Pharmacology of cyclooxygenase-2 inhibitors and preemptive analgesia in acute pain management

Adjuvant Drugs for Peripheral Nerve Blocks: The Role of Alpha-2 Agonists, Dexamethasone, Midazolam, and Non-steroidal Anti-inflammatory Drugs

Adjuvant drugs for peripheral nerve blocks are a promising solution to acute postoperative pain and the transition to chronic pain treatment. Peripheral nerve blocks (PNB) are used in the brachial plexus, lumbar plexus, femoral nerve, sciatic nerve, and many other anatomic locations for site-specific pain relief. However, the duration of action of a PNB is limited without an adjuvant drug. The use of non-opioid adjuvant drugs for single-shot peripheral nerve blocks (sPNB), such as alpha-2 agonists, dexamethasone, midazolam, and non-steroidal anti-inflammatory drugs, can extend the duration of local anesthetics and reduce the dose-dependent adverse effects of local anesthetics. Tramadol is a weak opioid that acts as a central analgesic. It can block voltage-dependent sodium and potassium channels, cause serotonin release, and inhibit norepinephrine reuptake and can also be used as an adjuvant in PNBs. However, tramadol's effectiveness and safety as an adjuvant to local anesthetic for PNB are inconsistent. The effects of the adjuvants on neurotoxicity must be further evaluated with further studies to delineate the safety in their use in PNB. Further research needs to be done. However, the use of adjuvants in PNB can be a way to help control postoperative pain.

A comparative experimental study of analgesic activity of a novel non-steroidal anti-inflammatory molecule - zaltoprofen, and a standard drug - piroxicam, using murine models

Purpose

Pain is an unpleasant sensation, but a protective mechanism of our body. It is the most common medical complaint requiring a visit to a physician. The new non-steroidal anti-inflammatory drug (NSAID) - zaltoprofen, is a preferential COX-2 inhibitor. It also inhibits bradykinin-induced nociceptive responses by blocking the B2 receptor-mediated pathway in the primary sensory neurons. The present study was conducted to evaluate and compare the anti-nociceptive activity of zaltoprofen with a conventional NSAID - piroxicam, in a mouse model of acute pain using hot plate and tail flick tests.

Materials and methods

Twenty-four adult Swiss albino mice (20-25 g) of either sex were used in this study. Oral zaltoprofen and piroxicam were used as test and standard drugs respectively. Anti-nociceptive activity was evaluated and compared using hot plate and tail flick tests.

Results

In comparison to the control group (vehicle), zaltoprofen showed a significant increase in reaction time at various time periods in the hot plate and tail flick tests. In the hot plate method, zaltoprofen groups (15 and 20 mg/kg) showed a significant elevation in pain threshold in comparison to control group (vehicle) (p<0.001). In the tail flick model also, zaltoprofen groups (15 and 20 mg/kg) showed a significant increase in the reaction time in comparison to control group (vehicle). In both the analgesiometer assays, zaltoprofen was found to be non-inferior compared to a standard drug - piroxicam (positive control).

Conclusion

Our study concludes that zaltoprofen is an effective analgesic agent in various pain models. Our results support that zaltoprofen has therapeutic potential for treating pain disorders and is non-inferior to a standard drug - piroxicam.

A comparison of effects of scalp nerve block and local anesthetic infiltration on inflammatory response, hemodynamic response, and postoperative pain in patients undergoing craniotomy for cerebral aneurysms: a randomized controlled trial

BACKGROUND

The purpose of this study was to compare the effects of scalp nerve block (SNB) and local anesthetic infiltration (LA) with 0.75% ropivacaine on postoperative inflammatory response, intraoperative hemodynamic response, and postoperative pain control in patients undergoing craniotomy.

METHODS

Fifty-seven patients were admitted for elective craniotomy for surgical clipping of a cerebral aneurysm. They were randomly divided into three groups: Group S (SNB with 15 mL of 0.75% ropivacaine), group I (LA with 15 mL of 0.75% ropivacaine) and group C (that only received routine intravenous analgesia). Pro-inflammatory cytokine levels in plasma for 72 h postoperatively, hemodynamic response to skin incision, and postoperative pain intensity were measured.

RESULTS

The SNB with 0.75% ropivacaine not only decreased IL-6 levels in plasma 6 h after craniotomy but also decreased plasma CRP levels and increased plasma IL-10 levels 12 and 24 h after surgery compared to LA and routine analgesia. There were significant increases in mean arterial pressure 2 and 5 mins after the incision and during dura opening in Groups I and C compared with Group S. Group S had lower postoperative pain intensity, longer duration before the first dose of oxycodone, less consumption of oxycodone and lower incidence of PONV through 48 h postoperatively than Groups I and C.

CONCLUSION

Preoperative SNB attenuated inflammatory response to craniotomy for cerebral aneurysms, blunted the hemodynamic response to scalp incision, and controlled postoperative pain better than LA or routine analgesia.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03073889 (PI:Xi Yang; date of registration:08/03/2017).

Selective cyclooxygenase inhibition and ulcerogenic liability of some newly prepared anti-inflammatory agents having thiazolo[4,5-d]pyrimidine scaffold

Novel candidates of thiazolo[4,5-d]pyrimidines (9a-l) were synthesized and their structures were elucidated by spectral and elemental analyses. All the novel derivatives were screened for their cyclooxygenase inhibitory effect, anti-inflammatory activity and ulcerogenic liability. All the new compounds exhibited anti-inflammatory activity, especially 1-(4-[7-(4-nitrophenyl)-5-thioxo-5,6-dihydro-3H-thiazolo[4,5-d]pyrimidin-2-ylideneamino]phenyl)ethanone (9g) was the most active derivative with 57%, 88% and 88% inhibition of inflammation after 1, 3 and 5h, respectively. Furthermore, this derivative 9g recorded higher anti-inflammatory activity than celecoxib which showed 43%, 43% and 54% inhibition after 1, 3 and 5h, sequentially. Moreover, the target derivatives 9a-l demonstrated moderate to high potent inhibitory action towards COX-2 (IC₅₀ = 0.87-3.78 µM), in particular, the derivatives 9e (IC₅₀ = 0.92 µM), 9g (IC₅₀ = 0.87 µM) and 9k (IC₅₀ = 1.02 µM) recorded higher COX-2 inhibitory effect than the selective COX-2 inhibitor drug celecoxib (IC₅₀ = 1.11 µM). The in vivo potent compounds (9e, 9g and 9k) caused variable ulceration effect (ulcer index = 5-12.25) in comparison to that of celecoxib (ulcer index = 3). Molecular docking was performed to the most potent COX-2 inhibitors (9e, 9g and 9k) to explore the binding mode of these derivatives with Cyclooxygenase-2 enzyme.

Effectiveness of Parecoxib Sodium Combined with Transversus Abdominis Plane Block for Pain Management After Hepatectomy for Hepatocellular Carcinoma: A Prospective Controlled Study

BACKGROUND This study aimed to investigate the effectiveness of perioperative parecoxib sodium combined with transversus abdominis plane (TAP) block on postoperative pain management following hepatectomy in patients with hepatocellular carcinoma (HCC). MATERIAL AND METHODS One hundred patients with HCC who underwent hepatectomy were randomized into a study group (n=51) and a control group (n=49). The study group received 40 mg of parecoxib sodium 30 minutes before anesthetic induction, and 150 mg of 0.375% ropivacaine with 5 mg dexamethasone as TAP inhibitors, before closing the abdominal incision. The control group received 40 mg of placebo 30 minutes before anesthetic induction, without TAP block. Postoperatively, all patients received patient-controlled intravenous analgesia (PCIA) and evaluation with subjective visual analog scale (VAS) pain scores. Data on adverse events, postoperative ambulation (>6 hours/day), time of flatus and defecation, and hospitalization duration were recorded. RESULTS Pain scores of the study group were significantly lower compared with the control group on the first three postoperative days. No significant differences were found between the two groups in terms of adverse events. In the study group, the number of cases of postoperative ambulation was significantly more than the control group. The onset of flatus and defecation and duration of hospital stay in the study group were significantly shorter in the study group compared with the control group. CONCLUSIONS Parecoxib sodium combined with TAP block effectively reduced postoperative pain, improved ambulation, improved gastrointestinal function, and shortened hospitalization time following hepatectomy in patients with HCC without adverse effects.

Novel multimodal analgesia regimen improves post-TACE pain in patients with hepatocellular carcinoma

BACKGROUD

Transarterial chemoembolization (TACE) is the primary palliative treatment for patients with unresectable hepatocellular carcinoma (HCC). However, it is often accompanied by postoperative pain which hinder patient recovery. This study was to examine whether preemptive parecoxib and sufentanil-based patient controlled analgesia (PCA) could improve the pain management in patients receiving TACE for inoperable HCC.

METHODS

From June to December 2016, 84 HCC patients undergoing TACE procedure were enrolled. Because of the willingness of the individuals, it is difficult to randomize the patients to different groups. We matched the patients' age, gender and pain scores, and divided the patients into the multimodal group (n = 42) and control group (n = 42). Patients in the multimodal group received 40 mg of parecoxib, 30 min before TACE, followed by 48 h of sufentanil-based PCA. Patients in the control group received a routine analgesic regimen, i.e., 5 mg of dezocine during operation, and 100 mg of tramadol or equivalent intravenous opioid according to patient's complaints and pain intensity. Postoperative pain intensity, percentage of patients as per the pain category, adverse reaction, duration of hospital stay, cost-effectiveness, and patient's satisfaction were all taken into consideration when evaluated.

RESULTS

Compared to the control group, the visual analogue scale scores for pain intensity was significantly lower at 2, 4, 6, and 12 h (all P < 0.05) in the multimodal group and a noticeably lower prevalence of post-operative nausea and vomiting in the multimodal group (31.0% vs. 59.5%). Patient's satisfaction in the multimodal group was also significantly higher than that in the control group (95.2% vs. 69.0%). No significant difference was observed in the duration of hospital stay between the two groups.

CONCLUSION

Preemptive parecoxib and sufentanil-based multimodal analgesia regime is a safe, efficient and cost-effective regimen for postoperative pain control in HCC patients undergoing TACE.

Variations in the Use of Perioperative Multimodal Analgesic Therapy

BACKGROUND

Practice guidelines for perioperative pain management recommend that multimodal analgesic therapy should be used for all postsurgical patients. However, the proportion of patients who actually receive this evidence-based approach is unknown. The objective of this study was to describe hospital-level patterns in the utilization of perioperative multimodal analgesia.

METHODS

Data for the study were obtained from the Premier Research Database. Patients undergoing below-knee amputation, open lobectomy, total knee arthroplasty, and open colectomy between 2007 and 2014 were included in the analysis. Patients were considered to have multimodal therapy if they received one or more nonopioid analgesic therapies. Mixed-effects logistic regression models were used to estimate the hospital-specific frequency of multimodal therapy use while adjusting for the case mix of patients and hospital characteristics and accounting for random variation.

RESULTS

The cohort consisted of 799,449 patients who underwent a procedure at 1 of 315 hospitals. The mean probability of receiving multimodal therapy was 90.4%, with 95% of the hospitals having a predicted probability between 42.6 and 99.2%. A secondary analysis examined whether patients received two or more nonopioid analgesics, which gave an average predicted probability of 54.2%, with 95% of the hospitals having a predicted probability between 9.3 and 93.2%.

CONCLUSIONS

In this large nationwide sample of surgical admissions in the United States, the authors observed tremendous variation in the utilization of multimodal therapy not accounted for by patient or hospital characteristics. Efforts should be made to identify why there are variations in the use of multimodal analgesic therapy and to promote its adoption in appropriate patients.

Effect of parecoxib combined with thoracic epidural analgesia on pain after thoracotomy

BACKGROUND

Thoracotomy results in severe postoperative pain potentially leading to chronic pain. We investigated the potential benefits of intravenous parecoxib on postoperative analgesia combined with thoracic epidural analgesia (TEA).

METHODS

Eighty-six patients undergoing thoracic surgery were randomized into two groups. Patient-controlled epidural analgesia (PCEA) was used until chest tubes were removed. Patients received parecoxib (group P) or placebo (group C) intravenously just 0.5 h before the operation and every 12 h after operation for 3 days. The intensity of pain was measured by using a visual analogue scale (VAS) and recorded at 2, 4, 8, 24, 48, 72 h after operation. The valid number of PCA, the side effects and the overall satisfaction to analgesic therapy in 72 h were recorded. Venous blood samples were taken before operation, the 1(st) and 3(rd) day after operation for plasma cortisol, adrenocorticotropic hormone (ACTH), interleukin-6 and tumor necrosis factor-α level. The occurrence of residual pain was recorded using telephone questionnaire 2 and 12 months after surgery.

RESULTS

Postoperative pain scores at rest and on coughing were significantly lower with the less valid count of PCA and greater patient satisfaction in group P (P<0.01). Adverse effect and the days fit for discharge were comparable between two groups. The cortisol levels in placebo group were higher than parecoxib group at T2. The level of ACTH both decreased in two groups after operation but it was significantly lower in group P than that in group C. There were no changes in plasma IL-6 and TNF-α levels before and after analgesia at T1 and T2 (P>0.05). The occurrence of residual pain were 25% and 51.2% separately in group P and C 3 months postoperatively (P<0.05).

CONCLUSIONS

Intravenous parecoxib in multimodal analgesia improves postoperative analgesia provided by TEA, relieves stress response after thoracotomy, and may restrain the development of chronic pain.

Preemptive, preventive, multimodal analgesia: what do they really mean?

SUMMARY

To improve postoperative pain management, several concepts have been developed, including preemptive analgesia, preventive analgesia, and multimodal analgesia. This article will discuss the role of these concepts in improving perioperative pain management. Preemptive analgesia refers to the administration of an analgesic treatment before the surgical insult or tissue injury. Several randomized clinical trials have, however, provided equivocal evidence regarding the benefits of preincisional compared with postincisional analgesic administration. Current general consensus, therefore, indicates that use of preemptive analgesia does not translate into consistent clinical benefits after surgery. Preventive analgesia is a wider concept where the timing of analgesic administration in relation to the surgical incision is not critical. The aim of preventive analgesia is to minimize sensitization induced by noxious stimuli arising throughout the perioperative period. Multimodal analgesia consists of the administration of 2 or more drugs that act by different mechanisms for providing analgesia. These drugs may be administered via the same route or by different routes. Thus, the aim of multimodal analgesia is to improve pain relief while reducing opioid requirements and opioid-related adverse effects. Analgesic modalities currently available for postoperative pain control include opioids, local anesthetic techniques [local anesthetic infiltration, peripheral nerve blocks, and neuraxial blocks (epidural and paravertebral)], acetaminophen, nonsteroidal anti-inflammatory drugs, and cyclooxygenase-2-specific inhibitors as well as analgesic adjuncts such as steroids, ketamine, α-2 agonists, and anticonvulsants.

Analgesic effect of preoperative topical nonsteroidal antiinflammatory drugs on postoperative pain after laser-assisted subepithelial keratectomy

PURPOSE

To assess the effect of preoperative topical nonsteroidal antiinflammatory drugs (NSAIDs) on postoperative pain after laser-assisted subepithelial keratectomy (LASEK) and to investigate their mechanism.

SETTING

Severance Eye Hospital and Saeyan Eye Clinic, Seoul, South Korea.

DESIGN

Prospective randomized clinical trial.

METHODS

Participants in 2 related studies were assessed. Study 1 comprised patients scheduled for bilateral LASEK (Group 1) who were randomized to receive an NSAID in 1 eye and a placebo in the fellow eye 30, 20, and 10 minutes before LASEK. Postoperative pain, glare, tearing, and irritation were assessed using a visual analog scale. Study 2 comprised healthy subjects (Group 2) who were randomly divided into subgroups. The participants in these subgroups were randomized to receive ketorolac tromethamine 0.5% in 1 eye and placebo (ofloxacin 0.3%) in the fellow eye (Group 2A), proparacaine hydrochloride 0.5% in 1 eye and placebo in the fellow eye (Group 2B), or ketorolac tromethamine 0.5% in 1 eye and placebo in the fellow eye, followed 10 minutes later by 1 drop of proparacaine hydrochloride 0.5% in both eyes (Group 2C). In all 3 groups, corneal sensitivity was measured after 1, 2, and 6 hours.

RESULTS

The mean postoperative pain score in the NSAID-pretreated eye was statistically significantly lower than in the placebo-pretreated eye 6, 12, and 24 hours postoperatively (P < .05). The mean corneal sensitivity was statistically significantly lower in the NSAID-treated eye than in the placebo-treated eye at 1 and 2 hours in Groups 2A and 2C (P < .05).

CONCLUSION

Preoperative administration of topical NSAIDs before LASEK effectively reduces postoperative pain.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Advances in perioperative pain management: use of medications with dual analgesic mechanisms, tramadol & tapentadol

Recovery from ambulatory surgical procedures can be limited by postoperative pain. Inadequate analgesia may delay or prevent patient discharge and can result in readmission. More frequently, postoperative pain produces discomfort and interrupts sleep, contributing to postoperative fatigue. The development of effective analgesic regimens for the management of postoperative pain is a priority especially in patients with impaired cardiorespiratory, hepatic, or renal function. Tramadol and tapentadol hydrochloride are novel in that their analgesic actions occur at multiple sites. Both agents are reported to be mu-opioid receptor agonists and monoamine-reuptake inhibitors. In contrast to pure opioid agonists, both drugs are believed to have lower risks of respiratory depression, tolerance, and dependence. The Food and Drug Administration has approved both drugs for the treatment of moderate-to-severe acute pain in adults. This article provides an evidence-based account of the role of tramadol and tapentadol in modern clinical practice.

Pre-emptive analgesia for postoperative pain control: a review

Pain can play an important role at the social and psychological level; hence one of the major goals of anaesthesia is to control and reduce the incidence of postoperative pain. The use of an analgesia before surgical incision may offer one of the most innovative and promising strategies for better pain control throughout the perioperative period. Pre-emptive analgesia refers to pharmacological intervention initiated prior to a painful stimulus in order to inhibit nociceptive mechanisms before they are triggered. Pre-emptive analgesia has three objectives: to reduce pain resulting from the activation of inflammatory mechanisms triggered by surgical incision; to hinder the pain memory response of the central nervous system; and to ensure a good control of postoperative pain in order to avoid the development of chronic pain. The following provides an overview of the scientific rationale for pre-emptive analgesia alongside an overview of published systematic reviews and randomized clinical trials related to this topic.

[What can we learn from the Scott Reuben case? Scientific misconduct in anaesthesiology]

In February 2009 a major case of scientific misconduct was discovered. The American pain researcher Dr. S. Reuben had published 21 papers over a period of 15 years that were found to be fraudulent. Suddenly many advances in postoperative pain therapy which had been assumed to be correct seemed questionable. In this review article the lessons which can be learnt from this case are described. This review also reveals that it is almost impossible for reviewers or readers of scientific journals to detect scientific fraud. However, several warning signs can be identified that might be useful when reading clinical papers. In retrospect many of these signs were detectable in Reuben's studies. Based on the fraudulent papers of Reuben it will be shown how and to what extent falsified results can affect other types of literature, such as practice guidelines, meta-analyses, review articles and oral presentations.

A prospective evaluation of 2 different pain management protocols for total hip arthroplasty

Pain management after total hip arthroplasty has improved dramatically in the past decade. However, most protocols use opioid medications for pain control. In the current study, 100 patients were prospectively selected to receive a traditional narcotic-based patient-controlled analgesia protocol or a nonnarcotic oral protocol for pain management after primary total hip arthroplasty. Therapy programs were similar for both groups. Postoperatively, patients were followed daily for opioid use, medication adverse effects, pain control, and overall satisfaction. The nonnarcotic oral group showed lower mean pain scores during the first 24 hours after surgery. The satisfaction rate was high in both groups. Both protocols provided adequate pain control after total hip arthroplasty; the nonnarcotic pain management protocol resulted in significantly decreased opioid consumption and fewer adverse effects.

The effects of pre-emptive analgesia with bupivacaine on acute post-laminectomy pain

INTRODUCTION

This is a prospective, non-randomized, hospital-based, case-controlled, clinical trial to assess the efficacy of perineural infiltration with bupivacaine at the related neural root for acute pain relief after lumbar laminectomy.

METHOD

Fifty-one patients undergoing unilateral one spinal level (lumbar 4) hemi-partial laminectomy were included in the study. In 22 of the patients (Group 2), bupivacaine was infiltrated onto the neural root immediately after the exposure; the 29 patients in the control group (Group 1) were not infiltrated. All patients were monitored post-operatively regarding pain determination using a visual analog scale, and the exact time of analgesic requirement during the first post-operative day was noted. Total analgesic dose given during the first post-operative day was also recorded.

RESULTS

The patients who received bupivacaine infiltration intraoperatively onto the neural root (Group 2) had a statistically significantly longer time to first analgesia request (P < 0.001) and also required significantly less analgesic when compared to the control group (Group 1) (P < 0.001). Perineural bupivacaine infiltration extended the early post-operative analgesic period. While the pain was not completely suppressed, the bupivacaine infiltration helped to manage the post-operative pain more effectively.

CONCLUSION

Our data suggests that pre-emptive analgesia via perineural infiltration of bupivacaine is a simple, and effective method for post-operative acute pain relief.

Silent Partner in Blood Vessel Homeostasis? Pervasive Role of Nitric Oxide in Vascular Disease

The endothelium generates powerful mediators that regulate blood flow, temper inflammation and maintain a homeostatic environment to prevent both the initiation and progression of vascular disease. Nitric oxide (NO) is arguably the single most influential molecule in terms of dictating blood vessel homeostasis. In addition to direct effects associated with altered NO production (e.g. vasoconstriction, excessive inflammation, endothelial dysfunction), NO is a critical modulator of vaso-relevant pathways including cyclooxygenase (COX)-derived prostaglandin production and angiotensin II generation by the renin-angiotensin system. Furthermore, NO may influence the selectivity of COX-2 inhibitors and ultimately contribute to controversies associated with the use of these drugs. Consistent with a central role for NO in vascular disease, disruptions in the production and bioavailability of NO have been linked to hypertension, diabetes, hypercholesterolemia, obesity, aging, and smoking. The ability of the vessel wall to control disease-associated oxidative stress may be the most critical determinant in maintaining homeostatic levels of NO and subsequently the prospect of stroke, myocardial infarction and other CV abnormalities. To this end, investigation of mechanisms that alter the balance of protective mediators, including pathways that are indirectly modified by NO, is critical to the development of effective therapy in the treatment of CV disease.