Practice guidelines for transdermal opioids in malignant pain

Effects of Gabapentin on Postoperative Pain and Opioid Consumption Following Laparoscopic Cholecystectomy: A Systematic Review and Meta-analysis

PURPOSE

Examine the efficacy of gabapentin on postoperative pain scores and opioid consumption in laparoscopic cholecystectomy.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, EBSCO, CINAHL, the Cochrane Central Register of Controlled Trials, Google Scholar, and gray literature was used to search the literature. Only randomized controlled trials were included. Outcomes were reported using the risk ratio and mean difference (MD). Risk of bias and the grades of recommendation, assessment, development, and evaluation (GRADE) system was used to the assessed quality of evidence.

FINDINGS

Nineteen trials involving 2,068 patients were analyzed. Compared to placebo, gabapentin reduced the cumulative pain scores in the first 24 hours after surgery (MD, -1.19; 95% CI, -1.39-0.99; P < .00011), opioid consumption (MD, -3.51; 95% CI, -4.67 to -2.35; P < .00001), and the incidence of postoperative nausea and vomiting (risk ratio, 0.64; 95% CI, 0.52-0.78; P < .00001) with prolonged time to first analgesic rescue (MD, 210.9; 95% CI, 76.90-344.91; P = .002). However, gabapentin has little to no effect on the incidence of sedation, somnolence, and respiratory depression.

CONCLUSIONS

Gabapentin can be added as part of the multimodal pain management for patients undergoing laparoscopic cholecystectomy. Extrapolation of these findings to clinical settings must take into consideration the limitations identified in this review.

Erector Spinae Plane Block on Postoperative Pain and Opioid Consumption After Lumbar Spine Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

Evaluate the effectiveness of the erector spinae plane (ESP) block in lumbar spine surgeries.

DESIGN

Systematic review with meta-analysis.

METHODS

PubMed, Cochrane Library, CINAHL, Google Scholar, and other gray literature were searched for eligible studies. Risk ratio (RR), mean difference (MD), and standardized mean difference were used to estimate outcomes with suitable effect models. The quality of evidence was assessed using the Risk of Bias algorithm and the grades of recommendation, assessment, development, and evaluation (GRADE) approach.

FINDINGS

Twenty-two randomized controlled trials involving 1,327 patients were included. The erector spinae plane (ESP) block demonstrated a lower cumulative pain score within the first 48 hours at rest (MD, -1.03; 95% CI, -1.19 to -0.87; P < .00001) and during activity (MD, -1.16; 95% CI, -1.24 to -1.08; P < .00001). In addition, ESP block decreased opioid consumption (MD, -6.25; 95% CI, -8.33 to -4.17; P < .00001) and prolonged the time to first analgesic rescue (MD, 5.66; 95% CI, 3.11-8.20; P < .0001) resulting in fewer patients requesting rescue analgesic (RR, 0.33; 95% CI, 0.13-0.83; P = .02), lower incidence of postoperative nausea and vomiting (RR, 0.29; 95% CI, 0.10-0.79; P = .02) with improved patient satisfaction score (standardized mean difference, 2.17; 95% CI, 1.40-2.94; P < .00001).

CONCLUSIONS

ESP block can provide effective postoperative pain control for lumbar spine surgery, improve patient satisfaction, and reduce the amount of postoperative opioid use.

Impact of an extrafascial versus intrafascial injection for supraclavicular brachial plexus block on respiratory function: a randomized, controlled, double-blind trial

Introduction

Hemidiaphragmatic paresis after ultrasound-guided supraclavicular brachial plexus block is reported to occur in up to 67% of patients. We tested the hypothesis that an injection outside the brachial plexus sheath reduces the incidence of hemidiaphragmatic paresis compared with an intrafascial injection while providing similar analgesia.

Methods

Fifty American Society of Anesthesiologists I–III patients scheduled for elective upper limb surgery received a supraclavicular brachial plexus block using 30 mL of 1:1 mixture of mepivacaine 1% and ropivacaine 0.5%. The block procedures were randomized to position the needle tip either within the brachial plexus after piercing the sheath (intrafascial injection) or outside the brachial plexus sheath (extrafascial injection). The primary outcome was the incidence of hemidiaphragmatic paresis 30 min after the injection, measured by M-mode ultrasonography. Additional outcomes included time to surgery readiness, and resting and dynamic pain scores at 24 hours postoperatively (Numeric Rating Scale, 0–10).

Results

The incidence of hemidiaphragmatic paresis 30 min after the injection was 9% (95% CI 1% to 29%) and 0% (95% CI 0% to 15%) in the intrafascial and extrafascial groups respectively (p=0.14). Extrafascial injection was associated with a longer time to surgery readiness (intrafascial: 18 min (95% CI: 16 to 21 min); extrafascial: 37 min (95% CI: 31 to 42 min); p<0.001). At 24 hours, resting and dynamic pain scores were similar between groups.

Discussion

Ultrasound-guided supraclavicular brachial plexus block with an extrafascial injection does not reduce the incidence of hemidiaphragmatic paresis although it provides similar analgesia, when compared with an intrafascial injection. The longer time to surgery readiness is less compatible with contemporary operating theater efficiency requirements.

Trial registration number

NCT03957772.

Laparoscopic-Assisted Transversus Abdominis Plane Block is Superior to Port Site Infiltration in Reducing Post-Operative Opioid Use in Laparoscopic Surgery

BACKGROUND

The ultrasound-guided transversus abdominis plane (TAP) block can be time-consuming, costly, and technically challenging in the bariatric patient population. Laparoscopic-assisted TAP (L-TAP) block was developed and has been shown to be non-inferior to ultrasound-guided blocks. Postoperative pain can be significant, and pain control in the morbidly obese patients can be challenging. This study's aim was to compare L-TAP block to traditional port site infiltration in terms of postoperative opioid requirement for morbidly obese patients after laparoscopic Roux-en-Y gastric bypass (RYGB) surgery.

METHODS

A retrospective chart review was performed from February 2019 through February 2020. Two study groups: L-TAP block and port site infiltration. Outcomes examined the amount of opioid used at different time segments relative to the operation. All intravenous (IV) and oral opioids used were converted into IV morphine milligram equivalents (MME) for standardization.

RESULTS

150 patients were included. The patient characteristics were not statistically significant between the two groups. Post-operative opioid use trended lower in the L-TAP block group in all time segments. A significant difference was detected in IV opioid use during post-operative day 0 with the mean MME for the L-TAP block group being 1.1±3.8 and port site infiltration group being 2.8±4.5 (P = .02).

CONCLUSIONS

The L-TAP block more effectively reduces postoperative opioid use in comparison to port site infiltration in laparoscopic Roux-en-Y gastric bypass (RYGB) surgery. Based on these findings, as well as the efficiency and cost-effectiveness of L-TAP blocks, its routine use in laparoscopy should be considered.

Smoking, Pain Intensity, and Opioid Consumption 1-3 Months After Major Surgery: A Retrospective Study in a Hospital-Based Transitional Pain Service

Introduction

The present study investigated the associations between smoking, pain, and opioid consumption in the 3 months after major surgery in patients seen by the Transitional Pain Service. Current smoking status and lifetime pack-years were expected to be related to higher pain intensity, more opioid use, and poorer opioid weaning after surgery.

Methods

A total of 239 patients reported smoking status in their presurgical assessment (62 smokers, 92 past smokers, and 85 never smokers). Pain and daily opioid use were assessed in hospital before postsurgical discharge, at first outpatient visit (median of 1 month postsurgery), and at last outpatient visit (median of 3 months postsurgery). Pain was measured using numeric rating scale. Morphine equivalent daily opioid doses were calculated for each patient.

Results

Current smokers reported significantly higher pain intensity (p < .05) at 1 month postsurgery than never smokers and past smokers. Decline in opioid consumption differed significantly by smoking status, with both current and past smokers reporting a less than expected decline in daily opioid consumption (p < .05) at 3 months. Decline in opioid consumption was also related to pack-years, with those reporting higher pack-years having a less than expected decline in daily opioid consumption at 3 months (p < .05).

Conclusions

Smoking status may be an important modifiable risk factor for pain intensity and opioid use after surgery.

Implications

In a population with complex postsurgical pain, smoking was associated with greater pain intensity at 1 month after major surgery and less opioid weaning 3 months after surgery. Smoking may be an important modifiable risk factor for pain intensity and opioid use after surgery.

Electrophysiological Study of Femoral Nerve Function After a Continuous Femoral Nerve Block for Anterior Cruciate Ligament Reconstruction: A Randomized, Controlled Single-Blind Trial

BACKGROUND

A continuous femoral nerve block (CFNB) is an effective analgesic treatment after anterior cruciate ligament (ACL) reconstruction but may result in transient femoral nerve injuries and quadriceps muscle weakness, which in turn contribute to worsened functional outcomes.

PURPOSE

To compare electrophysiological criteria of a femoral nerve injury as well as functional and pain-related outcomes after ACL reconstruction when analgesia was provided by a CFNB or intravenous patient-controlled analgesic of morphine (IV PCA).

STUDY DESIGN

Randomized controlled clinical trial; Level of evidence, 1.

METHODS

A total of 74 patients scheduled for ACL reconstruction were randomized to receive a CFNB before surgery, followed by a ropivacaine infusion for 2 days and oxycodone, or IV PCA. The primary outcome was the rate of femoral nerve injuries at 4 weeks postoperatively, defined as a reduction of the compound muscle action potential (CMAP) area from the vastus medialis muscle after supramaximal femoral nerve stimulation at the groin, associated with an absent H-reflex of the femoral nerve and signs of vastus medialis muscle denervation. Secondary functional outcomes were quadriceps muscle strength, active flexion range, and distance walked, as measured on postoperative days 1 and 2. Secondary pain-related outcomes were IV morphine consumption and pain scores at rest and on movement in phase 1 recovery and on postoperative days 1 and 2.

RESULTS

No patients met the electrophysiological criteria of a femoral nerve injury. The mean CMAP area at 4 weeks was equivalent in both the CFNB and IV PCA groups (47 ± 16 mV·ms and 51 ± 13 mV·ms, respectively; P = .50). While no differences were detected in functional outcomes or pain scores, the consumption of an IV morphine equivalent was reduced by the administration of a CFNB in phase 1 recovery (6 ± 5 mg and 13 ± 7 mg, respectively; P = .0003), on postoperative day 1 (6 ± 7 mg and 19 ± 17 mg, respectively; P = .0005), and on postoperative day 2 (11 ± 10 mg and 19 ± 17 mg, respectively; P = .03) compared with an IV PCA.

CONCLUSION

Despite prior contrary reports, a CFNB did not result in femoral nerve injuries or worsened functional outcomes after ACL reconstruction. The improvement of analgesia with a CFNB was only marginal and not clinically relevant beyond 24 hours. Registration: NCT01321138 ( ClinicalTrials.gov identifier).

The Analgesic Efficacy of Ultrasound-Guided Transversus Abdominis Plane Block in Adult Patients: A Meta-Analysis

BACKGROUND

Previous meta-analyses of the transversus abdominis plane (TAP) block have examined a maximum of 12 articles, including fewer than 650 participants, and have not examined the effect of ultrasound-guided techniques specifically. Recently, many trials that use ultrasound approaches to TAP block have been published, which report conflicting analgesic results. This meta-analysis aims to evaluate the analgesic efficacy of ultrasound-guided TAP blocks exclusively for all types of abdominal surgeries in adult patients.

METHODS

This meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. The primary outcome was cumulative IV morphine consumption at 6 hours postoperatively, analyzed according to the type of surgery, the type of surgical anesthesia, the timing of injection, the block approach adopted, and the presence of postoperative multimodal analgesia. Secondary outcomes included IV morphine consumption at 24 hours postoperatively; pain scores at rest and on movement at 6 and 24 hours postoperatively; and postoperative nausea and vomiting, pruritus, and rates of complications.

RESULTS

Thirty-one controlled trials including 1611 adult participants were identified. Independent of the type of surgery (abdominal laparotomy, abdominal laparoscopy, and cesarean delivery) but not independent of the type of surgical anesthesia (general anesthesia, spinal anesthesia with or without intrathecal long-acting opioid), ultrasound-guided TAP block reduced IV morphine consumption at 6 hours postoperatively by a mean difference of 6 mg (95% confidence interval [CI], -7 to -4 mg; I2 = 94%; P < 0.00001). The magnitude of the reduction in morphine consumption at 6 hours postoperatively was not influenced by the timing of injection (I2 = 0%; P = 0.72), the block approach adopted (I2 = 0%; P = 0.72), or the presence of postoperative multimodal analgesia (I2 = 73%; P = 0.05). This difference persisted at 24 hours postoperatively (mean difference, -11 mg; 95% CI, -14 to -8 mg; I2 = 99%; P < 0.00001). Pain scores at rest and on movement were reduced at 6 hours postoperatively (mean difference at rest, -10; 95% CI, -15 to -5; I2 = 92%; P = 0.0002; mean difference on movement, -9; 95% CI, -14 to -5; I2 = 58%; P < 0.00001). There were neither differences in the incidence of postoperative nausea and vomiting (I2 = 1%; P = 0.59) nor in the pruritus (I2 = 12%; P = 0.58) Two minor complications (1 bruise and 1 anaphylactoid reaction) were reported in 1028 patients.

CONCLUSIONS

Ultrasound-guided TAP block provides marginal postoperative analgesic efficacy after abdominal laparotomy or laparoscopy and cesarean delivery. However, it does not provide additional analgesic effect in patients who also received spinal anesthesia containing a long-acting opioid. The minimal analgesic efficacy is independent of the timing of injection, the approach adopted, or the presence of postoperative multimodal analgesia. Because of heterogeneity of the results, these findings should be interpreted with caution.

Breakthrough pain in elderly patients with cancer: treatment options

The prevalence of pain is high in the elderly and increases with the occurrence of cancer. Pain treatment is challenging because of age-related factors such as co-morbidities, and over half of the patients with cancer pain experience transient exacerbation of pain that is known as breakthrough pain (BTP). As with background pain, BTP should be properly assessed before being treated. The first step to be taken is optimizing around-the-clock analgesia with expert titration of the painkiller. Rescue medication should then be provided as per the requested need, while at the same time preventing identified potential precipitating factors. In the elderly, starting treatment with a lower dose of analgesics may be justified because of age-related physiological changes such as decreased hepatic and renal function. Whenever possible, oral medication should be provided prior to a painful maneuver. In the case of unpredictable BTP, immediate rescue medication is mandatory and the subcutaneous route is preferred unless patient-controlled analgesia via continuous drug infusion is available. Recently, transmucosal preparations have appeared in the medical armamentarium but it is not yet known whether they represent a truly efficient alternative, although their rapid onset of activity is already well recognized. Adjuvant analgesics, topical analgesics, anesthetic techniques and interventional techniques are all valid methods to help in the difficult management of pain and BTP in elderly patients with cancer. However, none has reached a satisfying scientific level of evidence as to nowadays make the development of undisputed best practice guidelines possible. Further research is therefore on the agenda.

Single-injection or continuous femoral nerve block for total knee arthroplasty?

BACKGROUND

The ideal local anesthetic regime for femoral nerve block that balances analgesia with mobility after total knee arthroplasty (TKA) remains undefined.

QUESTIONS/PURPOSES

We compared two volumes and concentrations of a fixed dose of ropivacaine for continuous femoral nerve block after TKA to a single injection femoral nerve block with ropivacaine to determine (1) time to discharge readiness; (2) early pain scores and analgesic consumption; and (3) functional outcomes, including range of motion and WOMAC scores at the time of recovery.

METHODS

Ninety-nine patients were allocated to one of three continuous femoral nerve block groups for this randomized, placebo-controlled, double-blind trial: a high concentration group (ropivacaine 0.2% infusion), a low concentration group (ropivacaine 0.1% infusion), or a placebo infusion group (saline 0.9% infusion). Infusions were discontinued on postoperative Day (POD) 2. The primary outcome was time to discharge readiness. Secondary outcomes included opioid consumption, pain, and functional outcomes. Ninety-three patients completed the study protocol; the study was halted early because of unanticipated changes to pain protocols at the host institution, by which time only 61% of the required number of patients had been enrolled.

RESULTS

With the numbers available, the mean time to discharge readiness was not different between groups (high concentration group, 62 hours [95% confidence interval [CI], 51-72 hours]; low concentration group, 73 hours [95% CI, 63-83 hours]; placebo infusion group 65 hours [95% CI, 56-75 hours]; p = 0.27). Patients in the low concentration group consumed significantly less morphine during the period of infusion (POD 1, high concentration group, 56 mg [95% CI, 42-70 mg]; low concentration group, 35 mg [95% CI, 27-43 mg]; placebo infusion group, 48 mg [95% CI, 38-59 mg], p = 0.02; POD 2, high concentration group, 50 mg [95% CI, 41-60 mg]; low concentration group, 33 mg [95% CI, 24-42 mg]; placebo infusion group, 39 mg [95% CI, 30-48 mg], p = 0.04); however, there were no important differences in pain scores or opioid-related side effects with the numbers available. Likewise, there were no important differences in functional outcomes between groups.

CONCLUSIONS

Based on this study, which was terminated prematurely before the desired sample size could be achieved, we were unable to demonstrate that varying the concentration and volume of a fixed-dose ropivacaine infusion for continuous femoral nerve block influences time to discharge readiness when compared with a conventional single-injection femoral nerve block after TKA. A low concentration of ropivacaine infusion can reduce postoperative opioid consumption but without any important differences in pain scores, side effects, or functional outcomes. These pilot data may be used to inform the statistical power of future randomized trials.

LEVEL OF EVIDENCE

Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Ultrasound-guided transversus abdominis plane (TAP) block for laparoscopic gastric-bypass surgery: a prospective randomized controlled double-blinded trial

BACKGROUND

Despite the laparoscopic approach, patients can suffer moderate to severe pain following bariatric surgery. This randomized controlled double-blinded trial investigated the analgesic efficacy of ultrasound-guided transversus abdominis plane (TAP) blocks for laparoscopic gastric-bypass surgery.

METHODS

Seventy patients undergoing laparoscopic gastric-bypass surgery were randomized to receive either bilateral ultrasound-guided subcostal TAP block injections after induction of general anesthesia or none. All patients received trocar insertion site local anesthetic infiltration and systemic analgesia. The primary outcome was cumulative opioid consumption (IV morphine equivalent) during the first 24 h postoperatively. Interval opioid consumption, pain severity scores, rates of nausea or vomiting, and rates of pruritus were measured during phase I recovery, and at 24 and 48 h postoperatively.

RESULTS

There was no difference in cumulative opioid consumption during the first 24 h postoperatively between the TAP (32.2 mg [95% CI, 27.6-36.7]) and control (35.6 mg [95% CI, 28.6-42.5]; P = 0.41) groups. Postoperative opioid consumptions during phase I recovery and the 24-48-h interval were similar between groups, as were pain scores at rest and with movement during all measured intervals. The rates of nausea or vomiting and pruritus were equivalent.

CONCLUSIONS

Bilateral TAP blocks do not provide additional analgesic benefit when added to trocar insertion site local anesthetic infiltration and systemic analgesia for laparoscopic gastric-bypass surgery.

EGFR dependent subcellular communication was responsible for morphine mediated AC superactivation

Compensatory adenylyl cyclase (AC) superactivation has been postulated to be responsible for the development of morphine tolerance and dependence, the underlying mechanism was demonstrated to comprise c-Src-dependent upregulation of AC5 within the lipid rafts. In the present study, we demonstrated that chronic morphine treatment sensitized EGFR signaling by augmenting EGFR phosphorylation and translocation into ER, which was essential for CRT-MOR tethering within the lipid rafts and AC5 superactivation. Intriguingly, synaptic clustering of CRT-MOR was dependent on EGFR phosphorylation and presumed to implicate in alignment and organization of synaptic compartments. Taken together, our data raised the possibility that an adaptive change in MOR and EGFR signal systems might establish CRT related subcellular communication, the signaling network within brain synaptic zone was proposed to implicate in morphine tolerance and dependence.

The analgesic efficacy and safety of neuraxial magnesium sulphate: a quantitative review

Eighteen published trials have examined the use of neuraxial magnesium as a peri-operative adjunctive analgesic since 2002, with encouraging results. However, concurrent animal studies have reported clinical and histological evidence of neurological complications with similar weight-adjusted doses. The objectives of this quantitative systematic review were to assess both the analgesic efficacy and the safety of neuraxial magnesium. Eighteen trials comparing magnesium with placebo were identified. The time to first analgesic request increased by 11.1% after intrathecal magnesium administration (mean difference: 39.6 min; 95% CI 16.3-63.0 min; p = 0.0009), and by 72.2% after epidural administration (mean difference: 109.5 min; 95% CI 19.6-199.3 min; p = 0.02) with doses of between 50 and 100 mg. Four trials monitored for neurological complications: of the 140 patients included, only a 4-day persistent headache was recorded. Despite promising peri-operative analgesic effect, the risk of neurological complications resulting from neuraxial magnesium has not yet been adequately defined.

Ultrastructural relationship between the mu opioid receptor and its interacting protein, GPR177, in striatal neurons

GPR177, the mammalian ortholog of Drosophila Wntless/Evi/Sprinter, was recently identified as a novel mu-opioid receptor (MOR) interacting protein. GPR177 is a trans-membrane protein pivotal to mediating the secretion of Wnt signaling proteins. Wnt proteins, in turn, are essential in regulating neuronal development, a phenomenon inhibited upon chronic exposure to MOR agonists such as morphine and heroin. We previously showed that GPR177 and MOR are co-localized in the mouse dorsolateral striatum; however, the nature of this interaction was not fully elucidated. Therefore, in the present study, we examined cellular substrates for interactions between GPR177 and MOR using a combined immunogold-silver and peroxidase detection approach in coronal sections in the dorsolateral segment of the striatum. Semi-quantitative analysis of the ultrastructural distribution of GPR177 and MOR in striatal somata and in dendritic processes showed that, of the somata and dendritic processes exhibiting GPR177, 32% contained MOR immunolabeling while for profiles exhibiting MOR, 37% also contained GPR177 immunoreactivity. GPR177-labeled particles were localized predominantly along both the plasma membrane and within the cytoplasm of MOR-labeled dendrites. Somata and dendritic processes that contained both GPR177 and MOR more often received symmetric (inhibitory-type) synapses from unlabeled axon terminals. To further define the phenotype of GPR177 and MOR-containing cellular profiles, triple immunofluorescence detection showed that GPR177 and MOR are localized in neurons containing the opioid peptide, enkephalin, within the dorsolateral striatum. The results provide an anatomical substrate for interactions between MOR and its interacting protein, GPR177, in striatal opioid-containing neurons that may underlie the morphological alterations produced in neurons by chronic opiate use.

Transdermal Opioids for Cancer Pain Management

The prevalence of pain in cancer is up to 90%, more than 45% of this can be adequately managed using the World Health Organisation three step analgesic ladder.Transdermal opioids are safe, effective, and produce significantly fewer side effects than oral morphine when used for moderate to severe cancer pain.Transdermal buprenorphine has a lower incidence of systemic side effects than transdermal fentanyl and it is indicated for use in cancer patients with neuropathic pain and renal dysfunction.Transdermal opioids require a long lag period for dose stabilisation and elimination, hence are unsuitable for acute or unstable pain, and may result in prolonged side effects.Transdermal analgesics reduce the need for frequent dosing, clock watching and are more convenient for patients, physicians and carers, hence increasing treatment compliance.

Management of cancer-related pain

Patients and families struggling with cancer fear pain more than any other physical symptom. There are also significant barriers to optimal pain management in the emergency setting, including lack of knowledge, inexperienced clinicians, myths about addiction, and fears of complications after discharge. In this article, we review the assessment and management options for cancer-related pain based on the World Health Organization (WHO) 3-step approach.

Formulations of fentanyl for the management of pain

Fentanyl is an opioid initially developed for parenteral administration. While oral administration is not an option due to a high first-pass metabolism, its high potency and lipophilicity have made a number of new routes of administration feasible. The transdermal therapeutic system offers an excellent option for long-term treatment of cancer and chronic pain, achieving stable plasma concentrations over the treatment period. The recent change from reservoir to matrix systems has made these systems more convenient to wear and safer to use, while being bioequivalent. In contrast, the patient-controlled iontophoretic transdermal system has been developed to enable on-demand delivery of transdermal bolus doses of fentanyl to treat postoperative pain. It offers a needle-free system to provide patient-controlled analgesia otherwise offered by intravenous pumps. However, due to technical difficulties the system is currently not clinically available. Oral transmucosal fentanyl utilizes the rapid uptake through the buccal mucosa to achieve high plasma concentrations rapidly and is indicated to treat breakthrough pain in patients who are not opioid-naive. The recently introduced fentanyl buccal tablets offer slightly better pharmacokinetics for the same indication. The intranasal route is another option to achieve rapid uptake of fentanyl, and is currently being investigated to provide acute and breakthrough pain relief. Transpulmonary administration of fentanyl remains experimental and this route of administration is not yet in clinical use. Overall, the specific pharmacological and physicochemical properties of fentanyl have made this compound highly suitable for novel routes of administration in a range of clinical indications.

Bidirectional effects of fentanyl on dendritic spines and AMPA receptors depend upon the internalization of mu opioid receptors

Fentanyl is a frequently used and abused opioid analgesic and can cause internalization of mu opioid receptors (MORs). Receptor internalization modulates the signaling pathways of opioid receptors. As changes in dendritic spines and synaptic AMPA receptors play important roles in addiction and memory loss, we investigated how fentanyl affects dendritic spines and synaptic AMPA receptors in cultured hippocampal neurons. Fentanyl at low concentrations (0.01 and 0.1 microM) caused the collapse of dendritic spines and decreased the number of AMPA receptor clusters. In contrast, fentanyl at high concentrations (1 and 10 microM) had opposite effects, inducing the emergence of new spines and increasing the number of AMPA receptor clusters. These dose-dependent bidirectional effects of fentanyl were blocked by a selective MOR antagonist CTOP at 5 microM. In neurons that had been transfected with HA-tagged or GFP-tagged MORs, fentanyl at high concentrations induced persistent and robust internalization of MORs, whereas fentanyl at lower concentrations induced little or transient receptor internalization. The blockade of receptor internalization with the expression of dominant-negative Dynamin I (the K44E mutant) reversed the effect of fentanyl at high concentrations, supporting a role of receptor internalization in modulating the dose-dependent effects of fentanyl. In contrast to morphine, the effects of fentanyl on dendritic spines are distinctively bidirectional and concentration dependent, probably due to its ability to induce robust internalization of MORs at high concentrations. The characterization of the effects of fentanyl on spines and AMPA receptors may help us understand the roles of MOR internalization in addiction and cognitive deficits.

Management of cancer-related pain

Patients and families struggling with cancer fear pain more than any other physical symptom. There are also significant barriers to optimal pain management in the emergency setting, including lack of knowledge, inexperienced clinicians, myths about addiction, and fears of complications after discharge. In this article, we review the assessment and management options for cancer-related pain based on the World Health Organization (WHO) 3-step approach.

Transdermal buprenorphine in children with cancer-related pain

We present three cases of children (aged 3-5 years) in which cancer-related pain was adequately controlled by Transdermal Buprenorphine. The endpoints for evaluating analgesic efficacy consisted of the assessment of pain using a visual scale and the possibility of reducing other pain treatment. Improvement of pain level was demonstrated by the decrease in pain scores, by reduction of the overall amount of medications, especially opioids, and by improvement of uninterrupted sleep. Only limited data is available on the use of Transdermal Buprenorphine in children. In our experience, Transdermal Buprenorphine allowed good analgesia without significant side effects in these three children with cancer-related pain.

A randomized, open, parallel group, multicenter trial to investigate analgesic efficacy and safety of a new transdermal fentanyl patch compared to standard opioid treatment in cancer pain

A new 72-hour transdermal fentanyl matrix patch has been designed, which has a 35%-50% reduction of the absolute fentanyl content compared with other currently available transdermal fentanyl patches that are using the matrix technology. The new patch has previously been shown to be pharmacokinetically bioequivalent to the marketed fentanyl patch. To determine noninferiority in efficacy in cancer patients and to compare safety, a clinical trial comparing the new fentanyl patch with standard oral or transdermal opioid treatment was planned. The design was an open, parallel group, multicenter trial, in which 220 patients were randomized to receive either the fentanyl patch or standard opioid treatment for 30 days. The primary efficacy variable, pain intensity (PI) on a 0-10-point numerical rating scale, was recorded once daily. The primary endpoint was the relative area under the curve of PI expressed as a percentage of the maximum possible PI area under the curve. Any adverse events were recorded; four tolerability endpoints, constipation, nausea, daytime drowsiness, and sleeping disturbances, were assessed daily. Noninferiority was shown; the upper 95% confidence interval limits of the mean difference in relative PI area under the curve between the fentanyl patch and standard opioid treatment were less than 10% for both the intention-to-treat and per-protocol populations. Scores for the tolerability endpoints were similar in the treatment groups. The new fentanyl matrix patch with a lower drug load was found noninferior and as safe as established standard oral and transdermal opioid treatment.

Metastatic bone pain: treatment options with an emphasis on bisphosphonates

INTRODUCTION

One of the key targets for metastatic cancer cells is the skeleton. Once metastatic cells are established within the bone matrix, skeletal integrity becomes increasingly compromised. Bone lesions lead to various complications, including bone pain, fractures and spinal cord compression.

MECHANISMS OF BONE PAIN

Bone pain is debilitating and affects quality of life of the patient. In addition, it increases the use of health care resources. Many patients with metastatic bone disease experience substantial bone pain despite state-of-the-art systemic analgesic treatment. Incident pain is the predominant pain syndrome.

TREATMENT OPTIONS FOR BONE PAIN

Typically, this syndrome requires moderate baseline analgesia with increased on-demand doses. Other techniques for treating bone pain, including radiation therapy, neuraxial application of analgesics, nerve blocks and local stabilisation procedures, should be considered. In addition, therapy with bisphosphonates targeting bone-specific pain is an important strategy. This review discusses the various management options for bone pain arising from metastatic bone disease.

Distinct effects of individual opioids on the morphology of spines depend upon the internalization of mu opioid receptors

This study has examined the relationship between the effects of opioids on the internalization of mu opioid receptors (MORs) and the morphology of dendritic spines. Several opioids (morphine, etorphine, DAMGO or methadone) were applied to cultured hippocampal neurons. Live imaging and biochemical techniques were used to examine the dynamic changes in MOR internalization and spine morphology. This study reveals that MOR internalization can regulate opioid-induced morphological changes in dendritic spines: (1) Chronic treatment with morphine, which induced minimal receptor internalization, caused collapse of dendritic spines. In contrast, "internalizing" opioids such as DAMGO and etorphine induced the emergence of new spines. It reveals that opioid-induced changes in spines vary greatly depending on how the applied opioid agonist affects MOR internalization. (2) The blockade of receptor internalization by dominant negative mutant of dynamin, K44E, reversed the effects of DAMGO and etorphine. It indicates that receptor internalization is necessary for the distinct effects of DAMGO and etorphine on spines. (3) In neurons that were cultured from MOR knock-out mice and had been co-transfected with DsRed and MOR-GFP, morphine caused collapse of spines whereas DAMGO induced emergence of new spines, indicating that opioids can alter the structure of spines via postsynaptic MORs. (4) Methadone at a low concentration induced minimal internalization and had effects that were similar to morphine. At a high concentration, methadone induced robust internalization and had effects that are opposite to morphine. The concentration-dependent opioid-induced changes in dendritic spines might also contribute to the variation in the effects of individual opioids.

Rational Use of Sublingual Opioids in Palliative Medicine

The sublingual administration of opioid analgesics has been a mainstay in the pain management of homebound dying hospice patients who are no longer able to swallow. It is also a potentially useful route of administration in other situations in which the oral route is not available and other routes are impractical or inappropriate. Potential advantages of the sublingual route include rapid analgesic onset and avoidance of hepatic first-pass metabolism. Pharmacokinetic and pharmacodynamic studies have yielded widely disparate data on sublingual morphine. Other opioids have been less studied. Available data suggests limited sublingual availability of hydrophilic opioids (e.g., morphine, oxycodone, and hydromorphone) and superior absorption of the lipophilic opioids (e.g., methadone and the fentanils). Buprenorphine, a potent, lipophilic, partial mu-opioid receptor agonist, appears promising but awaits further study.

Pharmacological management of cancer pain in the elderly

Existing studies indicate a high prevalence rate and poor management of cancer pain in the elderly. Pain is often considered an expected concomitant of aging, and older patients are considered more sensitive to opioids. Despite the well known pharmacokinetic changes in the elderly, the complex network of factors involved in the opioid response make the evaluation of a single element, such as age, more difficult. Notwithstanding such difficulties, appropriate analgesic treatment is able to control cancer pain in the elderly in most cases. Skills necessary to optimise pain control in older cancer patients include the ability to objectively assess functional age (not necessarily related to chronological age since the rate of decline is variable), understand the impact of coexisting conditions, carefully manage the numbers and types of drugs taken at the same time and adequately communicate with patients and relatives. The most common treatment of cancer pain consists of the use of regularly given oral analgesics. The elderly are at increased risk of developing toxicity from NSAIDs, and the overall safety of these drugs in frail elderly patients should be considered. When older patients have clear contraindications to NSAIDs, manifest signs of toxicity from these agents, or find that pain is no longer controlled with this class of drugs, opioids should be started. A variety of opioids are available, and they differ widely with respect to analgesic potency and adverse effects among the elderly. Although the aged population requires lower doses of opioids, only careful titration based on individual response can ensure the appropriate response to clinical demand. Elderly patients are potentially more likely to be affected by opioid toxicity because of the physiological changes associated with aging. Nevertheless, appropriate dosage and administration may limit these risks. Cancer patients with pain who do not respond to increasing doses of opioids because they develop adverse effects before achieving acceptable analgesia may be switched to alternative opioids. Despite the favourable effects reported with opioid switching, monitoring is crucial, particularly in the elderly or patients who are switched from high doses of opioids. Adjuvant analgesics, including antidepressants, antiepileptics, corticosteroids and bisphosphonates may help in the treatment of certain types of chronic pain. With an appropriate and careful approach, it should be possible to reduce or eliminate unrelieved cancer pain in most elderly patients and, consequently, to enhance their quality of life. Older patients with cancer should be continuously assessed for cancer pain, both before and after analgesic treatment.

Pain management

This article provides information regarding treatments for the management of moderate to severe pain in patients who are at the end of life. Discussion focuses on the use of strong opioids and adjuvant analgesics. Special attention also is given to the most frequently used forms of interventional pain management. Although pain in terminally ill patients is not always related to cancer, many of the studies cited in this article were performed in cancer patients, a model that informs much of what is presented.

Opioids in pain management of blood-related malignancies

Opioids are basic analgesics used in the treatment of moderate to severe pain in patients affected by blood-related malignancies. They should be sequentially administered according to the World Health Organisation scale for cancer pain. Initial treatment and titration with opioids should be based on immediate-release preparations, to be administered at appropriate intervals in order to relieve pain and to satisfy the individual opioid requirement. Once a relatively good pain control has been achieved, a slow release formulation at equivalent doses can be given. Most patients can be adequately managed using oral formulation opioids. However, a small group, such as those presenting severe mucositis or requiring a rapid pain relief, should be managed by intravenous continuous infusion and/or by a patient-controlled analgesia system; while for patients in the community, there are distinct advantages to using the subcutaneous route. Other available routes of administration for opioids, can be used in selected circumstances, including rectal, transdermal, epidural, intrathecal and intramuscular. The invasive neuraxial route has a very limited role in patients with haematological malignancies, given the high risk of infection and bleeding. Through a close observation and a careful management, opioid-related side effects can be effectively prevented and treated. This article reviews the principles of opioid therapy and how opioids can be adapted for patients with pain due to haematological malignancies.

Is the use of transdermal fentanyl inappropriate according to the WHO guidelines and the EAPC recommendations? A study of cancer patients in Italy

BACKGROUND

World Health Organization (WHO) guidelines, Agency for Health Care Policy and Research (AHCPR) clinical practice guidelines, and EAPC recommendations indicate oral route of opioid administration as the preferred route. Transdermal administration of opioids is considered an alternative when patients cannot take medications orally. Moreover, WHO and EAPC indicate orally administered morphine as the first-choice drug for the treatment of moderate to severe cancer-related pain. However, we can see that in Italy there is an increasing use of transdermal fentanyl (TF) as first-choice strong opioid (and route) even when oral administration of opioids is possible.

AIMS

The aims of this study are to describe the modality in the use of TF administration in two settings of care, taking into consideration (1) the drugs previously taken by the patients, (2) the reasons for switching from any drug to TF, (3) the conversion ratio used, and (4) the frequency of "inappropriate use of transdermal fentanyl according to the WHO guidelines and the EAPC recommendations", i.e., switching to fentanyl patch from any drug, even if there were no contraindications in using oral morphine. The settings of care considered were the out-patient palliative care unit (OP-PCU) and the oncological wards (OWs) of the National Cancer Institute (NCI) of Milan.

PATIENTS AND METHODS

The clinical charts of 98 patients prescribed with and given fentanyl patch for the first time at the NCI of Milan in 2002 were reviewed and the data gathered were grouped according to the administration of fentanyl at the OP-PCU (63 out-patients) or at the OWs (35 in-patients). Summary descriptive statistics and bar and box plots have been used. Fisher two-tailed exact text was applied to test the differences between in- and out-patients.

RESULTS

Before switching to TF, (1) in-patients were more frequently treated with nonsteroidal anti-inflammatory drugs (NSAIDs) and weak opioids (mostly tramadol) in respect to the out-patients (44.1 vs 25.8%) who were mostly treated with oral morphine (48.4 vs 20.6%) (p=0.045), and (2) 88.7% of the out-patients were treated with oral opioids and only 1.6% with parenteral opioids in respect to OWs where 69.7% were on oral opioids and 18.2% on parenteral opioids (p=0.006). In 29% of out-patients and in 53% of in-patients, changing to fentanyl patch was considered as "inappropriate" (p=0.028) according to the WHO guidelines and the EAPC recommendations. No statistically significant differences between the two settings were observed regarding the reasons for switching and the conversion ratio used.

CONCLUSIONS

There is a trend to use fentanyl patch as first-choice strong opioid in cancer patients in situations such as titration phase, in the presence of instable pain, and in the absence of dysphagia or gastrointestinal symptoms where the use of oral morphine is, however, not contraindicated.

Buprenorphine in cancer pain

Buprenorphine is a broad spectrum, highly lipophilic, and long-acting partial mu opioid receptor agonist that is noncross tolerant to other opioids. Buprenorphine can be given by several routes. Metabolism is through CYP3A4 and CYP2C8 and by conjugases. Constipation and sexual dysfunction appear to be less with buprenorphine than with other opioids. The recent development of a polymer matrix patch delivery system for buprenorphine prevents "dose dumping" and facilitates pain management in those unable to take oral analgesics. Sublingual buprenorphine has been combined with naloxone to prevent illicit conversion to parenteral administration. Buprenorphine has been used extensively to control cancer pain. In certain clinical situations, buprenorphine may have particular advantages over other opioids.