[Efficacy Survey of Naldemedine in the Poor-performance Status Group].

Naldemedine (Nal) is widely used as a therapeutic drug against opioid-induced constipation. However, patients in phase III trials are limited to those with good performance status (PS). Cancer patients may have inferior PS owing to progression of symptoms and adverse events from chemotherapy. Therefore, it is important to survey the efficacy of Nal in patients with poor PS. This study aimed to evaluate Nal efficacy in patients with poor PS. We retrospectively investigated patients from July 2017 to June 2019 and compared Nal efficacy between patients with good and poor PS. The efficacy of Nal was evaluated using changes in the number of spontaneous bowel movements 7 days before and after the introduction of Nal with reference to previous reports. Multivariate analysis was performed to reveal whether poor PS affects Nal efficacy. In total, 141 patients at the Hokkaido University Hospital were analyzed. The effective rate of Nal from day 1 to day 7 of administration was 71.7% and 71.4% in the patients with good and poor PS, respectively, that from day 1 to day 2 of administration was 61.1% and 57.1%, respectively, and that from day 3 to day 7 of administration was 60.2% and 71.4%, respectively, suggesting an absence of significant differences. Furthermore, results of multivariate analysis showed that "best supportive care" and "body weight (55 kg and above)" reduced Nal efficacy. In conclusion, Nal showed similar effectiveness in patients with poor PS as that in those with good PS.

Construction of a Risk Prediction Model of Extended Release Oxycodone Tablet-Induced Nausea and Clarification of Predictive Factors.

Nausea is a typical adverse event associated with opioids. In this study, we performed logistic regression analysis with the aim of clarifying the risk factors for nausea induced by extended-release oxycodone (ER-OXY). Furthermore, we constructed a decision tree (DT) model, a typical data mining method, to estimate the risk of oxycodone-induced nausea by combining multiple factors. A retrospective study was conducted on patients who newly received ER-OXY for cancer pain during hospitalization at Hokkaido University Hospital in Japan from April 2015 to March 2018. In logistic regression and DT analyses, the dependent variable was the presence or absence of nausea. Independent variables were the potential risk factors. First, univariate analyses were performed to screen potential factors associated with oxycodone-induced nausea. Then, multivariate and DT analyses were performed using factors with p-values <0.1 in the univariate analysis. Of 267 cases included in this study, nausea was observed in 30.3% (81/267). In multivariate logistic regression analysis, only female sex was extracted as an independent factor affecting nausea (odds ratio, 1.98). In the DT analysis, we additionally revealed that an age <50 years was a risk factor for nausea in female patients. Thus, our DT model indicated that the risk of ER-OXY-induced nausea was highest in the subgroup comprising females <50 years of age (66.7%) and lowest in male patients (25.1%). The DT model suggested that the factor of young women may be an increased risk of ER-OXY-induced nausea.

Serotonin Syndrome Developing Immediately after the Initiation of Low-Dose Methadone Therapy: A Case Report.

We present a case in which serotonin syndrome developed immediately after the initiation of low-dose methadone following an increase in oxycodone dose and the initiation of duloxetine. The symptoms of serotonin syndrome were alleviated and later disappeared upon cessation of methadone alone. The case was a 47-year-old woman with a desmoid tumor. The administration of duloxetine (20 mg/day) was initiated while the patient took oxycodone sustained-release tablets (40 mg/day). The following day, excessive perspiration, chills, and tremors appeared after the initiation of 15 mg/day methadone. Discontinuation of methadone led to an alleviation of the symptoms which completely disappeared 3 days later. The results suggest that low-dose methadone can trigger serotonin syndrome as early as after the first dose. Thus, it is important to be aware of the risks and to immediately take action if symptoms appear.

A pediatric cancer patient with suspected chemical coping following high-dose opioid therapy: a case report.

BACKGROUND: Chemical coping is an inappropriate method for dealing with stress through the use of opioids; it is considered the stage prior to abuse and dependence. In patients with cancer, it is important to evaluate the risk of chemical coping when using opioids. There are some pediatric opioid use-related tolerances and addictions; however, no mention of chemical coping has been found. CASE PRESENTATION: We present a case of an 11-year-old Japanese boy with acute lymphocytic leukemia. After transplantation, he complained of abdominal and articular pain, which are considered as symptoms of graft-versus-host disease; thus, opioid therapy was initiated, and the dose was gradually increased for pain management, resulting in a high dose of 2700 µg/day of fentanyl (4200-4700 µg/day including the rescue dose). After switching from fentanyl to oxycodone injections, he continued to experience pain, and there was no change in the frequency of oxycodone rescue doses. Physically, his pain was considered to have alleviated; thus, there was the possibility of mental anxiety resulting in the lowering of pain threshold and the possibility of chemical coping. Mental anxiety and stress with progress through schooling was believed to have resulted in chemical coping; thus, efforts were made to reduce the boy's anxiety, and opioid education was provided. However, dose reduction was challenging. Ultimately, with guidance from medical care providers, the opioid dose was reduced, and the patient was successfully weaned off opioids. CONCLUSIONS: When chemical coping is suspected in pediatric patients, after differentiating from pseudo-addiction, it might be necessary to restrict the prescription for appropriate use and to provide opioid education while taking into consideration the emotional background of the patient that led to chemical coping.

Isoflurane induces c-Fos expression in the area postrema of the rat.

INTRODUCTION: Volatile anesthetics are speculated to cause postoperative nausea and vomiting via stimulation of the chemoreceptor trigger zone (CTZ). However, the precise mechanism underlying the emetic action of these drugs is not well understood. In this study, we assessed whether isoflurane induced the expression of c-Fos, a neuronal activation marker, in the area postrema (AP), the locus of the CTZ, in rats, which do not have vomiting action. MATERIALS AND METHODS: Male rats were exposed to 1.3% isoflurane for 0-240 min, or to various concentrations of isoflurane (0, 1.3%, or 2.6%) for 120 min. Finally, the rats were exposed to 1.3% isoflurane for 120 min after ondansetron administration. After the treatments, immunohistochemistry of the rat AP was performed using c-Fos antibody staining. RESULTS: One-way analysis of variance showed that isoflurane exposure significantly increased c-Fos expression in the AP; however, the rats pretreated with 4 mg/kg ondansetron showed significantly decreased c-Fos expression. Moreover, we evaluated the effect of the anesthetic on inducing pica in the rats, and found that kaolin intake was not influenced by isoflurane exposure. CONCLUSION: Overall, these results suggest that isoflurane activates AP neurons and may be involved in the emetic mechanism of isoflurane. This study further suggests the feasibility of using rats as a model for studying emetic mechanisms of drugs, despite their lack of vomit action.

Influence of nitrous oxide on granule cell migration in the dentate gyrus of the neonatal rat.

For several decades, the neurotoxicities of anesthetics to the developing brain have been reported by many researchers focusing on various phenomena such as apoptosis, neurodegeneration, electrophysiological aberrations, and behavioral abnormalities. According to these reports, signals via N-methyl-D-aspartate receptors (NMDA-r) and/or γ-aminobutyric acid type A receptors (GABAA-r) are implicated in the anesthetic neurotoxicity. On the other hand, during brain development, NMDA-r and GABAA-r are also recognized to play primary roles in neural cell migration. Therefore, anesthetics exposed in this period may influence the neural cell migration of neonates, and increase the number of hilar ectopic granule cells, which are reported to be a cause of continuous neurological deficits. To examine this hypothesis, we investigated immunohistochemically granule cell distribution in the hippocampal dentate gyrus of Wistar/ST rats after nitrous oxide (N2O) exposure. At postnatal day (P) 6, 5-bromo-2'-deoxyuridine (BrdU) was administered to label newly generated cells. Then, rats were divided into groups (n = 6 each group), exposed to 50% N2O at P7, and evaluated at P21. As a result, we found that ectopic ratios (ratio of hilar/total granule cells generated at P6) were decreased in rats at P21 compared with those at P7, and increased in N2O exposed rats for over 120 min compared with the other groups. These results suggest that 50% N2O exposure for over 120 min increases the ratios of ectopic granule cells in the rat dentate gyrus.

Plantar injection of formalin in rats reduces the expression of a potassium chroride cotransporter KCC2 in the spinal cord and a kinase inhibitor suppresses this reduction.

Brain-derived neurotrophic factor (BDNF) is released from activated microglia during neuropathic pain and is hypothesized to downregulate the expression of the potassium chloride cotransporter 2 (KCC2) via the TrkB receptor. Previous studies reported that KCC2 is downregulated 5 min after the plantar injection of formalin in rats; however, the mechanism behind this decrease in KCC2 expression during acute inflammatory pain remains unknown. In this study, we determined whether the TrkB receptor contributes to the expression of KCC2 during the acute pain. Five minutes after the plantar injection of formalin in rats, the ratio of KCC2-immunoreactive area in layer II of the spinal cord significantly decreased on the stimulated side compared to the unaffected side. On the other hand, this response was inhibited by the injection of a kinase inhibitor, K252a, in the subarachnoid space 15 min before the formalin injection. These findings suggest that in acute pain, the TrkB receptor may contribute to the decrease in the expression of KCC2.

Neonatal exposure to sevoflurane causes significant suppression of hippocampal long-term potentiation in postgrowth rats.

BACKGROUND: The inhaled anesthetic sevoflurane is commonly used for neonates in the clinical setting. Recent studies have indicated that exposure of neonatal rodents to sevoflurane causes acute widespread neurodegeneration and long-lasting neurocognitive dysfunction. Although acute toxic effects of sevoflurane on cellular viability in the hippocampus have been reported in some studies, little is known about the effects of neonatal sevoflurane exposure on long-term hippocampal synaptic plasticity, which has been implicated in the processes of learning and memory formation. Our study is the first to examine the long-term electrophysiological impact of neonatal exposure to a clinically relevant concentration of sevoflurane. METHODS: On postnatal day 7, rats were exposed to sevoflurane (1% or 2% for 2 hours) with oxygen. To eliminate the influence of blood gas abnormalities caused by sevoflurane-induced respiratory suppression, a group of rats were exposed to a high concentration of carbon dioxide (8% for 2 hours) to duplicate respiratory disturbances caused by 2% sevoflurane exposure. RESULTS: Exposure of neonatal rats to 2% sevoflurane for 2 hours caused significant suppression of long-term potentiation (LTP) induction in the postgrowth period. There was no significant difference between the control group and the CO2-exposed group in LTP induction, indicating that sevoflurane-induced LTP suppression was not caused by blood gas abnormalities. CONCLUSION: Our present findings indicate that neonatal exposure to sevoflurane at a higher concentration can cause alterations in the hippocampal synaptic plasticity that persists into adulthood.

Long-lasting effects of neonatal pentobarbital administration on spatial learning and hippocampal synaptic plasticity.

Exposure of newborn rats to antiepileptics such as barbiturates has long-lasting detrimental effects on the hippocampus and hippocampus-dependent behavior. However, the long-term consequences of neonatal administration with barbiturates on the hippocampal synaptic plasticity remain unresolved. In this study, we investigated the long-lasting effects of a neonatal administration of pentobarbital on spatial memory, paired-pulse plasticity in the population spikes, and long-term potentiation (LTP) in the hippocampal CA1 region of rats in vivo. Eight weeks after administration of pentobarbital (10 or 20mg/kg) on the seventh postnatal day (P7), rats showed impaired induction in LTP. During paired-pulse stimulation, pentobarbital-treated rats exhibited a greater facilitation of the test pulse population spike, suggesting a disruption in the inhibitory GABAergic synaptic transmission. Spatial learning in hidden platform task of the Morris water maze was impaired in pentobarbital-treated rats. Our present findings indicate that neonatal treatment with pentobarbital causes alterations in function of the hippocampal inhibitory synaptic transmission that persist into adulthood, likely contributing to the long-lasting abnormalities in the hippocampal LTP as well as learning ability. We also demonstrated significant respiratory disturbances, i.e., severe hypoxia, hypercapnia, and extracellular acidosis, in rats treated with pentobarbital on P7. Given that extracellular acidosis can also modulate synaptic transmission in the developing hippocampus, this finding led us to speculate regarding the influence of respiratory disturbances in pentobarbital-induced long-lasting hippocampal dysfunctions.

Altered synaptic transmission in rat anterior cingulate cortex following peripheral nerve injury.

BACKGROUND: Patients with neuropathic pain present not only with persistent pain but also a complex set of additional symptoms, including mood disorders and cognitive disturbance. Given the important roles of the anterior thalamic nuclei (ATN) and anterior cingulate cortex (ACC) in the cognitive and emotional aspects of pain, investigation of the properties of ATN-ACC synapses will help us to understand the mechanisms underlying neuropathic pain. METHODS: We studied changes in ATN-evoked ACC excitatory postsynaptic potentials (EPSPs) induced by neuropathic pain in a rat model under halothane anaesthesia. RESULTS: Neuropathic pain caused significant suppression of EPSPs in the ACC compared with rats subjected to sham surgery. Similar to previous evidence, acute inflammatory pain induced by formalin injection into the hind paw significantly increased synaptic efficacy in the ACC compared with naive rats. Neither of the pain paradigms altered the paired-pulse responses. CONCLUSIONS: A possible explanation for the neuropathic pain-related suppression of EPSPs is that the ACC was already sufficiently active at baseline as a result of neuropathic pain, and ATN stimulation could not further increase the already elevated level of ACC activity. This abnormal excitability of the ATN-ACC synapse may be important in understanding the mechanism underlying neuropathic pain, particularly with respect to the affective and cognitive aspects.

[A new device for pediatric one-lung anesthesia].

We were using an L type connector with single side port with a Fogarty catheter in pediatric one-lung anesthesia. This method was not as good as roported, because modification of catheter position was rather too difficult during operation. We have made a new device with two side ports to improve weak points of the old device. We used this device for pediatric one-lung anesthesia, and obtained good results.

[A comparison of combined spinal-epidural anesthesia with epidural anesthesia for postoperative pain relief after transurethral resection of the prostate].

BACKGROUND: We compared combined spinal-epidural anesthesia (S group) and epidural anesthesia (E group) in terms of pain control after transurethral resection of the prostate (TUR-P). METHODS: All 32 patients received 0.2% ropivacaine at a rate of 2 ml x hr(-1) by a portable disposable pump postoperatively. RESULTS: S group was superior to E group in urethral pain control within three hours after operation. E group was superior to S group in decrease of back pain over six hours after operation. Fifteen patients (47%) suffered from irritability or low back pain and needed rescue analgesics. CONCLUSIONS: Our result indicates that 0.2% ropivacaine at a rate of 2 ml x hr(-1) is not satisfactory to relieve the postoperative pain. Long acting local anesthetics for spinal anesthesia are not suitable for TUR-P. Supplemental administration of opioid to epidural space or higher rate of continuous epidural infusor after operation might be better analgesic choice for TUR-P.