Effects of oral pregabalin and aprepitant on pain and central sensitization in the electrical hyperalgesia model in human volunteers †

The Effect of Oral Gabapentin and Pregabalin as a Prodrug in Pain Control after Orthopedic Surgery on the Upper Limb: A Double-Blind Parallel Randomized Clinical Trial Study

Objective

To compare the effects of oral gabapentin (GBP) and pregabalin (PGB) in pain control after orthopedic surgery on the upper limb.

Methods

In this double-blind randomized clinical trial study, 80 patients who were the candidates for elective orthopedic surgery on one of the parts of the upper limb were divided into two groups using balance-block randomization. For the first group, a 150 mg capsule of PGB (one hour before the surgery) and for the second group, a 300 mg capsule of GBP (two hours before the surgery) were prescribed. Patients were subjected to standard monitoring at the beginning and during surgery. The pain scores were evaluated at before surgery, in PACU (postanesthesia care unit), and 6 and 12 hours after the surgery by VAS (visual analog scale).

Results

In this study, 37 subjects were allocated to each group. The participation rate was 92.5%. The mean with 95% confidence interval (CI) of pain scores over 4 times in the PGB group was 4.03 (3.25-4.79), 3.76 (3.02-4.49), 3.65 (3.06-4.23), and 3.41 (2.88-3.93) and in the GBP group was 4.08 (3.33-4.83), 2.78 (2.11-4.45), 2.3 (2.05-2.54), and 2 (1.51-2.50), respectively. The within-group comparisons showed a significant decrease in the pain score over time (P < 0.001). Also, the between-group comparison showed significant differences between the two groups in terms of pain score (P < 0.001). In the end, results showed that there is a significant interaction between time and intervention for pain score (P=0.042).

Conclusion

Although two medicines led to a reduction in the pain score, but the rate reduction in the PGB group was significantly more than that in the GBP group. This trial is registered with IRCT20211013052759N1.

Assessing the impact of aprepitant and ondansetron on postoperative nausea and vomiting in orthognathic surgeries: a randomized controlled trial

BACKGROUND

Postoperative nausea and vomiting (PONV) is a common side effect associated with general anesthesia. Both ondansetron and aprepitant been effectively used to prevent PONV. However, there is a disagreement of opinions regarding the superiority of these two drugs. This study aims to compare the efficacy of aprepitant with ondansetron in preventing PONV following orthognathic surgeries.

METHODS

In this double-blinded clinical trial, 80 patients scheduled for orthognathic surgery at Imam Hossein Hospital, Tehran, Iran, were randomly assigned to two groups. A standardized anesthesia protocol was used for all patients. The first group received a placebo capsule administered one hour before the surgical procedure along with 4 mg (2 ml) of ondansetron intravenously after anesthesia induction. The second group was given 80 mg aprepitant capsules one hour before the surgery, followed by an injection of 2 ml intravenous distilled water after anesthesia induction. The occurrence and severity of PONV, the amount of rescue medication required, and the complete response of patients assessed within 24 h after the surgery.

RESULTS

There were no significant differences in demographic data between the two groups. Patients in the aprepitant group had a significantly lower incidence and severity of nausea (2.5% versus 27.5%), vomiting (5% versus 25%), and required fewer rescue medications (7.5% versus 62.5%) compared to the ondansetron group. Additionally, the aprepitant group showed a higher complete response rate (90% versus 67.5%) in the 0-2 and 12-24 postoperative hours.

CONCLUSION

According to the findings of this study, aprepitant has demonstrated a greater efficacy in preventing PONV following orthognathic surgery, when compared to ondansetron.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (IRCT code: IRCT20211205053279N3), date of registration: 16/12/2022.

The Role of Substance P Within Traumatic Brain Injury and Implications for Therapy

This review examines the role of the neuropeptide substance P within the neuroinflammation that follows traumatic brain injury. It examines it in reference to its preferential receptor, the neurokinin-1 receptor, and explores the evidence for antagonism of this receptor in traumatic brain injury with therapeutic intent. Expression of substance P increases following traumatic brain injury. Subsequent binding to the neurokinin-1 receptor results in neurogenic inflammation, a cause of deleterious secondary effects that include an increased intracranial pressure and poor clinical outcome. In several animal models of TBI, neurokinin-1 receptor antagonism has been shown to reduce brain edema and the resultant rise in intracranial pressure. A brief overview of the history of substance P is presented, alongside an exploration into the chemistry of the neuropeptide with a relevance to its functions within the central nervous system. This review summarizes the scientific and clinical rationale for substance P antagonism as a promising therapy for human TBI.

Pharmacological interventions for preventing opioid-induced hyperalgesia in adults after opioid-based anesthesia: a systematic review and network meta-analysis

Background: Opioid-induced hyperalgesia (OIH) is an adverse event of prolonged opioid use that increases pain intensity. The optimal drug to prevent these adverse effects is still unknown. We aimed to conduct a network meta-analysis to compare different pharmacological interventions for preventing the increase in postoperative pain intensity caused by OIH. Methods: Several databases were searched independently for randomized controlled trials (RCTs) comparing various pharmacological interventions to prevent OIH. The primary outcomes were postoperative pain intensity at rest after 24 h and the incidence of postoperative nausea and vomiting (PONV). Secondary outcomes included pain threshold at 24 h after surgery, total morphine consumption over 24 h, time to first postoperative analgesic requirement, and shivering incidence. Results: In total, 33 RCTs with 1711 patients were identified. In terms of postoperative pain intensity, amantadine, magnesium sulphate, pregabalin, dexmedetomidine, ibuprofen, flurbiprofen plus dexmedetomidine, parecoxib, parecoxib plus dexmedetomidine, and S (+)-ketamine plus methadone were all associated with milder pain intensity than placebo, with amantadine being the most effective (SUCRA values = 96.2). Regarding PONV incidence, intervention with dexmedetomidine or flurbiprofen plus dexmedetomidine resulted in a lower incidence than placebo, with dexmedetomidine showing the best result (SUCRA values = 90.3). Conclusion: Amantadine was identified as the best in controlling postoperative pain intensity and non-inferior to placebo in the incidence of PONV. Dexmedetomidine was the only intervention that outperformed placebo in all indicators. Clinical Trial Registration: https://www.crd.york.ac. uk/prospero/display_record.php?, CRD42021225361.

Efficacy and safety of pregabalin in eye pain: A systematic review

BACKGROUND

The pregabalin is approved for the management of persistent pain. The aim of this study is to assess the advantages and disadvantages of the use of pregabalin in eye pain management.

METHODS

The PubMed, Cochrane Library, Embase, and Web of Science databases were searched until January 2022 for randomized controlled trials. Randomized, double-blinded trials comparing pregabalin with placebo in eye pain management were included. The primary outcome was visual analog scale or numerical rating scale at acute (24 hours) and chronic (≥7 days after surgery) timepoints. The secondary outcomes were analgesic medication requirements and pregabalin-related complications (nausea, vomiting, dizziness, and headache). We also compared the effect of pregabalin on dry-eye syndrome.

MAIN RESULTS

Six relevant articles were identified that studied the use of pregabalin as pain relief for photorefractive keratectomy (n = 2), laser epithelial keratomileusis (n = 1), laser-assisted in situ keratomileusis (n = 1), eyelid surgery (n = 1), and dacryocystorhinostomy (n = 1). Pregabalin was associated with a significant reduction in pain scores (95% confidence interval = -0.41 [-0.76--0.06]) 24 hours after surgical procedures. The data were insufficient to draw conclusions regarding dry eye symptoms. Because of the high heterogeneity of outcomes regarding adverse effects, there is no conclusion regarding the safety of pregabalin in eye pain.

CONCLUSIONS

Pregabalin reduced acute eye pain but had no significant effect on long-term analgesia after ophthalmological surgery in adults. It had no effect on dry-eye symptoms after ocular surgery. Further studies on the safety of pregabalin in eye pain management are required to draw solid conclusions.

Neurogenic inflammation as a novel treatment target for chronic pain syndromes

Chronic pain syndrome is a heterogeneous group of diseases characterized by several pathological mechanisms. One in five adults in Europe may experience chronic pain. In addition to the individual burden, chronic pain has a significant societal impact because of work and school absences, loss of work, early retirement, and high social and healthcare costs. Several anti-inflammatory treatments are available for patients with inflammatory or autoimmune diseases to control their symptoms, including pain. However, patients with degenerative chronic pain conditions, some with 10-fold or more elevated incidence relative to these manageable diseases, have few long-term pharmacological treatment options, limited mainly to non-steroidal anti-inflammatory drugs or opioids. For this review, we performed multiple PubMed searches using keywords such as "pain," "neurogenic inflammation," "NGF," "substance P," "nociception," "BDNF," "inflammation," "CGRP," "osteoarthritis," and "migraine." Many treatments, most with limited scientific evidence of efficacy, are available for the management of chronic pain through a trial-and-error approach. Although basic science and pre-clinical pain research have elucidated many biomolecular mechanisms of pain and identified promising novel targets, little of this work has translated into better clinical management of these conditions. This state-of-the-art review summarizes concepts of chronic pain syndromes and describes potential novel treatment strategies.

Aprepitant Inhibits JNK and p38/MAPK to Attenuate Inflammation and Suppresses Inflammatory Pain

Substance P contributes to the pathogenesis of pain by acting on NK-1R, specialized sensory neurons that detect noxious stimuli. Aprepitant, an antagonist of NK-1R, is widely used to treat chemotherapy-induced nausea and vomiting. In this study, we used LPS-stimulated BV-2 microglia cell line and animal models of inflammatory pain to explore the analgesic effect of aprepitant on inflammatory pain and its underlying mechanism. The excitability of DRG neurons were measured using whole-cell patch-clamp recordings. The behavioral tests were measured and the morphological changes on inflamed paw sections were determined by HE staining. Changes in the expressions of cytokine were measured by using real-time quantitative PCR analysis and ELISA method. Immunofluorescence and western blotting were used to detect the microglia activation and MAPK. Aprepitant treatment significantly inhibited the excitability of DRG neurons. The pain behavior and the paw tissues inflammatory damage were significantly relived after the administration of aprepitant compared to formalin group. Aprepitant significantly suppressed the activation of microglia, phosphorylation of JNK and p38 MAPK, as well as the mRNA and protein expressions of MCP-1, TNF-α, IL-6, and IL-1β, in vivo and in vitro. The LPS-induced over-translocation into nucleus of NF-κBp65 was down-regulated following aprepitant treatment in BV-2 cells. The present study suggests that aprepitant attenuates inflammatory pain in mice via suppressing the phosphorylation of JNK and p38, and inhibiting the NF-κB signaling pathway.

Recent advances in nanoplatforms for the treatment of neuropathic pain

STUDY DESIGN

Narrative review.

OBJECTIVES

The objective was to summarize the literature on nanoplatforms in spinal cord injury (SCI) and describe their effect in facilitating experiments for SCI. Currently, the primary clinical treatment for neuropathic pain (NP) is drug therapy, but these traditional drugs have many disadvantages, such as high dose, rapid clearance from the circulatory system, off-target side effects, and cytotoxicity. Moreover, the treatment for NP is complicated by the existence of blood-brain barrier. In recent years, nanomedicine has been receiving increased attention; this novel modality could help deliver drugs to treat NP via nanoplatforms, making it a promising alternative therapy. The use of nanoplatforms can enhance pharmaceutic effectiveness by either avoiding rapid clearance from the blood or ensuring adequate concentration in the lesion.

METHODS

A literature review was conducted, with a focus on nanoplatforms that have been described in the experimental studies of neuropathic pain.

RESULTS

We provide a brief description of the roles of liposomes, polymeric nanoparticles, metal nanoparticles, micelles, and dendrimers in the treatment of NP and discuss the prospective development of the nanoplatform system for NP.

CONCLUSION

The emergence of various nanoplatform drug delivery systems can provide an advantageous resource tool for real-time diagnosis and effective treatment of SCI-related NP.

Evaluation of the postoperative morphine-sparing effect of oral premedicants used as pre-emptive analgesics in breast-conserving cancer surgeries: A randomised placebo-controlled trial

Background and Aims:

Breast cancer surgeries are associated with both nociceptive and neuropathic pain, requiring strong analgesics. We aimed to evaluate the postoperative morphine-sparing effect of pre-emptive oral premedication with tramadol versus pregabalin in patients undergoing breast-conserving cancer surgeries (BCCS).

Methods:

This prospective, randomised, placebo-controlled trial was carried out at tertiary care centre on 90 patients undergoing BCCS randomised into three groups of 30 each. Group C received placebo, Group T received tramadol 100 mg and Group P received pregabalin 75 mg as oral premedication, 1 hour before surgery. General anaesthesia was administered. Postoperatively morphine 1 mg.h^-1 through intravenous PCA was started at a visual analogue scale score ≥4. Total morphine consumption in 24 hours was calculated and its sparing effect was evaluated as the primary outcome.

Results:

The median with interquartile range (IQR) of total postoperative morphine consumed in 24 hours, was found to be 22 mg (IQR 0-25.77), 15 mg (IQR 0-16) and 17.50 mg (IQR 0-19.25) in groups C, T, P respectively, (P = 0.000, 0.003, 0.060). The median duration of analgesia in group C was 5.40 hours (IQR 3.30-11.40), 11.6 hours (IQR 9.30-24.0) in group T and 8.60 hours (IQR 6.97-16.27) in group P (P value C/T = 0.000, C/P = 0.007, T/P = 0.002). The postoperative side effects were comparable.

Conclusion:

Oral tramadol 100 mg and oral pregabalin 75 mg as premedication reduced the 24 hours postoperative morphine requirement as compared to placebo in BCCS. However, tramadol 100 mg provided superior analgesia for longer duration than pregabalin 75 mg and was associated with more side effects.

Effectiveness of pregabalin treatment for trigger points in patients with comorbid myofascial pain syndrome and fibromyalgia syndrome: a randomized controlled trial

AIM OF THE STUDY

Myofascial pain syndrome (MPS) is a common problem in the general population. MPS should not be a local/peripheral painful syndrome and considered to be a syndrome of central sensitivity. We aimed to investigate the effect of pregabalin in patients with MPS in this study.

MATERIALS AND METHODS

We randomized 40 patients into two groups, and 17 patients per group completed the study. Female patients in group I received pregabalin and exercise therapy, whereas those in group II received exercise therapy alone. All patients were evaluated as follows: for pain by visual analog scale (VAS); trigger-point pressure pain threshold-(PPT) by algometry; neuropathic pain using the Douleur Neuropathique en 4 Questions (DN4) and quality of life with the Short Form-36 (SF36). Evaluations were performed pre-treatment and at the end of the first and third months of treatment. Clinical trial ID: NCT04600037, retrospectively registered 20/10/2020.

RESULTS

In group I, significant improvements were observed in VAS, trigger-point-PPT, physical component summary-SF-36, at the first and third months. In group II, statistically significant improvements were observed in VAS, trigger-point-PPT after the first and third months. Group I showed statistically better improvements in VAS, trigger points-PPT, physical component summary-SF36 compared with group II by the third month.

CONCLUSION

Pregabalin treatment is effective for controlling trigger points. Pregabalin treatment is also more effective than exercise treatment at improving quality of life in patients with MPS.

Human surrogate models of central sensitization: A critical review and practical guide

Background

As in other fields of medicine, development of new medications for management of neuropathic pain has been difficult since preclinical rodent models do not necessarily translate to the clinics. Aside from ongoing pain with burning or shock‐like qualities, neuropathic pain is often characterized by pain hypersensitivity (hyperalgesia and allodynia), most often towards mechanical stimuli, reflecting sensitization of neural transmission.

Data treatment

We therefore performed a systematic literature review (PubMed‐Medline, Cochrane, WoS, ClinicalTrials) and semi‐quantitative meta‐analysis of human pain models that aim to induce central sensitization, and generate hyperalgesia surrounding a real or simulated injury.

Results

From an initial set of 1569 reports, we identified and analysed 269 studies using more than a dozen human models of sensitization. Five of these models (intradermal or topical capsaicin, low‐ or high‐frequency electrical stimulation, thermode‐induced heat‐injury) were found to reliably induce secondary hyperalgesia to pinprick and have been implemented in multiple laboratories. The ability of these models to induce dynamic mechanical allodynia was however substantially lower. The proportion of subjects who developed hypersensitivity was rarely provided, giving rise to significant reporting bias. In four of these models pharmacological profiles allowed to verify similarity to some clinical conditions, and therefore may inform basic research for new drug development.

Conclusions

While there is no single “optimal” model of central sensitization, the range of validated and easy‐to‐use procedures in humans should be able to inform preclinical researchers on helpful potential biomarkers, thereby narrowing the translation gap between basic and clinical data.

Significance

Being able to mimic aspects of pathological pain directly in humans has a huge potential to understand pathophysiology and provide animal research with translatable biomarkers for drug development. One group of human surrogate models has proven to have excellent predictive validity: they respond to clinically active medications and do not respond to clinically inactive medications, including some that worked in animals but failed in the clinics. They should therefore inform basic research for new drug development.

Neuropathic Pain: Mechanism-Based Therapeutics

Neuropathic pain (NeP) can result from sources as varied as nerve compression, channelopathies, autoimmune disease, and incision. By identifying the neurobiological changes that underlie the pain state, it will be clinically possible to exploit mechanism-based therapeutics for maximum analgesic effect as diagnostic accuracy is optimized. Obtaining sufficient knowledge regarding the neuroadaptive alterations that occur in a particular NeP state will result in improved patient analgesia and a mechanism-based, as opposed to a disease-based, therapeutic approach to facilitate target identification. This will rely on comprehensive disease pathology insight; our knowledge is vastly improving due to continued forward and back translational preclinical and clinical research efforts. Here we discuss the clinical aspects of neuropathy and currently used drugs whose mechanisms of action are outlined alongside their clinical use. Finally, we consider sensory phenotypes, patient clusters, and predicting the efficacy of an analgesic for neuropathy.

Preoperative oral pregabalin for anxiety control: a systematic review

OBJECTIVE

The objective of this systematic review was to determine the effectiveness of preoperative oral pregabalin for anxiety control, the most effective dosage regimen, its impact on postoperative pain, and its adverse effects.

MATERIALS AND METHODS

A search was conducted of PubMed/Medline and clinicaltrials.gov (National Library of Medicine, Washington, DC), Scopus, Web of Science, and Cochrane databases for studies published between January 2009 and November 2018, with no language restriction. Based on PRISMA guidelines, the specific question was: is preoperative oral pregabalin effective and safe for anxiety control in patients undergoing surgery? The critical reading of retrieved studies followed questions prepared by the CASPe Network, and their methodological quality was evaluated using the Jadad Scale.

RESULTS

Twelve randomized controlled trials were selected for review. All twelve studies were trials of high quality. A dose of 75 mg preoperative oral pregabalin has been found to reduce anxiety and stabilize intraoperative hemodynamics, although a more significant improvement appears to be achieved with a single dose of 150 mg pregabalin at least 1 h before the surgery. It is not associated with any severe adverse effects.

CONCLUSION

Preoperative administration of oral pregabalin in a single dose of 150 mg appears to be effective to significantly reduce the anxiety of patients, intraoperative hemodynamic changes, and postoperative pain.

CLINICAL RELEVANCE

These findings suggest that pregabalin is useful and safe for preoperative and intraoperative anxiety control in patients undergoing surgery.

The effects of pregabalin and adductor canal block on postoperative pain in arthroscopic anterior cruciate ligament reconstruction

Background/aim

To determine the effectiveness of pregabalin and adductor canal block on opioid consumption, postoperative pain, and fast-tracking.

Materials and methods

A total of 51 American Society of Anaesthesiologists (ASA) classification I–II patients aged 18–70 years who were scheduled to undergo elective anterior cruciate ligament reconstruction were included in the study. Patients were randomized into groups P, A, and C. Patients in group P (n = 16), received 150 mg of preoperative oral pregabalin, patients in group A (n = 17) received postoperative adductor canal blockade, and patients in group C (n = 18) received neither adductor canal block nor pregabalin. Surgeries were performed under spinal anaesthesia with hyperbaric bupivacaine following monitorization. Demographic data along with block features, hemodynamic data, mean opioid consumption, numerical rating scale score, White’s fast-track score, and postoperative adverse effects were recorded.

Results

Fifty-seven patients were enrolled in the study, and 6 patients were excluded from the study; the data of 51 patients were included in the final analyses. Demographic characteristics and hemodynamic data were similar between the 3groups. Postoperative opioid consumption was significantly lower in groups A and P compared with group C (group P = 178.75 mg, group C = 318.61 mg, group A = 236.47 mg; P < 0.05). The regression of sensory block was significantly slower in group P (P < 0.05). The first analgesic requirement was earlier in group C than in groups P and A (P < 0.05). Patients in group P had higher fast-track scores at 8 h and 12 h compared with group C (P < 0.05); however, group A fast-track scores were similar to those of the other 2groups (P > 0.05). The rate of postoperative adverse effects was similar between the groups (P > 0.05).

Conclusion

Preoperative pregabalin (150 mg) reduced postoperative opioid consumption as much as adductor canal block in patients undergoing anterior cruciate ligament reconstruction. The first analgesic requirement was earlier in group C than in groups P and A. In addition, pregabalin can prolong the duration of spinal sensory block and shorten the time required to achieve high fast-tracking scores. We recommend the use of both methods as a part of multimodal analgesia.

Translational issues in precision medicine in neuropathic pain

Neuropathic pain remains poorly treated, with most new drugs falling through the translational gap. The traditional model of bench-to-bedside research has relied on identifying new mechanisms/targets in animal models and then developing clinical applications. Several have advocated bridging the translational gap by beginning with clinical observations and back-translating to animal models for further investigation of mechanisms. There is good evidence that phenotyping of patients through quantitative sensory testing can lead to improved treatment selection and hence improved patient outcomes. This practice has been widely adopted in clinical investigations, but its application in preclinical research is not mainstream. In this review, we retrospectively examine our historical rodent data sets with the aim of reconsidering drug effects on sensory neuronal endpoints, their alignment with clinical observations, and how these might guide future clinical studies.

Interventions to chronic prostatitis/Chronic pelvic pain syndrome treatment. Where are we standing and what's next?

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a frustrating syndrome. The pathogenesis and state of the art treatment of CP/CPPS are not known. A wide variety of therapies including anti-inflammatories, antibiotics, alpha-blockers, neuropathic pain modulators, and 5α-reductase inhibitors are in practice. These treatment strategies focus on alleviating symptoms in specific domains without treating root-cause and therapeutic outcome is far from satisfactory. We review the literature on current pharmacological treatments for CP/CPPS in detail and suggest future perspectives to modify the treatment strategies. We suggest that introducing novel treatment strategies such as gene editing, and T_regs expressing chimeric receptors may improve the treatment outcomes by inducing immune tolerance and controlling expression of pro-inflammatory cytokines.

Prostaglandin Signaling Governs Spike Timing-Dependent Plasticity at Sensory Synapses onto Mouse Spinal Projection Neurons

Highly correlated presynaptic and postsynaptic activity evokes spike timing-dependent long-term potentiation (t-LTP) at primary afferent synapses onto spinal projection neurons. While prior evidence indicates that t-LTP depends upon an elevation in intracellular Ca²⁺ within projection neurons, the downstream signaling pathways that trigger the observed increase in glutamate release from sensory neurons remain poorly understood. Using in vitro patch-clamp recordings from female mouse lamina I spino-parabrachial neurons, the present study demonstrates a critical role for prostaglandin synthesis in the generation of t-LTP. Bath application of the selective phospholipase A₂ (PLA₂) inhibitor arachidonyl trifluoromethyl ketone (AACOCF₃) or the cyclooxygenase 2 (Cox-2) inhibitor nimesulide prevented t-LTP at sensory synapses onto spino-parabrachial neurons. Similar results were observed following the block of the EP2 subtype of prostaglandin E₂ (PGE₂) receptor with PF 04418948. Meanwhile, perfusion with PGE₂ or the EP2 agonist butaprost potentiated the amplitude of monosynaptic primary afferent-evoked EPSCs while decreasing the paired-pulse ratio, suggesting a presynaptic site of action. Cox-2 was constitutively expressed in both spinal microglia and lamina I projection neurons within the superficial dorsal horn (SDH). Suppression of microglial activation with minocycline had no effect on the production of t-LTP, suggesting the possibility that prostaglandins produced within projection neurons could contribute to an enhanced probability of glutamate release at primary afferent synapses. Collectively, the results suggest that the amplification of ascending nociceptive transmission by the spinal SDH network is governed by PLA₂-Cox-2-PGE₂ signaling.SIGNIFICANCE STATEMENT Long-term potentiation (LTP) of primary afferent synapses contributes to the sensitization of spinal nociceptive circuits and has been linked to greater pain sensation in humans. Prior work has implicated elevated glutamate release in the generation of spike timing-dependent LTP (t-LTP) at sensory synapses onto ascending spinal projection neurons, but the underlying mechanisms remain unknown. Here we provide evidence that the activation of EP2 prostaglandin receptors by prostaglandin E₂, occurring downstream of phospholipase A₂ and cyclooxygenase 2 activation, mediates t-LTP at these synapses via changes in presynaptic function. This suggests that prostaglandins can increase the flow of nociceptive information from the spinal cord to the brain independently of their known ability to suppress synaptic inhibition within the dorsal horn.

Calcium channel modulation as a target in chronic pain control

Neuropathic pain remains poorly treated for large numbers of patients, and little progress has been made in developing novel classes of analgesics. To redress this issue, ziconotide (Prialt™) was developed and approved as a first-in-class synthetic version of ω-conotoxin MVIIA, a peptide blocker of Cav 2.2 channels. Unfortunately, the impracticalities of intrathecal delivery, low therapeutic index and severe neurological side effects associated with ziconotide have restricted its use to exceptional circumstances. Ziconotide exhibits no state or use-dependent block of Cav 2.2 channels; activation state-dependent blockers were hypothesized to circumvent the side effects of state-independent blockers by selectively targeting high-frequency firing of nociceptive neurones in chronic pain states, thus alleviating aberrant pain but not affecting normal sensory transduction. Unfortunately, numerous drugs, including state-dependent calcium channel blockers, have displayed efficacy in preclinical models but have subsequently been disappointing in clinical trials. In recent years, it has become more widely acknowledged that trans-aetiological sensory profiles exist amongst chronic pain patients and may indicate similar underlying mechanisms and drug sensitivities. Heterogeneity amongst patients, a reliance on stimulus-evoked endpoints in preclinical studies and a failure to utilize translatable endpoints, all are likely to have contributed to negative clinical trial results. We provide an overview of how electrophysiological and operant-based assays provide insight into sensory and affective aspects of pain in animal models and how these may relate to chronic pain patients in order to improve the bench-to-bedside translation of calcium channel modulators.

LINKED ARTICLES

This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.

Administering of pregabalin and acetaminophen on management of postoperative pain in patients with nasal polyposis undergoing functional endoscopic sinus surgery

BACKGROUND

Management of postoperative pain is a common problem in endoscopic sinus surgery. The objective of this study is the evaluation of pregabalin and acetaminophen effects on the management of postoperative pain in patients with nasal polyposis undergoing functional endoscopic sinus surgery (FESS).

MATERIALS AND METHODS

In this clinical trial, double-blinded study, 70 patients with nasal polyposis who have indication of FESS were enrolled to this study. After operation, patients were divided randomly into pregabalin and acetaminophen therapy groups. The pregabalin group (n = 35) was treated under pregabalin 50 mg TDS and the acetaminophen group (n = 35) was treated under tablet acetaminophen 500 mg/6 h. Each group was administered for 3 d. The visual analogue scale (VAS) was measured in onset, 12, 24, 48 and 72 h after surgery. All data were entered into SPSS software (SPSS Inc., Chicago, IL) and appropriate statistical tests were assessed to every relation.

RESULTS

In this study, there was no significant difference between two groups according to VAS in onset (p = .37); however, VAS in 12, 24, 48 and 72 h after operation was significantly lower in the pregabalin group compared with the acetaminophen group (p < .0001, for every four). Also in the pregabalin group, adverse effects were significantly lower than the acetaminophen group (p < .03).

CONCLUSIONS

Pregabalin has more effect, safely and usefully than acetaminophen on the management of postoperative pain in the patients with nasal polyposis undergoing functional endoscopic sinus surgery.

Preoperative pregabalin has no effect on intraoperative neurophysiological monitoring in adolescents undergoing posterior spinal fusion for spinal deformities: a double-blind, randomized, placebo-controlled clinical trial

PURPOSE

This study was designed to evaluate the effect of preoperative pregabalin on intraoperative neurophysiological monitoring in adolescents undergoing surgery for spinal deformities.

METHODS

Thirty-one adolescents undergoing posterior spinal fusion were randomized to receive preoperatively either pregabalin 2 mg/kg twice daily or placebo. The ability to make reliable intraoperative neurophysiological measurements, transcranial motor (MEPs) and sensory evoked potentials (SSEP) was evaluated.

RESULTS

Two patients (pregabalin group) did not fulfil the inclusion criteria and one patient's (placebo group) spinal monitoring was technically incomplete and these were excluded from the final data. In the rest, spinal cord monitoring was successful. Anaesthesia prolonged the latency of MEPs and increased the threshold current of MEP. The current required to elicit MEPs did not differ between the study groups. There were no statistically significant differences between the study groups regarding the latency of bilateral SSEP (N32 and P37) and MEP latencies at any time point.

CONCLUSIONS

Preoperative pregabalin does not interfere spinal cord monitoring in adolescents undergoing posterior spinal fusion.

LEVEL OF EVIDENCE

I.

Oral pregabalin for acute pain relief after cervicofacial surgery: a systematic review

OBJECTIVE

The objectives of this systematic review were to unify criteria on the effectiveness of oral pregabalin to treat acute post-operative pain after cervicofacial surgery, to establish the most effective dose regimens, and to determine its effect on rescue medicine consumption and its association with adverse effects.

MATERIALS AND METHODS

PubMed/Medline (National Library of Medicine, Washington, DC), Scopus, Web of Science, and Cochrane databases were searched for studies in any language published between January 2000 and September 2016. The following question was posed, in accordance with PRISMA guidelines: Is oral pregabalin effective and safe for the relief of acute pain after cervicofacial surgery? The critical reading of the literature utilized a list of questions prepared by the CASPe Network, applying the Jadad scale for evaluation of the methodological quality of trials.

RESULTS

Eleven randomized controlled clinical trials were selected. The 11 trials obtained a score ≥ 3, considered as Ib evidence level and high quality. A single oral dose of 75-mg pregabalin before or after cervicofacial surgery alleviates pain and lessens the need for rescue analgesia consumption, while the statistical significance of these effects is higher with a single dose of 150-mg pregabalin, either before or after the surgery.

CONCLUSION

Oral pregabalin appears to significantly alleviate post-operative pain and reduce rescue analgesia consumption, with no severe adverse effects. However, the ideal dose and most effective administration regimen remain controversial issues that need to be addressed in further high-quality clinical trials.

CLINICAL RELEVANCE

These findings suggest that pregabalin may be useful for acute pain relief after cervicofacial surgery.

Pregabalin reduces opioid consumption and hyperalgesia but not pain intensity after laparoscopic donor nephrectomy

BACKGROUND

Gabapentinoids are increasingly used to reduce acute postoperative pain, opioid consumption and opioid-related adverse effects. We explored the opioid-sparing, analgesic and anti-hyperalgesic effect of perioperative administered pregabalin in laparoscopic living donor nephrectomy.

METHODS

In this randomized controlled trial, 80 patients were recruited and randomized to receive pregabalin 150 mg twice daily or placebo on the day of surgery and the first postoperative day as part of a multimodal analgesic regimen. Primary outcome was opioid consumption 0-48 h after surgery. Secondary outcomes were pain intensity at rest and with movement 0-48 h after surgery using the 0-10 Numeric Rating Scale and incisional hyperalgesia measured 24 h post-surgery and at hospital discharge. Further secondary outcomes were adverse effects. Persistent post-surgical pain was registered 6 weeks, 6 and 12 months after surgery.

RESULTS

Pregabalin significantly reduced opioid consumption compared with placebo 0-48 h after surgery (median mg [25th, 75th percentile]); 29.0 (22.0-45.5) vs. 41.8 (25.8-63.6) (P = 0.04). Pain intensity 0-48 h after surgery calculated as area under the pain (NRS) vs. time curve was not statistically different between groups at rest (P = 0.12) or with movement (P = 0.21). Pregabalin decreased incisional hyperalgesia 24 h after surgery (median cm [25th, 75th percentile] 8.5 (1.0-18.5) vs. 15.5 (9.5-24.0) (P = 0.02). Nausea (P ≤ 0.01), use of antiemetics (P ≤ 0.01) and pain-related sleep interference (P = 0.02) were reduced with pregabalin.

CONCLUSIONS

Perioperative pregabalin added to a multimodal analgesic regimen was opioid-sparing, but made no difference to pain intensity score 0-48 h after surgery. Pregabalin may reduce incisional hyperalgesia on the first day after surgery.

Challenges in translational drug research in neuropathic and inflammatory pain: the prerequisites for a new paradigm

AIM

Despite an improved understanding of the molecular mechanisms of nociception, existing analgesic drugs remain limited in terms of efficacy in chronic conditions, such as neuropathic pain. Here, we explore the underlying pathophysiological mechanisms of neuropathic and inflammatory pain and discuss the prerequisites and opportunities to reduce attrition and high-failure rate in the development of analgesic drugs.

METHODS

A literature search was performed on preclinical and clinical publications aimed at the evaluation of analgesic compounds using MESH terms in PubMed. Publications were selected, which focused on (1) disease mechanisms leading to chronic/neuropathic pain and (2) druggable targets which are currently under evaluation in drug development. Attention was also given to the role of biomarkers and pharmacokinetic-pharmacodynamic modelling.

RESULTS

Multiple mechanisms act concurrently to produce pain, which is a non-specific manifestation of underlying nociceptive pathways. Whereas these manifestations can be divided into neuropathic and inflammatory pain, it is now clear that inflammatory mechanisms are a common trigger for both types of pain. This has implications for drug development, as the assessment of drug effects in experimental models of neuropathic and chronic pain is driven by overt behavioural measures. By contrast, the use of mechanistic biomarkers in inflammatory pain has provided the pharmacological basis for dose selection and evaluation of non-steroidal anti-inflammatory drugs (NSAIDs).

CONCLUSION

A different paradigm is required for the identification of relevant targets and candidate molecules whereby pain is coupled to the cause of sensorial signal processing dysfunction rather than clinical symptoms. Biomarkers which enable the characterisation of drug binding and target activity are needed for a more robust dose rationale in early clinical development. Such an approach may be facilitated by quantitative clinical pharmacology and evolving technologies in brain imaging, allowing accurate assessment of target engagement, and prediction of treatment effects before embarking on large clinical trials.

An integrated perspective on diabetic, alcoholic, and drug-induced neuropathy, etiology, and treatment in the US

Neuropathic pain (NeuP) is a syndrome that results from damaged nerves and/or aberrant regeneration. Common etiologies of neuropathy include chronic illnesses and medication use. Chronic disorders, such as diabetes and alcoholism, can cause neuronal injury and consequently NeuP. Certain medications with antineoplastic effects also carry an exquisitely high risk for neuropathy. These culprits are a few of many that are fueling the NeuP epidemic, which currently affects 7%-10% of the population. It has been estimated that approximately 10% and 7% of US adults carry a diagnosis of diabetes and alcohol disorder, respectively. Despite its pervasiveness, many physicians are unfamiliar with adequate treatment of NeuP, partly due to the few reviews that are available that have integrated basic science and clinical practice. In light of the recent Centers for Disease Control and Prevention guidelines that advise against the routine use of μ-opioid receptor-selective opioids for chronic pain management, such a review is timely. Here, we provide a succinct overview of the etiology and treatment options of diabetic and alcohol- and drug-induced neuropathy, three different and prevalent neuropathies fusing the combined clinical and preclinical pharmacological expertise in NeuP of the authors. We discuss the anatomy of pain and pain transmission, with special attention to key ion channels, receptors, and neurotransmitters. An understanding of pain neurophysiology will lead to a better understanding of the rationale for the effectiveness of current treatment options, and may lead to better diagnostic tools to help distinguish types of neuropathy. We close with a discussion of ongoing research efforts to develop additional treatments for NeuP.

Preventive Analgesia with Pregabalin in Neuropathic Pain from “Failed Back Surgery Syndrome”: Assessment of Sleep Quality and Disability

OBJECTIVE

Pregabalin group (PGB) is an antiepileptic used to treat neuropathic pain. We evaluated analgesic efficacy and safety for postoperative/chronic pain, disability, and sleep quality in patients who underwent spine surgery administered with PGB, or not, during the presurgical and postsurgical periods.

DESIGN

Retrospective cohort study of 60 patients (two groups with 30 patients) with full information on 50 (29 with PGB and 21 without PGB). Ten patients were dismissed as information was lacking. The PGB group (P) (29 patients) received 75 mg/12 hours before surgery, 150 mg 10 hours after surgery, and 150 mg/12 hours 3 days after surgery. The control group (C; 21 patients) took no PGB.

METHODS

Neuropathic pain was assessed before surgery, and 2 and 6 months later using visual analog scales (VAS), DN4, disability (Oswestry), and sleep quality. No serious adverse events occurred with PGB.

RESULTS

The median VAS pain score at rest was lower in the PGB group at 2 months postsurgery (1 vs 2, P = 0.032), as was the median DN4 score (0 vs 3, P = 0.032) and the median Oswestry disability index (ODI: 12 vs 18, P = 0.001). At 6 months postsurgery, pain scores were also lower in the PGB group for VAS (0 vs 4, P = 0.001), DN4 score (0 vs 4, P = 0.001) and the ODI (10 vs 24, P = 0.001). Improvement in the functionality and sleep quality of the PGB group was noteworthy (P = 0.018).

CONCLUSIONS

PGB has analgesic/antihyperalgesic effects on postoperative neuropathic pain after surgery for lumbar disc hernia. Our findings show that this benefit increases with time.

Transmission pathways and mediators as the basis for clinical pharmacology of pain

INTRODUCTION

Mediators in pain transmission are the targets of a multitude of different analgesic pharmaceuticals. This review explores the most significant mediators of pain transmission as well as the pharmaceuticals that act on them. Areas covered: The review explores many of the key mediators of pain transmission. In doing so, this review uncovers important areas for further research. It also highlights agents with potential for producing novel analgesics, probes important interactions between pain transmission pathways that could contribute to synergistic analgesia, and emphasizes transmission factors that participate in transforming acute injury into chronic pain. Expert commentary: This review examines current pain research, particularly in the context of identifying novel analgesics, highlighting interactions between analgesic transmission pathways, and discussing factors that may contribute to the development of chronic pain after an acute injury.

Analgesic efficacy of pregabalin in acute postmastectomy pain: placebo controlled dose ranging study

STUDY OBJECTIVE

We hypothesized that oral administration of a single dose of pregabalin 2 hours before modified radical mastectomy (MRM) would produce dose-related reduction in postoperative opioid consumption.

DESIGN

Prospective randomized controlled clinical trial.

SETTING

Postanesthesia care unit.

PATIENTS

One hundred twenty adult women scheduled for unilateral (MRM) with axillary evacuation.

INTERVENTIONS

Patients were randomized to receive either, placebo capsule, pregabalin 75 mg, pregabalin 150 mg, or pregabalin 300 mg.

MEASUREMENTS

The assessment parameters were the postoperative analgesic effect using visual analog scale (VAS) pain scores, the subsequent 24-hour morphine consumption, and the systemic adverse effects of pregabalin doses.

MAIN RESULTS

The VAS score at rest and movement was significantly decreased only in group P300 and group P150 in comparison to group P0 and group P75 at 0 hour (P<.01). The median (interquartile range) consumption of morphine in the first postoperative 24 hours was significantly decreased in group P300 in comparison to group P0 and group P75 (P300 vs P0: 6.5 [5-6.5] vs 20.5 [15.8-20.5] [P<.001]; P300 vs P75: 6.5 [5-6.5] vs 20 [14-20] [P<.001]), but there was no significant difference between group P300 and group P150. In addition, there was a significant decrease in consumption of morphine in group P150 in comparison to group P0 and group P75 (P150 vs P0: 7 [5-7] vs 20.5 [15.8-20.5] [P<.001]; P150 vs P75: 7 [5-7] vs 20 [14-20] [P<.001]). There were statistical significant increase in dizziness and blurred vision in group P300 in comparison to other groups (P<.05).

CONCLUSIONS

A single preoperative oral dose of pregabalin 150 mg is an optimal dose for reducing postoperative pain and morphine consumption in patients undergoing MRM.

Mechanisms of the gabapentinoids and α 2 δ-1 calcium channel subunit in neuropathic pain

The gabapentinoid drugs gabapentin and pregabalin are key front‐line therapies for various neuropathies of peripheral and central origin. Originally designed as analogs of GABA, the gabapentinoids bind to the α₂δ‐1 and α₂δ‐2 auxiliary subunits of calcium channels, though only the former has been implicated in the development of neuropathy in animal models. Transgenic approaches also identify α₂δ‐1 as key in mediating the analgesic effects of gabapentinoids, however the precise molecular mechanisms remain unclear. Here we review the current understanding of the pathophysiological role of the α₂δ‐1 subunit, the mechanisms of analgesic action of gabapentinoid drugs and implications for efficacy in the clinic. Despite widespread use, the number needed to treat for gabapentin and pregabalin averages from 3 to 8 across neuropathies. The failure to treat large numbers of patients adequately necessitates a novel approach to treatment selection. Stratifying patients by sensory profiles may imply common underlying mechanisms, and a greater understanding of these mechanisms could lead to more direct targeting of gabapentinoids.

Oral pregabalin for postoperative pain relief after third molar extraction: a randomized controlled clinical trial

OBJECTIVES

The aim of this randomized controlled clinical trial was to evaluate the efficacy and safety of pregabalin administered pre- and postoperatively in patients with pain and swelling due to the surgical removal of impacted lower third molars.

MATERIALS AND METHODS

The final study sample comprised 60 volunteers (23 males and 37 females). Group 1 (n = 30) received 75 mg oral pregabalin 1 h before surgery and 1 h after surgery. Group 2 (n = 30) served as a control group and received no pregabalin. Both groups were administered with 650 mg paracetamol every 8 h for 2 days. Postoperative pain intensity and swelling were measured using a visual analog scale (VAS); pain relief experienced was reported using a four-point verbal rating scale (VRS); the rescue medication requirement, adverse effects, and global impression of the medication were also recorded.

RESULTS

No significant difference in pain intensity (VAS) was observed between the groups. However, fewer rescue medication tablets were needed by pregabalin-treated patients than by controls (p = 0.021). The frequency and intensity of adverse effects were significantly higher in pregabalin-treated patients (p < 0.001), although no serious adverse events occurred. No significant difference in the degree of swelling was observed in any measurement except that from mandibular angle to lip junction, which showed lesser inflammation in the pregabalin group at 24 h post-surgery (p = 0.011). The global opinion on the medication received was more positive in the pregabalin group (p = 0.042).

CONCLUSIONS

The administration of pregabalin reduces the requirement for rescue medication after third molar surgery and results in a more constant pain level, with fewer peaks of pain intensity.

CLINICAL RELEVANCE

These findings suggest that pregabalin may be useful to control acute postoperative pain. Adverse effects are known to be reduced at the low pregabalin dose used in our study.

Effect of preoperative pregabalin on post-caesarean delivery analgesia: a dose-response study

INTRODUCTION

We hypothesised that preoperative administration of a single-dose of pregabalin would be associated with lower morphine consumption after uncomplicated caesarean delivery.

METHODS

After Institutional Ethics Committee approval, 135 parturients scheduled for elective caesarean delivery under spinal anaesthesia were randomly allocated to receive either placebo, or oral pregabalin 150mg or 300mg, one hour before induction of anaesthesia. Maternal cumulative morphine requirement at 24h, pain scores, sedation scores, nausea and vomiting, pruritus, pregabalin-related adverse effects, Apgar scores, Neurologic and Adaptive Capacity scores and umbilical cord acid-base status were recorded.

RESULTS

Compared with placebo or pregabalin 150mg, the use of a preoperative dose of pregabalin 300mg resulted in significantly lower cumulative morphine consumption at 24h (mean dose: placebo 12.9mg [95% CI 11.6 to 14.2]; pregabalin 150mg 11.9mg; [95% CI 10.7 to 13.1]; pregabalin 300mg 6mg [95% CI 5.4 to 7.3]; P<0.001). Pregabalin 300mg resulted in lower pain scores at 4h and 6h after delivery (P<0.001), and fewer instances of nausea, vomiting and pruritus (P<0.009). Dizziness and abnormal vision were observed most frequently in the pregabalin 300mg group (P<0.05 and P<0.009, respectively). The three groups were similar in terms of maternal sedation, Apgar scores, Neurologic and Adaptive Capacity scores and umbilical cord acid-base status. Three babies in the pregabalin 300mg group (6.7%) experienced short-term poor latching-on for breastfeeding.

CONCLUSION

In our study, preoperative administration of pregabalin 300mg reduced postoperative morphine consumption and early postoperative pain in parturients undergoing elective caesarean delivery, although maternal side effects were more common.

The effect of a combination of gabapentin and donepezil in an experimental pain model in healthy volunteers: Results of a randomized controlled trial

This double-blind, placebo-controlled, 3-period cross-over, 4-treatment option, incomplete block study (ClinicalTrials.gov number NCT01485185), with an adaptive design for sample size re-estimation, was designed to evaluate gabapentin plus donepezil in an established experimental model of electrical hyperalgesia. Thirty healthy male subjects aged 18-55 years were randomized to receive gabapentin 900 mg or gabapentin 900 mg+donepezil 5mg for 2 of the 3 treatment periods, with 50% of subjects randomized to receive placebo (negative control) and 50% to gabapentin 1800 mg (positive control) for the remaining period. Each treatment period was 14 days. Gabapentin or corresponding placebo was administered on Day 13 and the morning of Day 14. Donepezil or corresponding placebo was administered nocturnally from Day 1-13 and the morning of Day 14. Co-primary endpoints were the area of pinprick hyperalgesia (260 mN von Frey filament) and allodynia (stroking by cotton bud) evoked by electrical hyperalgesia on Day 14. Gabapentin 1800 mg (n=14) significantly reduced the area of allodynia vs placebo (n=14; -12.83 cm(2); 95% confidence interval [CI] -23.14 to -2.53; P=0.015) with supportive results for hyperalgesia (-14.04 cm(2); 95% CI -28.49-0.41; P=0.057), validating the electrical hyperalgesia model. Gabapentin+donepezil (n=30) significantly reduced the area of hyperalgesia vs gabapentin 900 mg (n=30; -11.73 cm(2); 95% CI -21.04 to -2.42; P=0.014), with supportive results for allodynia (-6.62 cm(2); 95% CI -13.29-0.04; P=0.052). The adverse event profile for gabapentin+donepezil was similar to the same dose of gabapentin. Data are supportive of further clinical investigation of a gabapentin-and-donepezil combination in patients with an inadequate response to gabapentin.

Comparing the effect of pregabalin, gabapentin, and acetaminophen on post-dural puncture headache

Introduction:

Post-dural puncture headache (PDPH) is a common complication of lumbar puncture for any purpose. To avoid the need for invasive methods of treating PDPH such as blood patch, the search for novel pharmacological agents to manage PDPH continues. The aim of this study was to compare the effects of acetaminophen, gabapentin and pregabalin in controlling PDPH in patients who underwent surgery under spinal anesthesia.

Materials and Methods:

A total of 90 patients who underwent elective orthopedic surgery under spinal anesthesia and suffered from PDPH consequently were enrolled in this randomized trial. Patients were categorized randomly into three groups. Group A, B and C have received Acetaminophen, Gabapentin and Pregabalin (3 times a day for 3 days), respectively. The effect of medications on the severity of PDPH was evaluated and compared using visual analog scale (VAS).

Results:

The mean VAS score was significantly lower in pregabalin group compared with others 24, 48 and 72 h after the onset of headache (P = 0.001 for all of them) and lower in Gabapentin group compared with Acetaminophen group 24, 48 and 72 h after the onset of headache (P = 0.001 for all analyses). No adverse outcome was reported in groups.

Conclusion:

Pregabalin and gabapentin are both useful and safe in management of PDPH, but pregabalin is more effective in this regard.

Perioperative Pregabalin for Acute Pain After Gynecological Surgery: A Meta-analysis

BACKGROUND

Pregabalin has been used as an adjuvant in some trials to control postoperative pain after gynecologic surgery. However, the potential clinical advantage remains debatable.

OBJECTIVE

We performed a meta-analysis of clinical trials of pregabalin to evaluate its ability to control acute postoperative pain after gynecologic surgery.

METHODS

We searched PubMed, ScienceDiret, and the Cochrane Library of Randomized Controlled Trials up to January 2014. We performed a systematic review and meta-analysis of prospective controlled studies reporting pregabalin for gynecologic surgery. The primary outcome was pain outcomes and postoperative cumulative opioid consumption. Data were reported as weighted mean differences (WMDs) and 95% CIs. The secondary outcome was adverse effects after surgery.

RESULTS

Six valid randomized trials met the eligibility criteria and were included in the meta-analysis. Pooled data were collected from 452 patients between 2007 and 2012 (These trials were separately conducted in Greece 2012, India 2011-2012, Turkey 2011, Denmark 2009 and Australia 2007). The pregabalin-treated patients consumed fewer opioids during the first 24 hours postoperatively (WMD, -8.50 mg; 95% CI, -11.29 to -5.71 mg; P < 0.00001). Pain intensity at rest and on movement or coughing revealed a statistically significant pain relief effect of pregabalin during 24 hours postoperatively (at rest: WMD, -6.20 mm; 95% CI, -11.83 to -0.58 mm; P = 0.03; on movement or coughing: WMD, -5.32 mm; 95% CI, -9.73 to -0.91 mm; P = 0.02). No differences were found between the pregabalin and control groups for the adverse effects.

CONCLUSIONS

Pregabalin has an analgesic and opioid-sparing effect and does not increase the frequency of adverse effects in acute postoperative pain management after gynecologic surgery.

Effect of pregabalin and dexamethasone on postoperative analgesia after septoplasty

Objectives. The aim of this study was to explore effect of a combination of pregabalin and dexamethasone on pain control after septoplasty operations. Methods. In this study, 90 patients who were scheduled for septoplasty under general anesthesia were randomly assigned into groups that received either placebo (Group C), pregabalin (Group P), or pregabalin and dexamethasone (Group PD). Preoperatively, patients received either pregabalin 300 mg one hour before surgery, dexamethasone 8 mg intravenously during induction, or placebo according to their allocation. Postoperative pain treatment included tramadol and diclofenac sodium 30 minutes before the end of the operation. Numeric rating scale (NRS) for pain assessment, side effects, and consumption of tramadol, pethidine, and ondansetron were recorded. Results. The median NRS score at the postoperative 0 and the 2nd h was significantly higher in Group C than in Group P and Group PD (P ≤ 0.004 for both). The 24 h tramadol and pethidine, consumptions were significantly reduced in Groups P and PD compared to Group C (P < 0.001 and P < 0.001). The incidence of blurred vision was significantly higher in Group PD compared to Group C within both 0–2 h and 0–24 h periods (P = 0.002 and P < 0.001, resp.). Conclusions. We conclude that administration of 300 mg pregabalin preoperatively may be an adequate choice for pain control after septoplasty. Addition of dexamethasone does not significantly reduce pain in these patients.

Effect of pregabalin and dexamethasone addition to multimodal analgesia on postoperative analgesia following rhinoplasty surgery

BACKGROUND

We investigated the effect of a combination of pregabalin and dexamethasone, when used as part of a multimodal analgesic regimen, on pain control after rhinoplasty operations.

METHODS

Sixty patients were enrolled in this study. They were randomly assigned into three groups: Group C (placebo + placebo), Group P (pregabalin + placebo), and Group PD (pregabalin + dexamethasone). Patients received either pregabalin 300 mg orally 1 h before surgery, dexamethasone 8 mg intravenously during induction, or placebo according to their allocation. Postoperative pain was treated with intravenous patient-controlled analgesia (tramadol, 20-mg bolus dose, 45-min lockout time). The numeric rating scale (NRS), side effects, and consumption of tramadol, pethidine, and ondansetron were assessed.

RESULTS

The median NRS scores at 0, 1, and 6 h after surgery were significantly higher in Group C than in Group PD (p < 0.001 for all). The 24-h consumption of tramadol and pethidine was significantly reduced in Groups P and PD compared to Group C (p < 0.01 and p < 0.01). The total tramadol consumption was decreased by 54.5 % in Group P and 81.9 % in Group PD compared to Group C (p < 0.001 for both). The incidence of nausea was higher in Group C than in Groups P and PD between the postoperative 0-2 and 0-24-h periods (p < 0.05 for both). The frequency of blurred vision was significantly higher in Groups P and PD than in Group C within the 0-24-h period (p < 0.05 for both).

CONCLUSION

We found that the addition of a single dose of pregabalin and dexamethasone to multimodal analgesia in rhinoplasty surgeries provided efficient analgesia and thus decreased opioid consumption.

LEVEL OF EVIDENCE I

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effects of single-dose pregabalin on postoperative pain in dacryocystorhinostomy surgery

Background

Postoperative pain of dacryocystorhinostomy (DCA) surgery is one of the serious issues to be considered. Administrating opioids to relieve postoperative pain and facing their increasing side effects in eye surgeries, make the use of non-opioid drugs inevitable.

Objectives

The present study examined the efficacy of pregabalin in alleviating the postoperative pain of DCA surgery.

Patients and Methods

The present study has been carried out as a double-blind, randomized clinical trial on the patient candidates for DCR. The patients were randomly divided in to two groups of pregabalin and placebo. Patients in pregabalin group received 300 mg of pregabalin, an hour before the operation in the morning of the surgery. Pain intensity on visual analog scale (VAS) was recorded until 24 hours after the operation; also the rate of administrated opioids and nausea/vomiting frequency were recorded during the first 24-hour period after the operation and the resultsof the two groups were compared.

Results

Postoperative pain intensity in the pregabalin group at the time of recovery was significantly lower than that of the placebo group (P = 0.001) until 24 hours after the surgery. In the pregabalin group 17.5% of the patients received opioids while in the placebo group the figure was 52.5% (P = 0.001). Nausea frequency was also higher in the placebo group than the pregabalin group (P = 0.003).

Conclusions

A single 300 mg dose of pregabalin, an hour before DCA can effectively reduce pain intensity and also reduce opioid dose and nausea/vomiting.