Tramadol-associated hallucinations: a systematic review and narrative synthesis of their pathophysiology, diagnosis, and treatment.

BACKGROUND: Recent prescribing trends reflect government-led efforts undertaken in both the U.S. and Canada to decrease opioid use. These provisions reflect a reduction in the use of many potent opioids in favour of tramadol. Despite the purported benefits of tramadol over other opioids, little remains known about tramadol-associated hallucinations (TAH). METHODS: We conducted a systematic literature search in Embase, Medline, Cochrane CENTRAL, CINAHL, PubMed, Scopus, PAHO Virtual Health Library, MedNar, and ClinicalTrials.gov to find reported cases of hallucinations associated with the use of tramadol. For all corresponding cases reporting hallucinations secondary to tramadol use, we extracted data on patient demographics, medical management, and the details on hallucinations. Cases were categorized as "probable TAH" if the evidence supported an association between hallucinations and tramadol use, or "possible TAH" if hallucinations were attributed to tramadol use but the supporting evidence was weak. The "probable TAH" cases were further classified as "isolated TAH" if hallucinations were the primary complaint, or "other existing medical condition" if concurrent signs and symptoms alluded to a diagnosis of an existing medical condition. We then conducted a narrative synthesis of the available literature to contextualize these results. RESULTS: A total of 941 articles were identified in the initial search. No observational studies or randomized clinical trials were identified with our systematic review; only case reports were found. After a thorough screening, 34 articles comprising 101 patients reported an association between tramadol use and hallucinations. Among these 101 cases, 31 were "probable TAH" and 70 were "possible TAH". Of the 31 cases of "probable TAH", 16 cases were "isolated TAH" while the remaining 15 cases belonged to "other existing medical condition". CONCLUSIONS: Tramadol-associated hallucinations can result in auditory or visual disturbances, although multisensory symptoms have also been reported. The mechanism underlying TAH remains poorly understood and likely involves numerous receptor types. The relative risk of hallucinations from tramadol compared with other opioids remains unclear.

Sufentanil postoperative analgesia reduce the increase of T helper 17 (Th17) cells and FoxP3+ regulatory T (Treg) cells in rat hepatocellular carcinoma surgical model: A randomised animal study.

BACKGROUND: Surgery-related pain and opioids might exacerbate immune defenses in immunocompromised cancer patients which might affect postoperativd overall survival. Sufentanil is a good postoperative pain control drug,the present study aimed to figure out whether it effect T cell immunity in rat hepatocellular carcinoma surgical model. METHODS: A rat hepatocellular carcinoma (HCC) models was established by N-nitrosodiethylamine. Forty-eight of them were randomly divided into 3 equal groups: surgery without postoperative analgesia (Group C), surgery with morphine postoperative analgesia (Group M), surgery with sufentanil postoperative analgesia (Group S). Each animal underwent a standard left hepatolobectomy, and intraperitoneally implanted with osmotic minipumps filled with sufentanil, morphine or normal saline according to the different group. The food and water consumptions, body weight changes, locomotor activity and mechanical pain threshold (MPT) were observed. The ratio of CD4+/CD8+, proportions of Th1, Th2, Th17 and Treg cells in blood were detected using flow cytometry. The liver function and the rats' survival situation of each group were observed. RESULTS: The food and water consumption, locomotor activity and MPT of group C declined than those of group S and M on d1, d2, d3 (P < 0.05). The CD4+/CD8+ ratio and the proportion of Th1 cells were significantly higher while the proportion of Th2, Th17 and Treg cells were significantly lower in group S and group M compared with group C. The rats of group S have higher CD4+/CD8+ ratio on d3, while lower proportion of Treg cells on d7 compared with group M. The plasma ALT and AST values in group C were significantly higher than that of group S and group M on both d3 and d7. There were not significant differences in mortality rate between 3 groups. CONCLUSIONS: Sufentanil and morphine postoperative analgesia in HCC rats accepted hepatectomy could relieve postoperative pain, promote the recovery of liver function after surgery, alleviate the immunosuppressive effect of pain. Furthermore, Compared to morphine, sufentanil might have a slighter effect on CD4+/CD8+ ratio and Treg frequencies. Therefore, sufentanil postoperative analgesia is better than morphine in HCC hepatectomy rats.

Amisulpride for the Rescue Treatment of Postoperative Nausea or Vomiting in Patients Failing Prophylaxis: A Randomized, Placebo-controlled Phase III Trial.

BACKGROUND: Although antiemetics are commonly used to prevent postoperative nausea or vomiting, the failure rate is appreciable and there is currently no generally accepted standard for rescue treatment of postoperative nausea or vomiting after failed prophylaxis. This prospective, randomized, double-blind, parallel-group, placebo-controlled, multicenter study was designed to test the hypothesis that intravenous amisulpride, a dopamine D2/D3-antagonist, is superior to placebo at treating established postoperative nausea or vomiting after failed prophylaxis. METHODS: A total of 2,285 adult patients undergoing surgery under general inhalational anesthesia and receiving standard antiemetic prophylaxis were enrolled at 23 sites in Canada, France, Germany, and the United States. Of these, 702 patients experienced postoperative nausea or vomiting in the 24-h period after surgery and were randomized to receive a single dose of 5 or 10 mg intravenous amisulpride or matching placebo. The primary endpoint was complete response, defined as no emesis or rescue antiemetic use for 24 h after study drug administration, excluding emesis in the first 30 min. Secondary endpoints included incidence of emesis and rescue medication use, nausea burden, time to treatment failure, and length of stay in postanesthesia care unit and hospital. RESULTS: Complete response occurred in significantly more patients receiving 10 mg amisulpride (96 of 230, 41.7%) than placebo (67 of 235, 28.5%), a 13.2% difference (95% CI, 4.6 to 21.8; odds ratio, 1.80; P = 0.006). A 5-mg dose of amisulpride did not show a significant benefit (80 of 237, 33.8%); the difference from placebo was 5.2% (95% CI, 3.1 to 13.6; odds ratio, 1.24; P = 0.109). The total number of adverse events recorded and proportion of patients with at least one adverse event were comparable between the placebo and amisulpride groups. No clinically relevant toxicities were observed. CONCLUSIONS: A single 10-mg dose of intravenous amisulpride was safe and more effective than placebo at treating established postoperative nausea or vomiting in patients failing postoperative nausea or vomiting prophylaxis.

Randomized, Double-Blind, Placebo-Controlled Study of Intravenous Amisulpride as Treatment of Established Postoperative Nausea and Vomiting in Patients Who Have Had No Prior Prophylaxis.

BACKGROUND: Postoperative nausea and vomiting (PONV) occurs commonly in surgical patients despite widespread prophylactic antiemetic use. Rescue options are currently limited. 5HT3 antagonists are most frequently used for prophylaxis, but if they fail, additional doses are not effective as rescue medication. Intravenous (IV) amisulpride, a well-studied D2/D3 antagonist, has been shown in trials to prevent PONV. This study was designed to determine if amisulpride could be used to treat established PONV in patients at low-to-moderate risk of PONV who had not received any prior prophylaxis. METHODS: Men and women aged over 18 years were permitted to enroll if they were to undergo general inhalational anesthesia, expected to last at least 1 hour, for an outpatient or inpatient surgical procedure. Patients who then suffered PONV were randomized equally to 1 of 3 single-dose IV regimens: placebo or 5 or 10 mg amisulpride. The primary end point was complete response, defined as no emesis in the period 30 minutes to 24 hours after study drug treatment and no use of rescue medication in the entire 24-hour period. RESULTS: One thousand nine hundred eighty-eight patients were enrolled preoperatively, of whom 560 were randomized to a treatment arm. Complete response occurred in 39 of 181 patients (21.5%) in the placebo group compared to 60 of 191 patients (31.4%; P = .016) and 59 of 188 patients (31.4%; P = .016) in the amisulpride 5 and 10 mg groups, respectively. The adverse event profile of amisulpride at either dose was similar to placebo. CONCLUSIONS: IV amisulpride at 5 and 10 mg was safe and efficacious in the treatment of established PONV in surgical patients undergoing general anesthesia with no prior PONV prophylaxis.

Amisulpride Prevents Postoperative Nausea and Vomiting in Patients at High Risk: A Randomized, Double-blind, Placebo-controlled Trial.

BACKGROUND: Postoperative nausea and vomiting causes distress for patients and can prolong care requirements. Consensus guidelines recommend use of multiple antiemetics from different mechanistic classes as prophylaxis in patients at high risk of postoperative nausea and vomiting. The prophylactic efficacy of the dopamine D2/D3 antagonist amisulpride in combination with other antiemetics was investigated. METHODS: This double-blind, randomized, placebo-controlled, international, multicenter trial was conducted in 1,147 adult surgical patients having three or four postoperative nausea and vomiting risk factors. Patients were randomized to receive either intravenous amisulpride (5 mg) or matching placebo at induction of general anesthesia, in addition to one standard, nondopaminergic antiemetic, most commonly ondansetron or dexamethasone. Vomiting/retching, nausea, and use of rescue medication were recorded for 24 h after wound closure. The primary endpoint was complete response, defined as no emesis or rescue medication use in the 24-h postoperative period. RESULTS: Complete response occurred in 330 of 572 (57.7%) of the amisulpride group and 268 of 575 (46.6%) of the control group (difference 11.1 percentage points; 95% CI, 5.3 to 16.8; P < 0.001). The incidences of emesis (13.8% vs. 20.0%, P = 0.003), any nausea (50.0% vs. 58.3%, P = 0.002), significant nausea (37.1% vs. 47.7%, P < 0.001), and rescue medication use (40.9% vs. 49.4%, P = 0.002) were significantly lower in the amisulpride group. Adverse events and laboratory and electrocardiogram abnormalities occurred no more frequently with amisulpride than with placebo. CONCLUSIONS: Intravenous amisulpride was safe and effective as prophylaxis of postoperative nausea and vomiting when given in combination with an antiemetic from another class to adult patients at high risk for suffering postoperative nausea and vomiting undergoing elective surgery under inhalational general anesthesia. VISUAL ABSTRACT: An online visual overview is available for this article at http://links.lww.com/ALN/B727.

Survey of anesthesiologists' practices related to steep Trendelenburg positioning in the USA.

BACKGROUND: Steep Trendelenburg during surgery has been associated with many position-related injuries. The American Society of Anesthesiology practice advisory recommends documentation, frequent position checks, avoiding shoulder braces, and limiting abduction of upper extremities to avoid brachial plexopathy. We conducted a web-based survey to assess anesthesiologists' practices, institutional policies, and complications encountered when using steep Trendelenburg. METHODS: Two thousand fifty randomly selected active members of the American Society of Anesthesiology were invited via email to participate in a 9-item web-based survey. Results are reported as absolute numbers and proportions with 95% confidence interval (CI). RESULTS: Survey response rate was 290 of 2050 (14.1%). 44.6% (95% CI, 38.9-50.3) of the respondents documented anesthesia start and finish, 73.9% (95% CI, 68.8-79) frequently checked positioning during surgery, 30.8% (95% CI, 25.4-36.2) reported using shoulder braces, 66.9% (95% CI, 61.5-72.3) tucked patients' arms to the side, 54.0% (95% CI, 48.2-59.8) limited fluid administration, and more than two-thirds did not limit the duration or inclination angle. Notably, 63/290 (21.7%) reported a complication and only 6/289 (2.1%) had an institutional policy. The most common complication was airway and face edema, second was brachial plexus injury, and third was corneal abrasions. Most institutional policies, when present, focused on limiting duration of steep Trendelenburg and communication with surgical team. Only 1/6 policies required avoiding use of shoulder braces. CONCLUSION: Based on survey results, practices related to steep Trendelenburg varied among USA anesthesiologists. Differences included protective measures, documentation, positioning techniques, fluid management, and institutional guidelines. The singular commonality found among all respondents was lack of institutional policies. Survey results highlighted the need for institutional policies and more education.

Intravenous Amisulpride for the Prevention of Postoperative Nausea and Vomiting: Two Concurrent, Randomized, Double-blind, Placebo-controlled Trials.

BACKGROUND: Two essentially identical, randomized, double-blind, placebo-controlled, parallel-group phase III studies evaluated the efficacy of intravenous amisulpride, a dopamine D2/D3 antagonist, in the prevention of postoperative nausea and vomiting in adult surgical patients. METHODS: Adult inpatients undergoing elective surgery during general anesthesia and having at least two of the four Apfel risk factors for postoperative nausea and vomiting were enrolled at 9 U.S. and 10 European sites. A single 5-mg dose of amisulpride or matching placebo was given at induction of anesthesia. The primary endpoint was complete response, defined as no vomiting/retching and no use of antiemetic rescue medication in the 24-h postoperative period. Nausea incidence was a secondary endpoint. RESULTS: Across the two studies, 689 patients were randomized and dosed with study medication, of whom 626 were evaluable per protocol. In the U.S. study, 46.9% (95% CI, 39.0 to 54.9) of patients achieved complete response in the amisulpride group compared to 33.8% (95% CI, 26.2 to 42.0) in the placebo group (P = 0.026). In the European study, complete response rates were 57.4% (95% CI, 49.2 to 65.3) for amisulpride and 46.6% (95% CI, 38.8 to 54.6) for placebo (P = 0.070). Nausea occurred less often in patients who received amisulpride than those who received placebo. There was no clinically significant difference in the safety profile of amisulpride and placebo; in particular, there were no differences in terms of QT prolongation, extrapyramidal side effects, or sedation. CONCLUSIONS: One of the two trials demonstrated superiority, while pooling both in a post hoc change to the plan of analysis supported the hypothesis that amisulpride was safe and superior to placebo in reducing the incidence of postoperative nausea and vomiting in a population of adult inpatients at moderate to high risk of postoperative nausea and vomiting.

Opioid-induced Hallucinations: A Review of the Literature, Pathophysiology, Diagnosis, and Treatment.

Despite their association with multiple adverse effects, opioid prescription continues to increase. Opioid-induced hallucination is an uncommon yet significant adverse effect of opioid treatment. The practitioner may encounter patient reluctance to volunteer the occurrence of this phenomenon because of fears of being judged mentally unsound. The majority of the literature concerning opioid-induced hallucinations arises from treatment during end-of-life care and cancer pain. Because the rate of opioid prescriptions continues to increase in the population, the rate of opioid-associated hallucinations may also conceivably increase. With a forecasted increase in the patient-to-physician ratio, opioid therapy is predicted to be provided by practitioners of varying backgrounds and medical specialties. Hence, knowledge of the pharmacology and potential adverse effects of these agents is required. This review seeks to increase awareness of this potential complication through a discussion of the literature, potential mechanisms of action, diagnosis, and treatment strategies.

Inhibition of Mitochondrial Fission Protein Reduced Mechanical Allodynia and Suppressed Spinal Mitochondrial Superoxide Induced by Perineural Human Immunodeficiency Virus gp120 in Rats.

BACKGROUND: Mitochondria play an important role in many cellular and physiologic functions. Mitochondria are dynamic organelles, and their fusion and fission regulate cellular signaling, development, and mitochondrial homeostasis. The most common complaint of human immunodeficiency virus (HIV)-sensory neuropathy is pain on the soles in patients with HIV, but the exact molecular mechanisms of HIV neuropathic pain are not clear. In the present study, we investigated the role of mitochondrial dynamin-related protein 1 (Drp1, a GTPase that mediates mitochondrial fission) in the perineural HIV coat glycoprotein gp120-induced neuropathic pain state. METHODS: Neuropathic pain was induced by the application of recombinant HIV-1 envelope protein gp120 into the sciatic nerve. Mechanical threshold was tested using von Frey filaments. The mechanical threshold response was assessed over time using the area under curves. Intrathecal administration of antisense oligodeoxynucleotide (ODN) against Drp1, mitochondrial division inhibitor-1 (mdivi-1), or phenyl-N-tert-butylnitrone (a reactive oxygen species scavenger) was given. The expression of spinal Drp1 was examined using western blots. The expression of mitochondrial superoxide in the spinal dorsal horn was examined using MitoSox imaging. RESULTS: Intrathecal administration of either antisense ODN against Drp1 or mdivi-1 decreased mechanical allodynia (a sensation of pain evoked by nonpainful stimuli) in the gp120 model. Intrathecal ODN or mdivi-1 did not change basic mechanical threshold in sham surgery rats. Intrathecal Drp1 antisense ODN decreased the spinal expression of increased Drp1 protein induced by peripheral gp120 application. Intrathecal phenyl-N-tert-butylnitrone reduced mechanical allodynia. Furthermore, both intrathecal Drp1 antisense ODN and mdivi-1 reversed the upregulation of mitochondrial superoxide in the spinal dorsal horn in the gp120 neuropathic pain state. CONCLUSIONS: These data suggest that mitochondrial division plays a substantial role in the HIV gp120-related neuropathic pain state through mitochondrial reactive oxygen species and provides evidence for a novel approach to treating chronic pain in patients with HIV.

Gene Transfer of Glutamic Acid Decarboxylase 67 by Herpes Simplex Virus Vectors Suppresses Neuropathic Pain Induced by Human Immunodeficiency Virus gp120 Combined with ddC in Rats.

BACKGROUND: Human immunodeficiency virus (HIV)-related painful sensory neuropathies primarily consist of the HIV infection-related distal sensory polyneuropathy and antiretroviral toxic neuropathies. Pharmacotherapy provides only partial relief of pain in patients with HIV/acquired immune deficiency syndrome because little is known about the exact neuropathological mechanisms for HIV-associated neuropathic pain (NP). Hypofunction of γ-aminobutyric acid (GABA) GABAergic inhibitory mechanisms has been reported after peripheral nerve injury. In this study, we tested the hypothesis that HIV gp120 combined with antiretroviral therapy reduces spinal GABAergic inhibitory tone and that restoration of GABAergic inhibitory tone will reduce HIV-related NP in a rat model. METHODS: The application of recombinant HIV-1 envelope protein gp120 into the sciatic nerve plus systemic ddC (one antiretroviral drug) induced mechanical allodynia. The hind paws of rats were inoculated with replication-defective herpes simplex virus (HSV) vectors genetically encoding gad1 gene to express glutamic acid decarboxylase 67 (GAD67), an enzyme that catalyzes the decarboxylation of glutamate to GABA. Mechanical threshold was tested using von Frey filaments before and after treatments with the vectors. The expression of GAD67 in both the lumbar spinal cord and the L4-5 dorsal root ganglia was examined using western blots. The expression of mitochondrial superoxide in the spinal dorsal horn was examined using MitoSox imaging. The immunoreactivity of spinal GABA, pCREB, and pC/EBPß was tested using immunohistochemistry. RESULTS: In the gp120 with ddC-induced neuropathic pain model, GAD67 expression mediated by the HSV vector caused an elevation of mechanical threshold that was apparent on day 3 after vector inoculation. The antiallodynic effect of the single HSV vector inoculation expressing GAD67 lasted >28 days. The area under the time-effect curves in the HSV vector expressing GAD67 was increased compared with that in the control vectors (P = 0.0005). Intrathecal GABA-A/B agonists elevated mechanical threshold in the pain model. The HSV vectors expressing GAD67 reversed the lowered GABA immunoreactivity in the spinal dorsal horn in the neuropathic rats. HSV vectors expressing GAD67 in the neuropathic rats reversed the increased signals of mitochondrial superoxide in the spinal dorsal horn. The vectors expressing GAD67 reversed the upregulated immunoreactivity expression of pCREB and pC/EBPß in the spinal dorsal horn in rats exhibiting NP. CONCLUSIONS: Based on our results, we suggest that GAD67 mediated by HSV vectors acting through the suppression of mitochondrial reactive oxygen species and transcriptional factors in the spinal cord decreases pain in the HIV-related neuropathic pain model, providing preclinical evidence for gene therapy applications in patients with HIV-related pain states.

CYP3A4 * 1G Genetic Polymorphism Influences Metabolism of Fentanyl in Human Liver Microsomes in Chinese Patients.

PURPOSE: This study aimed to investigate whether CYP3A4*1G genetic polymorphism influences the metabolism of fentanyl in human liver microsomes in Chinese patients. METHODS: The human liver microsomes were obtained from 88 hepatobiliary surgery patients who accepted liver resection surgery in this study. A normal liver sample (confirmed by the Department of Pathology) was taken from the outer edge of the resected tissue. The metabolism of fentanyl in human liver microsomes was studied. The concentration of fentanyl was measured by high performance liquid chromatography. The CYP3A4*1G variant allele was genotyped using the PCR restriction fragment length polymorphism method. RESULTS: The frequency of the CYP3A4*1G variant allele was 0.188 in the 88 Chinese patients who had received hepatobiliary surgery. The metabolic rate of fentanyl in patients homozygous for the *1G/*1G variant (0.85 ± 0.37) was significantly lower than that in patients bearing the wild-type allele *1/*1 (1.89 ± 0.58) or in patients heterozygous for the *1/*1G variant (1.82 ± 0.65; p < 0.05). There were no gender-related differences in the metabolic rate of fentanyl (p > 0.05) nor was there any correlation between age and metabolic rate of fentanyl (p > 0.05). Results from different hepatobiliary diseases showed no significant difference in the metabolic rate of fentanyl (p > 0.05). The difference of CYP3A4 mRNA among different CYP3A4*1G variant alleles was significant (p < 0.05). There was positive correlation between CYP3A4 mRNA and metabolic rate of fentanyl (p < 0.01). CONCLUSIONS: CYP3A4*1G genetic polymorphism decreases the metabolism of fentanyl. There is a positive correlation between CYP3A4 mRNA level and metabolism of fentanyl.

A Comparison of Fentanyl and Flurbiprofen Axetil on Serum VEGF-C, TNF-α, and IL-1ß Concentrations in Women Undergoing Surgery for Breast Cancer.

BACKGROUND: Vascular endothelial growth factor-C (VEGF-C), tumor necrosis factor-α (TNF-α), and interleukin-1ß(IL-1ß) have been shown to be associated with the recurrence and metastasis of breast cancer after surgery. This study tested the hypothesis that patients undergoing surgery for breast cancer, who received postoperative analgesia with flurbiprofen axetil combined with small doses of fentanyl (FA), exhibited reduced levels of VEGF-C, TNF-α, and IL-1ß compared with those patients receiving fentanyl alone (F). METHOD: Forty-women with primary breast cancer undergoing a modified radical mastectomy were randomized to receive postoperative analgesia with flurbiprofen axetil combined with fentanyl or fentanyl alone. Venous blood was sampled before anesthesia, at the end of surgery, and at 48 hours after surgery, and the serum was analyzed. The primary endpoint was changes in the VEGF-C concentrations in serum. RESULTS: Group FA patients reported similar analgesic effects as group F patients at 2, 24, and 48 hours. At 48 hours, mean postoperative concentrations of VEGF-C in group F patients were higher than in group FA patients, 730.9 versus. 354.1 pg/mL (P = 0.003), respectively. The mean postoperative concentrations of TNF-α in group F patients were also higher compared with group FA patients 27.1 vs. 15.8 pg/mL (P = 0.005). Finally, the mean postoperative concentrations of IL-1ß in group F were also significantly higher than in group FA 497.5 vs. 197.7 pg/mL (P = 0.001). CONCLUSION: In patients undergoing a mastectomy, postoperative analgesia with flurbiprofen axetil, combined with fentanyl, were associated with decreases in serum concentrations of VEGF-C, TNF-α, and IL-1ß compared with patients receiving doses of only fentanyl.

IL-10 mediated by herpes simplex virus vector reduces neuropathic pain induced by HIV gp120 combined with ddC in rats.

BACKGROUND: HIV-associated sensory neuropathy affects over 50% of HIV patients and is a common peripheral nerve complication of HIV infection and highly active antiretroviral therapy (HAART). Evidence shows that painful HIV sensory neuropathy is influenced by neuroinflammatory events that include the proinflammatory molecules, MAP Kinase, tumor necrosis factor-α (TNFα), stromal cell-derived factor 1-α (SDF1α), and C-X-C chemokine receptor type 4 (CXCR4). However, the exact mechanisms of painful HIV sensory neuropathy are not known, which hinders our ability to develop effective treatments. In this study, we investigated whether inhibition of proinflammatory factors reduces the HIV-associated neuropathic pain state. RESULTS: Neuropathic pain was induced by peripheral HIV coat protein gp120 combined with 2',3'-dideoxycytidine (ddC, one of the nucleoside reverse transcriptase inhibitors (NRTIs)). Mechanical threshold was tested using von Frey filament fibers. Non-replicating herpes simplex virus (HSV) vectors expressing interleukin 10 (IL10) were inoculated into the hindpaws of rats. The expression of TNFα, SDF1α, and CXCR4 in the lumbar spinal cord and L4/5 dorsal root ganglia (DRG) was examined using western blots. IL-10 expression mediated by the HSV vectors resulted in a significant elevation of mechanical threshold. The anti-allodynic effect of IL-10 expression mediated by the HSV vectors lasted more than 3 weeks. The area under the effect-time curves (AUC) in mechanical threshold in rats inoculated with the HSV vectors expressing IL-10, was increased compared with the control vectors, indicating antinociceptive effect of the IL-10 vectors. The HSV vectors expressing IL-10 also concomitantly reversed the upregulation of p-p38, TNFα, SDF1α, and CXCR4 induced by gp120 in the lumbar spinal dorsal horn and/or the DRG at 2 and/or 4 weeks. CONCLUSION: The blocking of the signaling of these proinflammatory molecules is able to reduce HIV-related neuropathic pain, which provide a novel mechanism-based approach to treating HIV-associated neuropathic pain using gene therapy.

Interleukin 10 mediated by herpes simplex virus vectors suppresses neuropathic pain induced by human immunodeficiency virus gp120 in rats.

BACKGROUND: Human immunodeficiency virus (HIV)-associated sensory neuropathy is a common neurological complication of HIV infection affecting up to 30% of HIV-positive individuals. However, the exact neuropathological mechanisms remain unknown, which hinders our ability to develop effective treatments for HIV-related neuropathic pain (NP). In this study, we tested the hypothesis that inhibition of proinflammatory factors with overexpression of interleukin (IL)-10 reduces HIV-related NP in a rat model. METHODS: NP was induced by the application of recombinant HIV-1 envelope protein gp120 into the sciatic nerve. The hindpaws of rats were inoculated with nonreplicating herpes simplex virus (HSV) vectors expressing anti-inflammatory cytokine IL-10 or control vector. Mechanical threshold was tested using von Frey filaments before and after treatments with the vectors. The mechanical threshold response was assessed over time using the area under curves. The expression of phosphorylated p38 mitogen-activated kinase, tumor necrosis factor-α, stromal cell-derived factor-1α, and C-X-C chemokine receptor type 4 in both the lumbar spinal cord and the L4/5 dorsal root ganglia (DRG), was examined at 14 and 28 days after vector inoculation using Western blots. RESULTS: We found that in the gp120-induced NP model, IL-10 overexpression mediated by the HSV vector resulted in a significant elevation of the mechanical threshold that was apparent on day 3 after vector inoculation compared with the control vector (P < 0.001). The antiallodynic effect of the single HSV vector inoculation expressing IL-10 lasted >28 days. The area under curve in the HSV vector expressing IL-10 was increased compared with that in the control vector (P < 0.0001). HSV vectors expressing IL-10 reversed the upregulation of phosphorylated p38 mitogen-activated kinase, tumor necrosis factor-α, stromal cell-derived factor-1α, and C-X-C chemokine receptor type 4 expression at 14 and/or 28 days in the DRG and/or the spinal dorsal horn. CONCLUSIONS: Our studies demonstrate that blocking the signaling of these proinflammatory molecules in the DRG and/or the spinal cord using the HSV vector expressing IL-10 is able to reduce HIV-related NP. These results provide new insights on the potential mechanisms of HIV-associated NP and a proof of concept for treating painful HIV sensory neuropathy with this type of gene therapy.

Catechol-o-methyltransferase polymorphisms predict opioid consumption in postoperative pain.

BACKGROUND: Previous studies have associated the catechol-O-methyltransferase (COMT) enzyme rs4680 polymorphism with opioid consumption in the treatment of chronic cancer pain. In this study, we evaluated the association between COMT rs4680 and rs4818 polymorphisms and opioid consumption in the acute postoperative period after a nephrectomy. METHODS: Opioid consumption and pain scores were evaluated in 152 patients for 48 hours after nephrectomy. The genotype of each patient was determined using polymerase chain reaction on DNA extracted from blood samples. The association between rs4680 and rs4818 genotypes and opioid consumption was evaluated using general linear model regression analysis. All P values and confidence intervals were Bonferroni corrected for the 3 comparisons among genotypes. RESULTS: In the 24-hour period after surgery (COMT rs4680), patients homozygous for the variant Val/Val consumed 36% (95% confidence interval, 31%-41%) more opioids than patients homozygous for the Met/Met group (P = 0.009). No statistically significant differences among the 3 genotype groups were noted for pain scores or emesis medication use in the first 24 hours after surgery. There was a statistically significant increase in emesis medication use in patients possessing the CC genotype of rs4818 when compared to patients carrying the GG genotypes (P = 0.035). In the 6- to 48-hour postsurgery period, there was significantly higher opioid consumption in the high-activity homozygotes Val/Val than in the homozygous Met/Met group for COMT rs4680 (0-6 h: P = 0.005; 0-12 h: P = 0.015; 0-24 h: P = 0.015; and 0-48 h: P = 0.023). Patients in the homozygous GG group COMT rs4818 single nucleotide polymorphism showed statistically significant differences in opioid consumption in the first 6 hours after nephrectomy compared with heterozygous CG patients (P = 0.02). CONCLUSIONS: The genetic variant of the COMT rs4680 single nucleotide polymorphism is associated with variability in opioid consumption in postoperative nephrectomy patients. The COMT rs4818 polymorphism may prove useful in predicting emesis medication use postoperatively.

Mechanical allodynia induced by nucleoside reverse transcriptase inhibitor is suppressed by p55TNFSR mediated by herpes simplex virus vector through the SDF1α/CXCR4 system in rats.

BACKGROUND: In the human immunodeficiency virus (HIV)-associated sensory neuropathy, neuropathic pain associated with the use of nucleoside reverse transcriptase inhibitors (NRTIs) in patients with HIV/acquired immunodeficiency syndrome is clinically common. While evidence demonstrates that neuropathic pain is influenced by neuroinflammatory events that include the proinflammatory molecules, tumor necrosis factor-α (TNF-α), stromal cell-derived factor 1-α (SDF1-α), and C-X-C chemokine receptor type 4 (CXCR4), the detailed mechanisms by which NRTIs contribute to the development of neuropathic pain are not known. In this study, we investigated the role of these proinflammatory molecules in the dorsal root ganglion (DRG) and the spinal dorsal horn in NRTIs-mediated neuropathic pain state. METHODS: Neuropathic pain was induced by intraperitoneal administration of 2',3'-dideoxycytidine (ddC, one of the NRTIs). Mechanical threshold was tested using von Frey filament fibers. Nonreplicating herpes simplex virus (HSV) vectors expressing p55 TNF soluble receptor (p55TNFSR) were inoculated into hindpaw of rats. The expression of TNF-α, SDF1-α, and CXCR4 in both the lumbar spinal cord and the L4/5 DRG was examined using Western blots. Intrathecal CXCR4 antagonist was administered. RESULTS: The present study demonstrated that (1) systemic ddC induced upregulation of TNF-α, SDF1-α, and CXCR4 in both the lumbar spinal cord and the L4/5 DRG; (2) p55TNFSR mediated by a nonreplicating HSV vector reversed mechanical allodynia induced by systemic ddC; (3) intrathecal administration of the CXCR4 antagonist AMD3100 increased mechanical threshold; and (4) HSV vector expressing p55TNFSR reversed upregulation of TNF-α, SDF1-α, and CXCR4 induced by ddC in the lumbar spinal dorsal horn and the DRG. CONCLUSIONS: Our studies demonstrate that TNF-α through the SDF1/CXCR4 system is involved in the NRTIs-related neuropathic pain state and that blocking the signaling of these proinflammatory molecules is able to reduce NRTIs-related neuropathic pain. These results provide a novel mechanism-based approach (gene therapy) to treating HIV-associated neuropathic pain.

Consensus guidelines for the management of postoperative nausea and vomiting.

The present guidelines are the most recent data on postoperative nausea and vomiting (PONV) and an update on the 2 previous sets of guidelines published in 2003 and 2007. These guidelines were compiled by a multidisciplinary international panel of individuals with interest and expertise in PONV under the auspices of the Society for Ambulatory Anesthesia. The panel members critically and systematically evaluated the current medical literature on PONV to provide an evidence-based reference tool for the management of adults and children who are undergoing surgery and are at increased risk for PONV. These guidelines identify patients at risk for PONV in adults and children; recommend approaches for reducing baseline risks for PONV; identify the most effective antiemetic single therapy and combination therapy regimens for PONV prophylaxis, including nonpharmacologic approaches; recommend strategies for treatment of PONV when it occurs; provide an algorithm for the management of individuals at increased risk for PONV as well as steps to ensure PONV prevention and treatment are implemented in the clinical setting.

Liposome Bupivacaine for Postsurgical Analgesia in Adult Patients Undergoing Laparoscopic Colectomy: Results from Prospective Phase IV Sequential Cohort Studies Assessing Health Economic Outcomes.

BACKGROUND: Opioid-based postsurgical analgesia exposes patients undergoing laparoscopic colectomy to elevated risk for gastrointestinal motility problems and other opioid-related adverse events (ORAEs). The purpose of our research was to investigate postsurgical outcomes, including opioid consumption, hospital length of stay, and ORAE risk associated with a multimodal analgesia regimen, employing a single administration of liposome bupivacaine as well as other analgesics that act by different mechanisms. METHODS: We analyzed combined results from 6 Phase IV, prospective, single-center studies in which patients undergoing laparoscopic colectomy received opioid-based intravenous patient-controlled analgesia (PCA) or multimodal analgesia incorporating intraoperative administration of liposome bupivacaine. As-needed rescue therapy was available to all patients. Primary outcome measures were postsurgical opioid consumption, hospital length of stay, and hospitalization costs. Secondary measures included time to first rescue opioid use, patient satisfaction with analgesia (assessed using a 5-point Likert scale), and ORAEs. RESULTS: Eighty-two patients underwent laparoscopic colectomy and did not meet intraoperative exclusion criteria (PCA n = 56; multimodal analgesia n = 26). Compared with the PCA group, the multimodal analgesia group had significantly lower mean total postsurgical opioid consumption (96 vs 32 mg, respectively; P < 0.0001) and shorter median postsurgical hospital length of stay (3.0 vs 4.0 days; P = 0.0019). Geometric mean costs were $11,234 and $13,018 in the multimodal analgesia and PCA groups, respectively (P = 0.2612). Median time to first rescue opioid use was longer in the multimodal analgesia group versus PCA group (1.1 hours vs 0.6 hours, respectively; P=0.0003). ORAEs were experienced by 41% of patients receiving intravenous opioid PCA and 8% of patients receiving multimodal analgesia (P = 0.0019). Study limitations included use of an open-label, nonrandomized design; small population size; and the inability to isolate treatment-related effects specifically attributable to liposome bupivacaine. CONCLUSIONS: Compared with intravenous opioid PCA, a liposome bupivacaine-based multimodal analgesia regimen reduced postsurgical opioid use, hospital length of stay, and ORAEs, and may lead to improved postsurgical outcomes following laparoscopic colectomy.

Diabetic neuropathic pain development in type 2 diabetic mouse model and the prophylactic and therapeutic effects of coenzyme Q10.

UNLABELLED: The early onset of type 2 diabetes mellitus (DM), driven by increasing obesity, is associated with peripheral neuropathy. Here, we characterize diabetic neuropathic pain in New Zealand obese diabetic mice (NZO/HILtJ) as a polygenic model of obesity with type 2 diabetes and investigate the role of coenzyme Q10 (CoQ10) in the prevention and treatment of diabetic neuropathic pain. Since the overexpression of mitogen-activated protein kinase (MAPK), nuclear factor-κB proteins (NF-Kb), toll-like receptor 4 (TLR4) and downstream cytokines (such as CCL2, CXCL10) are considered important factors contributing to the development of neuropathic pain, the expression of these factors and the inhibitory effects of CoQ10 were evaluated. NZO/HILtJ mice spontaneously developed type 2 DM and increased body mass with diabetic neuropathic pain. CoQ10 treatment decreased pain hypersensitivity and long-term supplementation prevented the development of diabetic neuropathic pain but did not attenuate diabetes. Spinal cord, blood serum, liver tissue, and dorsal root ganglia (DRG) from diabetic mice demonstrated increased lipid peroxidation, which was decreased by CoQ10 treatment. The percentage of positive neurons of p65 (the activated marker of NF-KB) and MAPK in DRG were significantly higher in DM mice compared to controls. However, CoQ10 treatment significantly decreased p65 and MAPK positive neurons in the DRG of DM mice. RT-PCR demonstrated that elevated levels of mRNA of CCL2, CXCL10 or TLR4 in the spinal cord of DM mice decreased significantly when DM mice were treated with CoQ10. CONCLUSION: This model may be useful in understanding the mechanisms of neuropathic pain in type 2 DM induced neuropathic pain and may facilitate preclinical testing of therapies. CoQ10 may decrease oxidative stress in the central and peripheral nervous system by acting as an anti-oxidant and free-radical scavenger. These results suggest that CoQ10 might be a reasonable preventative strategy for long-term use and using CoQ10 treatment may be a safe and effective long-term approach in the treatment of diabetic neuropathy.

Prophylactic and antinociceptive effects of coenzyme Q10 on diabetic neuropathic pain in a mouse model of type 1 diabetes.

BACKGROUND: Oxidative stress is a key factor implicated in the development of diabetic neuropathy. This study evaluates the prophylactic and antinociceptive effects of the antioxidant coenzyme Q10 (CoQ10) on diabetes-induced neuropathic pain in a diabetic mouse model. METHODS: Total 56 mice with type 1 diabetes induced by streptozotocin were used, 20 normal mice were used as control. Mechanical and thermal nociceptive behavioral assays were applied to evaluate diabetic neuropathic pain. Tissue lipid peroxidation, immunohistochemistry, reverse transcription, and polymerase chain reaction were used to evaluate the molecular mechanisms of CoQ10. Data are presented as mean ± SEM. RESULTS: CoQ10 administration was associated with reduced loss of body weight compared with nontreated diabetic mice, without affecting blood glucose levels. Low dose and long-term administration of CoQ10 prevented the development of neuropathic pain. Treatment with CoQ10 produced a significant dose-dependent inhibition of mechanical allodynia and thermal hyperalgesia in diabetic mice. Dorsal root ganglia, sciatic nerve, and spinal cord tissues from diabetic mice demonstrated increased lipid peroxidation that was reduced by CoQ10 treatment. CoQ10 administration was also noted to reduce the proinflammatory factors in the peripheral and central nervous system. CONCLUSIONS: The results of this study support the hypothesis that hyperglycemia induced neuronal oxidative damage and reactive inflammation may be pathogenic in diabetic neuropathic pain. CoQ10 may be protective by inhibiting oxidative stress and reducing inflammation by down-regulating proinflammatory factors. These results suggest that CoQ10 administration may represent a low-risk, high-reward strategy for preventing or treating diabetic neuropathy.