenance doses for a typical 5-year-old child are 100 mcg.kg-1 and 33 mcg.kg-1 .h-1 . In a typical adult, the loading dose is 100 mcg.kg-1 and maintenance dose 23 mcg.kg-1 .h-1 . CONCLUSION: Simulation was used to suggest loading and maintenance doses to attain an oxycodone concentration of 35 mcg.L-1 predicted in adults. Although the covariates age and weight contribute 92% variability for clearance, there remains variability accounting for 16% of concentrations outside the target range. Duration of analgesic effect after ceasing infusion is anticipated to be longer in neonates where context-sensitive halftime is greater than older children and adults.

Single dose epidural hydromorphone in labour pain: maternal pharmacokinetics and neonatal exposure.

INTRODUCTION: Epidural hydromorphone could be useful in obstetric analgesia as there is a need for a more water-soluble opioid than sufentanil or fentanyl with prolonged analgesic effect. To our knowledge, the pharmacokinetics of epidural hydromorphone has not been evaluated in parturients. MATERIALS AND METHODS: In this pilot study, seven healthy parturients were given a single epidural dose of hydromorphone for labour pain. One parturient received 1.5 mg, two 0.75 mg and four 0.5 mg of hydromorphone hydrochloride. Dose was decreased due to nausea and pruritus. Hydromorphone's effect, adverse effects and plasma concentrations were evaluated. Neonatal drug exposure was evaluated by umbilical vein and artery opioid concentration at birth. Neonatal outcomes were assessed using Apgar and the Neurologic Adaptive Capacity Score (NACS). RESULTS: All patients received additional levobupivacaine doses on parturients' requests. The first dose was requested at a median of 163 min (range 19-303 min) after hydromorphone administration. A total of 12 opioid related expected adverse events were reported by seven parturients. All newborn outcomes were uneventful. Hydromorphone's distribution and elimination after single epidural dose seem similar to that reported for non-pregnant subjects after intravenous hydromorphone administration, but further research is required to confirm this observation. CONCLUSIONS: The optimal dose of hydromorphone in labour pain warrants further evaluation.

Oxycodone for pain management in the latent phase of labour - A pragmatic trial.

BACKGROUND: Parenteral opioids are used for pain relief in labour but there are little data for oxycodone in this context. The aim of this study was to evaluate the efficacy, foetal exposure and safety of subcutaneous oxycodone in the latent phase of labour. METHODS: This pragmatic trial included 76 parturients, who received subcutaneous oxycodone for pain relief in the latent phase of labour according to the hospital protocol: an initial dose 0.1 mg/kg, and a second dose, 0.05 mg/kg, could be administered four hours later. Pain intensity and pain relief were assessed using a numerical rating scale of 0-10. After delivery, blood samples from the maternal and umbilical veins were collected, and plasma concentrations of oxycodone and its main metabolites were quantified using UPLC-MS/MS. The Apgar scores and maternal and neonatal adverse effects were recorded. RESULTS: The foetal exposure at birth was low, the median oxycodone and oxymorphone umbilical vein plasma concentrations were 1.2 ng/mL (range 0.21-7.8) and 0.14 ng/mL (0-0.26), respectively. Pain scores decreased substantially, from a median pain score of 7/10 before oxycodone to median scores of 5/10 at 30 minutes after administration, 5/10 at 60 minutes and 6/10 at 120 minutes. The median Apgar score was 9 (range 2-10) at 1 minute and 9 (6-10) at 5 minutes. Maternal adverse effects were mild, and there were no oxycodone-related neonatal adverse effects. CONCLUSION: Subcutaneous oxycodone provided effective analgesia during the latent phase of labour. Newborn exposure at birth was low, and oxycodone was well-tolerated.

Physiologically based pharmacokinetic modelling of oxycodone drug-drug interactions.

Oxycodone is an opioid analgesic with several pharmacologically active metabolites and relatively narrow therapeutic index. Cytochrome P450 (CYP) 3A4 and CYP2D6 play major roles in the metabolism of oxycodone and its metabolites. Thus, inhibition and induction of these enzymes may result in substantial changes in the exposure of both oxycodone and its metabolites. In this study, a physiologically based pharmacokinetic (PBPK) model was built using GastroPlus™ software for oxycodone, two primary metabolites (noroxycodone, oxymorphone) and one secondary metabolite (noroxymorphone). The model was built based on literature and in house in vitro and in silico data. The model was refined and verified against literature clinical data after oxycodone administration in the absence of drug-drug interactions (DDI). The model was further challenged with simulations of oxycodone DDI with CYP3A4 inhibitors ketoconazole and itraconazole, CYP3A4 inducer rifampicin and CYP2D6 inhibitor quinidine. The magnitude of DDI (AUC ratio) was predicted within 1.5-fold error for oxycodone, within 1.8-fold and 1.3-4.5-fold error for the primary metabolites noroxycodone and oxymorphone, respectively, and within 1.4-4.5-fold error for the secondary metabolite noroxymorphone, when compared to the mean observed AUC ratios. This work demonstrated the capability of PBPK model to simulate DDI of the administered compounds and the formed metabolites of both DDI victim and perpetrator. However, the predictions for the formed metabolites tend to be associated with higher uncertainty than the predictions for the administered compound. The oxycodone model provides a tool for forecasting oxycodone DDI with other CYP3A4 and CYP2D6 DDI perpetrators that may be co-administered with oxycodone.

Analgesic efficacy and pharmacokinetics of epidural oxycodone in pain management after gynaecological laparoscopy-A randomised, double blind, active control, double-dummy clinical comparison with intravenous administration.

AIMS: Early pain after laparoscopy is often severe. Oxycodone is a feasible analgesic option after laparoscopy, but there are sparse data on epidural administration. The aim was to evaluate the analgesic efficacy and pharmacokinetics of a single dose of epidural oxycodone as a part of multimodal analgesia after gynaecological laparoscopy. METHODS: Women (n = 60), aged 23-71 years, undergoing elective gynaecological laparoscopy, were administrated either epidural oxycodone 0.1 mg kg-1 and intravenous (i.v.) saline (EPI-group n = 31), or epidural saline and i.v. oxycodone 0.1 mg kg-1 (IV-group = 29) in a randomised, double blind, active control, double dummy clinical trial. A pharmacokinetic model was developed using population modelling of plasma and cerebrospinal fluid (CSF) concentrations obtained in these patients and data of 2 published studies. The primary outcome was the amount of i.v. fentanyl for rescue analgesia during the first 4 hours. RESULTS: Twenty of the 31 patients in the EPI-group and 26 of the 29 patients in the IV-group needed i.v. fentanyl for rescue analgesia, P = .021. The median (interquartile range) number of fentanyl doses were 1.0 (1.0-3.0) in the EPI-group and 2.5 (1.0-4.0) doses in the IV-group, P = .008. Plasma concentrations were similar, but CSF concentrations were 100-fold higher in the EPI-group. The population model indicated that 60% of oxycodone injected into the epidural space enters into CSF and 40% is absorbed into the systemic circulation. CONCLUSIONS: The data support superiority of epidural administration of oxycodone compared to i.v. administration during the first hours after laparoscopic surgery. This is likely to be based on enhanced permeation into the central nervous system after epidural administration.

The analgesic efficacy and pharmacokinetics of epidural oxycodone after gynaecological laparotomy: a randomized, double-blind, double-dummy comparison with intravenous administration.

AIM: The aim of the present study was to compare the analgesic efficacy of epidural and intravenous (i.v.) oxycodone at the same dose. METHODS: In this randomized, double-blind, double-dummy clinical trial, 30 women, aged 24-67 years, undergoing elective gynaecological laparotomy, were administrated either i.v. saline and epidural oxycodone 0.1 mg·kg-1 (EPI group; n = 15) or i.v. oxycodone 0.1 mg·kg-1 and epidural saline (IV group; n = 15). For multimodal analgesia, patients received i.v. paracetamol and dexketoprofen, and a triple-mixture epidural infusion after the first 4 h postoperatively. The primary outcome was the total dose of i.v. fentanyl for rescue analgesia during the first 4 h postoperatively. RESULTS: All patients required fentanyl during the first 4 h. The median number of fentanyl doses were three (quartiles 1, 8) in the EPI group and seven (6, 9) in the IV group (mean difference 3.1; 95% confidence interval 0.9, 5.2; P = 0.01). After the first 4 h, the two groups needed a similar total dose of epidural infusion. Patient satisfaction was similarly high in both groups, and both administration routes were well tolerated. CONCLUSIONS: The data support the superiority of epidural oxycodone compared with that of i.v. administration in pain management after laparotomy.

Life satisfaction and pain interference in spine surgery patients before and after surgery: comparison between on-opioid and opioid-naïve patients.

PURPOSE: Pain has a negative impact on life satisfaction (LS). Our primary aims were to compare LS in on-opioid and opioid-naïve spine surgery patients and to evaluate whether surgery affects LS during the first 3 weeks after surgery. METHODS: After informed consent 200 patients (99 on-opioid, 101 opioid-naïve; 112 male; aged 23-71 years) having elective spine surgery were enrolled. Their LS was evaluated using a four-item Life Satisfaction Scale (4-20, lower score more satisfied) and pain interference using Brief Pain Inventory (BPI)-questionnaire (0-10, lower score, less interference) before and 21 days after surgery. RESULTS: At baseline LS was lower in the ON-OPIOID-group, mean LS-score 10.6 (SD 3.9), than that in the OPIOID-NAÏVE-group, 9.3 (3.0) (p = .027). At 3 weeks after surgery LS had increased in both groups compared to baseline (p < .001). However, LS was still lower in the ON-OPIOID-group, 9.1 (3.7) than that in the OPIOID-NAÏVE-group, 7.6 (2.7) (p = .005). Patients with lower LS experienced more pain interference pre- and post-operatively (p < .001). At 3 weeks the pain interference had decreased in both groups, in the ON-OPIOID-group from mean BPI-score 5.1 (2.0) to 3.0 (2.0) (p < .001) and in the OPIOID-NAÏVE-group from 4.0 (2.1) to 2.4 (2.3) (p < .001), but BPI-score was still higher in the ON-OPIOID-group (p = .045). CONCLUSION: Life satisfaction increased and pain interference decreased in both groups after spine surgery. However, LS was lower and pain interference was more significant in on-opioid patients than that in opioid-naïve patients.

Oxycodone pharmacokinetics and fetal exposure after intravenous or epidural administration to the ewe.

INTRODUCTION: There are limited data on oxycodone pharmacokinetics during pregnancy and on fetal exposure after maternal administration. The present study describes the pharmacokinetics of intravenous (i.v.) oxycodone in pregnant sheep and fetal exposure after intravenous and epidural administration. MATERIAL AND METHODS: Ten pregnant sheep received 0.1 mg·kg-1 oxycodone intravenously, and blood samples were collected up to 24 hours. Seven days later, the ewes were randomized to receive 0.5 mg·kg-1 oxycodone intravenously (n = 5) or epidurally (n = 5) as a single bolus, before laparotomy for placement of catheters into the fetal superior vena cava and carotid artery. Paired maternal and fetal blood samples were taken when the fetal arterial catheter was in place and at the end of surgery. Maternal blood samples were taken up to 24 hours. RESULTS: After 0.1 mg·kg-1 oxycodone intravenously, the median clearance was 5.2 L·h-1 ·kg-1 (range 4.6-6.2), but the volume of distribution varied between 1.5 and 4.7 L·kg-1 . The area under the curve was 17 h·ng·mL-1 (range 14-19) and the plasma concentration at 2 minutes 60 ng·mL-1 (range 50-74). Following administration of 0.5 mg·kg-1 intravenously or epidurally, oxycodone concentrations were similar in the maternal and the fetal plasma. Accumulation of oxymorphone in the fetus occurred; fetal-to-maternal ratios were 1.3-3.5 (median 2.1) in the i.v.-group and 0.9-3.0 (1.3) in the Epidural-group. CONCLUSIONS: We determined the pharmacokinetics of oxycodone in pregnant sheep. We showed accumulation of oxymorphone, which an active metabolite of oxycodone, in the fetus. Further studies in human pregnancies are required to evaluate the safety of oxycodone.

Maturation of oxycodone pharmacokinetics in neonates and infants: Oxycodone and its metabolites in plasma and urine.

AIMS: This study aimed to characterize the pharmacokinetics of oxycodone and its major metabolites in infants and covered the age range between extremely preterm neonates and 2-year-old infants. METHODS: Seventy-nine infants (gestational age 23-42 weeks; postnatal age 0-650 days) received intravenous oxycodone hydrochloride trihydrate at a dose of 0.1 mg kg-1 during or after surgery. Three to seven blood samples were taken from each infant, and plasma concentrations of oxycodone, noroxycodone, oxymorphone, and noroxymorphone were quantified. The unconjugated forms of these compounds were determined in urine collected after up to 24 or 48 h from 25 infants. Pharmacokinetics was determined using noncompartmental analysis and reported for six clinically relevant age groups based on postmenstrual age. RESULTS: Oxycodone pharmacokinetics changed markedly with patient age. Preterm neonates were found to have the highest pharmacokinetic variability out of the study population. In extremely preterm neonates (n = 6) median of elimination half-life was 8.8 h (range 6.8-12.5), in preterm (n = 11) 7.4 h (4.2-11.6), and in older neonates (n = 22) 4.1 h (2.4-5.8), all of which were significantly longer than that in infants aged 6-24 months (n = 12) 2.0 h (1.7-2.6). Median renal clearance was fairly constant in all age groups, whereas non-renal clearance markedly increased with age. Noroxycodone was the major metabolite in plasma and urine. CONCLUSIONS: Oxycodone elimination is slower and pharmacokinetic variability more pronounced in neonates when compared to older infants. These findings highlight the importance of careful dose titration for neonates.