Long-term effects of safinamide adjunct therapy on levodopa-induced dyskinesia in Parkinson's disease: post-hoc analysis of a Japanese phase III study.

This post-hoc analysis investigated the long-term effects of safinamide on the course of dyskinesia and efficacy outcomes using data from a phase III, open-label 52-week study of safinamide 50 or 100 mg/day in Japanese patients with Parkinson's disease (PD) with wearing-off. Patients (N = 194) were grouped using the UPDRS Part IV item 32: with and without pre-existing dyskinesia (pre-D subgroup; item 32 > 0 at baseline [n = 81], without pre-D subgroup; item 32 = 0 at baseline [n = 113]). ON-time with troublesome dyskinesia (ON-TD) increased significantly from baseline to Week 4 in the pre-D subgroup (+ 0.25 ± 0.11 h [mean ± SE], p = 0.0355) but gradually decreased up to Week 52 (change from baseline: - 0.08 ± 0.17 h, p = 0.6224); ON-TD did not change significantly in the Without pre-D subgroup. UPDRS Part IV item 32 score increased significantly at Week 52 compared with baseline in the Without pre-D subgroup, but no UPDRS Part IV dyskinesia related-domains changed in the pre-D subgroup. Both subgroups improved in ON-time without TD, UPDRS Part III, and Part II [OFF-phase] scores. The cumulative incidence of new or worsening dyskinesia (adverse drug reaction) at Week 52 was 32.5 and 5.0% in the pre-D and Without pre-D subgroups, respectively. This study suggested that safinamide led to short-term increasing dyskinesia but may be not associated with marked dyskinesia at 1-year follow-up in patients with pre-existing dyskinesia, and that it improved motor symptoms regardless of the presence or absence of dyskinesia at baseline. Further studies are warranted to investigate this association in more details.Trial registration: JapicCTI-153057 (Registered: 2015/11/02).

Comparative examination of levodopa pharmacokinetics during simultaneous administration with lactoferrin in healthy subjects and the relationship between lipids and COMT inhibitory activity in vitro.

Background: Lactoferrin (bLF) is an iron-binding multifunctional protein that is abundant in milk. In mice, it inhibits catechol-O-methyltransferase (COMT) activity and increases blood levodopa levels. However, the clinical effects are unknown.Objective: The objective of this study was to determine the effect of bLF on the kinetics of levodopa in blood.Design: The effects of the concomitant administration of a combined formulation of levodopa and an aromatic amino acid decarboxylase inhibitor and bLF on the concentration of levodopa in blood and its metabolism were assessed in eight healthy subjects. In addition, we analyzed the association with clinical factors and evaluated whether clinical factors affected the COMT inhibitory activity of bLF in vitro.Results: Although not statistically significant, the peak plasma concentration (Cmax) of levodopa increased by 18.5%. From the results of the stratified analysis of total cholesterol, a relationship with ΔCmax was predicted. Therefore, bLF was reacted with cholesterol in the presence of lecithin and sodium deoxycholate in vitro to evaluate COMT inhibitory activity, and an increase in inhibitory activity was observed. By contrast, the ester compound cholesteryl oleate had no effect. The inhibitory activity of free fatty acids, which are known to interact with bLF, was also enhanced.Conclusion: The COMT inhibitory activity of bLF is not effective in elevating blood levodopa levels. However, in humans with high lipid levels, such as cholesterol, interactions may enhance the inhibitory effect, resulting in the enhanced absorption of levodopa.Trial registration: ID, UMIN000026787, registered 30 March 2017; URL, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000030749Trial registration: UMIN Japan identifier: UMIN000026787.

Randomized, Controlled Study of Opicapone in Japanese Parkinson's Patients with Motor Fluctuations.

OBJECTIVES: This placebo-controlled, randomized study evaluated the efficacy and safety of opicapone 25-mg and 50-mg tablets in Japanese levodopa-treated patients with Parkinson's disease and motor fluctuations. METHODS: Japanese adults (n = 437, age 39-83 years) with Parkinson's disease (United Kingdom Parkinson's Disease Society criteria) received opicapone 25-mg (n = 145), opicapone 50-mg (n = 145), or placebo (n = 147) tablets over the double-blind treatment period (14-15 weeks). The primary efficacy assessment was change in OFF-time; secondary efficacy assessments included OFF/ON-time responders (≥1 hour change from baseline), total ON-time, ON-time with and without troublesome dyskinesia, and Unified Parkinson's Disease Rating Scale. RESULTS: The least squares mean (standard error) change in OFF-time from baseline to the last visit was -0.42 (0.21) hour for the placebo group, -1.16 (0.22) hour for the opicapone 25 mg group, and -1.04 (0.21) hour for the opicapone 50 mg group. The percentage of ON-time responders, changes in total ON-time/ON-time without troublesome dyskinesia, and Unified Parkinson's Disease Rating Scale II (at OFF) all showed statistically significant improvements versus placebo for both opicapone tablet doses (P < 0.05). Unified Parkinson's Disease Rating Scale III (at ON) was improved versus placebo in patients who received opicapone 50 mg (P < 0.05). Adverse events were more common in patients treated with opicapone 25 mg (60.0%) or opicapone 50 mg (54.5%) versus placebo (48.3%). The most commonly reported adverse event was dyskinesia (placebo, 2.7%; opicapone 25 mg, 9.0%; opicapone 50 mg, 12.4%). CONCLUSIONS: In Japanese patients, both opicapone 25 and 50 mg were significantly more effective than placebo with no dose-dependent difference in efficacy, and both doses were well tolerated. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Long-term safety and efficacy of opicapone in Japanese Parkinson's patients with motor fluctuations.

The double-blind part of the COMFORT-PD (COMt-inhibitor Findings from Opicapone Repeated Treatment for Parkinson's Disease) study in Japanese levodopa-treated patients with Parkinson's disease and motor fluctuations found that both opicapone 25 and 50 mg were significantly more effective than placebo. This 52-week open-label extension study evaluated the long-term safety and efficacy of opicapone 50 mg tablets in patients who completed the double-blind part of the COMFORT-PD study. Safety was monitored via adverse events, laboratory testing, and physical, cardiovascular and neurological examinations. Efficacy was primarily assessed by change in OFF-time. Secondary efficacy measures included: ON-time, percentage of OFF/ON-time responders, other outcomes from the double-blind part. 391/437 patients were transferred to the open-label extension period and included in the safety analysis set (full analysis set, n = 387; open-label completers, n = 316). Adverse events were frequently reported (n = 338, 86.4%), but < 50% were considered drug-related (39.9%) and few were considered serious (2.6%) or led to discontinuation (2.8%). Decreased OFF-time was consistently observed over the open-label period regardless of initial randomization. Change [LSM (SE)] in OFF-time from the open-label baseline to the last visit showed a persistent effect in patients initially randomized to opicapone 25 mg [- 0.37 (0.20) h, P = 0.0689] and opicapone 50 mg [- 0.07 (0.21) h, P = 0.6913] whereas opicapone 50 mg led to a statistically significant reduction in the previous placebo group [- 1.26 (0.19) h, P < 0.05]. Once-daily opicapone 50 mg was generally well tolerated and consistently reduced OFF-time over 52 weeks in Japanese levodopa-treated patients with motor fluctuations.Trial registration JapicCTI-153112; date of registration: December 25, 2015.

Phagocytic elimination of synapses by microglia during sleep.

Synaptic strength reduces during sleep, but the underlying mechanisms of this process are unclear. This study showed reduction of synaptic proteins in rat prefrontal cortex (PFC) at AM7 or Zeitgeber Time (ZT0), when the light phase or sleeping period for rats started. At this time point, microglia were weakly activated, displaying larger and more granular somata with increased CD11b expression compared with those at ZT12, as revealed by flow cytometry. Expression of opsonins, such as complements or MFG-E8, matrix metalloproteinases, and microglial markers at ZT0 were increased compared with that at ZT12. Microglia at ZT0 phagocytosed synapses, as revealed by immunohistochemical staining. Immunoblotting detected more synapsin I in the isolated microglia at ZT0 than at ZT12. Complement C3- or MFG-E8-bound synapses were the most abundant at ZT0, some of which were phagocytosed by microglia. Systemic administration of synthetic glucocorticoid dexamethasone reduced microglial size, granularity and CD11b expression at ZT0, resembling microglia at ZT12, and increased synaptic proteins and decreased the sleeping period. Noradrenaline (NA) suppressed glutamate-induced phagocytosis in primary cultured microglia. Systemic administration of the brain monoamine-depleting agent reserpine decreased NA content and synapsin I expression in PFC, and increased expression of microglia markers, C3 and MFG-E8, while increasing the sleeping period. A NA precursor l-threo-dihydroxyphenylserine abolished the reserpine-induced changes. These results suggest that microglia may eliminate presumably weak synapses during every sleep phase. The circadian changes in concentrations of circulating glucocorticoids and brain NA might be correlated with the circadian changes of microglial phenotypes and synaptic strength.

Ropinirole Patch Versus Placebo, Ropinirole Extended-Release Tablet in Advanced Parkinson's Disease.

BACKGROUND: A dopamine agonist patch is an important treatment option for PD. OBJECTIVES: A randomized, double-blind, parallel-group, placebo-controlled trial was conducted to evaluate superiority of ropinirole hydrochloride patch over placebo and noninferiority to ropinirole hydrochloride extended-release tablet. METHODS: PD patients using levodopa received ropinirole patch (up to 64 mg/d), ropinirole tablets (up to 16 mg/d), or placebo once-daily (double-dummy technique). The primary endpoint was the change from baseline in the total score for the UPDRS Part III (on state) at week 16. RESULTS: The change of the least squares mean (95% confidence interval) in the UPDRS Part III total score was -9.8 (-10.8 to -8.7) with ropinirole patch, -4.3 (-5.8 to -2.8) with placebo, and -10.1 (-11.2 to -9.1) with ropinirole tablet. The difference between the ropinirole patch and placebo groups was -5.4 (-7.3 to -3.6), demonstrating superiority of the patch over placebo. The difference between the ropinirole patch and tablet groups was 0.3 (-1.2 to 1.8). The upper limit of the 95% confidence interval was smaller than the noninferiority limit of 2.5, demonstrating noninferiority of ropinirole patch to ropinirole tablet. In all three groups, most adverse events were mild or moderate and there were no serious safety concerns. CONCLUSIONS: Once-daily ropinirole patch was effective in advanced PD patients, having demonstrated superiority over placebo and noninferiority to ropinirole tablet, without causing serious safety problems. Ropinirole patch can be an alternative option for PD patients. © 2020 International Parkinson and Movement Disorder Society.

DRD2 methylation to differentiate dementia with Lewy bodies from Parkinson's disease.

OBJECTIVE: The aim was to clarify whether DRD2 methylation changes in leukocytes of dementia with Lewy bodies (DLB) or Parkinson's disease (PD) patients are seen and can be used to discriminate between them. METHODS: Methylation rates were examined in 23 DLB subjects and 23 age- and sex-matched healthy controls and 37 PD patients and 37 age- and sex-matched healthy controls. RESULTS: Significant DRD2 DNA methylation changes were found in leukocytes of DLB and PD patients compared with healthy subjects. Discriminant analysis between DLB and PD using seven CpG sites demonstrated sensitivity and specificity of 83.8% and 90.9%, respectively. None of the CpG sites were associated with sex, age, age of onset, disease duration, and any of the neuropsychological tests in DLB and PD patients. CONCLUSION: This is the first report showing that DRD2 DNA methylation rates in leukocytes were increased in DLB patients and decreased in PD patients. These results may be an important step in understanding epigenetic mechanisms underlying DLB and PD pathogenesis and providing a novel biomarker for discriminating between them.

In Vitro Human Onychopharmacokinetic and Pharmacodynamic Analyses of ME1111, a New Topical Agent for Onychomycosis.

ME1111 is a novel antifungal agent currently under clinical development as a topical onychomycosis treatment. A major challenge in the application of topical onychomycotics is penetration and dissemination of antifungal agent into the infected nail plate and bed. In this study, pharmacokinetic/pharmacodynamic parameters of ME1111 that potentially correlate with clinical efficacy were compared with those of marketed topical onychomycosis antifungal agents: efinaconazole, tavaborole, ciclopirox, and amorolfine. An ME1111 solution and other launched topical formulations were applied to an in vitro dose model for 14 days based on their clinical dose and administration. Drug concentrations in the deep layer of the nail and within the cotton pads beneath the nails were measured using liquid chromatography-tandem mass spectrometry. Concentrations of ME1111 in the nail and cotton pads were much higher than those of efinaconazole, ciclopirox, and amorolfine. Free drug concentrations of ME1111 in deep nail layers and cotton pads were orders of magnitude higher than the MIC90 value against Trichophyton rubrum (n = 30). Unlike other drugs, the in vitro antifungal activity of ME1111 was not affected by 5% human keratin and under a mild acidic condition (pH 5.0). The in vitro antidermatophytic efficacy coefficients (ratio of free drug concentration to MIC90s against T. rubrum) of ME1111, as measured in deep nail layers, were significantly higher than those of efinaconazole, tavaborole, ciclopirox, and amorolfine (P < 0.05). This suggests that ME1111 has excellent permeation of human nails and, consequently, the potential to be an effective topical onychomycosis treatment.

Modafinil alleviates levodopa-induced excessive nighttime sleepiness and restores monoaminergic systems in a nocturnal animal model of Parkinson's disease.

Treatment with dopaminergic agents result excessive daytime sleepiness (EDS) and some studies have shown the benefit of using modafinil for treating excessive daytime sleepiness of Parkinson's disease (PD) patient. We investigated whether modafinil have ameliorative properties against levodopa induced excessive nighttime sleepiness (ENS) in MPTP-treated murine nocturnal PD model. Our EEG analyses of whole day recordings revealed that modafinil reduce ENS of this nocturnal PD models with levodopa medications. Therefore, we investigated whether, modafinil post-treatment followed by MPTP shows any effect on monoamine contents of brain and found to robustly increased noradrenaline (NA) concentration of MPTP treated mice. Modafinil post-treatment, in neurorestorative context (5 days post-lesion) led to increased striatal dopamine (DA) concentrations of MPTP-treated mice. Here, we first confirmed that modafinil ameliorates levodopa induced excessive sleepiness and restores monoaminergic systems. The arousal and anti-parkinsonian effects displayed by modafinil indicate that in combination with dopaminergic agents, modafinil co-administration may be worthwhile in trying to suppress the excessive daytime sleepiness and progressive dopaminergic neuron loss in PD.

Microglia may compensate for dopaminergic neuron loss in experimental Parkinsonism through selective elimination of glutamatergic synapses from the subthalamic nucleus.

Parkinson's disease (PD) symptoms do not become apparent until most dopaminergic neurons in the substantia nigra pars compacta (SNc) degenerate, suggesting that compensatory mechanisms play a role. Here, we investigated the compensatory involvement of activated microglia in the SN pars reticulata (SNr) and the globus pallidus (GP) in a 6-hydroxydopamine-induced rat hemiparkinsonism model. Activated microglia accumulated more markedly in the SNr than in the SNc in the model. The cells had enlarged somata and expressed phagocytic markers CD68 and NG2 proteoglycan in a limited region of the SNr, where synapsin I- and postsynaptic density 95-immunoreactivities were reduced. The activated microglia engulfed pre- and post-synaptic elements, including NMDA receptors into their phagosomes. Cells in the SNr and GP engulfed red fluorescent DiI that was injected into the subthalamic nucleus (STN) as an anterograde tracer. Rat primary microglia increased their phagocytic activities in response to glutamate, with increased expression of mRNA encoding phagocytosis-related factors. The synthetic glucocorticoid dexamethasone overcame the stimulating effect of glutamate. Subcutaneous single administration of dexamethasone to the PD model rats suppressed microglial activation in the SNr, resulting in aggravated motor dysfunctions, while expression of mRNA encoding glutamatergic, but not GABAergic, synaptic elements increased. These findings suggest that microglia in the SNr and GP become activated and selectively eliminate glutamatergic synapses from the STN in response to increased glutamatergic activity. Thus, microglia may be involved in a negative feedback loop in the indirect pathway of the basal ganglia to compensate for the loss of dopaminergic neurons in PD brains.

ERBB4 mutations that disrupt the neuregulin-ErbB4 pathway cause amyotrophic lateral sclerosis type 19.

Amyotrophic lateral sclerosis (ALS) is a devastating neurological disorder characterized by the degeneration of motor neurons and typically results in death within 3-5 years from onset. Familial ALS (FALS) comprises 5%-10% of ALS cases, and the identification of genes associated with FALS is indispensable to elucidating the molecular pathogenesis. We identified a Japanese family affected by late-onset, autosomal-dominant ALS in which mutations in genes known to be associated with FALS were excluded. A whole- genome sequencing and parametric linkage analysis under the assumption of an autosomal-dominant mode of inheritance with incomplete penetrance revealed the mutation c.2780G>A (p. Arg927Gln) in ERBB4. An extensive mutational analysis revealed the same mutation in a Canadian individual with familial ALS and a de novo mutation, c.3823C>T (p. Arg1275Trp), in a Japanese simplex case. These amino acid substitutions involve amino acids highly conserved among species, are predicted as probably damaging, and are located within a tyrosine kinase domain (p. Arg927Gln) or a C-terminal domain (p. Arg1275Trp), both of which mediate essential functions of ErbB4 as a receptor tyrosine kinase. Functional analysis revealed that these mutations led to a reduced autophosphorylation of ErbB4 upon neuregulin-1 (NRG-1) stimulation. Clinical presentations of the individuals with mutations were characterized by the involvement of both upper and lower motor neurons, a lack of obvious cognitive dysfunction, and relatively slow progression. This study indicates that disruption of the neuregulin-ErbB4 pathway is involved in the pathogenesis of ALS and potentially paves the way for the development of innovative therapeutic strategies such using NRGs or their agonists to upregulate ErbB4 functions.

Transdermal rotigotine in early stage Parkinson's disease: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: We conducted a randomized, double-blind, placebo-controlled trial to determine the safety and efficacy of transdermal rotigotine at doses up to 16 mg/24 hours in patients with early stage Parkinson's disease (PD) in Japan. METHODS: Patients received once-daily rotigotine 2 to 16 mg/24 hours (mean dose, 12.8 mg/24 hours; n = 82) or placebo (n = 90) for 12 weeks. The primary endpoint was the change in Unified Parkinson's Disease Rating Scale (UPDRS) part II (activities of daily living) and part III (motor function) scores from baseline to the end of treatment. RESULTS: The mean (± standard deviation) changes in UPDRS part II and III scores were -8.4 ± 9.7 in the rotigotine group and -4.1 ± 8.2 in the placebo group and were significantly different (P = 0.002). More patients in the rotigotine group than in the placebo group had a ≥ 20% score reduction. No serious drug-related adverse events were reported. CONCLUSIONS: Rotigotine at doses up to 16 mg/24 hours was well tolerated and improved function in patients with early stage PD.

White matter hyperintensity predicts independent walking function at 6 months after stroke: A retrospective cohort study.

BACKGROUND: White matter hyperintensity (WMH) is reported to have a potential prevalence in healthy people and is a predictor of walking disability. However, WMH has not been adequately considered as a predictor of independent walking after stroke. OBJECTIVE: To investigate the effects of WMH severity on walking function in patients with acute stroke. METHODS: The retrospective cohort study included 422 patients with acute stroke. The WMH severity from magnetic resonance images was evaluated using the Fazekas scale. Age, type of stroke, Fazekas scale, Brunnstrom motor recovery stage, Motricity Index, and Mini-Mental State Examination were used as independent variables. Multivariable logistic regression analysis was conducted on the factors of independent walking at discharge and 6 months after onset, respectively. RESULTS: Multivariable analysis revealed that the Fazekas scale is not a predictive factor of independent walking at discharge (odds ratio [OR] = 0.89, 95% confidence intervals [CI] = 0.65-1.22), but at 6 months (OR = 0.54, 95% CI = 0.34-0.86). CONCLUSION: The WMH severity was a predictive factor of independent walking in patients with acute stroke after 6 months. WMH is a factor that should be considered to improve the accuracy of predicting long-term walking function in patients with stroke.

The Assessment of the Diagnostic Delay in Japanese People with Parkinson's Disease Using a Web-based Survey of Patients and Physicians.

Objective Although diagnostic criteria of Parkinson's disease (PD) have been established, the details of the process by which patients notice symptoms, visit a physician, and receive a diagnosis of PD is unclear. We therefore explored factors influencing latency in diagnosing PD. Methods We performed an internet-based survey of patients with PD and their families as well as physicians treating patients with PD to identify any diagnostic latency and its determinants. Evaluated factors included motor and non-motor symptoms, the diagnosis history and symptoms, patients' feelings toward PD prior to the diagnosis, and physician-determined reasons for the diagnostic delay. Results Among the 186 eligible patient respondents (including 87 responses from family members of patients), 24% received a PD diagnosis >1 year after the onset of PD-related symptoms, 58.6% had mid- or late-stage PD at the diagnosis, and 29% of patients had initially thought their symptoms were common age-related phenomena. Tremor (42%) was the most frequent symptom that led patients to visit a medical institution, whereas gait disturbance (14%) was the least frequent. More patients diagnosed with early-stage PD than those diagnosed with mid- or late-stage PD consulted a neurologist at their first visit. Among the 331 eligible physicians, patients' misinterpretation of their symptoms as being age-related was deemed one of or the most common cause (s) of a diagnostic delay by 67% and 36%, respectively. Conclusion Patients' insufficient or misinterpreted information about PD may cause delays in accessing healthcare services, leading to diagnostic delay.

Risk factors for developing dyskinesia among Parkinson's disease patients with wearing-off: J-FIRST.

BACKGROUND: Dyskinesia frequently occurs during long-term treatment with levodopa in patients with Parkinson's disease (PD) and impacts quality of life. Few studies have examined risk factors for developing dyskinesia in PD patients exhibiting wearing-off. Therefore, we investigated the risk factors and impact of dyskinesia in PD patients exhibiting wearing-off. METHODS: We investigated the risk factors and impact of dyskinesia in a 1-year observational study of Japanese PD patients exhibiting wearing-off (J-FIRST). Risk factors were assessed by logistic regression analyses in patients without dyskinesia at study entry. Mixed-effect models were used to evaluate the impact of dyskinesia on changes in Movement Disorder Society-Unified PD Rating Scale (MDS-UPDRS) Part I and PD Questionnaire (PDQ)-8 scores from one timepoint before dyskinesia was observed. RESULTS: Of 996 patients analyzed, 450 had dyskinesia at baseline, 133 developed dyskinesia within 1 year, and 413 did not develop dyskinesia. Female sex (odds ratio [95% confidence interval]: 2.636 [1.645-4.223]) and administration of a dopamine agonist (1.840 [1.083-3.126]), a catechol-O-methyltransferase inhibitor (2.044 [1.285-3.250]), or zonisamide (1.869 [1.184-2.950]) were independent risk factors for dyskinesia onset. MDS-UPDRS Part I and PDQ-8 scores increased significantly after the onset of dyskinesia (least-squares mean change [standard error] at 52 weeks: 1.11 [0.52], P = 0.0336; 1.53 [0.48], P = 0.0014; respectively). CONCLUSION: Female sex and administration of a dopamine agonist, a catechol-O-methyltransferase inhibitor, or zonisamide were risk factors for dyskinesia onset within 1 year in PD patients exhibiting wearing-off. Nonmotor symptoms and quality of life deteriorated after dyskinesia onset.

Pramipexole upregulates dopamine receptor D2 and D3 expression in rat striatum.

Randomized clinical trials have shown that pramipexole has an antidepressant effect in patients with Parkinson's disease. We investigated the comparative efficacy of pramipexole toward dopamine receptor D(2) and D(3) expression in rat brain. Groups of rats were treated subacutely with pramipexole (1 mg/kg), imipramine (10 mg/kg), or bromocriptine (5 mg/kg), with appropriate controls. Using real-time RT-PCR and immunoblotting, dopamine receptor D(2) and D(3) expression was up-regulated in the striatum following pramipexole treatment, while imipramine and bromocriptine had no significant effects. These findings support that pramipexole exerts additional therapeutic benefits such as decreasing depression by increasing dopamine receptor D(3) expression in the striatum.

Effect of renal impairment on the pharmacokinetics of memantine.

The effect of renal impairment on the pharmacokinetics of a single oral dose of memantine (10 mg) was determined in Japanese subjects. Subjects were assigned to four groups based on baseline creatinine clearance (CL(CR)): normal renal function (> 80 mL/min, n = 6), and mild (50 to ≤ 80 mL/min, n = 6), moderate (30 to < 50 mL/min, n = 6), and severe renal impairment (5 to < 30 mL/min, n = 7). Mean memantine maximum plasma concentration (C(max)) was similar in the groups (12.66, 17.25, 15.75, and 15.83 ng/mL, respectively), as was mean time to C(max) (6.2, 5.2, 4.3, and 5.4 h, respectively). However, exposure to memantine determined from mean area under the plasma concentration-time curve was 1.62-, 1.97-, and 2.33-times higher in subjects with mild, moderate, and severe renal impairment, respectively, as compared to controls with normal renal function. Mean memantine plasma elimination half-life increased according to increasing renal impairment (61.15, 83.00, 100.13, and 124.31 h, respectively), while mean cumulative urinary recovery of unchanged memantine in 72 h after dosing decreased according to increasing renal impairment (33.68%, 33.47%, 23.60%, and 16.17%, respectively). These results are the same as those in the previous study on caucasian individuals, when compared per body weight. It is suggested that the dose of memantine should be halved in patients with renal impairment.