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Dive into the research topics where Ralf Kohnen is active.

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Featured researches published by Ralf Kohnen.


Lancet Neurology | 2008

Efficacy of rotigotine for treatment of moderate-to-severe restless legs syndrome: a randomised, double-blind, placebo-controlled trial

Claudia Trenkwalder; Heike Benes; Werner Poewe; Wolfgang H. Oertel; Diego Garcia-Borreguero; Al de Weerd; Luigi Ferini-Strambi; Pasquale Montagna; Per Odin; Karin Stiasny-Kolster; Birgit Högl; K. Ray Chaudhuri; Markku Partinen; Erwin Schollmayer; Ralf Kohnen

BACKGROUND Continuous administration of a dopamine agonist could be used to treat patients with restless legs syndrome. Our aim was to investigate the efficacy of transdermal rotigotine in the treatment of idiopathic restless legs syndrome. METHODS In this randomised, double-blind, placebo-controlled trial, 458 patients with moderate-to-severe idiopathic restless legs syndrome (average baseline International Restless Legs Syndrome Study Group severity rating scale [IRLS] sum score of 28.1) were randomly assigned to receive transdermal rotigotine 1 mg over 24 h (n=115), 2 mg over 24 h (n=112), or 3 mg over 24 h (n=114), or to receive placebo (n=117). Study medication was delivered via patches, applied once a day for 6 months. Randomisation was done with a computer-generated randomisation list, stratified by centre. Primary efficacy outcomes were absolute change from baseline to end of maintenance in IRLS sum score and in the clinical global impressions (CGI) item 1 score, assessed by analysis of covariance in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT00136045. FINDINGS Efficacy analyses were done on 112 patients in the 1 mg group, 109 in the 2 mg group, 112 in the 3 mg group, and 114 in the placebo group. Mean change in IRLS sum score from baseline at the end of the maintenance phase was -13.7 (SE 0.9) in the 1 mg group, -16.2 (0.9) in the 2 mg group, -16.8 (0.9) in the 3 mg group, and -8.6 (0.9) in the placebo group (p<0.0001 for treatment difference vs placebo with each dose). Mean change in CGI item 1 score from baseline at the end of the maintenance phase was -2.09 (0.14) in the 1 mg group, -2.41 (0.14) in the 2 mg group, -2.55 (0.14) in the 3 mg group, and -1.34 (0.14) in the placebo group (p<0.0001 for treatment difference vs placebo with each dose). Skin reactions, mostly mild or moderate, were seen in 145 (43%) of 341 patients who received rotigotine and in two (2%) of 117 who received placebo. Ten patients had serious adverse event that were deemed to be related to rotigotine: elevation of liver enzymes (one patient), worsening of tinnitus (one patient), non-response to anticoagulation (one patient), electrocardiogram changes (one patient), and application-site reactions (six patients). No admissions to hospital were needed for the application-site reactions, and they all resolved within a short time of patch removal without any other therapeutic intervention. The rate of typical dopaminergic side-effects in patients who received rotigotine was low; no signs of augmentation were noted. INTERPRETATION 24 h transdermal delivery of low-dose rotigotine could be used to relieve the night-time and daytime symptoms of restless legs syndrome. FUNDING Schwarz Biosciences.


Neurology | 1999

A controlled study of additional sr-l-dopa in l-dopa–responsive restless legs syndrome with late-night symptoms

V. Collado-Seidel; J. Kazenwadel; T. C. Wetter; Ralf Kohnen; Juliane Winkelmann; R. Selzer; Wolfgang H. Oertel; Claudia Trenkwalder

Objective: To investigate whether a combination treatment of regular-release levodopa (rr-l-dopa) and sustained-release levodopa (sr-l-dopa) compared with monotherapy of rr-l-dopa improves sleep quality and reduces periodic limb movements (PLM) in patients with restless legs syndrome (RLS) and problems with maintaining sleep. Background: Reappearance of RLS symptoms during the second half of the night while being treated with rr-l-dopa is a common problem in the treatment of sleep disturbances caused by RLS. Methods: A randomized, controlled, double-blind crossover trial was undertaken. Eligible patients fulfilled the diagnostic criteria of the International RLS Study Group, and met an actigraphically confirmed higher number of PLM per hour time in bed (PLM index) during the second half compared with the first half of the night under treatment with rr-l-dopa. During the crossover periods the patients received 100 to 200 mg rr-l-dopa plus either placebo or 100 to 200 mg sr-l-dopa at bedtime for 4 weeks each period. Results: Thirty patients with RLS (11 men and 19 women) were assessed by actigraphy and subjective sleep quality, and showed a significant improvement in PLM index (p < 0.0001), in “time in bed without movements” (p < 0.0001), and in subjective sleep quality (p < 0.001). Eight of 30 patients reported an altered pattern of RLS symptoms, characterized by a time shift of RLS symptoms into the afternoon or evening, five of these during monotherapy with rr-l-dopa. Conclusions: A combination therapy of rr-l-dopa and sr-l-dopa is better than monotherapy with rr-l-dopa in reducing the frequency of PLM and problems maintaining sleep, even in patients who are severely affected.


Movement Disorders | 2011

Parkinson's disease sleep scale—validation of the revised version PDSS‐2

Claudia Trenkwalder; Ralf Kohnen; Birgit Högl; Vinod Metta; Friederike Sixel-Döring; Birgit Frauscher; Julia Hülsmann; Pablo Martinez-Martin; Kallol Ray Chaudhuri

The previous Parkinsons disease sleep scale (PDSS) is a 15‐item visual analogue scale that assesses the profile of nocturnal disturbances in Parkinsons disease (PD) patients.


Pharmacogenomics Journal | 2005

The catechol-O-methyltransferase Val108/158Met polymorphism affects short-term treatment response to mirtazapine, but not to paroxetine in major depression.

Armin Szegedi; Dan Rujescu; André Tadić; Matthias J. Müller; Ralf Kohnen; H.H. Stassen; Norbert Dahmen

The catechol-O-methyltransferase (COMT) is a major degrading enzyme in the metabolic pathways of catecholaminergic neurotransmitters such as dopamine and norepinephrine. This study investigated whether the functionally relevant Val108/158Met gene variant is associated with differential antidepressant response to mirtazapine and/or paroxetine in 102 patients with major depression (DSM-IV criteria) participating in a randomized clinical trial with both drugs. In patients treated with mirtazapine, but not paroxetine, allelic variations in the COMT gene were associated with differential response. COMTVAL/VAL and COMTVAL/MET genotype carriers showed a better response than COMTMET/MET-bearing patients in the mirtazapine group. Moreover, carriers of the COMTVAL/VAL or COMTVAL/MET genotype had significantly greater HAMD-17 (Hamilton Rating Scale for Depression 17 item version) score reductions than COMTMET/MET homozygotes from week 2 to 6, respectively, in the mirtazapine group. Time course of response and antidepressant efficacy of mirtazapine, but not paroxetine, seem to be influenced in a clinically relevant manner by this allelic variation within the COMT gene.


Movement Disorders | 2004

Patch application of the dopamine agonist rotigotine to patients with moderate to advanced stages of Restless Legs Syndrome: A double-blind, placebo-controlled pilot study

Karin Stiasny-Kolster; Ralf Kohnen; Erwin Schollmayer; J. Carsten Möller; Wolfgang H. Oertel

Efficacy and safety of the dopamine agonist rotigotine (RTG) was investigated in patients with moderate to severe idiopathic restless legs syndrome (RLS), including daytime symptoms. Three fixed doses of rotigotine (1.125 mg, 2.25 mg, and 4.5 mg) and placebo were applied by patches (size, 2.5 cm2 per 1.125 mg) in a double‐blind, randomized, parallel‐group, multicenter, 1‐week, proof‐of‐principle trial. The primary efficacy measure was the total score on the International Restless Legs Syndrome Scale (IRLS). Additionally, the RLS‐6 scale, the Clinical Global Impressions (CGI), and a sleep diary were used. Of 68 enrolled patients, 63 (mean age, 58±; 9 years; 64% women) were randomly assigned. RLS severity improved related to dose by 10.5 (1.125 mg RTG/die; P = 0.41), 12.3 (2.25 mg RTG/die; P = 0.18), and 15.7 points (4.5 mg RTG/die; P < 0.01) on the IRLS compared to placebo (8 points). According to the RLS‐6 scales, daytime symptoms significantly improved with all rotigotine doses. The CGI items supported the favorable efficacy of the 4.5‐mg dose. Skin tolerability of the patches and systemic side effects were similar between rotigotine and placebo. This pilot study suggests that continuous delivery of rotigotine by means of a patch may provide an effective and well‐tolerated treatment of RLS symptoms both during night and day.


Movement Disorders | 2007

Definition of restless legs syndrome, how to diagnose it, and how to differentiate it from RLS mimics

Heike Benes; Arthur S. Walters; Richard P. Allen; Wayne A. Hening; Ralf Kohnen

Restless legs syndrome (RLS) is a clinical diagnosis based primarily on self‐reports of individuals. The International RLS Study Group has published diagnostic criteria that are essential for an operational diagnosis of RLS; further clinical features are considered by the group supportive for or associated with RLS. However, sensitivity and specificity are not perfect and “mimics” of RLS have been reported, i.e., other conditions like nocturnal cramps sometimes can appear to fulfill the essential diagnostic criteria indicating the need for more thorough understanding of the diagnostic criteria and better differential diagnoses. To contribute to the accuracy of diagnostic processes in RLS, we recapitulate the definition of RLS as an urge to move focused on the legs (and arms in some patients). This urge to move often but not always occurs together with dysesthesia, i.e. unpleasant abnormal sensations appearing without any apparent sensory stimulation. The urge to move and any accompanying dysesthesia must be engendered by rest, relieved by movement and worse in the evening or night. Succinctly, RLS can be summarized in medical terminology as a “movement‐responsive quiescegenic nocturnal focal akathisia usually with dysesthesias.” Empirical approaches to investigate the independence of the essential criteria “worsening at night” and “worsening at rest” are reported. Possible differential diagnoses of RLS are discussed under the perspective of the NIH diagnostic criteria of RLS. Standardized methods to assess a RLS diagnosis are presented which might improve differential diagnosis and in general the reliability and validity of RLS diagnosis.


Lancet Neurology | 2013

Prolonged release oxycodone–naloxone for treatment of severe restless legs syndrome after failure of previous treatment: a double-blind, randomised, placebo-controlled trial with an open-label extension

Claudia Trenkwalder; Heike Benes; Ludger Grote; Diego Garcia-Borreguero; Birgit Högl; Michael Hopp; Björn Bosse; Alexander Oksche; Karen Reimer; Juliane Winkelmann; Richard P. Allen; Ralf Kohnen

BACKGROUND Opioids are a potential new treatment for severe restless legs syndrome. We investigated the efficacy and safety of a fixed-dose combination of prolonged release oxycodone-naloxone for patients with severe restless legs syndrome inadequately controlled by previous, mainly dopaminergic, treatment. METHODS This multicentre study consisted of a 12-week randomised, double-blind, placebo-controlled trial and 40-week open-label extension phase done at 55 sites in Austria, Germany, Spain, and Sweden. Patients had symptoms for at least 6 months and an International RLS Study Group severity rating scale sum score of at least 15; patients with severe chronic obstructive pulmonary disease or a history of sleep apnoea syndrome were excluded. Patients were randomly assigned (1:1) to either study drug or matched placebo with a validated interactive response technology system in block sizes of four. Study drug was oxycodone 5·0 mg, naloxone 2·5 mg, twice per day, which was up-titrated according to investigators opinion to a maximum of oxycodone 40 mg, naloxone 20 mg, twice per day; in the extension, all patients started on oxycodone 5·0 mg, naloxone 2·5 mg, twice per day, which was up-titrated to a maximum of oxycodone 40 mg, naloxone 20 mg, twice per day. The primary outcome was mean change in severity of symptoms according to the International RLS Study Group severity rating scale sum score at 12 weeks. This study is registered with ClinicalTrials.gov (number NCT01112644) and with EudraCT (number 2009-011107-23). FINDINGS We screened 495 patients, of whom 306 were randomly assigned and 276 included in the primary analysis (132 to prolonged release oxycodone-naloxone vs 144 to placebo). 197 patients participated in the open-label extension. Mean International RLS Study Group rating scale sum score at randomisation was 31·6 (SD 4·5); mean change after 12 weeks was -16·5 (SD 11·3) in the prolonged release oxycodone-naloxone group and -9·4 (SD 10·9) in the placebo group (mean difference between groups at 12 weeks 8·15, 95% CI 5·46-10·85; p<0·0001). After the extension phase, mean sum score was 9·7 (SD 7·8). Treatment-related adverse events occurred in 109 of 150 (73%) patients in the prolonged release oxycodone-naloxone group and 66 of 154 (43%) in the placebo group during the double-blind phase; during the extension phase, 112 of 197 (57%) had treatment-related adverse events. Five of 306 (2%) patients had serious treatment-related adverse events when taking prolonged release oxycodone-naloxone (vomiting with concurrent duodenal ulcer, constipation, subileus, ileus, acute flank pain). INTERPRETATION Prolonged release oxycodone-naloxone was efficacious for short-term treatment of patients with severe restless legs syndrome inadequately controlled with previous treatment and the safety profile was as expected. Our study also provides evidence of open-label long-term efficacy of this treatment. Opioids can be used to treat patients with severe restless legs syndrome who have had no benefit with first-line drugs. FUNDING Mundipharma Research.


Neurology | 2004

Effective cabergoline treatment in idiopathic restless legs syndrome

Karin Stiasny-Kolster; Heike Benes; I. Peglau; M. Hornyak; B. Holinka; K. Wessel; W. Emser; M. Leroux; Ralf Kohnen; Wolfgang H. Oertel

Objective: To assess the efficacy and safety of the dopamine agonist cabergoline (CAB) in patients with restless legs syndrome (RLS). Methods: Patients with moderate to severe RLS were randomized into four groups receiving placebo, 0.5 mg, 1 mg, or 2 mg CAB once daily in a double-blind, placebo-controlled, multicenter dose-finding trial followed by an open long-term extension trial of 47 weeks. Efficacy was assessed with the RLS-6 scales and International RLS Study Group severity scale (IRLS). Results: A total of 85 patients (age 56 ± 10 years, 71% females) were treated. Severity of RLS-6 scale symptoms during the night (the primary endpoint) was markedly improved by all CAB doses compared to placebo (placebo: −1.4 ± 3.1, 0.5 mg CAB: −4.2 ± 3.0 [p = 0.0082], 1.0 mg CAB: −4.0 ± 2.9 [p = 0.0040], 2.0 mg CAB: −4.8 ± 3.7 [p = 0.0026]). Similar results were found for the RLS severity at bedtime and during the day, IRLS, and satisfaction with sleep. A stable, clinically relevant improvement was achieved in all efficacy measures (severity during the night: change between last assessment and baseline: −5.6 ± 2.5, rate of remission: 71.2%) throughout 1 year with a mean CAB dose of 2.2 mg per day. During long-term treatment, 6 of 66 treated patients were affected (n = 2) or possibly affected (n = 4) by mild augmentation. Under CAB therapy up to 1 year, 11 of 85 patients discontinued treatment due to a drug-related adverse event. Conclusions: Cabergoline is an efficacious and well-tolerated option for the treatment of restless legs symptoms during the night and the day.


Movement Disorders | 2007

Cabergoline compared to levodopa in the treatment of patients with severe restless legs syndrome: results from a multi-center, randomized, active controlled trial.

Claudia Trenkwalder; Heike Benes; Ludger Grote; Svenja Happe; Birgit Högl; Johannes Mathis; Gerda M. Saletu-Zyhlarz; Ralf Kohnen

We report the first large‐scale double‐blind, randomly assigned study to compare two active dopaminergic therapies for Restless Legs Syndrome (RLS), the dopamine agonist cabergoline (CAB) and levodopa/benserazide (levodopa). Patients with idiopathic RLS were treated with fixed daily doses of 2 or 3 mg CAB or 200 or 300 mg levodopa for 30 weeks. Efficacy was assessed by changes in the IRLS (International RLS Severity Scale) and by time to discontinuation of treatment due to loss of efficacy or augmentation. 361 of 418 screened patients (age 58 ± 12 years, 71% females) were randomly assigned and treated (CAB: n = 178; levodopa: n = 183) in 51 centers of four European countries. Baseline IRLS total score was 25.7 ± 6.8. The baseline‐adjusted mean change from baseline to week 6 in IRLS sum score was d = −16.1 in the CAB group and d = −9.5 in the levodopa group (d = −6.6, P < 0.0001). More patients in the levodopa group (24.0%) than in the CAB group (11.9%, P = 0.0029, log‐rank test) discontinued because of loss of efficacy (14.2% vs. 7.9%, P = 0.0290) or augmentation (9.8% vs. 4.0%, P = 0.0412). Adverse events (AEs) occurred in 83.1% of the CAB group and in 77.6% of the levodopa group. In both groups, most frequent AEs were gastrointestinal symptoms (CAB: 55.6%, levodopa: 30.6%, P < 0.0001). This first large‐scale active controlled study in RLS showed superior efficacy of cabergoline versus levodopa after a 30‐week long‐term therapy. Tolerability was found more favorable with levodopa than with cabergoline.


Lancet Neurology | 2011

Long-term safety and efficacy of rotigotine transdermal patch for moderate-to-severe idiopathic restless legs syndrome: a 5-year open-label extension study.

Wolfgang H. Oertel; Claudia Trenkwalder; Heike Benes; Luigi Ferini-Strambi; Birgit Högl; Werner Poewe; Karin Stiasny-Kolster; Andreas Fichtner; Erwin Schollmayer; Ralf Kohnen; Diego Garcia-Borreguero

BACKGROUND Safety and efficacy of non-ergot dopamine agonists for the treatment of idiopathic restless legs syndrome have been shown in short-term trials. We did a prospective open-label extension of a 6-week, double-blind randomised trial to assess the safety, tolerability, and efficacy of rotigotine transdermal patch for up to 5 years in patients with restless legs syndrome. METHODS Patients (aged 18-75 years) with moderate-to-severe idiopathic restless legs syndrome were treated with once-daily rotigotine transdermal patch in 33 centres in Austria, Germany, and Spain between July 31, 2003, and April 15, 2009. The dose was titrated in weekly increments (up to 4 weeks) from 0·5 mg/24 h to a maximum of 4 mg/24 h, and was followed by up to 5 years of maintenance at the optimum dose. Primary safety outcomes included occurrence of adverse events and dropouts. Efficacy assessments were secondary and included the International Restless Legs Syndrome study group severity rating scale (IRLS). Augmentation of symptoms was assessed by means of standard diagnostic criteria and was confirmed by an international expert panel. All patients who received at least one dose of study drug were included in assessments. This study is registered with ClinicalTrials.gov, number NCT00498186. FINDINGS 295 patients entered the open-label study, of whom 126 (43%) completed 5 years of follow-up. 169 (57%) patients discontinued treatment, 89 (30%) because of adverse events and 31 (11%) because of lack of efficacy. 70 patients (24%) discontinued during year 1 of maintenance. The most common adverse events were application site reactions, which occurred in 37% (106/290) of patients in year 1, 17% (38/220) of patients in year 2, 14% (27/191) of patients in year 3, and in less than 6% of patients during year 4 (8/159) and year 5 (8/147). 56 patients (19%) discontinued because of application site reactions. Mean rotigotine dose was 2·43 mg/24 h (SD 1·21) after initial titration and 3·09 mg/24 h (1·07) at the end of maintenance. Of 89 patients who discontinued because of adverse events, 28 (31%) were on 4 mg/24 h rotigotine. Mean IRLS score of patients entering the open-label study was 27·8 (SD 5·9) at baseline of the double-blind trial. In patients who completed the maintenance period, mean IRLS score was reduced from a baseline score of 27·7 (SD 6·0) by a mean of 18·7 points (SD 9·5) to a score of 9·0 (SD 9·2) at the end of maintenance. 39% (48/123) of patients who completed the trial were classified as symptom free according to the IRLS. Clinically significant augmentation was recorded in 39 patients (13%), of whom 15 (5%) were receiving a dose of rotigotine within the range approved by the European Medicines Agency (EMA; 1-3 mg/24 h) and 24 (8%) were receiving 4 mg/24 h rotigotine. INTERPRETATION Rotigotine transdermal patch is generally well tolerated after 1 year and provides sustained efficacy for patients with moderate-to-severe restless legs syndrome at a stable dose for up to 5 years. Thus, rotigotine transdermal patch is an appropriate long-term treatment option for moderate-to-severe restless legs syndrome, a disorder that often requires lifelong treatment. FUNDING UCB BioSciences, on behalf of Schwarz Pharma, Ireland.

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Birgit Högl

Innsbruck Medical University

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Diego Garcia-Borreguero

Autonomous University of Madrid

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Magdolna Hornyak

University Medical Center Freiburg

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