Nonopioid analgesics for postoperative pain management

The Adequacy of Anesthesia Guidance for Vitreoretinal Surgeries with Preemptive Paracetamol/Metamizole

Despite the possibility of postoperative pain occurrence, in some patients, vitreoretinal surgeries (VRSs) require performance of general anesthesia (GA). The administration of intraoperative intravenous rescue opioid analgesics (IROA) during GA constitutes a risk of perioperative adverse events. The Adequacy of Anesthesia (AoA) concept consists of an entropy electroencephalogram to guide the depth of GA and surgical pleth index (SPI) to optimize the titration of IROA. Preemptive analgesia (PA) using cyclooxygenase-3 (COX-3) inhibitors is added to GA to minimize the demand for IROA and reduce postoperative pain. The current analysis evaluated the advantage of PA using COX-3 inhibitors added to GA with AoA-guided administration of IROA on the rate of postoperative pain and hemodynamic stability in patients undergoing VRS. A total of 165 patients undergoing VRS were randomly allocated to receive either GA with AoA-guided IROA administration with intravenous paracetamol/metamizole or with preemptive paracetamol or metamizole. Preemptive paracetamol resulted in a reduction in the IROA requirement; both preemptive metamizole/paracetamol resulted in a reduced rate of postoperative pain as compared to metamizole alone. We recommend using intraoperative AOA-guided IROA administration during VRS to ensure hemodynamic stability alongside PA using both paracetamol/metamizole to reduce postoperative pain.

Ketorolac and bone healing: a review of the basic science and clinical literature

Although the efficacy of ketorolac in pain management and the short duration of use align well with current clinical practice guidelines, few studies have specifically evaluated the impact of ketorolac on bony union after fracture or surgery. The purpose of this study was to review the current basic science and clinical literature on the use of ketorolac for pain management after fracture and surgery and the subsequent risk of delayed union or nonunion. Animal studies demonstrate a dose-dependent risk of delayed union in rodents treated with high doses of ketorolac for 4 weeks or greater; however, with treatment for 7 days or low doses, there is no evidence of risk of delayed union or nonunion. Current clinical evidence has also shown a dose-dependent increased risk of pseudoarthrosis and nonunion after post-operative ketorolac administration in orthopedic spine surgery. However, other orthopedic subspecialities have not demonstrated increased risk of delayed union or nonunion with the use of peri-operative ketorolac administration. While evidence exists that long-term ketorolac use may represent risks with regard to fracture healing, insufficient evidence currently exists to recommend against short-term ketorolac use that is limited to the peri-operative period. LEVEL OF EVIDENCE V: Narrative Review.

Comparison of in vivo behaviors of intramuscularly long-acting celecoxib nanosuspensions with different particle sizes for the postoperative pain treatment

Celecoxib (CXB) has a good analgesic effect on postoperative acute pain, but clinically its compliance is compromised because of frequent administration. Therefore, the development of injectable celecoxib nanosuspensions (CXB-NS) for long-acting analgesic effects is highly desirable. However, how the particle size affects the in vivo behaviors of CXB-NS remains unclear. Herein, CXB-NS with different sizes were prepared by the wet-milling method. Following intramuscular (i.m.) injection in rats (50 mg/kg), all CXB-NS achieved sustained systemic exposure and long-acting analgesic effects. More importantly, CXB-NS showed size-dependent pharmacokinetic profiles and analgesic effects, and the smallest CXB-NS (about 0.5 μm) had the highest C_max, T_1/2, and AUC_0-240h and the strongest analgesic effects on incision pain. Therefore, small sizes are preferred for long action by i.m. injection, and the CXB-NS developed in this study were alternative formulations for the treatment of postoperative acute pain.

Risk of serious adverse events associated with non-steroidal anti-inflammatory drugs in orthopaedic surgery. A protocol for a systematic review

BACKGROUND

Postoperative pain is a common condition following orthopaedic surgeries and causes prolonged hospitalisation, delayed rehabilitation and hamper the quality of life. Non-steroidal anti-inflammatory drugs (NSAIDs) are effective analgesics and anti-inflammatory mediators in the treatment of postoperative pain. The association of NSAIDs with serious adverse events may however keep some clinicians and clinical decision makers from using NSAIDs perioperatively. The evidence regarding the risks of serious adverse events following perioperative use of NSAIDs in orthopaedic surgery is sparse and needs to be assessed in a systematic review. This is a protocol for a systematic review that aims to identify the risks of serious adverse events from perioperative use of NSAIDs in orthopaedic patients.

METHODS

Our methodology is based on the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols and the eight-step assessment procedure suggested by Jakobsen and colleagues. We wish to assess if NSAIDs versus placebo, usual care or no intervention, will influence the risks of serious adverse events in patients undergoing orthopaedic surgery. We will include all randomised trials assessing the use of NSAIDs perioperatively. To identify trials we will search the Medical Literature Analysis and Retrieval System Online, Excerpta Medica database, Cochrane Central Register, Science Citation Index Expanded on Web of Science and BIOSIS. Two authors will screen the literature and extract data. We will use the 'Risk of Bias 2 tool' to assess trials. Extracted data will be analysed using RStudio and Trial Sequential Analysis. We will create a 'Summary of Findings' table in which we will present our primary and secondary outcomes. We will assess the quality of evidence using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

DISCUSSION

This systematic review can potentially aid clinicians and clinical decision makers in the use of NSAIDs for treatment of postoperative pain following orthopaedic surgeries.

Nonopioid analgesics for analgesia in critically ill patients: Friends, enemies, or collaborators

Patients in intensive care units (ICUs) experience pain, which they describe as a significant cause of stress during treatment. It can progress to chronic pain and significantly affect the quality of life. Opioids have long been the backbone of ICU pain therapy. The consequences of their long-term use are known today, such as prolonged ICU stay and mechanical ventilation, resulting in increased treatment costs. Additionally, abstinence syndrome is a consequence of abrupt opioid withdrawal. Also, there is a risk of tolerance and hyperalgesia after prolonged opioid use. Globally, opioid dependence after hospital opioid treatment is alarming, although there is still a lack of data on its incidence after ICU. Multimodal analgesia enables comfort to the patient, opioid-sparing, and avoidance of side effects of non-opioid analgesics. Nonsteroidal anti-inflammatory drugs (NSAIDs) are a broad group of drugs recommended with paracetamol to treat mild to moderate acute postoperative pain. Although often prescribed by intensivists, their use in treating painful conditions in ICU is controversial due to the possible consequences on the organs of critically ill patients. Due to the inhibition of cyclooxygenases, NSAIDs indirectly cause vasoconstriction of the renal arteries and arterioles, leading to kidney damage. NSAIDs inhibit platelet aggregation and may predispose to bleeding. Analgesia of a critically ill patient is a important part of their treatment, however it can be challenging in certain patients. Numerous combinations of pharmacological and non-pharmacological approaches can be adapted to the patient's current characteristics.

Developing nociceptor-selective treatments for acute and chronic pain

Despite substantial efforts dedicated to the development of new, nonaddictive analgesics, success in treating pain has been limited. Clinically available analgesic agents generally lack efficacy and may have undesirable side effects. Traditional target-based drug discovery efforts that generate compounds with selectivity for single targets have a high rate of attrition because of their poor clinical efficacy. Here, we examine the challenges associated with the current analgesic drug discovery model and review evidence in favor of stem cell–derived neuronal-based screening approaches for the identification of analgesic targets and compounds for treating diverse forms of acute and chronic pain.

Paracetamol, non-steroidal anti-inflammatory drugs and glucocorticoids for postoperative pain: A protocol for a systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Multimodal analgesia is the leading principle for managing postoperative pain. Recent guidelines recommend combinations of paracetamol and a non-steroidal anti-inflammatory drug (NSAID) for most surgeries. Glucocorticoids have been used for decades due to their potent anti-inflammatory and antipyretic properties. Subsequently, glucocorticoids may improve postoperative analgesia. We will perform a systematic review to assess benefits and harms of adding glucocorticoids to paracetamol and NSAIDs. We expect to uncover pros and cons of the addition of glucocorticoid to the basic standard regimen of paracetamol and NSAIDs for postoperative analgesia.

METHOD

This protocol for a systematic review was written according to the The Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines. We will search for trials in the following electronic databases: Medline, CENTRAL, CDSR and Embase. Two authors will independently screen trials for inclusion using Covidence, extract data and assess risk of bias using Cochrane's ROB 2 tool. We will analyse data using Review Manager and Trial Sequential Analysis. Meta-analysis will be performed according to the Cochrane guidelines and results will be validated according to the eight-step procedure suggested by Jakobsen et al We will present our primary findings in a 'summary of findings' table. We will evaluate the overall certainty of evidence using the GRADE approach.

DISCUSSION

This review will aim to explore the combination of glucocorticoids together with paracetamol and NSAIDs for postoperative pain. We will attempt to provide reliable evidence regarding the role of glucocorticoids as part of a multimodal analgesic regimen in combination with paracetamol and NSAID.

Preventive Analgesia, Hemodynamic Stability, and Pain in Vitreoretinal Surgery

Background and Objectives: Although vitreoretinal surgery (VRS) is most commonly performed under regional anaesthesia (RA), in patients who might be unable to cooperate during prolonged procedures, general anaesthesia (GA) with intraprocedural use of opioid analgesics (OA) might be worth considering. It seems that the surgical pleth index (SPI) can be used to optimise the intraprocedural titration of OA, which improves haemodynamic stability. Preventive analgesia (PA) is combined with GA to minimise intraprocedural OA administration. Materials and Methods: We evaluated the benefit of PA combined with GA using SPI-guided fentanyl (FNT) administration on the incidences of PIPP (postprocedural intolerable pain perception) and haemodynamic instability in patients undergoing VRS (p < 0.05). We randomly assigned 176 patients undergoing VRS to receive GA with SPI-guided FNT administration alone (GA group) or with preventive topical 2% proparacaine (topical anaesthesia (TA) group), a preprocedural peribulbar block (PBB) using 0.5% bupivacaine with 2% lidocaine (PBB group), or a preprocedural intravenous infusion of 1.0 g of metamizole (M group) or 1.0 g of paracetamol (P group). Results: Preventive PBB reduced the intraprocedural FNT requirement without influencing periprocedural outcomes (p < 0.05). Intraprocedural SPI-guided FNT administration during GA resulted in PIPP in 13.5% of patients undergoing VRS and blunted the periprocedural effects of preventive intravenous and regional analgesia with respect to PIPP and haemodynamic instability. Conclusions: SPI-guided FNT administration during GA eliminated the benefits of preventive analgesia in the PBB, TA, M, and P groups following VRS.

Femoral nerve blocks for the treatment of acute pre-hospital pain: A systematic review with meta-analysis

BACKGROUND

Pain management is one of the most important interventions in the emergency medical services. The femoral nerve block (FNB) is, among other things, indicated for pre- and post-operative pain management for patients with femoral fractures but its role in the pre-hospital setting has not been determined. The aim of this review was to assess the effect and safety of the FNB in comparison to other forms of analgesia (or no treatment) for managing acute lower extremity pain in adult patients in the pre-hospital setting.

METHODS

A systematic review (PROSPERO registration (CRD42018114399)) was conducted. The Cochrane and GRADE methods were used to assess outcomes. Two authors independently reviewed each study for eligibility, extracted the data and performed risk of bias assessments.

RESULTS

Four studies with a total of 252 patients were included. Two RCTs (114 patients) showed that FNB may reduce pain more effectively than metamizole (mean difference 32 mm on a 100 mm VAS (95% CI 24 to 40)). One RCT (48 patients) compared the FNB with lidocaine and magnesium sulphate to FNB with lidocaine alone and was only included here for information regarding adverse effects. One case series included 90 patients. Few adverse events were reported in the included studies. The certainty of evidence was very low. We found no studies comparing FNB to inhaled analgesics, opioids or ketamine.

CONCLUSIONS

Evidence regarding the effectiveness and adverse effects of pre-hospital FNB is limited. Studies comparing pre-hospital FNB to inhaled analgesics, opioids or ketamine are lacking.

Nonenteral Pain Management

Otolaryngologic surgeries present challenges to ensuring postoperative pain control owing to their location and nature that may require patients to be NPO for long periods of time, making enteral medication administration difficult or impossible. There are several alternative administration routes to bypass the gastrointestinal tract, including intravenous, transdermal, subcutaneous, and rectal. Options exist for opioid administration in the perioperative setting, including intravenous boluses, patient controlled analgesia, and transdermal patches. Acetaminophen, nonsteroidal anti-inflammatory drugs, and ketamine exist in nonenteral formulations. When applied in a multimodal strategy, nonenteral medications can provide appropriate analgesia, reduce opioid consumption, and increase patient satisfaction.

Postoperative pain after tonsillectomy - the value of standardized analgesic treatment protocols

OBJECTIVE

To alleviate pain after tonsillectomy (TE) with escalating gradual treatment protocols in a prospective trial.

MATERIALS & METHODS

Following TE, 83 consecutive adult patients were treated with two different four-staged escalating analgesic protocols. Metamizole served as basic medication in protocol 1 (PT1; n = 44), whereas with protocol 2 (PT2; n = 39) ibuprofen was applied as baseline analgesic. Both protocols were escalated according to the patient´s needs to metamizole and ibuprofen vice versa and additional weak to strong opioids. The primary efficacy endpoint was defined as the minimum and maximum pain as well as pain on ambulation (NRS, 0-10). Secondary endpoints comprised analgesic score, patient satisfaction and treatment-related side-effects.

RESULTS

Both patient groups exhibited similar demographic characteristics (PT1: Ø 28.8 years; 64% ♀ and PT2: Ø 26.6 years; 56% ♀). Maximum pain (6.7 ± 1.9 vs. 7.6 ± 1.6, t₍₈₁₎ = -2.254, p = 0.027) and pain on ambulation (5.0 ± 1.8 vs. 5.8 ± 1.8, t₍₈₁₎ = -2.114, p = 0.038) were significantly higher with PT2. 68.2% of patients with PT1 needed an escalation of analgesic treatment compared to 100% with PT2 (p < 0.001). The opioid consumption was also significantly higher with PT2 (43.2% vs. 71.8%, p < 0.001). There were no significant differences regarding functional impairments, side-effects and patient satisfaction (7.0 ± 2.0 vs. 7.4 ± 2.4, t₍₇₉₎ = -0.897, p = 0.373).

CONCLUSION

Both treatment protocols yielded in a high degree of patient satisfaction but dissatisfactory pain relief following TE. Metamizole can be recommended as a basic medication allowing for improved pain relief. Reported pain intensities were independent of the amount of opioid intake. Further research is mandatory to standardize and improve analgesic treatment after TE.

Pain Response to Open Label Placebo in Induced Acute Pain in Healthy Adult Males

Background

Open label placebos with patient education are effective in reducing chronic pain, and recent studies on their effect on pain have established interest in this field. Nevertheless, data on their effect on acute pain are scarce, and on hyperalgesia and allodynia, absent. This study assessed the effect of open label placebos on acute pain in healthy adult males and the influence of placebo education.

Methods

Thirty-two healthy males were included in this prospective, randomized, assessor-blinded crossover, single-center study assessing pain intensities (via numeric rating scale), area of hyperalgesia (von Frey filament), and allodynia (dry cotton swab) in a pain model utilizing intracutaneous electrical stimulation. The authors compared the effect of intravenous open label placebo on pain compared to no treatment. The authors further examined the effect of placebo on hyperalgesia and allodynia, and the influence of education (short vs. detailed) before placebo application. Saliva cortisol concentrations were also measured.

Results

Pain ratings (median, first to third quartile) were 21% lower during placebo treatment compared to no treatment, 4.0 (3.2 to 4.9) versus 5.1 (4.7 to 5.4), respectively (P = 0.001). The areas of hyperalgesia and allodynia were lower during placebo treatment compared to no treatment (hyperalgesia, 30 cm2 [17 to 47] vs. 55 cm2 [42 to 68], P = 0.003; allodynia, 24 cm2 [11 to 39] vs. 45 cm2 [31 to 62], P = 0.007). This corresponds to reductions of 47%. The extent of placebo education had no effect on pain. Saliva cortisol decreased significantly over time and was under the limit of detectability in the majority of participants in postbaseline measurements in both treatment branches. Baseline cortisol was not associated with the placebo effect or strength applied of current to reach defined pain ratings.

Conclusions

Open label placebos might play a role in multimodal analgesic concepts.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Safety, Tolerability, and Effect on Opioid Use of Meloxicam IV Following Orthopedic Surgery

Objective

A Phase 3 randomized multicenter, double-blind, placebo-controlled trial (NCT02720692) compared once-daily intravenous (IV) meloxicam 30 mg to placebo, when added to the standard of care pain management regimens, in adults with moderate-to-severe pain following major elective surgery and concluded that meloxicam IV had a safety profile similar to placebo and reduced opioid consumption.

Methods

In this post hoc subgroup analysis of orthopedic surgery subjects, 379 subjects received meloxicam IV 30 mg or IV-administered placebo every 24 hrs for ≤7 doses. Safety was assessed via AEs, laboratory tests, vital signs, and ECG, with an emphasis on specific AEs, including injection site reactions, bleeding, cardiovascular, hepatic, renal, thrombotic, and wound healing events. Daily opioid consumption was assessed during treatment.

Results

Among meloxicam IV-treated subjects, 64.7% experienced ≥1 AE versus 68.8% of placebo-treated subjects. Investigators assessed most AEs to be mild or moderate in intensity and unrelated to treatment. Total opioid consumption (36.8 mg versus 50.3 mg IV morphine equivalent dose; P=0.0081) and opioid consumption during time points 0‒24, 24‒48, 0‒48, and 0‒72 hrs were statistically significantly lower in the meloxicam IV group.

Conclusion

Meloxicam IV demonstrated no significant differences in the number and frequency of AEs versus placebo in subjects following orthopedic surgery. Opioid consumption was reduced in the meloxicam IV group versus placebo.

Trial registration

ClinicalTrials.gov (Identifier: NCT02720692).

Metamizole vs. ibuprofen at home after day case surgery: A double-blind randomised controlled noninferiority trial

BACKGROUND

NSAIDs and paracetamol are the cornerstones of pain treatment after day case surgery. However, NSAIDs have numerous contraindications and consequently are not suitable in up to 25% of patients. Metamizole is a non-opioid compound with a favourable gastro-intestinal and cardiovascular profile compared with NSAIDs.

OBJECTIVES

The study aimed to assess if a combination of metamizole and paracetamol is noninferior to a combination of ibuprofen and paracetamol in treating pain at home after painful day case surgery.

DESIGN

A double-blind randomised controlled trial.

SETTING

Single centre.

PATIENTS

Two hundred patients undergoing elective ambulatory haemorrhoid surgery, arthroscopic shoulder or knee surgery, or inguinal hernia repair.

INTERVENTION

Patients were randomly allocated to receive either metamizole and paracetamol (n = 100) or ibuprofen and paracetamol (n = 100) orally for four days.

MAIN OUTCOME MEASURES

Average postoperative pain intensity using a numerical rating scale and use of rescue medication were measured in the postanaesthesia care unit (PACU) and on postoperative days (POD) 1 to 3. A difference in mean numerical rating scale score of 1 point or less was considered noninferior. Adverse effects of study medication and satisfaction with study medication were measured on PODs 1 to 3 by telephone follow-up.

RESULTS

In the PACU, the difference in mean ± SD pain score between metamizole and paracetamol and ibuprofen and paracetamol was 0.85 ± 0.78. From POD 1 to 3, this difference was lower than 1, resulting in noninferiority. Rescue opioid consumption in the PACU and on PODs 1 and 3 was not significantly different between treatment groups. Rescue opioid consumption on POD2 was significantly higher in the ibuprofen and paracetamol group (P = 0.042). Adverse effects of study medication and overall patient satisfaction were similar in both groups.

CONCLUSION

Paracetamol/metamizole and paracetamol/ibuprofen are equally effective in treatment of acute postoperative pain at home after ambulatory surgery with comparable patient satisfaction levels.

TRIAL REGISTRATION

European Union Clinical Trials Register 2015-003987-35.

Emergence times and airway reactions during general anaesthesia with remifentanil and a laryngeal mask airway: A multicentre randomised controlled trial

BACKGROUND

Avoidance of airway complications and rapid emergence from anaesthesia are indispensable for the use of a laryngeal mask airway (LMA). Evidence from adequately powered randomised studies with a low risk of bias for the optimal anaesthetic in this context is limited.

OBJECTIVE

We tested the hypothesis that when using remifentanil-based intra-operative analgesia, desflurane would be the most suitable anaesthetic: with noninferiority in the occurrence of upper airway complications and superiority in emergence times compared with sevoflurane or propofol.

DESIGN

A randomised, multicentre, partially double-blinded, three-arm, parallel-group study.

SETTING

Two university and two regional German hospitals, from February to October 2015.

PATIENTS

A total of 352 patients (age 18 to 75 years, ASA physical status I to III, BMI less than 35 kg m⁻² and fluent in German) were enrolled in this study. All surgery was elective with a duration of 0.5 to 2 h, and general anaesthesia with a LMA was feasible.

INTERVENTION

The patients were randomised to receive desflurane, sevoflurane or propofol anaesthesia.

MAIN OUTCOME MEASURES

This study was powered for the primary outcome ‘time to state date of birth’ and the secondary outcome ‘intra-operative cough’. Time to emergence from anaesthesia and the incidence of upper airway complications were assessed on the day of surgery.

RESULTS

The primary outcome was analysed for 343 patients: desflurane (n=114), sevoflurane (n=111) and propofol (n=118). The desflurane group had the fastest emergence. The mean (± SD) times to state the date of birth following desflurane, sevoflurane and propofol were 8.1 ± 3.6, 10.1 ± 4.0 and 9.8 ± 5.1 min, respectively (P < 0.01). There was no difference in upper airway complications (cough and laryngospasm) across the groups, but these complications were less frequent than in previous studies.

CONCLUSION

When using a remifentanil infusion for intra-operative analgesia in association with a LMA, desflurane was associated with a significantly faster emergence and noninferiority in the incidence of intra-operative cough than either sevoflurane or Propofol.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02322502; EudraCT identifier: 2014-003810-96.

Intravenous Paracetamol in Adjunct to Intravenous Ketoprofen for Postoperative Pain in Children Undergoing General Surgery: A Double-Blinded Randomized Study

Background and objectives: The combination of non-steroidal anti-inflammatory drugs and paracetamol is widely used for pediatric postoperative pain management, although the evidence of superiority of a combination over either drug alone is insufficient. We aimed to find out if intravenous (i.v.) paracetamol in a dose of 60 mg kg^-1 24 h^-¹, given in addition to i.v. ketoprofen (4.5 mg kg^-1 24 h^-¹), improves analgesia, physical recovery, and satisfaction with postoperative well-being in children and adolescents following moderate and major general surgery. Materials and Methods: Fifty-four patients were randomized to receive either i.v. paracetamol or normal saline as a placebo in adjunct to i.v. ketoprofen. For rescue analgesia in patients after moderate surgery, i.v. tramadol (2 mg kg^-¹ up two doses in 24 h), and for children after major surgery, i.v. morphine-patient-controlled analgesia (PCA) were available. The main outcome measure was the amount of opioid consumed during the first 24 h after surgery. Pain level at 1 and over 24 h, time until the resumption of normal oral fluid intake, spontaneous urination after surgery, and satisfaction with postoperative well-being were also assessed. Results: Fifty-one patients (26 in the placebo group and 25 in the paracetamol group) were studied. There was no difference in required rescue tramadol doses (n = 11 in each group) or 24-h morphine consumption (mean difference (95% CI): 0.06 (⁻0.17; 0.29) or pain scores between placebo and paracetamol groups. In patients given morphine-PCA, time to normal fluid intake was faster in the paracetamol than the placebo subgroup: median difference (95% CI): 7.5 (1.3; 13.7) h, p = 0.02. Parental satisfaction score was higher in the paracetamol than the placebo group (mean difference: ⁻1.3 (⁻2.5; ⁻0.06), p = 0.04). Conclusions: There were no obvious benefits to opioid requirement or analgesia of adding regular intravenous paracetamol to intravenous ketoprofen in used doses. However, intravenous paracetamol may contribute to faster recovery of normal functions and higher satisfaction with postoperative well-being.

Systematic review and meta-analysis on non-opioid analgesics in palliative medicine

Non-opioid analgesics are widely used for pain relief in palliative medicine. However, there is a lack of evidence-based recommendations addressing the efficacy, tolerability, and safety of non-opioids in this field. A comprehensive systematic review and meta-analysis on current evidence can provide a basis for sound recommendations in clinical practice. A database search for controlled trials on the use of non-opioids in adult palliative patients was performed in Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PsycINFO, and EMBASE from inception to 18 February 2018. Endpoints were pain intensity, opioid-sparing effects, safety, and quality of life. Studies with similar patients, interventions, and outcomes were included in the meta-analyses. Our systematic search was able to only identify studies dealing with cancer pain. Of 5991 retrieved studies, 43 could be included (n = 2925 patients). There was no convincing evidence for satisfactory pain relief by acetaminophen alone or in combination with strong opioids. We found substantial evidence of moderate quality for a satisfactory pain relief in cancer by non-steroidal anti-inflammatory drugs (NSAIDs), flupirtine, and dipyrone compared with placebo or other analgesics. There was no evidence for a superiority of one specific non-opioid. There was moderate quality of evidence for a similar pain reduction by NSAIDs in the usual dosage range compared with up to 15 mg of morphine or opioids of equianalgesic potency. The combination of NSAID and step III opioids showed a beneficial effect, without a decreased tolerability. There is scarce evidence concerning the combination of NSAIDs with weak opioids. There are no randomized-controlled studies on the use of non-opioids in a wide range of end-stage diseases except for cancer. Non-steroidal anti-inflammatory drugs, flupirtine, and dipyrone can be recommended for the treatment of cancer pain either alone or in combination with strong opioids. The use of acetaminophen in the palliative setting cannot be recommended. Studies are not available for long-term use. There is a lack of evidence regarding pain treatment by non-opioids in specific cancer entities.

Efficacy and Safety of Intravenous Meloxicam in Subjects with Moderate-to-severe Pain Following Abdominoplasty

Background

A nanocrystal intravenous (IV) formulation of meloxicam is being studied with the aim of providing postoperative analgesia.

Methods

This randomized, multicenter, double-blind, placebo-controlled trial evaluated meloxicam IV 30 mg or placebo (≤ 3 doses) in 219 subjects undergoing abdominoplasty. The primary endpoint was the summed pain intensity difference over 24 hours postdose (SPID₂₄).

Results

Meloxicam IV-treated subjects had a statistically significant reduction in the least squares mean of SPID₂₄ compared with placebo-treated subjects (-4,262.1 versus -3,535.7; P = 0.0145). Meloxicam IV was associated with statistically significant differences over placebo on several other secondary endpoints, including other SPID intervals (ie, SPID₁₂, SPID₄₈, and SPID_24-48), achievement of perceptible pain relief, the proportion of subjects with a ≥ 30% improvement in the first 24 hours, and Patient Global Assessment of pain at hour 48. Meloxicam IV was also associated with a reduction in the number of subjects receiving opioid rescue medication during hours 24-48 and the total number of doses of opioid rescue analgesia. Meloxicam IV was generally well tolerated, with the numbers and frequencies of adverse events similar to that of the placebo group. There was no evidence of an increased risk of adverse events commonly associated with nonsteroidal anti-inflammatory drugs including bleeding, thrombotic, cardiovascular, renal, hepatic, cardiovascular, injection site, and wound healing events.

Conclusion

Meloxicam IV provided sustained pain relief and generally was well tolerated in subjects with moderate-to-severe pain following abdominoplasty.

Multimodal Analgesia, Current Concepts, and Acute Pain Considerations

PURPOSE OF REVIEW

Management of acute pain following surgery using a multimodal approach is recommended by the American Society of Anesthesiologists whenever possible. In addition to opioids, drugs with differing mechanisms of actions target pain pathways resulting in additive and/or synergistic effects. Some of these agents include alpha 2 agonists, NMDA receptor antagonists, gabapentinoids, dexamethasone, NSAIDs, acetaminophen, and duloxetine.

RECENT FINDINGS

Alpha 2 agonists have been shown to have opioid-sparing effects, but can cause hypotension and bradycardia and must be taken into consideration when administered. Acetaminophen is commonly used in a multimodal approach, with recent evidence lacking for the use of IV over oral formulations in patients able to take medications by mouth. Studies involving gabapentinoids have been mixed with some showing benefit; however, future large randomized controlled trials are needed. Ketamine is known to have powerful analgesic effects and, when combined with magnesium and other agents, may have a synergistic effect. Dexamethasone reduces postoperative nausea and vomiting and has been demonstrated to be an effective adjunct in multimodal analgesia. The serotonin-norepinephrine reuptake inhibitor, duloxetine, is a novel agent, but studies are limited and further evidence is needed. Overall, a multimodal analgesic approach should be used when treating postoperative pain, as it can potentially reduce side effects and provide the benefit of treating pain through different cellular pathways.

[Pain therapy with metamizole after ambulatory surgery?]

One third of operations are performed on an outpatient basis in Germany, but methods of postoperative pain therapy are less studied. We observed 126 patients with ambulatory and planned surgery in the field of orthopedics and trauma surgery. They were treated with the analgesic metamizole intra- and postoperatively and completed the patients' questionnaire QUIPS on the first postoperative day. In all, 79 patients (61.7%) reported current pain ≥4 on the numerical rating scale (NRS); 84 (66.6%) had restrictions in mobility, 48 (38.1%) described sleep disorders, and 26 (20.6%) wished for more or stronger analgesics. However, 91 (72.2%) of our patients were satisfied with the their pain therapy. Chances are that the treatment of nociceptive pain during movement with NSAID or COX-2-inhibitors is more successful. Further investigations should follow.

A Single Perioperative Injection of Dexamethasone Decreases Nausea, Vomiting, and Pain after Laparoscopic Donor Nephrectomy

Background. A single dose of perioperative dexamethasone (8–10 mg) reportedly decreases postoperative nausea, vomiting, and pain but has not been widely used in laparoscopic donor nephrectomy (LDN). Methods. We performed a retrospective cohort study of living donors who underwent LDN between 2013 and 2015. Donors who received a lower dose (4–6 mg)  (n = 70) or a higher dose (8–14 mg) of dexamethasone (n = 100) were compared with 111 donors who did not receive dexamethasone (control). Outcomes and incidence of postoperative nausea, vomiting, and pain within 24 h after LDN were compared before and after propensity-score matching. Results. The higher dose of dexamethasone reduced postoperative nausea and vomiting incidences by 28% (P = 0.010) compared to control, but the lower dose did not. Total opioid use was 29% lower in donors who received the higher dose than in control (P = 0.004). The higher dose was identified as an independent factor for preventing postoperative nausea and vomiting. Postoperative complication rates and hospital stays did not differ between the groups. After propensity-score matching, the results were the same as for the unmatched analysis. Conclusion. A single perioperative injection of 8–14 mg dexamethasone decreases antiemetic and narcotic requirements in the first 24 h, with no increase in surgical complications.

Metamizole/dipyrone for the relief of cancer pain: A systematic review and evidence-based recommendations for clinical practice

BACKGROUND

Dipyrone (metamizole) is one of the most widely used non-opioid analgesics for the treatment of cancer pain.

AIM

Because evidence-based recommendations are not yet available, a systematic review was conducted for the German Guideline Program in Oncology to provide recommendations for the use of dipyrone in cancer pain.

DESIGN

First, a systematic review for clinical trials assessing dipyrone in adult patients with cancer pain was conducted. Endpoints were pain intensity, opioid-sparing effects, safety, and quality of life.

DATA SOURCES

The search was performed in MedLine, Embase (via Ovid), and the Cochrane Library (1948-2013) and additional hand search was conducted. Finally, recommendations were developed and agreed in a formal structured consensus process by 53 representatives of scientific medical societies and 49 experts.

RESULTS

Of 177 retrieved studies, 4 could be included (3 randomized controlled trials and 1 cohort study, n = 252 patients): dipyrone significantly decreased pain intensity compared to placebo, even if low doses (1.5-2 g/day) were used. Higher doses (3 × 2 g/day) were more effective than low doses (3 × 1 g/day), but equally effective as 60 mg oral morphine/day. Pain reduction of dipyrone and non-steroidal anti-inflammatory drugs did not differ significantly. Compared to placebo, non-steroidal anti-inflammatory drugs, and morphine, the incidence of adverse effects was not increased.

CONCLUSION

Dipyrone can be recommended for the treatment of cancer pain as an alternative to other non-opioids either alone or in combination with opioids. It can be preferred over non-steroidal anti-inflammatory drugs due to the presumably favorable side effect profile in long-term use, but comparative studies are not available for long-term use.

Low-dose SoluMatrix diclofenac : a review of safety across two Phase III studies in patients with acute and osteoarthritis pain

INTRODUCTION

Similar to other NSAIDs, diclofenac is associated with serious dose-related cardiovascular, gastrointestinal, and renal adverse events. Low-dose SoluMatrix diclofenac , containing submicron particles of diclofenac, was developed to provide effective analgesia at lower drug doses compared with currently available NSAIDs.

AREAS COVERED

The efficacy and safety of low-dose SoluMatrix diclofenac was evaluated in two randomized, placebo-controlled Phase III studies: a study in patients with acute pain following bunionectomy surgery and a study in patients with osteoarthritis pain of the hip or knee. In this review article, we summarize safety data from these studies.

EXPERT OPINION

The safety results from the Phase III studies indicate that all dosing regimens of low-dose SoluMatrix diclofenac up to 12 weeks are generally well tolerated. Few serious gastrointestinal, cardiovascular, renal, or hepatic adverse events commonly associated with NSAID use were reported in these studies. Although not directly compared, the safety of SoluMatrix diclofenac was similar to findings for other diclofenac drug products. The potential for safe and effective management of acute and chronic pain at reduced NSAID doses is attractive; definitive characterization of SoluMatrix diclofenac safety requires confirmation by long-term studies.

The TRPA1 channel mediates the analgesic action of dipyrone and pyrazolone derivatives

BACKGROUND AND PURPOSE

Although still used by hundreds of millions of people worldwide, the mechanism of the analgesic action of the pyrazolone derivatives (PDs), dipyrone, propyphenazone and antipyrine remains unknown. The transient receptor potential ankyrin 1 (TRPA1) channel, expressed by nociceptors, is emerging as a major pain transduction pathway. We hypothesized that PDs target the TRPA1 channel and by this mechanism produce their analgesic effect.

EXPERIMENTAL APPROACH

Calcium responses and currents were studied in cultured TRPA1-expressing rodent dorsal root ganglion neurons and human cells. Acute nociception and mechanical hypersensitivity were investigated in naïve and genetically manipulated mice.

KEY RESULTS

Pyrazolone and PDs selectively inhibited calcium responses and currents in TRPA1-expressing cells and acute nocifensor responses in mice evoked by reactive channel agonists (allyl isothiocyanate, acrolein and H2 O2 ). In line with recent results obtained with TRPA1 antagonists and TRPA1 gene deletion, the two most largely used PDs, dipyrone and propyphenazone, attenuated TRPA1-mediated nociception and mechanical allodynia in models of inflammatory and neuropathic pain (formalin, carrageenan, partial sciatic nerve ligation and the chemotherapeutic drug, bortezomib). Notably, dipyrone and propyphenazone attenuated carrageenan-evoked mechanical allodynia, without affecting PGE2 levels. The main metabolites of PDs did not target TRPA1 and did not affect TRPA1-dependent nociception and allodynia.

CONCLUSIONS AND IMPLICATIONS

Evidence that in rodents the nociceptive/hyperalgesic effect produced by TRPA1 activation is blocked by PDs suggests that a similar pathway is attenuated by PDs in humans and that TRPA1 antagonists could be novel analgesics, devoid of the adverse haematological effects of PDs.

Metamizole-induced agranulocytosis revisited: results from the prospective Berlin Case-Control Surveillance Study

PURPOSE

Treatment with metamizole (dipyrone) has steadily increased in Germany over the last decade. The consequences of this increase for metamizole-induced agranulocytosis (MIA) are unclear. The present study addressed this topic using data from the Berlin Case-Control Surveillance Study.

METHODS

Adult patients (≥18 years of age) with acute nonchemotherapy-induced agranulocytosis were identified by active surveillance in all 51 Berlin hospitals between 2000 and 2010. Cases related to metamizole were ascertained applying the drug causality criteria of the World Health Organization. The incidence rate of MIA was calculated and standardised by age and sex based on the German standard population in 2010.

RESULTS

Twenty-six MIA cases out of 88 (30 %) patients with validated agranulocytosis were ascertained. The incidence of MIA was 0.96 (95 % confidence interval (CI) 0.95-0.97) cases per million per year. The median age of MIA cases was 50 years (quartile (Q)1 31 years; Q3 68 years) and 19 (73 %) of them were women. In 17 (65 %) cases, neutrophil granulocytes dropped below the value of 0.1 × 10(9) cells/L with three patients suffering from sepsis. Headache and postoperative pain were the most frequent indications for metamizole in outpatients (n = 16) and inpatients (n = 10), respectively. The median treatment duration was 6 days (Q1 4 days; Q3 19 days).

CONCLUSIONS

MIA persists as a severe condition in current pharmacotherapy. The continuous increase of metamizole applications should be critically assessed, especially in regard to indications in the outpatient setting and with respect to metamizole treatment duration.