The effects of pregabalin on sleep disturbance symptoms among individuals with fibromyalgia syndrome

Sedative drug-use in Denmark, 2000 to 2019: a nationwide drug utilization study

AIM

To describe trends in and characteristics of sedative drug use from 2000 through 2019 in relation to the introduction of central regulations and new drugs.

METHODS

In this descriptive study, we used individual prescription data on the entire Danish population from the Danish National Prescription Registry to calculate yearly incidence and prevalence of use of benzodiazepines, benzodiazepine-related drugs (Z-drugs), melatonin, olanzapine, low-dose quetiapine, mianserin/mirtazapine, pregabalin, and promethazine from 2000 through 2019. From the Danish National Patient Registry, we obtained data on drug users' psychiatric and somatic comorbidity.

RESULTS

The use of benzodiazepines and Z-drugs declined gradually from 2000 through 2019, whereas the newer alternatives, melatonin, low-dose quetiapine, pregabalin and promethazine, increased in use, while the use of olanzapine and mianserin/mirtazapine was relatively stable. This development was seen in both men and women and across all age groups except for hypnotic benzodiazepines which showed a steep increase in the oldest age group from 2010. For all sedative drugs depression, anxiety, alcohol and misuse disorder, pain and cancer were the most prevalent comorbidities. During our study period, the number of individuals without any of the selected diagnoses increased.

CONCLUSION

In Denmark different central regulations have influenced prescription practice toward more restrictive use of Z-drugs and benzodiazepines, except for hypnotic benzodiazepine prescriptions increased after the introduction of special palliative care. An increase in use of newer sedative drugs, however, indicates that the regulations do not remove the need for sedative drugs in the population.

Pregabalin administration in patients with fibromyalgia: a Bayesian network meta-analysis

Several studies investigated the effectiveness and the safety of different doses of pregabalin in fibromyalgia. However, the optimal protocol remains controversial. A Bayesian network meta-analysis comparing 300, 450, and 600 mg/daily of pregabalin for fibromyalgia was conducted. The literature search was conducted in January 2022. All the double-blind randomised clinical trials comparing two or more dose protocols of pregabalin for fibromyalgia were accessed. Studies enrolling less than 50 patients were not eligible, nor were those with a length of follow-up shorter than eight weeks. The outcomes of interests were: Fibromyalgia Impact Questionnaire (FIQ), sleep quality, and adverse events. The network meta-analyses were performed using the routine for Bayesian hierarchical random-effects model analysis, with log odd ratio (LOR) and standardized mean difference (SMD) effect measure. Data from 4693 patients (mean age 48.5 years) were retrieved. 93.1% (4370 of 4693 patients) were women. The median follow-up was 14.8 weeks. Pregabalin 450 mg/daily resulted in greater reduction in Fibromyalgia Impact Questionnaire (SMD - 1.83). Pregabalin 600 demonstrated the greatest sleep quality (SMD 0.15). Pregabalin 300 mg/daily evidenced the lowest rate of adverse events (LOR 0.12). The dose of pregabalin must be customised according to patients' characteristics and main symptoms.

Pregabalin abuse and dependence during insomnia and protocol for short-term withdrawal management with diazepam: examples from case reports

Introduction:

Pregabalin (PGN) is an anxiolytic, analgesic, antiepileptic, and hypnotic medication. There are concerns about its abuse in the community for managing chronic insomnia and other risks when assumed in overdose or combination with other abuse substances. PGN is classified as a controlled medication. While its discontinuation is accompanied by rebound insomnia and other neurological symptoms, cross-tapering PGN with short-term diazepam (DZ) during inpatient admissions has shown promising results in dealing with PGN withdrawal symptoms accompanied by rebound insomnia.

Material and Methods:

We report three cases that began abusing their prescribed PGN. During hospital admission, our teams used a protocol for cross-tapering PGN with DZ to reduce withdrawal symptoms. Other sedative medications are suspended while alcohol is not allowed if patients are on leave from the hospital. Standardized scales for assessment were clinical global impression scale-severity (CGI-S), generalized anxiety disorder scale (GAD-7), and insomnia severity index (ISI).

Results:

The cross-tapering PGN with DZ showed similar clinical outcomes with reduced withdrawal symptoms and rebound insomnia during two weeks of cross-tapering. Eventually, DZ, too, is stopped in the hospital to avoid another dependence syndrome.

Conclusion:

As emerging in the current study, PGN has strong addictive effects in people who have insomnia and is mostly abused for its hypnotic or sleep-inducing properties when other medications have failed. As applied in the current study, DZ can manage PGN withdrawal symptoms with rebound insomnia while cross-tapering. DZ is then discontinued.

The Safety and Efficacy of Pregabalin Add-on Therapy in Restless Legs Syndrome Patients

Pregabalin is increasingly being used as a first-line treatment for symptomatic control of restless legs syndrome (RLS). This study aimed to evaluate the efficacy and safety of pregabalin as add-on therapy in RLS patients already taking dopamine agonists (DA) but still in need of further management. Patients with idiopathic RLS were enrolled, and all had already been prescribed DA for at least 3 months but still had either persistent symptoms, side effects, or comorbid insomnia. An initial dose of 75 mg pregabalin was begun, adjusted as needed, and maintained at a stable dose for 4 weeks, followed by observation for a total of 8 weeks. RLS symptoms and insomnia scores were evaluated before and after add-on pregabalin treatment. Patients were monitored for side effects that could be attributed to pregabalin. A total of 32 RLS patients were enrolled, and 20 subjects remained until the endpoint. After the pregabalin add-on, the mean IRLS score showed significant improvement compared to the baseline (p < 0.001). The insomnia severity index score also improved (p = 0.036), and no serious adverse effects were observed. Our preliminary data suggests the potential for pregabalin as an add-on therapy to DA with regards to both efficacy and safety in patients who have inadequate RLS improvement.

Sleep and pain in humans with fibromyalgia and comorbid insomnia: double-blind, crossover study of suvorexant 20 mg versus placebo

STUDY OBJECTIVES

The chronic pain disorder, fibromyalgia, is associated with sleep disturbance, typically sleep maintenance. No studies have evaluated the effect of sleep medication on pain sensitivity in this population. Suvorexant, an orexin antagonist approved for treatment of insomnia, was evaluated for effects on both sleep and the pain of fibromyalgia.

METHODS

Women age 21 to 65 years with fibromyalgia and comorbid insomnia (n = 10) were treated, double-blind, for 9 nights each with suvorexant, 20 mg and placebo in counterbalanced order. All were in good psychiatric and stable physical health and met American College of Rheumatology 2010 criteria for fibromyalgia and Diagnostic and Statistical Manual for Mental Disorders, Fifth Edition criteria for insomnia. Screening 8-hour polysomnography (PSG) was used to rule out other sleep disorders. On nights 8 and 9 of each treatment 8-hour PSG were collected and on days 1 and 8 pain sensitivity was assessed at 1100 and 1500 hours by measuring finger withdrawal latency (FWL) to a radiant heat stimulus at 5 randomly presented intensity levels.

RESULTS

Suvorexant versus placebo increased total sleep time (7.2 versus 6.7 hours, P < .05) and reduced wake after sleep onset (37 versus 67 minutes, P < .04) with no night effects or interaction. Latency to persistent sleep and sleep stage measures were not altered. FWL on both am and pm tests varied as a function of intensity (P < .001). Average FWL (over 5 intensities and both days) was increased relative to placebo on both the am (13.9 versus 13.1 seconds) and pm tests (15.8 versus 14.1 seconds, P < .03) following suvorexant the previous night.

CONCLUSIONS

Suvorexant 20 mg in patients with fibromyalgia, improved sleep time and reduced next-day pain sensitivity on assessments of FWL to a radiant heat stimulus.

CLINICAL TRIAL REGISTRY

Registry: ClinicalTrials.gov; Name: A double-blind cross-over, study to compare the hypnotic, daytime sleepiness/fatigue, and pain effects of nighttime administration of suvorexant 20 mg versus placebo in patients with fibromyalgia and comorbid insomnia; Identifier: NCT02684136; URL: https://clinicaltrials.gov/ct2/show/NCT02684136.

Drugs for Insomnia beyond Benzodiazepines: Pharmacology, Clinical Applications, and Discovery

Although the GABAergic benzodiazepines (BZDs) and Z-drugs (zolpidem, zopiclone, and zaleplon) are FDA-approved for insomnia disorders with a strong evidence base, they have many side effects, including cognitive impairment, tolerance, rebound insomnia upon discontinuation, car accidents/falls, abuse, and dependence liability. Consequently, the clinical use of off-label drugs and novel drugs that do not target the GABAergic system is increasing. The purpose of this review is to analyze the neurobiological and clinical evidence of pharmacological treatments of insomnia, excluding the BZDs and Z-drugs. We analyzed the melatonergic agonist drugs, agomelatine, prolonged-release melatonin, ramelteon, and tasimelteon; the dual orexin receptor antagonist suvorexant; the modulators of the α₂δ subunit of voltage-sensitive calcium channels, gabapentin and pregabalin; the H₁ antagonist, low-dose doxepin; and the histamine and serotonin receptor antagonists, amitriptyline, mirtazapine, trazodone, olanzapine, and quetiapine. The pharmacology and mechanism of action of these treatments and the evidence-base for the use of these drugs in clinical practice is outlined along with novel pipelines. There is evidence to recommend suvorexant and low-dose doxepin for sleep maintenance insomnia; there is also sufficient evidence to recommend ramelteon for sleep onset insomnia. Although there is limited evidence for the use of the quetiapine, trazodone, mirtazapine, amitriptyline, pregabalin, gabapentin, agomelatine, and olanzapine as treatments for insomnia disorder, these drugs may improve sleep while successfully treating comorbid disorders, with a different side effect profile than the BZDs and Z-drugs. The unique mechanism of action of each drug allows for a more personalized and targeted medical management of insomnia.

An evidence-based review of pregabalin for the treatment of fibromyalgia

OBJECTIVES

Pregabalin, an α2-δ agonist, is approved for the treatment of fibromyalgia (FM) in the United States, Japan, and 37 other countries. The purpose of this article was to provide an in-depth, evidence-based summary of pregabalin for FM as demonstrated in randomized, placebo-controlled clinical studies, including open-label extensions, meta-analyses, combination studies and post-hoc analyses of clinical study data.

METHODS

PubMed was searched using the term "pregabalin AND fibromyalgia" and the Cochrane Library with the term "pregabalin". Both searches were conducted on 2 March 2017 with no other date limits set.

RESULTS

Eleven randomized, double-blind, placebo-controlled clinical studies were identified including parallel group, two-way crossover and randomized withdrawal designs. One was a neuroimaging study. Five open-label extensions were also identified. Evidence of efficacy was demonstrated across the studies identified with significant and clinically relevant improvements in pain, sleep quality and patient status. The safety and tolerability profile of pregabalin is consistent across all the studies identified, including in adolescents, with dizziness and somnolence the most common adverse events reported. These efficacy and safety data are supported by meta-analyses (13 studies). Pregabalin in combination with other pharmacotherapies (7 studies) is also efficacious. Post-hoc analyses have demonstrated the onset of pregabalin efficacy as early as 1-2 days after starting treatment, examined the effect of pregabalin on other aspects of sleep beyond quality, and shown it is effective irrespective of the presence of a wide variety of patient demographic and clinical characteristics.

CONCLUSIONS

Pregabalin is a treatment option for FM; its clinical utility has been comprehensively demonstrated.

Placebo analgesia persists during sleep: An experimental study

Although placebo analgesia is a well-recognized phenomenon with important clinical implications, the possibility that placebo effects occur during sleep has received little attention. This experimental study examined whether responsiveness to acute heat pain stimuli applied during sleep could be reduced following a placebo conditioning procedure administered before sleep. Healthy individuals (n = 9) underwent polysomnographic recordings for one habituation night followed by one placebo analgesia night and one control night in counterbalanced order. Conditioning induced robust analgesia expectations before the placebo night. In the morning after the placebo night, participants reported less nocturnal pain, anxiety, and associated sleep disturbance (all p's < 0.05) compared to the control night. Furthermore, placebo induction produced a 10% reduction in brain arousals evoked by noxious stimuli during rapid-eye-movement (REM) sleep (p = 0.03), consistent with our previous findings suggesting that analgesia expectations are reprocessed during REM sleep. In contrast, arousals increased by 14% during slow wave sleep (SWS) (p = 0.02). In the morning after the last recording night, placebo testing administered as a manipulation check confirmed that typical placebo analgesic responses were produced during waking (p's < 0.05). These results suggest that analgesia expectations developed before sleep reduced nocturnal pain perception and subjective sleep disturbances and activated brain processes that modulate incoming nociceptive signals differentially according to sleep stage. These results need to be replicated in future studies exploring how analgesia expectations may be reactivated during different sleep stages to modulate nociceptive responses.

Increased Risk of Myofascial Pain Syndrome Among Patients with Insomnia

Objective

The aim of this study is to evaluate the risk of developing myofascial pain syndrome among patients diagnosed with insomnia.

Methods

We conducted a population-based longitudinal study of a matched cohort with 7,895 participants (1,579 patients with insomnia and 6,316 controls) who were selected from the Taiwan National Health Insurance Research Database. The patients were observed for a maximum of 10 years to determine the incidence of newly diagnosed myofascial pain syndrome. A Cox regression analysis was performed to identify the risk factors associated with myofascial pain syndrome in patients with insomnia.

Results

During the 10-year follow-up period, 182 insomnia patients (14.9 per 1,000 person-years) and 379 controls (7.5 per 1,000 person-years) were diagnosed with myofascial pain syndrome. The incidence risk ratio of myofascial pain syndrome between the insomnia and control patients was 2.00 (95% confidence interval [CI] = 1.67-2.38, P  < 0.001). After adjusting for age, sex, monthly income, urbanization, and comorbidities, the insomnia patients were 1.93 times more likely to develop myofascial pain syndrome (95% CI = 1.62-2.31, P  < .001) than the control patients. Malignant neoplasm (hazard ratio = 3.08) and living in urban areas (hazard ratio = 3.05) were identified as independent risk factors for myofascial pain syndrome in patients with insomnia.

Conclusions

Patients with insomnia had a higher risk of developing myofascial pain syndrome than controls. This study adds to the understanding of the complex relationship between sleep disturbance and pain.

Interpreting the Effectiveness of Opioids and Pregabalin for Pain Severity, Pain Interference, and Fatigue in Fibromyalgia Patients

OBJECTIVE

To evaluate the effectiveness of opioids and/or pregabalin on patient-reported outcomes among fibromyalgia (FM) patients based on levels of improvement.

METHODS

A total of 1,421 FM patients were identified, with 3,082 observational periods of opioids with or without pregabalin use between April 2008 and February 2015. Patients were categorized by opioids, and pregabalin with and without opioids; opioids were designated by morphine equivalent dose (MED) of ≤ 20 (low MED), > 20 to < 100 (moderate MED), ≥ 100 (high MED), and pregabalin doses of ≤ 150 mg, 151 to 300 mg, and 301 to 450 mg. Proportions of patients meeting clinically relevant thresholds of ≥ 30% and ≥ 50% improvement for pain interference (ability to enjoy life; activity; mood; relationships; sleep), pain severity, and fatigue were compared among treatments, and area under the curve (AUC) for improvement and worsening of effects was determined, enabling ranking of treatments. Further analysis compared pregabalin doses.

RESULTS

Pregabalin without opioids resulted in the highest proportions of patients with ≥ 30% improvement on all pain items and pain interference with "ability to enjoy life," "activity" "mood," and "sleep." For the ≥ 50% threshold, pregabalin alone was highest for all pain interference items and for "average pain" and "worst pain." Pregabalin was consistently lowest across thresholds for fatigue, but showed better results combined with moderate MED opioids. Pregabalin doses recommended for treatment of FM (151 to 450 mg) generally resulted in the highest proportion of patients achieving thresholds relative to opioids. The AUC results were consistent with thresholds; pregabalin without opioids resulted in the greatest benefits with regard to improvement, with the highest ranking for overall improvement and overall effects.

CONCLUSION

Pregabalin without opioids provided the most favorable outcomes overall based on ≥ 30% and ≥ 50% improvement thresholds and AUC, with support for moderate MED opioids + pregabalin in patients suffering from fatigue. While most patients took less than recommended pregabalin doses, higher doses may lead to improved outcomes.

Effect modification, interaction and mediation: an overview of theoretical insights for clinical investigators

We revisited the three interrelated epidemiological concepts of effect modification, interaction and mediation for clinical investigators and examined their applicability when using research databases. The standard methods that are available to assess interaction, effect modification and mediation are explained and exemplified. For each concept, we first give a simple “best-case” example from a randomized controlled trial, followed by a structurally similar example from an observational study using research databases. Our explanation of the examples is based on recent theoretical developments and insights in the context of large health care databases. Terminology is sometimes ambiguous for what constitutes effect modification and interaction. The strong assumptions underlying the assessment of interaction, and particularly mediation, require clinicians and epidemiologists to take extra care when conducting observational studies in the context of health care databases. These strong assumptions may limit the applicability of interaction and mediation assessments, at least until the biases and limitations of these assessments when using large research databases are clarified.

Pregabalin for pain in fibromyalgia in adults

BACKGROUND

This review updates part of an earlier Cochrane review on 'Pregabalin for acute and chronic pain in adults' (Moore 2009), and considers only fibromyalgia pain.Antiepileptic drugs have been used in pain management since the 1960s. Pregabalin is an antiepileptic drug also used in management of chronic pain conditions, including fibromyalgia. Pain response with pregabalin is associated with major benefits for other symptoms, and improved quality of life and function in people with chronic painful conditions.

OBJECTIVES

To assess the analgesic efficacy and adverse events of pregabalin for pain in fibromyalgia in adults, compared with placebo or any active comparator.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and EMBASE for randomised controlled trials from inception to May 2009 for the original review and to 16 March 2016 for this update. We also searched the reference lists of retrieved studies and reviews, and online clinical trial registries.

SELECTION CRITERIA

We included randomised, double-blind trials of eight weeks' duration or longer, comparing pregabalin with placebo or another active treatment for relief of pain in fibromyalgia, and reporting on the analgesic effect of pregabalin, with subjective pain assessment by the participant.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality and potential bias. Primary outcomes were participants with moderate pain relief (at least 30% pain relief over baseline or much or very much improved on Patient Global Impression of Change scale (PGIC)) or substantial pain relief (at least 50% pain relief over baseline or very much improved on PGIC). Where pooled analysis was possible, we used dichotomous data to calculate risk ratio and number needed to treat (NNT), using standard methods. We assessed the quality of the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created 'Summary of findings' tables.

MAIN RESULTS

Our searches identified two new published studies with classic design, and one new published study with an enriched enrolment randomised withdrawal (EERW) design.We included eight studies. Five (3283 participants) had a classic design in which participants were randomised at the start of the study to pregabalin (150, 300, 450, or 600 mg daily) or placebo, with assessment after 8 to 13 weeks of stable treatment. No studies included active comparators. Studies had low risk of bias, except that the last observation carried forward (LOCF) imputation method used in analyses of the primary outcomes could overestimate treatment effect.Pregabalin increased the number of participants experiencing substantial benefit (at least 50% pain intensity reduction after 12 or 13 weeks' stable treatment (450 mg: RR 1.8, 95% CI 1.4 to 2.1, 1874 participants, 5 studies, high quality evidence)). Substantial benefit with pregabalin 300 to 600 mg was experienced by about 14% of participants with placebo, but about 9% more with pregabalin 300 to 600 mg (22% to 24%) (high quality evidence). Pregabalin increased the number of participants experiencing moderate benefit (at least 30% pain intensity reduction after 12 or 13 weeks' stable treatment) (450 mg: RR 1.5, 95% CI (1.3 to 1.7), 1874 participants, 5 studies, high quality evidence). Moderate benefit with pregabalin 300 to 600 mg was experienced by about 28% of participants with placebo, but about 11% more with pregabalin 300 to 600 mg (39% to 43%) (high quality evidence). A similar magnitude of effect was found using PGIC of 'very much improved' and 'much or very much improved'. NNTs for these outcomes ranged between 7 and 14 (high quality evidence).A small study (177 participants) compared nightly with twice-daily pregabalin, and concluded there was no difference in effect.Two studies (1492 participants began initial dose titration, 687 participants randomised) had an EERW design in which those with good pain relief after titration were randomised, double blind, to continuing the effective dose (300 to 600 mg pregabalin daily) or a short down-titration to placebo for 13 or 26 weeks. We calculated the outcome of maintained therapeutic response (MTR) without withdrawal, equivalent to a moderate benefit. Of those randomised, 40% had MTR with pregabalin and 20% with placebo (high quality evidence). The NNT was 5, but normalised to the starting population tested it was 12. About 10% of the initial population would have achieved the MTR outcome, similar to the result from studies of classic design. MTR had no imputation concerns.The majority (70% to 90%) of participants in all treatment groups experienced adverse events. Specific adverse events were more common with pregabalin than placebo, in particular dizziness, somnolence, weight gain, and peripheral oedema, with number needed to harm of 3.7, 7.4, 18, and 19 respectively for all doses combined (high quality evidence). Serious adverse events did not differ between active treatment groups and placebo (very low quality evidence). Withdrawals for any reason were more common with pregabalin than placebo only with the 600 mg dose in studies of classic design. Withdrawals due to adverse events were about 10% higher with pregabalin than placebo, but withdrawals due to lack of efficacy were about 6% lower (high quality evidence).

AUTHORS' CONCLUSIONS

Pregabalin 300 to 600 mg produces a major reduction in pain intensity over 12 to 26 weeks with tolerable adverse events for a small proportion of people (about 10% more than placebo) with moderate or severe pain due to fibromyalgia. The degree of pain relief is known to be accompanied by improvements in other symptoms, quality of life, and function. These results are similar to other effective medicines in fibromyalgia (milnacipran, duloxetine).

The influence of thiamin on the efficacy of pregabalin in rats with spinal nerve ligation (SNL)-induced neuropathic pain

OBJECTIVE

The thiamin is often used in the treatment of neuropathy, and pregabalin is often used to treat neuropathic pain. Our study examined the influence of thiamin on the efficacy of pregabalin in a rat model of spinal nerve ligation (SNL)-induced neuropathic pain.

METHODS

Sprague-Dawley male rats were randomly divided into six groups. The neuropathic pain-relieving properties were measured by plantar test, cold plate test, and hot plate test after administration of pregabalin (i.v) and/or thiamin (i.p) in SNL rats 14 days after operation.

RESULTS

In the therapy period, pregabalin, or thiamin alone all produced antinociceptive effects in rats with neuropathic pain. And combination treatment of thiamin and pregabalin resulted in an enhanced pain relief compared to the administration of pregabalin or thiamin alone.

CONCLUSION

Combination of thiamin and pregabalin produces an additive antinociceptive effect in neuropathic pain rats, this drug combination may offer a beneficial treatment option for neuropathic pain.

Clinical utility, safety, and efficacy of pregabalin in the treatment of fibromyalgia

Fibromyalgia is a chronic debilitating medical syndrome with limited therapeutic options. Pregabalin, an anticonvulsant and α-2-Δ subunit receptor ligand, is one of the anchor drugs approved by the US Food and Drug Administration for the treatment of fibromyalgia. The drug has shown clinically meaningful benefits across multiple symptom domains of fibromyalgia. Efficacy of pregabalin in fibromyalgia pain has been evaluated in at least five high-quality randomized trials, two long-term extension studies, a meta-analysis, a Cochrane database systematic review, and several post hoc analyses. These studies also hint towards a meaningful benefit on sleep, functioning, quality of life, and work productivity. Side effects of pregabalin, although common, are mild to moderate in intensity. They are noted early during therapy, improve or disappear with dose reduction, and are not usually life- or organ threatening. In most patients, tolerance develops to the most common side effects, dizziness, and somnolence, with time. With close clinical monitoring at initiation or dose titration, pregabalin can be effectively used in primary care setting. Pregabalin is cost saving with long-term use and its cost-effectiveness profile is comparable, if not better, to that of other drugs used in fibromyalgia. In the present era of limited therapeutic options, pregabalin undoubtedly retains its role as one of cardinal drugs used in the treatment of fibromyalgia. This review intends to discuss the clinical utility of pregabalin in the management of fibromyalgia with a focus on efficacy, safety, and cost-effectiveness.

Antinociceptive and hypnotic activities of pregabalin in a neuropathic pain-like model in mice

To evaluate the antinociceptive and hypnotic effects of pregabalin, we established a neuropathic pain-like model in mice using partial sciatic nerve ligation (PSNL), and examined thermal hyperalgesia, mechanical allodynia, electroencephalogram, rota-rod testing, and c-Fos expression in the anterior cingulate cortex. Gabapentin was used as a reference drug in the study. Pregabalin administered i.g. at 12.5 and 25mg/kg prolonged the duration of thermal latencies by 1.4- and 1.6-fold and increased the mechanical threshold by 2.2- and 3.1-fold 3h after administration, respectively, but did not affect motor coordination in PSNL mice, compared with vehicle control. Pregabalin (12.5 and 25mg/kg) given at 6:30 increased the amount of non-rapid eye movement sleep in a 4-h period by 1.3- and 1.4-fold, respectively, in PSNL mice. However, pregabalin (25mg/kg) given at 20:30 did not alter the sleep pattern in normal mice. Immunohistochemical study showed that PSNL increased c-Fos expression in the neurons of anterior cingulate cortex by 2.1-fold, which could be reversed by pregabalin. These results indicate that pregabalin is an effective treatment for both neuropathic pain and sleep disturbance in PSNL mice.

Effects of pregabalin in patients with hypnotic-dependent insomnia

STUDY OBJECTIVES

Long-term use of hypnotics runs the risk of dependency, and subjects usually experience difficulties in withdrawal. The objective of this study was to investigate the success of withdrawal using pregabalin and its efficacy on sleep in patients with hypnotic-dependent insomnia.

METHODS

We enrolled patients with hypnotic-dependent insomnia who were 18 years or older. The starting dosage of pregabalin was 75 mg/day and was increased up to as much as 300 mg/day, depending on the individual patient's condition, while tapering off hypnotics. After 4 weeks of titration, the final dosage amount was maintained for at least another 4 weeks. Sleep and clinical variables were evaluated at baseline and after treatment, using the Korean versions of various sleep questionnaires as well as polysomnography.

RESULTS

Forty subjects were enrolled, with a mean age of 52.0 ± 8.5 years, of whom 28 (70.0%) were women. Twenty-one (52.5%) subjects successfully withdrew from hypnotics. The duration of withdrawal was 42.1 ± 16.0 days (range: 27.0∼84.0). The mean pregabalin dose was 121.4 ± 69.0 mg/day (range: 75.0∼300.0). After pregabalin treatment, there was a significant improvement in the total score of the Pittsburgh Sleep Quality Index (15.0 ± 2.1, 8.9 ± 3.0, p < 0.001), and insomnia severity index (20.9 ± 4.3, 9.6 ± 4.4, p < 0.001); however, most of the sleep variables of the PSG showed no differences. The main adverse effects of pregabalin were nausea and dizziness.

CONCLUSIONS

Our results showed pregabalin may be a promising candidate for withdrawal from hypnotics and improved sleep in patients with hypnotic-dependent insomnia.

Daytime napping associated with increased symptom severity in fibromyalgia syndrome

Background

Previous qualitative research has revealed that people with fibromyalgia use daytime napping as a coping strategy for managing symptoms against clinical advice. Yet there is no evidence to suggest whether daytime napping is beneficial or detrimental for people with fibromyalgia. The purpose of this study was to explore how people use daytime naps and to determine the links between daytime napping and symptom severity in fibromyalgia syndrome.

Methods

A community based sample of 1044 adults who had been diagnosed with fibromyalgia syndrome by a clinician completed an online questionnaire. Associations between napping behavior, sleep quality and fibromyalgia symptoms were explored using Spearman correlations, with possible predictors of napping behaviour entered into a logistic regression model. Differences between participants who napped on a daily basis and those who napped less regularly, as well as nap duration were explored.

Results

Daytime napping was significantly associated with increased pain, depression, anxiety, fatigue, memory difficulties and sleep problems. Sleep problems and fatigue explained the greatest amount of variance in napping behaviour, p < 0.010. Those who engaged in daytime naps for >30 minutes had higher memory difficulties (t = −3.45) and levels of depression (t = −2.50) than those who napped for shorter periods (<30mins) (p < 0.010).

Conclusions

Frequent use and longer duration of daytime napping was linked with greater symptom severity in people with fibromyalgia. Given the common use of daytime napping in people with fibromyalgia evidence based guidelines on the use of daytime napping in people with chronic pain are urgently needed.

Primary sleep disorders in people with epilepsy: clinical questions and answers

The questions facing clinicians with patients with sleep disorder and epilepsy are addressed in this article. Both adult and child epilepsy are discussed in the context of the most typical questions a clinician would have, such as "Are parasomnias more common in people with epilepsy?", "Is sleep architecture abnormal in children with epilepsy", along with outcomes of numerous questionnaire-based, case-based, and double-blind placebo studies on such aspects as sleep duration, daytime sleepiness, anxiety and fears, limb movement, nocturnal seizures, agitation, behavioral disorders, and learning disorders.

Effect of Pregabalin on Cardiovascular Responses to Exercise and Postexercise Pain and Fatigue in Fibromyalgia: A Randomized, Double-Blind, Crossover Pilot Study

Pregabalin, an approved treatment for fibromyalgia (FM), has been shown to decrease sympathetic nervous system (SNS) activity and inhibit sympathetically maintained pain, but its effects on exercise responses have not been reported. Methods. Using a randomized double-blind crossover design, we assessed the effect of 5 weeks of pregabalin (versus placebo) on acute cardiovascular and subjective responses to moderate exercise in 19 FM patients. Blood pressure (BP), heart rate (HR), and ratings of perceived exertion (RPE) during exercise and ratings of pain, physical fatigue, and mental fatigue before, during, and for 48 hours after exercise were compared in patients on pregabalin versus placebo and also versus 18 healthy controls. Results. On placebo, exercise RPE and BP were significantly higher in FM patients than controls (p < 0.04). Pregabalin responders (n = 12, defined by patient satisfaction and symptom changes) had significantly lower exercise BP, HR, and RPE on pregabalin versus placebo (p < 0.03) and no longer differed from controls (p > 0.26). Cardiovascular responses of nonresponders (n = 7) were not altered by pregabalin. In responders, pregabalin improved ratings of fatigue and pain (p < 0.04), but negative effects on pain and fatigue were seen in nonresponders. Conclusions. These preliminary findings suggest that pregabalin may normalize cardiovascular and subjective responses to exercise in many FM patients.

Time to improvement of pain and sleep quality in clinical trials of pregabalin for the treatment of fibromyalgia

OBJECTIVE

To determine the time to immediate and sustained clinical improvement in pain and sleep quality with pregabalin in patients with fibromyalgia.

DESIGN

A post hoc analysis of four 8- to 14-week phase 2-3, placebo-controlled trials of fixed-dose pregabalin (150-600 mg/day) for fibromyalgia, comprising 12 pregabalin and four placebo treatment arms.

PATIENTS

A total of 2,747 patients with fibromyalgia, aged 18-82 years.

METHODS

Pain and sleep quality scores, recorded daily on 11-point numeric rating scales (NRSs), were analyzed to determine time to immediate improvement with pregabalin, defined as the first of ≥2 consecutive days when the mean NRS score was significantly lower for pregabalin vs placebo in those treatment arms with a significant improvement at endpoint, and time to sustained clinical improvement with pregabalin, defined as a ≥1-point reduction of the baseline NRS score of patient responders who had a ≥30% improvement on the pain NRS, sleep NRS, or Fibromyalgia Impact Questionnaire (FIQ) from baseline to endpoint, or who reported "much improved" or "very much improved" on the Patient Global Impression of Change (PGIC) at endpoint.

RESULTS

Significant improvements in pain and sleep quality scores at endpoint vs placebo were seen in 8/12 and 11/12 pregabalin treatment arms, respectively (P < 0.05). In these arms, time to immediate improvements in pain or sleep occurred by day 1 or 2. Time to sustained clinical improvement occurred significantly earlier in pain, sleep, PGIC, and FIQ responders (P < 0.02) with pregabalin vs placebo.

CONCLUSIONS

Both immediate and sustained clinical improvements in pain and sleep quality occurred faster with pregabalin vs placebo.

Weighing the balance: how analgesics used in chronic pain influence sleep?

Pain and sleep share a bidirectional relationship, with each influencing the other. Several excellent reviews have explored this relationship. In this article, we revisit the evidence and explore existing research on this complex inter-relationship. The primary focus of the article is on the pharmacological treatment of chronic non-malignant pain and the main purpose is to review the effect of various pharmacological agents used in the management of chronic pain on sleep. This has not been comprehensively done before. We explore the clinical use of these agents, their impact on sleep architecture and sleep physiology, the mechanism of action on sleep parameters and sleep disorders associated with these agents. Pharmacological classes reviewed include antidepressants, opioid analgesics, anti-epileptics, cannabinoids and non-steroidal anti-inflammatory agents, drugs most commonly used to manage chronic pain. The objective is to help health professionals gain better insight into the complex effect that commonly used analgesics have on an individual's sleep and how this could impact on the effectiveness of the drug as an analgesic. We conclude that antidepressants have both positive and negative effects on sleep, so do opioids, but in the latter case the evidence shifts towards the counterproductive side. Some anticonvulsants are sleep sparing and non-steroidal anti-inflammatory drugs (NSAIDs) are sleep neutral. Cannabinoids remain an underexplored and researched group.

Fibromyalgia

Fibromyalgia is a chronic pain condition present in 2-4% of the population. Fibromyalgia consists of widespread pain with similarities to neuropathic pain in clinical findings, pathophysiology, and neuropharmacology. Pain is the predominant symptom and allodynia and hyperalgesia are common signs. Extreme fatigue, impaired cognition and nonrestorative sleep difficulties coexist in addition to other somatic symptoms. Research including neuroimaging investigations shows abnormalities in neurotransmitters and an abnormal response to pain. Altered pain processing peripherally and centrally contribute to central sensitization and a dampened effect of the diffuse noxious inhibitory control (DNIC). Successful management incorporates education of the patient in self-management skills, cognitive behavioral therapy (CBT), exercise, and drug therapy. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors (SNRIs) (duloxetine and milnacipran), α2-δ ligands (gabapentin and pregabalin) are effective in reducing pain by≥30%. Some success has been shown with dopamine agonists (pramipexole), tramadol, other opioids and cannabinoids (nabilone). Further evidence-based trials using complementary treatments are needed. Fibromyalgia is complex and requires a multidisciplinary approach to treatment. Patient self-management is key.

Managing insomnia: an overview of insomnia and pharmacologic treatment strategies in use and on the horizon

This review explores basic sleep physiology, the mechanism of action for each class of hypnotic agents, their clinical application based on pharmacodynamic and pharmacokinetic factors, and potential pharmacologic sleep-inducing mechanisms of future hypnotics. The paper challenges the reader to understand the neuroscientific basis of insomnia and use this knowledge to guide prescription of hypnotic agents. Currently indicated hypnotic agents are discussed with regard to their mechanism of drug action and clinical application. A broader discussion is developed throughout this paper regarding other non-indicated agents that may improve sleep and describing newer pharmacological treatments that may become available in the future for use in sleep disorders and their comorbid conditions.

Sleep duration and glycemic control in patients with diabetes mellitus: Korea National Health and Nutrition Examination Survey 2007-2010

Short sleep duration has been reported to increase the risk of diabetes. However, the influence of sleep duration on glycemic control in diabetic patients has not been clarified. In this study we evaluated the association between sleep duration and glycemic control in diabetic patients. We analyzed the data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2007-2010. Sleep duration was classified into five groups: <6, 6, 7, 8, and ≥9 h/day. Fasting blood glucose and HbA1c showed a U-shaped trend according to sleep duration. Sleep duration of 7 h/day had the lowest HbA1c (7.26%) among the subjects (P=0.026). In the older age group (≥65 yr), a sleep duration of 6 h/day was associated with the lowest HbA1c (7.26%). The adjusted odds ratio (OR) with a 95% confidence interval (CI) of worse glycemic control (HbA1c ≥7.0%) in group of sleep duration of ≥9 h/day was 1.48 (1.04-2.13) compared with the group of 7 h/day. This relationship disappeared after adjusting duration of diabetes (OR, 1.38; 95% CI, 0.93-2.03). Our results suggest that sleep duration and glycemic control in diabetic patients has U-shaped relationship which was mainly affected by duration of diabetes.

Effects of pregabalin on sleep in generalized anxiety disorder

Sleep disturbance is a cardinal symptom in both DSM-IV and ICD-10 criteria for generalized anxiety disorder (GAD). This review summarizes the results of clinical trials and pooled analyses that provide data on pregabalin's effect on sleep disturbance in patients diagnosed with GAD. The hypothesized mechanism of action of pregabalin is distinctly different from other anxiolytics. Pregabalin binds to a membrane α2δ subunit protein to inhibit release in excited central nervous system neurons of neurotransmitters implicated in pathological anxiety. Treatment with pregabalin has been found to be associated with significant improvement in GAD-related sleep disturbance across seven placebo-controlled clinical trials. Treatment with pregabalin is associated with improvement in all forms of insomnia and improvement in sleep has been found to be correlated with reduction in functional impairment and improvement in quality of life on subjective global measures. Results of a mediational analysis suggest that 53% of the effect of pregabalin on sleep disturbance was due to a direct effect and 47% was due to an indirect effect, mediated through prior reduction in anxiety symptom severity. In patients with GAD, improvement in sleep has been found to be associated with a reduction in daytime sleepiness. However, dose-related sedation is reported, typically in the first 2 wk of treatment, in approximately 10-30% of patients, depending on the dose used and the speed of titration. Insomnia is a common component of the clinical presentation of GAD and pregabalin appears to be an efficacious treatment for this often chronic and disabling symptom.

Relationship between pain relief and improvements in patient function/quality of life in patients with painful diabetic peripheral neuropathy or postherpetic neuralgia treated with pregabalin

BACKGROUND

In patients with chronic pain due to diabetic peripheral neuropathy (DPN) or postherpetic neuralgia (PHN), pregabalin treatment results in pain relief and improved patient function/quality of life (QoL). Few studies, however, have examined the exact relationship between pain relief and improvements in patient function/QoL. It is unclear, for example, whether pregabalin has a direct independent effect on patient function/QoL or whether improvements in function/QoL are an indirect consequent of pain relief.

OBJECTIVES

To determine whether improvements in function/QoL in response to pregabalin treatment are related to the extent of pain relief in patients with neuropathic pain due to DPN or PHN and to determine whether pregabalin has a direct independent effect on patient function/QoL that is distinct from its effects on pain.

METHODS

Data from 11 randomized, double-blind, placebo-controlled trials of pregabalin for the treatment of DPN or PHN were pooled for this analysis. Changes in patient function/QoL scores were plotted according to the extent of pain relief to assess whether greater levels of pain relief were associated with greater improvement in function/QoL. A novel mediation analysis was used to asses to what extent the effects of pregabalin on function/QoL scores are a direct treatment effect as opposed to an indirect effect mediated through improvements in pain or sleep.

RESULTS

Moderate-to-substantial pain relief (a ≥30% decrease in pain) in response to pregabalin treatment was associated with significant (P < 0.05) improvements in 36-Item Short Form Health Survey (SF-36) scores (used to assess patient function/QoL). In many patients, greatest improvement in SF-36 scores was reported by patients achieving ≥50% decrease in pain. Analysis of Patient Global Impression of Change scores revealed a similar trend, where >80% of patients who achieved substantial pain relief also reported their status as much or very much improved. A substantial direct pregabalin treatment effect was evident for many SF-36 domains that could not be explained by pain relief or improvement in sleep.

CONCLUSIONS

In patients with chronic pain due to DPN or PHN, improvements in patient function/QoL in response to pregabalin treatment are correlated with the extent of pain relief. However, such improvements in function/QoL are not mediated entirely through pain relief but are the result of a combination of pregabalin's effects on pain and sleep disturbance and a direct effect on patient function itself.

Interpretation of patient-reported outcomes

A patient-reported outcome is any report on the status of a patient’s health condition that comes directly from the patient. Clear and meaningful interpretation of patient-reported outcome scores are fundamental to their use as they can be valuable in designing studies, evaluating interventions, educating consumers, and informing health policy makers involved with regulatory, reimbursement, and advisory agencies. Interpretation of patient-reported outcome scores, however, is often not well understood because of insufficient data or lack of experience or clinical understanding to draw from. This article provides an update review on two broad approaches – anchor-based and distributed-based – aimed at enhancing the understanding and meaning of patient-reported outcome scores. Anchor-based approaches include percentages based on thresholds, criterion-group interpretation, content-based interpretation, and clinical important difference. Distributed-based approaches include effect size, probability of relative benefit, and responder analysis and cumulative proportions. A third strategy called mediation analysis, which can elucidate a health condition measured by a patient-reported outcome in the context of an intervention’s mechanism of action, is also highlighted and illustrated. Mediation analysis in the context of interpretation of patient-reported outcome scores is a relatively new development. The logic and rationale of the three methods are expressed generally. While the three approaches themselves are not new, some applications of them taken from their examples published in the past few years are original and coalesced in this article to add real-life implications of the different methodologies in one integrated report.

What is the role of sedating antidepressants, antipsychotics, and anticonvulsants in the management of insomnia?

Psychiatric medications such as antidepressants, antipsychotics, and anticonvulsants are commonly prescribed by physicians for the off-label use of improving sleep. Reasons for preferential prescription of these medications over FDA-approved insomnia drugs may include a desire to treat concurrent sleep problems and psychiatric illness with a single medication, and/or an attempt to avoid hypnotic drugs due to their publicized side effects. However, there have been few large studies demonstrating the efficacy and safety of most off-label medications prescribed to treat insomnia. In addition, many of these medications have significant known side effect profiles themselves. Here we review the pertinent research studies published in recent years on antidepressant, antipsychotic, and anticonvulsant medications frequently prescribed for sleep difficulties. Although there have been few large-scale studies for most of these medications, some may be appropriate in the treatment of sleep issues in specific well-defined populations.

Effect of pregabalin on sleep in patients with fibromyalgia and sleep maintenance disturbance: a randomized, placebo-controlled, 2-way crossover polysomnography study

OBJECTIVE

To assess the effect of pregabalin on polysomnographic (PSG) measures of sleep and patient-rated sleep, tiredness, and pain in fibromyalgia patients.

METHODS

We performed a randomized, double-blind, placebo-controlled, 2-period crossover PSG study. Patients ages ≥18 years with fibromyalgia satisfied subjective and objective sleep disturbance criteria prior to randomization. Eligible patients were randomized (1:1) to pregabalin (300-450 mg/day) or placebo for crossover period 1, and vice versa for period 2. Each crossover period comprised a dose-adjustment and dose-maintenance phase, with a 2-week taper/washout between periods. In-laboratory PSGs were recorded during 2 consecutive nights at screening and at the end of each crossover period. The primary end point was the difference in sleep maintenance defined by PSG-recorded wake after sleep onset (WASO; minutes) between 4 weeks of treatment with pregabalin and with placebo. Other PSG measures; patient-rated sleep, tiredness, and pain; and tolerability were assessed.

RESULTS

Of 119 patients randomized (103 women [86.6%], mean age 48.4 years), 102 (85.7%) completed both periods. Patients treated with pregabalin showed a reduction in PSG-determined WASO versus treatment with placebo (week 4 difference: -19.2 minutes [95% confidence interval (95% CI) -26.7, -11.6]; P < 0.0001). Pain score improved (decreased) with pregabalin versus placebo treatment at all 4 weeks (week 4 difference: -0.52 [95% CI -0.90, -0.14]; P = 0.0084). Modest (ρ = <0.3) but significant correlations were found between PSG sleep assessments and ratings of pain and sleep quality. Frequently reported all-causality adverse events (pregabalin versus placebo) were: dizziness (30.4% versus 9.9%), somnolence (20.5% versus 4.5%), and headache (8.9% versus 8.1%).

CONCLUSION

Patients with fibromyalgia treated with pregabalin had statistically significant and meaningful improvements in sleep, as assessed by PSG. Patients with fibromyalgia also reported decreased daily pain. Pregabalin was well tolerated.

Chronic insomnia

Insomnia is a prevalent complaint in clinical practice that can present independently or comorbidly with another medical or psychiatric disorder. In either case, it might need treatment of its own. Of the different therapeutic options available, benzodiazepine-receptor agonists (BzRAs) and cognitive-behavioural therapy (CBT) are supported by the best empirical evidence. BzRAs are readily available and effective in the short-term management of insomnia, but evidence of long-term efficacy is scarce and most hypnotic drugs are associated with potential adverse effects. CBT is an effective alternative for chronic insomnia. Although more time consuming than drug management, CBT produces sleep improvements that are sustained over time, and this therapy is accepted by patients. Although CBT is not readily available in most clinical settings, access and delivery can be made easier through use of innovative methods such as telephone consultations, group therapy, and self-help approaches. Combined CBT and drug treatment can optimise outcomes, although evidence to guide clinical practice on the best way to integrate these approaches is scarce.

Multidisciplinary approach to fibromyalgia: what is the teaching?

Fibromyalgia (FM) is a rheumatic disease that is characterised by chronic musculoskeletal pain, stiffness, fatigue, sleep and mood disorder. FM patients demonstrate dysregulation of pain neurotransmitter function and experience a neurohormone-mediated association with sleep irregularities. There are currently no instrumental tests or specific diagnostic markers for FM, and many of the existing indicators are only significant for research purposes. Anti-depressants, non-steroidal anti-inflammatory drugs (NSAIDS), opioids, sedatives, muscle relaxants and antiepileptics have all been used to treat FM with varying results. It has been shown that interdisciplinary treatment programmes lead to greater improvements in subjective pain and function than monotherapies. Physical exercise and multimodal cognitive behavioural therapy are the most widely accepted and beneficial forms of non-pharmacological therapy.

Hypnosis for symptom management in women with breast cancer: a pilot study

Eight women who were in treatment for breast cancer (n = 4) or breast cancer survivors (n = 4), presenting with 1 or more of 4 symptoms (chronic pain, fatigue, hot flashes, and sleep difficulties), were given 4 to 5 sessions of self-hypnosis training for symptom management. Analyses revealed (a) significant pre- to posttreatment decreases in pain intensity, fatigue, and sleep problems and (b) that pain intensity continued to decrease from posttreatment to 6-month follow-up. Although there was a slight increase in fatigue severity and sleep problems from posttreatment to 6-month follow-up, the follow-up scores did not return to pretreatment levels. The findings provide initial support for using hypnosis to manage symptoms in women who are breast cancer survivors. Clinical trials evaluating hypnosis efficacy over and above other treatments are warranted.

Drug-induced sleep: theoretical and practical considerations

Faithful replication of normal sleep through medications--can it be achieved? Departure from normal sleep with the use of drugs--when is it desired? Answers to these questions depend on accurate understanding of sleep and on concrete criteria upon which to define it. Since these elements are evolving sciences, as yet incompletely known, one might take a nihilistic approach that we simply cannot judge whether we have successfully replicated sleep, since we do not fully grasp what sleep is or what it does. To address these potential obstacles, our article is written in two sections. The first addresses theoretical considerations for how medications might be seen in the larger framework of sleep. The purpose of this section is to inform readers about key issues in evaluating whether a drug has sufficient data to persuasively argue it is re-creating sleep. (We hope that researchers interested in conducting studies, or critical readers of the drug-study literature, might find this section particularly useful.) The second section of this article approaches exemplary, current concepts of pharmacologic manipulation of sleep, organized by disorders as articulated by the International Classification of Sleep Disorders (2005). This second section will combine practical knowledge of clinical sleep medicine, with emphasis on contemporary knowledge about molecular mechanisms that are felt to underlie some of these phenomena. We recognize that our collective knowledge about sleep will advance in the coming years. We hope that this article serves to facilitate that advance.

Relationships between changes in pain severity and other patient-reported outcomes: an analysis in patients with posttraumatic peripheral neuropathic pain

Background

The objective of this study is to use the pain numeric rating scale (NRS) to evaluate associations between change in pain severity and changes in sleep, function, and mood assessed via patient-reported outcomes (PROs) in patients with posttraumatic pain.

Methods

This is a secondary analysis of a clinical trial evaluating pregabalin in patients with posttraumatic peripheral neuropathic pain (N = 254). Regression models were used to determine associations between changes in pain (0-10 NRS) as the predictor and scores on the following PRO measures as the outcome: Pain Interference Index; Hospital Anxiety and Depression Scale anxiety and depression subscales; Medical Outcomes Study-Sleep Scale 9-item Sleep Problems Index and Sleep Disturbance subscale; and Daily Sleep Interference Scale (0-10 NRS).

Results

Change in pain severity showed clear, direct relationships with changes in function, anxiety, depression, and sleep PROs, all of which were statistically significant (P <.001). Results from subgroup analyses (≥30% or ≥50% pain responders, pregabalin or placebo treatment, age ≤ 51 years or > 51 years) tended to be consistent with results from the overall sample.

Conclusions

Overall, a direct relationship exists between pain and various aspects of patient's well-being and functioning, which can provide a quantitative assessment of how improvements in pain may be expected to relate to other patient outcomes. (http://ClinicalTrials.gov Identifier number NCT00292188; EudraCT #2005-003048-78).