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

Improved Postoperative Pain Management Outcomes After Implementation of Enhanced Recovery After Surgery (ERAS) Protocol for Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (CRS-HIPEC)

BACKGROUND

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for patients with peritoneal carcinomatosis is promising but has potential for significant morbidity and prolonged hospitalization. Enhanced Recovery After Surgery (ERAS) is a standardized protocol designed to optimize perioperative care. This study describes trends in epidural and opioid use after implementing ERAS for CRS-HIPEC at a tertiary academic center.

METHODS

A retrospective analysis of patients undergoing CRS-HIPEC from January 2020 to September 2023 was conducted. ERAS was implemented in February 2022. Medication and outcomes data were compared before and after ERAS initiation. All opioids were converted to morphine milligram equivalents (MMEs).

RESULTS

A total of 136 patients underwent CRS-HIPEC: 73 (54%) pre- and 63 (46%) post-ERAS. Epidural usage increased from 63% pre-ERAS to 87% post-ERAS (p = 0.001). Compared with those without epidurals, patients with epidurals had decreased total 7-day oral and intravenous (IV) opioid requirements (45 MME vs. 316 MME; p < 0.001). There was no difference in 7-day opioid totals between pre- and post-ERAS groups. After ERAS, more patients achieved early ambulation (83% vs. 53%; p < 0.001), early diet initiation (81% vs. 25%; p < 0.001), and early return of bowel function (86% vs. 67%; p = 0.012).

CONCLUSIONS

ERAS implementation for CRS-HIPEC was associated with increased epidural use, decreased oral and IV opioid use, and earlier bowel function return. Our study demonstrates that epidural analgesia provides adequate pain control while significantly decreasing oral and IV opioid use, which may promote gastrointestinal recovery postoperatively. These findings support the implementation of an ERAS protocol for effective pain management in patients undergoing CRS-HIPEC.

Epidural Oxycodone for Acute Pain

Epidural analgesia is commonly used in labour analgesia and in postoperative pain after major surgery. It is highly effective in severe acute pain, has minimal effects on foetus and newborn, may reduce postoperative complications, and enhance patient satisfaction. In epidural analgesia, low concentrations of local anaesthetics are combined with opioids. Two opioids, morphine and sufentanil, have been approved for epidural use, but there is an interest in evaluating other opioids as well. Oxycodone is one of the most commonly used opioids in acute pain management. However, data on its use in epidural analgesia are sparse. In this narrative review, we describe the preclinical and clinical data on epidural oxycodone. Early data from the 1990s suggested that the epidural administration of oxycodone may not offer any meaningful benefits over intravenous administration, but more recent clinical data show that oxycodone has advantageous pharmacokinetics after epidural administration and that epidural administration is more efficacious than intravenous administration. Further studies are needed on the safety and efficacy of continuous epidural oxycodone administration and its use in epidural admixture.

Endogenous opiates and behavior: 2019

This paper is the forty-second consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2019 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Oxycodone vs Sufentanil in Patient-Controlled Intravenous Analgesia After Gynecological Tumor Operation: A Randomized Double-Blind Clinical Trial

Background

This study aims to compare analgesic effect and side effects of oxycodone and sufentanil in transition analgesia and patient-controlled intravenous analgesia (PCIA) after gynecological tumor operation under general anesthesia.

Patients and Methods

A prospective, randomized, double-blind research was conducted. Patients undergoing elective gynecological tumor surgery were randomized into four groups: Group S (sufentanil transition analgesia and sufentanil PCIA), Group OS (oxycodone transition analgesia and sufentanil PCIA), Group SO (sufentanil transition analgesia and oxycodone PCIA) and Group O (oxycodone transition analgesia and oxycodone PCIA). The primary outcomes were Numerical Rating Scale (NRS) at rest and coughing, accumulated opioid consumption in PCIA and patients’ satisfaction.

Results

Patients in Group OS and Group O showed shorter time of consciousness recovery and extubation after surgery. Accumulated opioid consumption in PCIA (equal to morphine) in Group SO and Group O was significantly less than that in Group S and Group OS. Patients in Group O showed lower NRS at rest and coughing, but higher patients’ satisfaction 3, 24 and 48 hours after surgery. Patients in Group SO and Group O showed a shorter time of intestinal recovery, first feeding and first-time movement.

Conclusion

Both oxycodone and sufentanil provided adequate pain relief in transitional analgesia and PCIA treatment after surgery. Oxycodone without background infusion showed less analgesic drug consumption and faster recovery than sufentanil with background infusion in PCIA after gynecological tumor operation under general anesthesia.

Effects of Adding Oxycodone to Ropivacaine on Labor Analgesia: A Randomized Controlled Trial

BACKGROUND

It has been reported that oxycodone is superior to the other opioids for the treatment of visceral pain. During the first stage of labor, pain is mainly caused by uterine contractions (visceral pain). It seems that oxycodone is more suitable for labor analgesia. During this study, we investigated the effects of adding oxycodone to ropivacaine on epidural analgesia during labor.

MATERIALS AND METHODS

Eighty nulliparous parturients were randomly divided into 2 groups. Group A received 0.2 mg/mL oxycodone plus 0.1% ropivacaine for epidural analgesia and group C (control group) received 0.1% ropivacaine alone for epidural analgesia. The onset time and duration of analgesia, duration of labor stages, delivery outcome, analgesic effect, Bromage scores, blood pressure, heart rate, and neonatal Apgar scores were recorded. Umbilical arterial blood was collected to analyze. Side effects, if any, were also recorded.

RESULTS

The visual analog scale of pain was lower at 2 and 4 hours after analgesia and 10 cm cervical dilatation in group A compared with group C (P=0.021, 0.018, and 0.009, respectively). The onset time of analgesia was shorter in group A than that in group C (13.3±2.8 vs. 14.9±3.6 min, P=0.032). There were no significant differences between the 2 groups in terms of the duration of labor stages, delivery outcome, Bromage score, neonatal Apgar score, or umbilical arterial blood pH. The duration of analgesia was significantly longer in group A than in group C (326.2±56.5 vs. 68.4±10.5 min, P=0.000), but the incidence of pruritus was higher in group A than in group C (10% vs. 0%, P=0.115).

CONCLUSIONS

This study demonstrates that epidural oxycodone may accelerate the onset of analgesia and obviously prolong the duration of analgesia during labor without increasing adverse effects associated with the neonate. However, it may cause a higher incidence of maternal pruritus (registration number: ChiCTR1800016483).

Oxycodone concentrations in the central nervous system and cerebrospinal fluid after epidural administration to the pregnant ewe

The main sites of the analgesic action of oxycodone are the brain and spinal cord. The present study describes the concentrations of oxycodone and its metabolites in the brain and spinal cord after epidural administration to the ewe. Twenty pregnant ewes undergoing laparotomy were randomized into two groups to receive epidural oxycodone: infusion group (n = 10, 0.1 mg·kg^-1 bolus followed by continuous infusion of 0.05 mg·kg^-1 ·h^-1 for five days) or repeated boluses group (n = 10, 0.2 + 2x0.1 mg·kg^-1 bolus followed by a 0.2 mg·kg^-1 bolus every 12 hours for five days). After five days of oxycodone administration, arterial blood samples were collected, the sheep were killed, and a CSF sample and tissue samples from the cortex, thalamus, cerebellum and spinal cord were obtained for the quantification of oxycodone and its main metabolites. The median plasma and CSF concentrations of oxycodone were 9.0 and 14.2 ng·mL^-1 after infusion and 0.4 and 1.1 ng·mL^-1 after repeated boluses. In the infusion group, the cortex, thalamus and cerebellum oxycodone concentrations were 4-8 times higher and in the spinal cord 1310 times higher than in plasma. In the repeated boluses group, brain tissue concentrations were similar in the three areas, and in the spinal cord were 720 times higher than in plasma. Oxymorphone was the main metabolite detected, which accumulated in the brain and spinal cord tissue. In conclusion, first, accumulation of oxycodone and oxymorphone in the CNS was observed, and second, high spinal cord concentrations suggest that epidural oxycodone may provide segmental analgesia.

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.

Population pharmacokinetics of oxycodone in plasma and cerebrospinal fluid after epidural and intravenous administration

Objectives: To establish the first plasma and cerebrospinal fluid (CSF) oxycodone population pharmacokinetic (PopPK) model after epidural (EPI) and intravenous (IV) oxycodone administration. Methods: The study was conducted with 30 female subjects undergoing elective gynecological surgery with epidural analgesia. A parallel single dose of EPI oxycodone with IV placebo (EPI group; n = 18) or IV oxycodone with EPI placebo (IV group; n = 12) was administered. An epidural catheter for drug administration was placed at T12/L1 and a spinal catheter for CSF sampling at L3/4. Plasma and CSF for oxycodone analysis were frequently collected. A PopPK model was built using the NONMEM software package. Results: Plasma and CSF oxycodone concentrations were evaluated using separate central plasma and CSF compartments and separate peripheral plasma and CSF compartments. Epidural space served as a depot compartment with transfer to both the plasma and CSF central compartments. The population parameters for plasma clearance and apparent distribution volumes for central and peripheral compartments for plasma and CSF were 37.4 L/h, 90.2 L, 68.9 L, 0.035 L (fixed based on literature), and 0.039 L, respectively. Conclusion: A PopPK model was developed and found to precisely and accurately describe oxycodone time-concentration data in plasma and CSF.

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.