Pregabalin as mono- or add-on therapy for patients with refractory chronic neuropathic pain: a post-marketing prescription-event monitoring study

Management of Central Poststroke Pain: Systematic Review and Meta-analysis

Central poststroke pain (CPSP) is a neuropathic pain condition prevalent in 8 to 35% of stroke patients. This systematic review and meta-analysis aimed to provide insight into the effectiveness of available pharmacological, physical, psychological, and neuromodulation interventions in reducing pain in CPSP patients (PROSPERO Registration: CRD42022371835). Secondary outcomes included mood, sleep, global impression of change, and physical responses. Data extraction included participant demographics, stroke etiology, pain characteristics, pain reduction scores, and secondary outcome metrics. Forty-two original studies were included, with a total of 1,451 participants. No studies providing psychological therapy to CPSP patients were identified. Twelve studies met requirements for a random-effects meta-analyses that found pharmacological therapy to have a small effect on mean pain score (SMD = -.36, 96.0% confidence interval [-.68, -.03]), physical interventions did not show a significant effect (SMD = -.55 [-1.28, .18]), and neuromodulation treatments had a moderate effect (SMD = -.64 [-1.08, -.19]). Fourteen studies were included in proportional meta-analysis with pharmacological studies having a moderate effect (58.3% mean pain reduction [-36.51, -80.15]) and neuromodulation studies a small effect (31.1% mean pain reduction [-43.45, -18.76]). Sixteen studies were included in the narrative review, the findings from which largely supported meta-analysis results. Duloxetine, amitriptyline, and repetitive transcranial magnetic stimulation had the most robust evidence for their effectiveness in alleviating CPSP-induced pain. Further multicenter placebo-controlled research is needed to ascertain the effectiveness of physical therapies, such as acupuncture and virtual reality, and invasive and noninvasive neuromodulation treatments. PERSPECTIVE: This article presents a top-down and bottom-up overview of evidence for the effectiveness of different pharmacological, physical, and neuromodulation treatments of CPSP. This review could provide clinicians with a comprehensive understanding of the effectiveness and tolerability of different treatment types.

Sleep disturbance correlated with severity of neuropathic pain in sciatic nerve crush injury model

The association between sleep and pain has been investigated widely. However, inconsistent results from animal studies compared with human data show the need for a validated animal model in the sleep-pain association field. Our study aims to validate common neuropathic pain models as a tool for evaluating the sleep-pain association. Electrodes electroencephalogram (EEG) and electromyogram (EMG) were surgically implanted to measure sleep. The von Frey test was used to measure pain sensitivity. Following the baseline data acquisition, two pain-modelling procedures were performed: sciatic nerve crush injury (SCI) and common peroneal nerve ligation (CPL). Post-injury measurements were performed on days 1, 5, 10, and 15 post-surgery. The results presented decreased paw withdrawal thresholds and reduced NREM sleep duration in both models on the first post-surgery day. In the SCI model, NREM sleep duration was negatively correlated with paw withdrawal thresholds (p = 0.0466), but not in the CPL model. Wake alpha and theta EEG powers were also correlated with the pain threshold. The results confirm that the SCI model shows disturbed sleep patterns associated with increased pain sensitivity, suggesting it is a reliable tool for investigating sleep disturbances associated with neuropathic pain.

[The intensity of neuropathic pain and the severity of insomnia in diabetic polyneuropathy]

OBJECTIVE

To determine the prevalence of insomnia and the effectiveness of its treatment in patients with a painful form of diabetic polyneuropathy (DPN).

MATERIAL AND METHODS

Fifty patients with the painful form of DPN were randomly divided into 2 groups: the standard therapy group (ST) and the extended therapy group (ET). In the ST group, a single lesson on sleep hygiene was conducted, in the ET group there were 3-4 face-to-face individual sessions for the treatment of insomnia for two weeks. Both groups were interviewed at the time of hospitalization, after 3 and 6 months. The severity of polyneuropathy and the nature of neuropathic pain were assessed using the Neuropathic Neuropathy Impairment Score in the Lower Limbs (NIS-LL) and the Neuropathy Total Symptom Score - 9 (NTSS-9); the intensity of pain was assessed using a Visual Analog Scale (VAS). Sleep disorders were analyzed using the Pittsburgh Sleep Quality Index (PSQI) and the Insomnia Severity Index (ISI).

RESULTS

Sleep disorders of varying severity were observed in 82% of patients in the initial survey. In both groups, improvement in sleep quality was noted during treatment, but significantly better results were in the ET group, the ISI score after 6 months was 7.15±2.08 for the ST group and 3.07±2.49 for the ET group (p<0.0001). In the ST group, there was no significant decrease in the intensity of pain and the severity of polyneuropathy in dynamics. In the ET group, a significant decrease in NTSS-9 and VAS scores was found during the initial survey and after 6 months (p<0.0001). The intensity of pain also significantly decreased in the ET group compared with the ST group (p<0.0001) at the end of follow-up, which indicates the importance of sleep normalization in the treatment of neuropathic pain.

CONCLUSION

Most patients with the painful form of DPN have insomnia. Treatment of insomnia has shown its effectiveness as part of a multimodal approach to the managing of neuropathic pain in DPN and improving the quality of life of patients.

The Potential Role of Etanercept in the Management of Post-stroke Pain: A Literature Review

Strokes are the second leading cause of death and disability worldwide. The brain injury resulting from stroke produces a persistent neuroinflammatory response in the brain, resulting in a spectrum of neurologic dysfunction affecting stroke survivors chronically, also known as post-stroke pain. Excess production of tumor necrosis factor alpha (TNF alpha) in the cerebrospinal fluid (CSF) of stroke survivors has been implicated in post-stroke pain. Therefore, this literature review aims to assess and review the role of perispinal etanercept in the management of post-stroke pain. Several studies have shown statistically significant evidence that etanercept, a TNF alpha inhibitor, can reduce symptoms present in post-stroke syndrome by targeting the excess TNF alpha produced in the CSF. Studies have also shown improvements in not only post-stroke pain but also in traumatic brain injury and dementia. Further research is needed to explore the effects of TNF alpha on stroke prognosis and determine the optimal frequency and duration of etanercept treatment for post-stroke pain.

P2X7 receptor-activated microglia in cortex is critical for sleep disorder under neuropathic pain

Neuropathic pain (NP) is associated with sleep disturbances, which may substantially influence the quality of life. Clinical and animal studies demonstrated that neurotransmitter is one of the main contributors to cause sleep disturbances induced by NP. Recently, it was reported that P2X7 receptors (P2X7R) are widely expressed in microglia, which serves crucial role in neuronal activity in the pain and sleep-awake cycle. In this study, we adopted the chronic constriction injury (CCI) model to establish the progress of chronic pain and investigated whether P2X7R of microglia in cortex played a critical role in sleep disturbance induced by NP. At electroencephalogram (EEG) level, sleep disturbance was observed in mice treated with CCI as they exhibited mechanical and thermal hypersensitivity, and inhibition of P2X7R ameliorated these changes. We showed a dramatic high level of P2X7R and Iba-1 co-expression in the cortical region, and the inhibition of P2X7R also adversely affected it. Furthermore, the power of LFPs in ventral posterior nucleus (VP) and primary somatosensory cortex (S1) which changed in the CCI group was adverse after the inhibition of P2X7R. Furthermore, inhibition of P2X7R also decreased the VP-S1 coherence which increased in CCI group. Nuclear magnetic resonance demonstrated inhibition of P2X7R decreased glutamate (Glu) levels in thalamic and cortical regions which were significantly increased in the CCI mice. Our findings provide evidence that NP has a critical effect on neuronal activity linked to sleep and may built up a new target for the development of sleep disturbances under chronic pain conditions.

Patients With Neuropathic Pain Have Poor Sleep Quality

ABSTRACT

Although sleep disorders have been studied many times in neuropathic pain (NP), the effect of pain level, depression, and quality of life (QOL) on sleep quality in NP has been rarely investigated. In the present study, we aimed to investigate associations between possible quality of sleep (QOS) impairment and pain level, depression, and QOL. Average daily pain intensity, QOL, QOS, and depression status of the patients were evaluated using a 100-mm visual analog scale (VAS), the RAND 36-Item Health Survey 1.0, the Pittsburgh Sleep Quality Index, and Beck Depression Inventory (BDI), respectively. In 83.1% of patients QOS was found to be poor. We found that there was a significant difference between good and poor QOS in BDI, VAS, and RAND 36-Item Health Survey 1.0 scale's parameters, and patients with NP have poor sleep quality. Depression status is the main predictor for QOS, so pain level and QOL affect the QOS in NP. Physicians who aim healthy QOS must evaluate all characteristics of pain, depression status, and QOL in patients with NP.

Pregabalin in the Management of Painful Diabetic Neuropathy: A Narrative Review

Pregabalin is a first-line treatment in all major international guidelines on the management of painful diabetic neuropathy (pDPN). Treatment with pregabalin leads to a clinically meaningful improvement in pain scores, offers consistent relief of pain and has an acceptable tolerance level. Despite its efficacy in relieving neuropathic pain, more robust methods and comprehensive studies are required to evaluate its effects in relation to co-morbid anxiety and sleep interference in pDPN. The sustained benefits of modulating pain have prompted further exploration of other potential target sites and the development of alternative GABAergic agents such as mirogabalin. This review evaluates the role of pregabalin in the management of pDPN as well as its potential adverse effects, such as somnolence and dizziness, which can lead to withdrawal in ~ 30% of long-term use. Recent concern about misuse and an increase in deaths linked to its use has led to demands for reclassification of pregabalin as a class C controlled substance in the UK. We believe these demands need to be tempered in relation to the difficulties it would create for repeat prescriptions for the many millions of patients with pDPN for whom pregabalin provides benefit.Plain Language Summary: Plain language summary available for this article.

Long-term low-dose morphine for patients with moderate cancer pain is predominant factor effecting clinically meaningful pain reduction

PURPOSE

Patients with cancer often experience pain that affects their daily activities and quality of life. The analgesic ladder recommended by the World Health Organization has proved insufficient for many, and its scientific basis has been questioned. This retrospective study investigated factors related to adherence to long-term opioid therapy for patients with moderate cancer pain, including an evaluation of low-dose morphine relative to tramadol.

METHODS

Clinical data were collected of patients with moderate cancer pain (n = 353) who received either low-dose morphine or tramadol and were followed for ≥ 27 weeks. Factors related to regime adherence were investigated, including the analgesia type, cancer therapy (antitumor therapy or palliative care), pain type (nociceptive, neuropathic, or mixed), and living distance to the hospital. Factors related to clinically meaningful pain reduction (≥ 30% reduction in pain from baseline) were also investigated.

RESULTS

Patients taking tramadol, receiving antitumor therapy, experiencing neuropathic pain, and living far from the hospital were more likely to change analgesic strategy compared with, respectively, patients receiving low-dose morphine, palliative care, experiencing nociceptive pain, and living nearby. Factors that increased the likelihood of adherence to the analgesic regime were also associated with the likelihood of clinically meaningful pain reduction. Among adverse effects, a significantly higher percentage of patients experienced constipation in the tramadol group compared with those given morphine.

CONCLUSIONS

Among patients with moderate cancer pain, long-term low-dose morphine was safe and more effective than tramadol for clinically meaningful pain reduction, and patients were less likely to change the analgesic strategy.

Neuropathic Pain and Sleep: A Review

Neuropathic pain is associated with sleep disturbances, and in turn poor sleep quality leads to increased pain sensitivity, so it is essential to assess sleep alongside neuropathic pain. Responses to drugs are inconsistent and identifying the best treatment option that will reduce pain and improve sleep quality remains challenging for clinicians. Anticonvulsants such as pregabalin and gabapentin improve neuropathic pain and have a positive effect on comorbid sleep disturbances. Opioids and antidepressants are effective in reducing pain but can exacerbate sleep disturbances.

FUNDING

Pfizer, Italy.

Add-on treatment with pregabalin for patients with uncontrolled neuropathic pain who have been referred to pain clinics

OBJECTIVE

The aim of this study was to investigate the impact of pregabalin on pain, other symptoms, and patient-reported outcomes for patients with uncontrolled pain who have been referred to pain clinics.

PATIENTS AND METHODS

Adult patients with uncontrolled pain who had a score of ≥4 in the DN4 questionnaire were evaluated at baseline, month 3, and month 6. Evaluations included pain levels using a visual analog (VAS) scale as well as anxiety, depression, sleep, disability, and treatment satisfaction employing validated tools.

RESULTS

Our sample comprised 413 patients who met the selection criteria, had not received pregabalin previously, and were prescribed pregabalin at the study initiation, mainly (97 %) as add-on therapy. Overall, patients had a statistically significant reduction in VAS pain score of 41 points (54 % reduction, p < 0.001), varying from 64 % reduction (oncological pain) to 31 % reduction (central neuropathic pain). Effect sizes for anxiety, depression, sleep, and treatment satisfaction improvement were moderate to large depending on the dimension and clinical entity.

CONCLUSION

Our results suggest that in patients with uncontrolled neuropathic pain of various origins who were treated at pain clinics, the addition of pregabalin to a wider pharmacological treatment regimen was associated with a clinically relevant improvement of pain and psychological well-being and a reduction in the impact of neuropathic pain on daily activities. Add-on treatment with pregabalin was well tolerated.

Clinical and resource utilization patterns in patients with refractory neuropathic pain prescribed pregabalin for the first time in routine medical practice in primary care settings in Spain

CONTEXT AND OBJECTIVE

To describe clinical and resource utilization patterns in patients with refractory neuropathic pain (NeP) who were prescribed pregabalin for the first time in routine medical practice in primary care settings.

METHODS

Post-hoc analysis of a 12-week prospective observational study including pregabalin naïve adult patients with refractory chronic NeP of at least 6-months duration. Self-reported pain intensity, disability, sleep disturbances, symptoms of anxiety and depression, disability, health-related quality of life (HRQoL), health care resource utilization, and corresponding costs were assessed in this post-hoc analysis.

RESULTS

One thousand three hundred fifty-four patients were enrolled in the study, and three treatment groups were identified: (1) 598 patients replaced prior pain treatments with pregabalin as monotherapy; (2) 589 added pregabalin to their existing pain treatments; and (3) 167 other pain treatments were prescribed according with physician routine medical practice. Statistically significant differences were reported at baseline for intensity of pain, patient disability, severity of depressive symptoms, and HRQoL (P < 0.01 in all cases). No statistically significant differences were reported among the three treatment groups for anxiety severity or sleep disturbances. Subjects who received add-on pregabalin had greater use of direct and indirect resources vs the other groups, resulting in significantly higher quarterly overall costs per patient: €2,397 (2,308), €2,470 (1,857), and €3,110 (2,496), respectively (P < 0.001).

CONCLUSION

These findings suggest that primary care physicians chose pregabalin as an option for treating refractory patients who tended to have much more severe NeP profiles, costing society more than when they chose other therapeutic strategies not including pregabalin.

PRECISE - pregabalin in addition to usual care for sciatica: study protocol for a randomised controlled trial

Background

Sciatica is a type of neuropathic pain that is characterised by pain radiating into the leg. It is often accompanied by low back pain and neurological deficits in the lower limb. While this condition may cause significant suffering for the individual, the lack of evidence supporting effective treatments for sciatica makes clinical management difficult. Our objectives are to determine the efficacy of pregabalin on reducing leg pain intensity and its cost-effectiveness in patients with sciatica.

Methods/Design

PRECISE is a prospectively registered, double-blind, randomised placebo-controlled trial of pregabalin compared to placebo, in addition to usual care. Inclusion criteria include moderate to severe leg pain below the knee with evidence of nerve root/spinal nerve involvement. Participants will be randomised to receive either pregabalin with usual care (n = 102) or placebo with usual care (n = 102) for 8 weeks. The medicine dosage will be titrated up to the participant’s optimal dose, to a maximum 600 mg per day. Follow up consultations will monitor individual progress, tolerability and adverse events. Usual care, if deemed appropriate by the study doctor, may include a referral for physical or manual therapy and/or prescription of analgesic medication. Participants, doctors and researchers collecting participant data will be blinded to treatment allocation. Participants will be assessed at baseline and at weeks 2, 4, 8, 12, 26 and 52. The primary outcome will determine the efficacy of pregabalin in reducing leg pain intensity. Secondary outcomes will include back pain intensity, disability and quality of life. Data analysis will be blinded and by intention-to-treat. A parallel economic evaluation will be conducted from health sector and societal perspectives.

Discussion

This study will establish the efficacy of pregabalin in reducing leg pain intensity in patients with sciatica and provide important information regarding the effect of pregabalin treatment on disability and quality of life. The impact of this research may allow the future development of a cost-effective conservative treatment strategy for patients with sciatica.

Trial registration

ClinicalTrial.gov, ACTRN 12613000530729

Combination pharmacotherapy for the treatment of neuropathic pain in adults

BACKGROUND

Pharmacotherapy remains an important modality for the treatment of neuropathic pain. However, as monotherapy current drugs are associated with limited efficacy and dose-related side effects. Combining two or more different drugs may improve analgesic efficacy and, in some situations, reduce overall side effects (e.g. if synergistic interactions allow for dose reductions of combined drugs).

OBJECTIVES

This review evaluated the efficacy, tolerability and safety of various drug combinations for the treatment of neuropathic pain.

SEARCH METHODS

We identified randomised controlled trials (RCTs) of various drug combinations for neuropathic pain from CENTRAL, MEDLINE, EMBASE and handsearches of other reviews and trial registries. The most recent search was performed on 9 April 2012.

SELECTION CRITERIA

Double-blind, randomised studies comparing combinations of two or more drugs (systemic or topical) to placebo and/or at least one other comparator for the treatment of neuropathic pain.

DATA COLLECTION AND ANALYSIS

Data extracted from each study included: proportion of participants a) reporting ≥ 30% pain reduction from baseline OR ≥ moderate pain relief OR ≥ moderate global improvement; b) dropping out of the trial due to treatment-emergent adverse effects; c) reporting each specific adverse effect (e.g. sedation, dizziness) of ≥ moderate severity. The primary comparison of interest was between study drug(s) and one or both single-agent comparators. We combined studies if they evaluated the same drug class combination at roughly similar doses and durations of treatment. We used RevMan 5 to analyse data for binary outcomes.

MAIN RESULTS

We identified 21 eligible studies: four (578 participants) evaluated the combination of an opioid with gabapentin or pregabalin; two (77 participants) evaluated an opioid with a tricyclic antidepressant; one (56 participants) of gabapentin and nortriptyline; one (120 participants) of gabapentin and alpha-lipoic acid, three (90 participants) of fluphenazine with a tricyclic antidepressant; three (90 participants) of an N-methyl-D-aspartate (NMDA) blocker with an agent from a different drug class; five (604 participants) of various topical medications; one (313 participants) of tramadol with acetaminophen; and another one (44 participants) of a cholecystokinin blocker (L-365,260) with morphine. The majority of combinations evaluated to date involve drugs, each of which share some element of central nervous system (CNS) depression (e.g. sedation, cognitive dysfunction). This aspect of side effect overlap between the combined agents was often reflected in similar or higher dropout rates for the combination and may thus substantially limit the utility of such drug combinations. Meta-analysis was possible for only one comparison of only one combination, i.e. gabapentin + opioid versus gabapentin alone. This meta-analysis involving 386 participants from two studies demonstrated modest, yet statistically significant, superiority of a gabapentin + opioid combination over gabapentin alone. However, this combination also produced significantly more frequent side effect-related trial dropouts compared to gabapentin alone.

AUTHORS' CONCLUSIONS

Multiple, good-quality studies demonstrate superior efficacy of two-drug combinations. However, the number of available studies for any one specific combination, as well as other study factors (e.g. limited trial size and duration), preclude the recommendation of any one specific drug combination for neuropathic pain. Demonstration of combination benefits by several studies together with reports of widespread clinical polypharmacy for neuropathic pain surely provide a rationale for additional future rigorous evaluations. In order to properly identify specific drug combinations which provide superior efficacy and/or safety, we recommend that future neuropathic pain studies of two-drug combinations include comparisons with placebo and both single-agent components. Given the apparent adverse impact of combining agents with similar adverse effect profiles (e.g. CNS depression), the anticipated development and availability of non-sedating neuropathic pain agents could lead to the identification of more favourable analgesic drug combinations in which side effects are not compounded.