Cross-Over, Open-Label Trial of the Effects of Gabapentin versus Pregabalin on Painful Peripheral Neuropathy and Health-Related Quality of Life in Haemodialysis Patients

Gabapentin-Associated Movement Disorders: A Literature Review

BACKGROUND

Gabapentin (GBP)-induced movement disorders (MDs) are under-recognized adverse drug reactions. They are commonly not discussed with patients, and their sudden occurrence can lead to misdiagnosis. This literature review aims to evaluate the clinical-epidemiological profile, pathological mechanisms, and management of GBP-associated MD.

METHODS

Two reviewers identified and assessed relevant reports in six databases without language restriction between 1990 and 2023.

RESULTS

A total of 99 reports of 204 individuals who developed a MD associated with GBP were identified. The MDs encountered were 135 myoclonus, 22 dyskinesias, 7 dystonia, 3 akathisia, 3 stutterings, 1 myokymia, and 1 parkinsonism. The mean and median ages were 54.54 (SD: 17.79) and 57 years (age range: 10-89), respectively. Subjects were predominantly male (53.57%). The mean and median doses of GBP when the MD occurred were 1324.66 (SD: 1117.66) and 1033 mg/daily (GBP dose range: 100-9600), respectively. The mean time from GBP-onset to GBP-associated MD was 4.58 weeks (SD: 8.08). The mean recovery time after MD treatment was 4.17 days (SD: 4.87). The MD management involved GBP discontinuation. A total of 82.5% of the individuals had a full recovery in the follow-up period.

CONCLUSIONS

Myoclonus (GRADE A) and dyskinesia (GRADE C) were the most common movement disorders associated with GBP.

Gabapentinoids for Pain: A Review of Published Comparative Effectiveness Trials and Data Submitted to the FDA for Approval

Use of the gabapentinoids for pain continues to increase. In 2018, the US Food and Drug Administration (FDA) strengthened the warnings for both gabapentin and pregabalin to emphasize the central nervous system side effects and the risk of respiratory depression, especially when combined with other centrally acting drugs. We reviewed the published comparative effectiveness literature for gabapentinoids for pain as well as all trials (published and unpublished) used by the FDA for the approval of the five pain indications for these agents (one for gabapentin, four for pregabalin). Among the findings of interest are the fact that the FDA rejected the application for gabapentin for diabetic peripheral neuropathy based on the risk versus benefit profile of that drug in the clinical trials that were submitted by the manufacturer. Additionally, both the comparative effectiveness trials as well as the studies used by the FDA tend to be short in duration and show only modest pain benefits for the gabapentinoids. The placebo response in these trials was frequently one-third to one-half as great as the pain benefit demonstrated by the gabapentinoid. Based on the available clinical trial evidence, we feel prescribers should be cautious when using gabapentinoids for pain, particularly when using these agents for a prolonged period or when combined with other, centrally acting agents.

Interventions for itch in people with advanced chronic kidney disease

BACKGROUND

Itch in patients with chronic kidney disease (CKD) is common, often very distressing and associated with depression, reduced quality of life, and increased death. The most common first-line treatment has been the use of antihistamines despite the lack of substantial evidence for its use for uraemic itch. Few recommendations and guidelines exist for treatment.

OBJECTIVES

We aimed to determine: 1) the benefits and harms (both absolute and relative) of all topical and systemic interventions for the treatment of uraemic itch, either alone or in combination, when compared with placebo or standard care; and, 2) the dose strength or frequency, stage of kidney disease or method of dialysis used (where applicable) in cases where the effects of these interventions vary depending on co-interventions.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 17 December 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in adults with CKD stages 4 or 5 comparing treatments (pharmacological, topical, exposure, dialysis modality) for CKD associated itch to either placebo or other established treatments.

DATA COLLECTION AND ANALYSIS

Two authors independently abstracted study data and assessed study quality. Data were analysed using a random effects meta-analysis design estimating the relative effects of treatment versus placebo. Estimates of the relative effects between treatments are included where possible. For continuous measures of severity of itch up to three months, mean difference (MD) or standardised mean difference (SMD) were used. When reported, adverse effects were tabulated. The certainty of the evidence was estimated using GRADE.

MAIN RESULTS

Ninety-two RCTs, randomising 4466 participants were included. Fifty-eight studies (3285 participants) provided sufficient data to be meta-analysed. Of these, 30 compared an intervention to a placebo or control. The 10 cm Visual Analogue Scale (VAS) was the dominant instrument utilized for itch reporting and the Duo score was used in a minority of studies. GABA analogues including, gabapentin and pregabalin, reduce itch in patients with CKD (5 studies, 297 participants: 4.95 cm reduction, 95% CI 5.46 to 4.44 lower in VAS compared to placebo; high certainty evidence). Kappa opioid agonists, including nalfurafine also reduced itch in this population (6 studies, 661 participants: 1.05 cm reduction, 95% CI 1.40 to 0.71 lower in VAS compared to placebo; high certainty evidence). Ondansetron had little or no effect on itch scores (3 studies, 183 participants: 0.38 cm reduction, 95% CI 1.04 lower to 0.29 higher in VAS compared to placebo; high certainty evidence). Reduction in the severity of itch was reported with oral montelukast, turmeric, zinc sulfate and topical capsaicin. For all other interventions, the certainty of the evidence was low to moderate, and the interventions had uncertain effects on uraemic pruritus. Six studies have disclosed significant financial support from their respective manufacturers, six were affected by lack of blinding, and 11 studies have 15 participants or less. Older, smaller RCTs often failed to follow intention-to-treat protocols with unexplained dropouts after randomisation. Adverse effects were generally poorly and inconsistently reported across all RCTs. No severe adverse events were reported for any intervention.

AUTHORS' CONCLUSIONS

The RCTs of this meta-analysis contain a large array of interventions with a diverse set of comparators. For many interventions, trials are sparse. This served to make informative meta-analysis challenging. Of all treatments for uraemic pruritus, gabapentinoids (gabapentin and pregabalin) were the most studied and show the greatest reduction in itch scores. Further RCTs, even of the scale of the largest trials included in this review, are unlikely to significantly change this finding. Kappa-opioid agonists (mainly nalfurafine) also may reduce itch, but indirect comparison suggests a much more modest effect in comparison to GABA analogues. Evidence for oral montelukast, turmeric, zinc sulfate, and topical capsaicin also showed an itch score reduction. However, these reductions were reported in small studies, and warrant further investigation. Ondansetron did not reduce itch. It is somewhat unlikely that a further study of ondansetron will change this result.

Interventions for improving sleep quality in people with chronic kidney disease

BACKGROUND

Sleep disorders are commonly experienced by people with chronic kidney disease (CKD). Several approaches for improving sleep quality are used in clinical practice including relaxation techniques, exercise, acupressure, and medication.

OBJECTIVES

To assess the effectiveness and associated adverse events of interventions designed to improve sleep quality among adults and children with CKD including people with end-stage kidney disease (ESKD) treated with dialysis or kidney transplantation.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 8 October 2018 with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-randomised RCTs of any intervention in which investigators reported effects on sleep quality. Two authors independently screened titles and abstracts of identified records.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias for included studies. The primary outcomes were sleep quality, sleep onset latency, sleep duration, sleep interruption, and sleep efficiency. Risks of bias were assessed using the Cochrane tool. Evidence certainty was assessed using the GRADE approach. We calculated treatment estimates as risk ratios (RR) for dichotomous outcomes or mean difference (MD) or standardised MD (SMD) for continuous outcomes to account for heterogeneity in measures of sleep quality.

MAIN RESULTS

Sixty-seven studies involving 3427 participants met the eligibility criteria. Thirty-six studies involving 2239 participants were included in meta-analyses. Follow-up for clinical outcomes ranged between 0.3 and 52.8 weeks (median 5 weeks). Interventions included relaxation techniques, exercise, acupressure, cognitive-behavioural therapy (CBT), educational interventions, benzodiazepine treatment, dopaminergic agonists, telephone support, melatonin, reflexology, light therapy, different forms of peritoneal dialysis, music, aromatherapy, and massage. Incomplete reporting of key methodological details resulted in uncertain risk of bias in many studies.In very low certainty evidence relaxation techniques had uncertain effects on sleep quality and duration, health-related quality of life (HRQoL), depression, anxiety, and fatigue. Studies were not designed to evaluate the effects of relaxation on sleep latency or hospitalisation. Exercise had uncertain effects on sleep quality (SMD -1.10, 95% CI -2.26 to 0.05; I2 = 90%; 5 studies, 165 participants; very low certainty evidence). Exercise probably decreased depression (MD -9.05, 95% CI -13.72 to -4.39; I2 = 0%; 2 studies, 46 participants; moderate certainty evidence) and fatigue (SMD -0.68, 95% CI -1.07 to -0.29; I2 = 0%; 2 studies, 107 participants; moderate certainty evidence). Compared with no acupressure, acupressure had uncertain effects on sleep quality (Pittsburgh Sleep Quality Index (PSQI) scale 0 - 21) (MD -1.27, 95% CI -2.13 to -0.40; I2 = 89%; 6 studies, 367 participants: very low certainty evidence). Acupressure probably slightly improved sleep latency (scale 0 - 3) (MD -0.59, 95% CI -0.92 to -0.27; I2 = 0%; 3 studies, 173 participants; moderate certainty evidence) and sleep time (scale 0 - 3) (MD -0.60, 95% CI -1.12 to -0.09; I2 = 68%; 3 studies, 173 participants; moderate certainty evidence), although effects on sleep disturbance were uncertain as the evidence certainty was very low (scale 0 - 3) (MD -0.49, 95% CI -1.16 to 0.19; I2 = 97%). In moderate certainty evidence, acupressure probably decrease fatigue (MD -1.07, 95% CI -1.67 to -0.48; I2 = 0%; 2 studies, 137 participants). Acupressure had uncertain effects on depression (MD -3.65, 95% CI -7.63 to 0.33; I2 = 27%; 2 studies, 137 participants; very low certainty evidence) while studies were not designed to evaluate the effect of acupressure on HRQoL, anxiety, or hospitalisation. It was uncertain whether acupressure compared with sham acupressure improved sleep quality (PSQI scale 0 to 21) because the certainty of the evidence was very low (MD -2.25, 95% CI -6.33 to 1.82; I2 = 96%; 2 studies, 129 participants), but total sleep time may have been improved (SMD -0.34, 95% CI -0.73 to 0.04; I2 = 0%; 2 studies, 107 participants; low certainty evidence). 2 =2 =There were no studies designed to directly examine and/or correlate efficacy of any interventions aimed at improving sleep that may have been attempted for the spectrum of sleep disordered breathing. No studies reported treatment effects for children. Adverse effects of therapies were very uncertain.

AUTHORS' CONCLUSIONS

The evidence base for improving sleep quality and related outcomes for adults and children with CKD is sparse. Relaxation techniques and exercise had uncertain effects on sleep outcomes. Acupressure may improve sleep latency and duration, although these findings are based on few studies. The effects of acupressure were not confirmed in studies in which sham acupressure was used as the control. Given the very low certainly evidence, future research will very likely change the evidence base. Based on the importance of symptom management to patients, caregivers and clinicians, future studies of sleep interventions among people with CKD should be a priority.

Quality of Life in Painful Peripheral Neuropathies: A Systematic Review

Objective

Neuropathic pain is a common presenting complaint of patients with peripheral neuropathy (PN) and is considered one of the most disabling neuropathic symptoms, with detrimental effects on patients' quality of life (QoL). The aim of this review was to overview the current literature that focuses on QoL in painful PN of various aetiologies. We sought to clarify the direct effect of pain and its treatment on patients' QoL.

Methodology

A systematic computer-based literature search was conducted using the PubMed database to search for papers on QoL in painful PN. Information was extracted regarding prevalence, demographics, and response to treatment where relevant.

Results

We identified 66 articles eligible for inclusion. The vast majority of studies (n=47) focused on patients with diabetic PN. Other aetiologies of painful PN where QoL has been studied to date include gluten, immune-mediated, HIV, chemotherapy-induced, and chronic idiopathic axonal polyneuropathy. Pharmacological treatment is the mainstay in managing pain and has a direct positive and independent effect on the overall QoL. Other nonpharmacological approaches can also be of benefit, either alone or as adjuvant treatments, and are discussed.

Conclusion

The findings demonstrate that QoL is impaired in painful PN and should not be neglected in clinical practice. Patients' pain management and subsequent impact on QoL should routinely be assessed and monitored.

Clinical Pharmacology Considerations in Pain Management in Patients with Advanced Kidney Failure

Pain is common and poorly managed in patients with advanced CKD, likely due to both under and over prescription of appropriate analgesics. Poorly managed pain contributes to patients' poor quality of life and excessive health care use. There is tremendous variability within and between countries in prescribing patterns of analgesics, suggesting that factors other than patient characteristics account for these differences. This article discusses the pharmacologic management of acute and chronic pain in patients with advanced CKD, and the role analgesics, including opioids, play in the overall approach to pain management.

Recommendations for the Care of Patients Receiving Conservative Kidney Management: Focus on Management of CKD and Symptoms

Conservative kidney management is increasingly accepted as an appropriate treatment option for patients with eGFR category 5 CKD who are unlikely to benefit from dialysis and/or who choose a nondialysis care option. However, there remains great variation in the delivery of their care. As part of the development of a conservative kidney management pathway that is undergoing evaluation, a set of recommendations specific to conservative kidney management for managing the complications of CKD and common symptoms was developed. These recommendations focus on the patient's values and preferences and aim to optimize comfort and quality of life. Explanations for the interventions are provided to support the shared decision-making process between health care professionals, patients, and family members. The recommendations generally emphasize the preservation of function (cognitive, physical, and kidney) and address symptom burden, acknowledging that management priorities can change over time. The recommendations should be used in conjunction with other key elements of conservative kidney management, including clear communication and shared decision making for choosing conservative kidney management, advance care planning, and psychosocial support. Although there are limitations to the existing evidence specific to conservative kidney management, these recommendations are intended as a starting point toward reaching consensus and generating further evidence.

Pain in Maintenance Hemodialysis Patients: A Multicenter Study

CONTEXT

Pain is a common complaint in maintenance hemodialysis (MHD) patients yet is often inadequately assessed and undertreated.

OBJECTIVES

The objective of this study was to evaluate the prevalence, characteristics, intensity, and impact of pain in MHD patients.

METHODS

In a cross-sectional study conducted between 2013 and 2015, 336 MHD patients from five hemodialysis units in hospitals owned by Clalit were interviewed and evaluated. Study tools included the Brief Pain Inventory, The Leeds Assessment of Neuropathic Symptoms and Signs Pain Scale, and demographic and clinical characteristics. In addition, computerized pharmaceutical data were reviewed.

RESULTS

Pain was experienced by 82% of the study population (mean pain level: 7.2 ± 2.2) in the 24-hour period before the interview, while 61.5% experienced neuropathic pain characteristics. Of patients with pain, two-thirds reported being regularly treated with pain medications, while 24.5% received nondrug pain treatment. Mean pain relief due to Brief Pain Inventory was 62.5 ± 30%. In multivariate analysis, female gender, a high comorbidity index, and time on dialysis >24 months were associated with the presence of significant pain in the previous 24 hours. In addition, severe pain report was associated with female gender, depression, ≥4 painful sites, and unemployment. Finally, neuropathic pain was associated with time on dialysis >24 months, depression, ≥4 painful sites, and current intensity of pain >2.

CONCLUSION

Pain is common in MHD patients and is significantly associated with female gender, comorbidity, time on dialysis, and depression. Results of this study may serve as a starting point for palliative interventions for MHD patients.

Gabapentin and Pregabalin Use and Association with Adverse Outcomes among Hemodialysis Patients

Background Gabapentin and pregabalin are used to manage neuropathic pain, pruritus, and restless legs syndrome in patients on hemodialysis. These patients may be especially predisposed to complications related to these agents, which are renally cleared, but data regarding the risk thereof are lacking.Methods From the US Renal Data System, we identified 140,899 Medicare-covered adults receiving hemodialysis with Part D coverage in 2011. Using Cox regression models in which we adjusted for demographics, comorbidities, duration of exposure, number of medications, and use of potentially confounding concomitant medications, we investigated the association between gabapentin and pregabalin, modeled as separate time-varying exposures, and time to first emergency room visit or hospitalization for altered mental status, fall, and fracture. We evaluated risk according to daily dose categories: gabapentin (>0-100, >100-200, >200-300, and >300 mg) and pregabalin (>0-100 and >100 mg).Results In 2011, 19% and 4% of patients received gabapentin and pregabalin, respectively. Sixty-eight percent of gabapentin or pregabalin users had a diagnosis of neuropathic pain, pruritus, or restless legs syndrome. Gabapentin was associated with 50%, 55%, and 38% higher hazards of altered mental status, fall, and fracture, respectively, in the highest dose category, but even lower dosing was associated with a higher hazard of altered mental status (31%-41%) and fall (26%-30%). Pregabalin was associated with up to 51% and 68% higher hazards of altered mental status and fall, respectively.Conclusions Gabapentin and pregabalin should be used judiciously in patients on hemodialysis, and research to identify the most optimal dosing is warranted.

An Updated Overview on Therapeutic Drug Monitoring of Recent Antiepileptic Drugs

Given the distinctive characteristics of both epilepsy and antiepileptic drugs (AEDs), therapeutic drug monitoring (TDM) can make a significant contribution to the field of epilepsy. The measurement and interpretation of serum drug concentrations can be of benefit in the treatment of uncontrollable seizures and in cases of clinical toxicity; it can aid in the individualization of therapy and in adjusting for variable or nonlinear pharmacokinetics; and can be useful in special populations such as pregnancy. This review examines the potential for TDM of newer AEDs such as eslicarbazepine acetate, felbamate, gabapentin, lacosamide, lamotrigine, levetiracetam, perampanel, pregabalin, rufinamide, retigabine, stiripentol, tiagabine, topiramate, vigabatrin, and zonisamide. We describe the relationships between serum drug concentration, clinical effect, and adverse drug reactions for each AED as well as the different analytical methods used for serum drug quantification. We discuss retrospective studies and prospective data on the serum drug concentration-efficacy of these drugs and present the pharmacokinetic parameters, oral bioavailability, reference concentration range, and active metabolites of newer AEDs. Limited data are available for recent AEDs, and we discuss the connection between drug concentrations in terms of clinical efficacy and nonresponse. Although we do not propose routine TDM, serum drug measurement can play a beneficial role in patient management and treatment individualization. Standardized studies designed to assess, in particular, concentration-efficacy-toxicity relationships for recent AEDs are urgently required.

HCN Channel Targets for Novel Antidepressant Treatment

Major depressive disorder (MDD) is a chronic and potentially life threatening illness that carries a staggering global burden. Characterized by depressed mood, MDD is often difficult to diagnose and treat owing to heterogeneity of syndrome and complex etiology. Contemporary antidepressant treatments are based on improved monoamine-based formulations from serendipitous discoveries made > 60 years ago. Novel antidepressant treatments are necessary, as roughly half of patients using available antidepressants do not see long-term remission of depressive symptoms. Current development of treatment options focuses on generating efficacious antidepressants, identifying depression-related neural substrates, and better understanding the pathophysiological mechanisms of depression. Recent insight into the brain's mesocorticolimbic circuitry from animal models of depression underscores the importance of ionic mechanisms in neuronal homeostasis and dysregulation, and substantial evidence highlights a potential role for ion channels in mediating depression-related excitability changes. In particular, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential regulators of neuronal excitability. In this review, we describe seminal research on HCN channels in the prefrontal cortex and hippocampus in stress and depression-related behaviors, and highlight substantial evidence within the ventral tegmental area supporting the development of novel therapeutics targeting HCN channels in MDD. We argue that methods targeting the activity of reward-related brain areas have significant potential as superior treatments for depression.

Alpha2delta ligands, gabapentin, pregabalin and mirogabalin: a review of their clinical pharmacology and therapeutic use

INTRODUCTION

The first two alpha₂delta ligands - gabapentin (GBP) and pregabalin (PGB) - were initially synthesized as antiepileptics; however, they were later also found to be useful for the treatment of additional conditions. Areas covered: Relevant publications describing potential underlying mechanisms, clinical pharmacokinetics/pharmacokinetics, and clinical efficacy and safety of these drugs in various disease conditions were searched in PubMed and Scopus and included in this review. Expert commentary: GBP and PGB are effective for the treatment neuropathic pain, fibromyalgia and epilepsy; in addition, they may be useful for the reduction of postoperative pain. PGB is also effective for the treatment of generalized anxiety disorder and GBP for the treatment of restless legs syndrome. GBP may be considered a treatment option for pain associated with Guillain-Barré Syndrome and phantom limb and for the management of uremic pruritus. Mirogabalin (MGB), recently developed, is being investigated for the treatment of peripheral neuropathic pain and fibromyalgia, showing promising results in patients with diabetic peripheral neuropathy. Their most frequent adverse reactions are of neuropsychiatric nature and include fatigue, dizziness, sedation, somnolence, and ataxia; peripheral edema and weight gain are also frequently described. Pharmacokinetic interactions are scarce; however, pharmacodynamic interactions have been described in association with drugs with CNS-depressant effects.

Antidepressants for treating depression in adults with end-stage kidney disease treated with dialysis

BACKGROUND

Depression affects approximately one-quarter of people treated with dialysis and is considered an important research uncertainty by patients and health professionals. Treatment for depression in dialysis patients may have different benefits and harms compared to the general population due to different clearances of antidepressant medication and the severity of somatic symptoms associated with end-stage kidney disease (ESKD). Guidelines suggest treatment of depression in dialysis patients with pharmacological therapy, preferably a selective serotonin reuptake inhibitor. This is an update of a review first published in 2005.

OBJECTIVES

To evaluate the benefit and harms of antidepressants for treating depression in adults with ESKD treated with dialysis.

SEARCH METHODS

We searched Cochrane Kidney and Transplant's Specialised Register to 20 January 2016 through contact with the Information Specialist using search terms relevant to this review.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing antidepressant treatment with placebo or no treatment, or compared to another antidepressant medication or psychological intervention in adults with ESKD (estimated glomerular filtration rate < 15 mL/min/1.73 m(2)).

DATA COLLECTION AND ANALYSIS

Data were abstracted by two authors independently onto a standard form and subsequently entered into Review Manager. Risk ratios (RR) for dichotomous data and mean differences (MD) for continuous data were calculated with 95% confidence intervals (95% CI).

MAIN RESULTS

Four studies in 170 participants compared antidepressant therapy (fluoxetine, sertraline, citalopram or escitalopram) versus placebo or psychological training for 8 to 12 weeks. In generally very low or ungradeable evidence, compared to placebo, antidepressant therapy had no evidence of benefit on quality of life, had uncertain effects on increasing the risk of hypotension (3 studies, 144 participants: RR 1.72, 95% CI 0.75 to 3.92), headache (2 studies 56 participants: RR 2.91, 95% CI 0.73 to 11.57), and sexual dysfunction (2 studies, 101 participants: RR 3.83, 95% CI 0.63 to 23.34), and increased nausea (3 studies, 114 participants: RR 2.67, 95% CI 1.26 to 5.68). There were few or no data for hospitalisation, suicide or all-cause mortality resulting in inconclusive evidence. Antidepressant therapy may reduce depression scores during treatment compared to placebo (1 study, 43 participants: MD -7.50, 95% CI -11.94 to -3.06). Antidepressant therapy was not statistically different from group psychological therapy for effects on depression scores or withdrawal from treatment and a range of other outcomes were not measured.

AUTHORS' CONCLUSIONS

Despite the high prevalence of depression in dialysis patients and the relative priority that patients place on effective treatments, evidence for antidepressant medication in the dialysis setting is sparse and data are generally inconclusive. The relative benefits and harms of antidepressant therapy in dialysis patients are poorly known and large randomised studies of antidepressants versus placebo are required.

Neuropathic pain: treatment guidelines and updates

PURPOSE OF REVIEW

The purpose of this review is to provide an update on the diagnosis, treatment, and prevention of neuropathic pain.

RECENT FINDINGS

Neuropathic pain can be debilitating, leading to poor quality of life and functional status. Neuropathic pain results from numerous mechanisms of nerve injury including infectious diseases, complication of medical diseases, and mechanical damage. As a result of the lack of class I evidence for the treatment of numerous neuropathic pain conditions, those diseases without such evidence are often managed, as though neuropathic pain is a singular condition. In diseases such as diabetes, HIV, and herpes infections, the resultant neuropathic pain is often modifiable with prevention strategies. In one of the more prevalent neuropathic pain conditions, radiculopathy, the commonly used treatments lack sufficient evidence to explain their widespread use.

SUMMARY

The literature reveals that neuropathic pain is underdiagnosed and often undertreated or treated with ineffective or untested modalities. Evolving definitions of neuropathic pain has broadened the range of therapeutic approaches and brought current treatment paradigms under increased scrutiny. The lack of a mechanism-based approach to treatment may be responsible for the lackluster responses seen in most neuropathic pain conditions.

Abuse Potential of Pregabalin: A Systematic Review

BACKGROUND

Several case reports and epidemiological studies have raised concern about the abuse potential of pregabalin, the use of which has increased substantially over the last decade. Pregabalin is, in some cases, used for recreational purposes and it has incurred attention among drug abusers for causing euphoric and dissociative effects when taken in doses exceeding normal therapeutic dosages or used by alternative routes of administration, such as nasal insufflation or venous injection. The magnitude of the abuse potential and the mechanism behind it are not fully known.

OBJECTIVE

The aim of this study was to present a systematic review of the data concerning the abuse potential of pregabalin.

METHODS

We performed a systematic literature search and reviewed the preclinical, clinical and epidemiological data on the abuse potential of pregabalin.

RESULTS

We included preclinical (n = 17), clinical (n = 19) and epidemiological (n = 13) studies addressing the abuse potential of pregabalin. We also reviewed case reports (n = 9) concerning abuse of pregabalin. The preclinical studies indicated that pregabalin possesses modulatory effects on the GABA and glutamate systems, leaving room for an abuse potential. Further, clinical studies reported euphoria as a frequent side effect in patients treated with pregabalin. The majority of case reports concerning abuse of pregabalin involved patients with a history of substance abuse and, similarly, epidemiological studies found evidence of abuse, especially among opiate abusers.

CONCLUSIONS

Overall, the available literature suggests an important clinical abuse potential of pregabalin and prescribers should pay attention to signs of abuse, especially in patients with a history of substance abuse.

An Approach to Pain Management in End Stage Renal Disease: Considerations for General Management and Intradialytic Symptoms

The prevalence and severity of symptoms in patients with advanced chronic kidney disease is higher than those of the general population and comparable to those with other chronic and serious medical conditions. Despite the prevalence and severity in this population, symptoms continue to be under-recognized and inadequately managed. The recognition of specific intradialytic pain syndromes such as pain related to arteriovenous access, headaches, muscle cramps or generalized pain by providers may aid in improving patient compliance and quality of life. The approach to pain management in end stage renal disease patients follows that of the general population with specific considerations regarding clearance and potential side effects guiding selection of agents. Overall, evidence is limited regarding the pharmacology of many medications in this population.

Longitudinal associations of depressive symptoms and pain with quality of life in patients receiving chronic hemodialysis

Depressive symptoms and pain are common in patients on chronic hemodialysis (HD), yet their associations with quality of life (QOL) are not fully understood. We sought to characterize the longitudinal associations of these symptoms with QOL. As part of a trial comparing two symptom management strategies in patients receiving chronic HD, we assessed depressive symptoms using the Patient Health Questionnaire-9 (PHQ-9), and pain using the Short Form McGill Pain Questionnaire (SF-MPQ) monthly over 24 months. We assessed health-related QOL (HR-QOL) quarterly using the Short Form 12 (SF-12) and global QOL (G-QOL) using a single-item survey. We used random effects linear regression to analyze the independent associations of depressive symptoms and pain, scaled based on 5-point increments in symptom scores, with HR-QOL and G-QOL. Overall, 286 patients completed 1417 PHQ-9 and SF-MPQ symptom assessments, 1361 SF-12 assessments, and 1416 G-QOL assessments. Depressive symptoms were independently and inversely associated with SF-12 physical HR-QOL scores (β = -1.09; 95% confidence interval [CI]: -1.69, -0.50, P < 0.001); SF-12 mental HR-QOL scores (β = -4.52; 95% CI: -5.15, -3.89, P < 0.001); and G-QOL scores (β = -0.64; 95%CI: -0.79, -0.49, P < 0.001). Pain was independently and inversely associated with SF-12 physical HR-QOL scores (β = -0.99; 95% CI: -1.30, -0.68, P < 0.001) and G-QOL scores (β = -0.12; 95%CI: -0.20, -0.05, P = 0.002); but not with SF-12 mental HR-QOL scores (β = -0.16; 95%CI: -0.050, 0.17, P = 0.34). In patients receiving chronic HD, depressive symptoms and to a lesser extent pain, are independently associated with reduced HR-QOL and G-QOL. Interventions to alleviate these symptoms could potentially improve patients' HR-QOL and G-QOL.

Update on neuropathic pain treatment: ion channel blockers and gabapentinoids

Neuropathic pain is a debilitating chronic pain condition, which remains difficult to treat. The current mainstays of treatment include physical therapy, interventional procedures and medications. Among medications, ion channel blockers and gabapentinoids are the 2 classes of drugs commonly used to treat neuropathic pain. It has been suggested that these medications may be useful to treat a variety of neuropathic pain conditions. This article provides several updates on the utility of both ion channel blockers and gabapentinoids for the treatment of neuropathic pain.