Relationships between plasma concentrations of morphine, morphine-3-glucuronide, morphine-6-glucuronide, and intravenous morphine titration outcomes in the postoperative period

Opioid-related genetic polymorphisms do not influence postoperative opioid requirement: A prospective observational study

BACKGROUND

Among the various factors that may influence the pharmacological response to opioids, genetic polymorphisms [single nucleotide polymorphisms (SNP)] have generated some interest.

OBJECTIVES

To examine the influence on morphine dose requirements and adverse events in the postoperative period of four SNP [opioid receptor mu1 (OPRM1), ATP-binding cassette subfamily B, member 1 (ABCB1) ex-21 and ex-26, catechol-o-methyltransferase (COMT)] in candidate genes involved in morphine pharmacodynamics and pharmacokinetics.

DESIGN

A single centre prospective study.

SETTING

University Hospital, Paris, France, from 2 January 2007 to 15 November 2011.

PATIENTS

A total of 438 white adults scheduled for major orthopaedic surgery (spine, hip and knee) under general anaesthesia. The main exclusion criteria were receiving opioids for chronic pain, nonopioid drugs within 2 days prior to surgery, pregnancy, renal insufficiency, sleep apnoea obstruction syndrome, morbid obesity, severe hepatic impairment, cognitive dysfunction.

INTERVENTIONS

Assays of plasma concentrations of morphine and metabolites (morphine 3-glucuronide and morphine 6-glucuronide) were performed and common polymorphisms in four candidate genes [OPRM1 A118G rs1799971; P-glycoprotein (ABCB1) T3435C (rs1045642) and G2677T/A (rs2032582); COMT Val 158 Met (rs4680)] were analysed.Morphine was titrated by staff in the postanaesthesia care unit (PACU) and in the ward patient-controlled intravenous analgesia was used for 24 h.

MAIN OUTCOME MEASURES

The dose of morphine required to achieve pain relief and the influence of SNP in genes involved in morphine pharmacodynamics and kinetics on morphine dose requirements. Secondary endpoints were the concentrations of morphine, morphine 6-glucuronide and morphine 3-gluguronide, the proportion of patients requiring a rescue analgesic and the proportion of morphine-related adverse events.

RESULTS

A total of 404 patients completed the study to final analysis. The mean ± SD morphine dose to achieve pain relief was 15.8 ± 8.8 mg in the PACU and 22.7 ± 18.6 mg during patient-controlled intravenous administration. Morphine-related adverse events were observed in 37%. There was no relationship between any genetic polymorphisms and morphine dose, morphine 3-gluguronide and morphine 6-glucuronide concentration, morphine-related adverse events or pain level. In the PACU only, P-glycoprotein polymorphisms (ex-21; ex-26) were significantly associated with morphine concentration but the prediction of the model was poor (R = 0.04) CONCLUSION: No major relationship has been demonstrated between SNP of OPRM1, ABCB1, COMT and morphine requirement, pain level or adverse effects in the postoperative period.

TRIAL REGISTRATION

NCT00822549 (www.clinicaltrials.gov).

Morphine and ketamine treatment suppress the differentiation of T helper cells of patients with colorectal cancer in vitro

There have been conflicting reports regarding the effects of anesthetic and analgesic drugs on immune function in patients with cancer. The aim of the present study was to investigate changes to T helper (Th) cell populations in patients with colorectal cancer (CRC) and to assess the effects of morphine and ketamine on the differentiation of Th cells harvested from patients with CRC in vitro. Peripheral blood samples were extracted from 20 patients with CRC and 20 healthy participants. Peripheral blood mononuclear cells were isolated and incubated in a solution containing phorbol-myristate-acetate (PMA) and ionomycin in the presence or absence of morphine or various ketamine concentrations (25, 50, and 100 µM). Samples were analyzed 4 h later. Th1 and Th2 cells were significantly increased by PMA and ionomycin stimulation; however, Th1 cells and the Th1/Th2 ratio in PMA and ionomycin treatments were significantly decreased in the CRC group compared with the control group. Following incubation with PMA and ionomycin, morphine significantly decreased Th1 cells and the Th1/Th2 ratio in the CRC group. Ketamine did not significantly affect levels of Th1 or Th2 cells or the Th1/Th2 ratio at a concentration of 25 µM; however, a significant increase in the Th1/Th2 ratio was observed at a concentration of 50 µM and, at 100 µM, a significant decrease in Th1 and Th2 cells and an increase in the Th1/Th2 ratio were observed. The present study suggests that CRC may shift the balance of Th1/Th2 towards Th2 by inducing an immunological response, morphine is able to suppress the differentiation of Th cells and decreases the Th1/Th2 ratio, and ketamine may affect the differentiation of Th cells in a dose-dependent manner.

Metabolic profiling analysis of corilagin in vivo and in vitro using high-performance liquid chromatography quadrupole time-of-flight mass spectrometry

Corilagin is an Ellagitannin with favorable pharmacological activities. But there was no report regarding the metabolism of corilagin in vitro or in vivo. In this study, the metabolic profile of corilagin in rats as well as in rat intestinal bacteria and liver microsomes incubation system in vitro were investigated comprehensively for the first time. Consequently, with the aid of sensitive HPLC-Q-TOF-MS/MS, corilagin and its twenty-four metabolites (fourteen phase II conjugate metabolites of corilagin, three hydrolyzed metabolites EA, GA, M3 and their seven derived metabolites) were absolutely or tentatively identified in rat biological samples (urine, feces, plasma and tissues) after oral administration of corilagin. In vitro, the three hydrolyzed metabolites were identified in rat intestinal microflora and liver microsomes. These results demonstrated that corilagin itself not only could underwent extensive phase II metabolism in rats, but also could underwent hydrolysis reaction in rats as well as in rat intestinal bacteria and liver microsomes in vitro. This study is first report to identify phase II conjugate metabolites (except mono-methylate conjugated metabolites) of pure Ellagitannin and distribution of these metabolites in vivo. In addition, clear, detailed metabolic pathways of corilagin were shown to involve hydrolysis, methylation, glycosylation, reduction, glucuronidation and sulfation.

Morphine Suppresses T helper Lymphocyte Differentiation to Th1 Type Through PI3K/AKT Pathway

To investigate the effect of morphine on T helper lymphocyte differentiation and PI3K/AKT pathway mechanism, CD4+ lymphocytes were treated by phorbol-myristate-acetate (25 ng/ml) (PMA) plus ionomycin (1 μg/ml) in the presence of various concentrations of morphine (25, 50, 100, 200 ng/ml) for 4 h. Th1 and Th2 subsets, supernatant cytokines, and PI3K, AKT, and protein kinase C-theta (PKC-θ) levels were detected. The Th1 cell percentage, Th1-derived cytokines, and ratio of Th1/Th2 decreased in the presence of morphine in a concentration-dependent manner. However, Th2 cell percentage kept stable after morphine treatment. The phosphorylation of PI3K and AKT decreased, but the phosphorylation of PKC-θ did not change in the presence of morphine. The decreased percentage of Th1 cells and ratio of Th1/Th2 was recovered by naloxone concentration-dependently. Morphine can inhibit the differentiation of Th1 lymphocytes and decrease the ratio of Th1/Th2 via the pathway of PI3K/AKT. The effect can be inhibited by naloxone.

Morphine and ketamine inhibit immune function of gastric cancer patients by increasing percentage of CD4(+)CD25(+)Foxp3(+) regulatory T cells in vitro

BACKGROUND

There is conflicting evidence regarding effects of anesthetic and analgesic drugs on immune function of cancer patients. This study was designed to observe changes of T cell subpopulations in the gastric cancer (GC) patients and to assess effects of morphine and ketamine on the CD4(+) T cells, CD8(+) T cells, and regulatory T cells (Tregs) populations obtained from the GC patients in vitro.

METHODS

The peripheral blood samples from 20 GC patients and 20 healthy volunteers were obtained. The peripheral blood mononuclear cells were isolated and incubated in a solution containing phorbol-myristate-acetate and ionomycin (2 μL/mL) in the presence or absence of morphine (50 ng/mL) or different-concentration ketamine (25, 50, and 100 μM). The CD4(+) T cells, CD8(+) T cells, and Tregs were determined using the flow cytometric assay.

RESULTS

The percentages of CD8(+) T cells were significantly decreased, but the ratio of CD4(+)/CD8(+) T cells and Tregs populations was significantly increased in the GC control group compared with the normal control group (P < 0.05). The ratio of CD4(+)/CD8(+) T cells was significantly increased in the groups M and K3 compared with the control group (P < 0.05) but was significantly decreased in the group K1 compared with the group K3. The percentage of Tregs was significantly increased in the groups M, K1, K2, and K3 compared with the control group. With the increased concentrations, ketamine increased the number of Tregs.

CONCLUSIONS

GC shifts the balance of CD4(+)/CD8(+) T cells toward CD4(+) T cells and increases the Tregs populations by inducing immune responses. Morphine increases the ratio of CD4(+)/CD8(+) T cells and Tregs populations. Ketamine affects the ratio of CD4(+)/CD8(+) T cells and Tregs populations in a dose-dependent model.

Peri-operative management of the obese surgical patient 2015: Association of Anaesthetists of Great Britain and Ireland Society for Obesity and Bariatric Anaesthesia

Guidelines are presented for the organisational and clinical peri-operative management of anaesthesia and surgery for patients who are obese, along with a summary of the problems that obesity may cause peri-operatively. The advice presented is based on previously published advice, clinical studies and expert opinion.

Targeting Opioid-Induced Hyperalgesia in Clinical Treatment: Neurobiological Considerations

Opioid analgesics have become a cornerstone in the treatment of moderate to severe pain, resulting in a steady rise of opioid prescriptions. Subsequently, there has been a striking increase in the number of opioid-dependent individuals, opioid-related overdoses, and fatalities. Clinical use of opioids is further complicated by an increasingly deleterious profile of side effects beyond addiction, including tolerance and opioid-induced hyperalgesia (OIH), where OIH is defined as an increased sensitivity to already painful stimuli. This paradoxical state of increased nociception results from acute and long-term exposure to opioids, and appears to develop in a substantial subset of patients using opioids. Recently, there has been considerable interest in developing an efficacious treatment regimen for acute and chronic pain. However, there are currently no well-established treatments for OIH. Several substrates have emerged as potential modulators of OIH, including the N-methyl-D-aspartate and γ-aminobutyric acid receptors, and most notably, the innate neuroimmune system. This review summarizes the neurobiology of OIH in the context of clinical treatment; specifically, we review evidence for several pathways that show promise for the treatment of pain going forward, as prospective adjuvants to opioid analgesics. Overall, we suggest that this paradoxical state be considered an additional target of clinical treatment for chronic pain.

Do we have clarity on the therapeutic levels of morphine and its metabolites: seeking answers for the dilemma?

In spite of numerous investigations and decades of research, there is still a void in the complete understanding of the therapeutic action of morphine due to the complex nature of its pharmacokinetic/metabolic disposition coupled with elusive pharmacodynamics. This commentary attempts to collate current information on this very important topic and provide perspective to further tease out the relationship between morphine and its metabolites to its purported clinical effect. Similar to numerous acute therapies that need a close vigil for therapy optimization, postoperative pain management with morphine is a challenge due to its extreme intrasubject variability, a fragile therapeutic index, and complex pharmacology interlinked with formation and transport of active metabolite(s). Although numerous investigations of pharmacokinetics and pharmacodynamic effects of morphine and its active glucuronide metabolites have been carried out and excellent data published, still there remains a void in complete understanding of desired therapeutic levels for a meaningful therapeutic outcome without the avoidance of morphine-related side effect profile. The 2009 report of Hammoud et al. (Pain. 2009;144:139-146) confirms the challenges of which one need to be aware during postoperative pain management with morphine in spite of well-controlled intravenous titration using an institutional protocol. These authors have attempted to correlate the plasma concentrations of morphine and its key metabolites, morphine-3-glucuronide (3MG) and morphine-6-glucuronide (6MG), with clinical outcomes such as sedation and adverse effects. This report assumes high significance, since such an investigation to titrate postoperative patients to a fixed desired clinical efficacy outcome has hitherto been not performed in patients who underwent postoperative pain managemnt. Moreover, the intravenous titration option used in the study provided a clean collection of pharmacokinetic surrogate data of morphine along with its metabolites without the issue of absorption and/or oral bioavailability setback if morphine was given by oral route. However, the various pharmacokinetic surrogates used in this study was found insufficient to distinguish the clinical effects. Given the complicated pharmacokinetic and pharmacodynamic profiles of morphine and its metabolites (6MG and 3MG), this commentary provides some thoughts to seek answers for this interesting dilemma.

Endogenous opiates and behavior: 2011

This paper is the thirty-fourth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2011 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).

Morphine, but not ketamine, decreases the ratio of Th1/Th2 in CD4-positive cells through T-bet and GATA3

This study was conducted to investigate the effect of morphine on CD4-positive T cells differentiation and the transcriptional factors induced by phorbol myristate acetate (PMA) and ionomycin. CD4-positive lymphocytes separated from healthy volunteers were incubated by PMA (25 ng/ml) + ionomycin (1 μg/ml) with or without the presence of morphine, ketamine, or naloxone. Th subsets, supernatant cytokines, and transcriptional factors were detected 4 h later. Th1 and Th2 cells, levels of INF-γ, IL-2, IL-4 and the activities of T-bet and GATA3 were significantly increased after incubation with PMA and ionomycin. However, the number of Th1 cells, Th1/ Th2, the levels of INF-γ and INF-γ/IL-4, and the activities and protein levels of T-bet and GATA3 were decreased after incubation with PMA and ionomycin in the presence of morphine. Naloxone can abolish morphine's suppressive effect on Th cell differentiation. Morphine has a negative effect on Th cell balance induced by PMA and ionomycin, the mechanism is related to T-bet and GATA3.