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Memantine stimulates inositol phosphates production in neurones and nullifies N-methyl-D-aspartate-induced destruction of retinal neurones.

Whereas carbachol, noradrenaline, serotonin and memantine stimulated inositol phosphates production and calcium mobilization in 3-5 day old rabbit retinal cultures, only carbachol and noradrenaline were effective when 25-30 day old cultures were used. The older retinal cultures contain only Müller cells which shows that the memantine and serotonin effects on the 3-5 day old cultures are specifically associated with neurones. While the carbachol, noradrenaline and serotonin effects were respectively blocked by atropine, prazosin and ketanserin, none of these substances influenced the memantine responses. In all areas of the rat brain which were analysed, the effectiveness of memantine, noradrenaline and carbachol on the stimulation of inositol phosphates production was similar. However, in the rabbit retina, as opposed to the rat brain slices, carbachol had a more pronounced influence than noradrenaline in stimulating inositol phosphates production. Chick retina exposed to N-methyl-D-aspartate, quisqualate, glutamate or kainic acid resulted in cytopathological damage to cell bodies in the outer nuclear layer. The N-methyl-D-aspartate effect was nullified by memantine and MK-801 but not by kynurenic acid. In contrast the kainic acid-induced damage was specifically antagonized by kynurenic acid. The present results show that memantine influences the metabolism of inositol phosphates in neurones but not glial (Müller) cells and appears to counteract the N-methyl-D-aspartate induced cytopathological damage. How these two effects of memantine are interrelated and whether they are involved in the described beneficial therapeutic observations of memantine (as in dementia) remains to be established.

Animals↗

Memantine and its analogs: Potential applications in cancer therapy.

Drug repurposing refers to the process of using an existing drug or drug candidate for a new treatment or medical condition for which it was not indicated before. The process of "drug repurposing" usually involves an FDA-approved entity which has undergone clinical development and have a with well-established safety and toxicity profile in patients. Several convergent studies show that repurposed drugs may present a promising strategy for the management and therapy of several human cancers. Memantine is used to combat dementia in moderate-to-severe Alzheimer's disease (AD) patients. Several convergent studies show that memantine (and its analogs) may have applications in multiple disease conditions associated with human cancers. Memantine and its related compounds have shown promise as neuroprotective agents, anti-fatigue agents and pain-relieving agents to alleviate the toxic side effects of radiation therapy and chemotherapy. Recent publications have revealed that memantine displays anti-cancer activity by exerting direct growth-suppressive activity on the primary tumor as modulating the genomic/cellular landscape of the tumor microenvironment. Currently, clinical trials are in progress, which aim to evaluate the potential applications of memantine in cancer treatment. The adamantane scaffold in memantine has proved to be a versatile tool for the discovery of synthetic memantine analogs with robust anti-cancer activity. The discovery of second-generation memantine analogs may have wider applications in combating cancer recurrence and addressing clinical challenges in the treatment of drug-resistant and metastatic cancers.

Humans↗

Inhibition by memantine of the development of persistent oral dyskinesias induced by long-term haloperidol treatment of rats.

1. Tardive dyskinesia (TD) is a serious side-effect of long-term treatment with neuroleptics. To investigate if neuroleptic-induced excessive stimulation of striatal glutamate receptors may underlie TD development, the effect of the NMDA antagonist, memantine (1-amino-3,5-dimethyladamantane), was studied in a rat model of TD. 2. In an acute experiment, six groups of rats were treated daily for 1 week with either vehicle or memantine 20 or 40 mg kg-1 day-1, and on the seventh day they received one injection of either haloperidol 1.0 mg kg-1 i.p. or saline i.p. In a subsequent long-term experiment lasting 20 weeks, the same treatment was continued, except that haloperidol was injected i.m. as decanoate (38 mg kg-1 every 4 weeks) and control rats received sesame oil. The behaviour was videotaped and scored at intervals during both experiments, and for 16 weeks after cessation of the long-term treatment. 3. In the acute experiment, haloperidol decreased motor activity and memantine increased moving and tended to attenuate the immobility induced by haloperidol. Memantine also enhanced the haloperidol-induced increase in the putative TD-analogue vacuous chewing movements (VCM). 4. In the long-term experiment, the most marked effect of haloperidol was a gradual increase in VCM and the increase persisted significantly for 12 weeks after cessation of treatment. Memantine dose-dependently increased VCM and moving during long-term treatment. However, only one week after stopping treatment, both these effects of memantine disappeared. In contrast to rats previously treated with haloperidol alone, rats co-treated with memantine (both doses) and haloperidol had VCM at the level of controls two weeks after stopping treatment. The blood levels of drugs were within the therapeutic range achieved in human subjects. 5. These results suggest that long-lasting changes induced by haloperidol are prevented by memantine, which supports the theory that excessive NMDA receptor stimulation may be a mechanism underlying the development of persistent VCM in rats and maybe also TD in human subjects.

Animals↗

Efficacy and safety of memantine in patients with mild to moderate vascular dementia: a randomized, placebo-controlled trial (MMM 300).

BACKGROUND AND PURPOSE: Based on the hypothesis of glutamate-induced neurotoxicity (excitotoxicity) in cerebral ischemia, this study examined the efficacy and tolerability of memantine, an uncompetitive N-methyl-D-aspartate antagonist, in the treatment of mild to moderate vascular dementia. METHODS: In this multicenter, 28-week trial carried out in France, 321 patients received 10 mg/d memantine or placebo twice a day; 288 patients were valid for intent-to-treat analysis. Patients had to meet the criteria for probable vascular dementia and have a Mini-Mental State (MMSE) score between 12 and 20 at inclusion. The 2 primary end points were the cognitive subscale of the Alzheimers Disease Assessment Scale (ADAS-cog) and the global Clinician's Interview Based Impression of Change (CIBIC-plus). RESULTS: After 28 weeks, the mean ADAS-cog scores were significantly improved relative to placebo. In the intention-to-treat population, the memantine group mean score had gained an average of 0.4 points, whereas the placebo group mean score had declined by 1.6 points, ie, a difference of 2.0 points (95% confidence interval, 0.49 to 3.60). The response rate for CIBIC-plus, defined as improved or stable, was 60% with memantine compared with 52% with placebo (P=0.227, intention to treat). Among the secondary efficacy parameters, which were analyzed in the per-protocol subset, MMSE was significantly improved with memantine compared with deterioration with placebo (P=0.003). The Gottfries-Brane-Steen Scale intellectual function subscore and the Nurses' Observation Scale for Geriatric Patients disturbing behavior dimension also showed differences in favor of memantine (P=0.04 and P=0.07, respectively). Memantine was well tolerated with a frequency of adverse events comparable to placebo. CONCLUSIONS: In patients with mild to moderate vascular dementia, memantine 20 mg/d improved cognition consistently across different cognitive scales, with at least no deterioration in global functioning and behavior. It was devoid of concerning side effects.

Aged↗

Catatonic schizophrenia and the use of memantine.

OBJECTIVE: To report a case of catatonic schizophrenia treated with memantine that resulted in a rapid reduction of catatonic symptoms. CASE SUMMARY: A 68-year-old male with catatonic schizophrenia presented with bizarre and catatonic behavior manifested by mutism, waxy flexibility, immobility, staring, nonresponsiveness to verbal commands, grimacing, rigidity, and posturing. During the course of his hospitalization, he was treated with memantine up to 10 mg/day. The catatonia responded rapidly and significantly to memantine. DISCUSSION: Few treatment options are available for the management of catatonia. Lorazepam is generally the agent that has been used most often and has had varying degrees of success. Our report adds to a recently published case that also suggested that memantine might be useful for the management of catatonic behaviors in a patient with schizophrenia. While its mechanism of action is unknown, it has been thought that glutamate antagonists, such as memantine, may be beneficial in catatonic schizophrenia due to a glutamatergic dysfunction present in catatonic patients. It also has been hypothesized that there is a decrease in gamma-aminobutyric acid released to the supplementary motor areas, resulting in less glutamate inhibition. This results in a net effect of glutamatergic hyperfunction in the striatum, which may produce catatonia. Based on this hypothesis, memantine would be beneficial as an N-methyl-D-aspartic acid antagonist to decrease the amount of glutamate in the striatum and thereby relieve symptoms of catatonia. However, these potential benefits must be weighed against recently reported adverse reactions associated with memantine use, namely, psychosis and seizures. CONCLUSIONS: Memantine produced a rapid and significant reduction in catatonic symptoms in our patient with catatonic schizophrenia.

Aged↗

Evaluation of memantine for neuroprotection in dementia.

Memantine, a non-competitive NMDA antagonist, has been approved for use in the treatment of dementia in Germany for over ten years. The rationale for use is excitotoxicity as a pathomechanism of neurodegenerative disorders. Memantine acts as a neuroprotective agent against this pathomechanism, which is also implicated in vascular dementia. HIV-1 proteins Tat and gp120 have been implicated in the pathogenesis of dementia associated with HIV infection and the neurotoxicity caused by HIV-1 proteins can be blocked completely by memantine. Memantine has been investigated extensively in animal studies and following this, its efficacy and safety has been established and confirmed by clinical experience in humans. It exhibits none of the undesirable effects associated with competitive NMDA antagonists such as dizocilpine. The efficacy of memantine in a variety of dementias has been shown in clinical trials. Memantine is considered to be a promising neuroprotective drug for the treatment of dementias, particularly Alzheimer's disease for which there is no neuroprotective therapy available currently. It can be combined with acetylcholinesterase inhibitors which are the mainstay of current symptomatic treatment of Alzheimer's disease. Memantine has a therapeutic potential in numerous CNS disorders besides dementias which include stroke, CNS trauma, Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), epilepsy, drug dependence and chronic pain. If memantine is approved by the FDA for some of these indications by the year 2005, it can become a blockbuster drug by crossing the US$1 billion mark in annual sales.

Alzheimer Disease↗

A systematic review of the clinical and cost-effectiveness of memantine in patients with moderately severe to severe Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia and is characterised by a worsening of cognition, functional ability, and behaviour and mood. The objective of this study was to review the clinical and cost-effectiveness of memantine for the treatment of patients with moderately severe to severe AD. To achieve this, a systematic search and review of the clinical and cost effectiveness literature for memantine was undertaken. The literature search covered the period from the inception of MEDLINE, Cochrane Library, EMBASE and other electronic databases until July 2004. The search included randomised controlled trials (RCTs) and full economic evaluations that assessed the use of memantine in patients with moderately severe to severe AD. Two published RCTs were included in this review; in one of these trials the participants were already being treated with donepezil. The two RCTs showed benefit for patients receiving memantine compared with placebo on the outcome measures of the Alzheimer's Disease Cooperative Study Activities of Daily Living Inventory modified for severe dementia, the Clinician's Interview-Based Impression of Change Plus Caregiver Input, and the Severe Impairment Battery, and that memantine appeared to be slightly more effective in patients already receiving a stable dose of donepezil. Five cost-effectiveness studies were included in the review. Although these studies reported cost reductions and improved outcomes with memantine, the evaluations were based on a number of assumptions. In conclusion, memantine appears to be beneficial when assessed using functional and global measurements. However, the effect of memantine on cognitive scores and behaviour and mood outcomes is less clear. Cost-effectiveness is dependent upon assumptions surrounding clinical effect and context-specific cost data.

Aged↗

[Protective effect of memantine on N-methyl-D-aspartate receptor in dichlorvos-poisoned rat brain].

OBJECTIVE: To study the protective effect of memantine on the regulation of N-methyl-D-aspartate (NMDA) receptor in dichlorvos-poisoned rat brain, and to understand the mechanism of its role in organophosphate poisoning. METHODS: SD rats were administrated dichlorvos (25 mg/kg, ip) then three groups were treated with memantine at doses of 5, 15 and 45 mg/kg respectively. The activity of acetylcholinesterase (AChE) and binding capacity of NMDA receptor with [(3)H]MK-801 were determined 16 h after dichlorvos injection. RESULTS: The time of onset of toxic symptoms in 15, 45 mg memantine treated groups [(18.40 +/- 1.14) and (21.40 +/- 1.52) min respectively] was higher than that in dichlorvos alone group [(16.75 +/- 1.62) min]; the intensity of muscle fasciculation (1.60 +/- 1.14 and 0.80 +/- 0.84, respectively) was less than that in control group (2.85 +/- 0.37); the total score of poisoning symptoms (8.80 +/- 1.79 and 9.00 +/- 2.24 respectively) was also less than that in dichlorvos group (14.60 +/- 1.70). The AChE activities both in blood and brain of memantine treated groups were not significantly different from those in dichlorvos alone group. The affinity (Kd value) and density (Bmax value) of brain NMDA receptor in dichlorvos exposed rats [(75.55 +/- 7.87) nmol/L, (0.46 +/- 0.06) pmol/mg pro respectively] were higher and lower respectively than those in control group [(37.37 +/- 4.17) nmol/L, (0.62 +/- 0.04) pmol/mg pro respectively]. Lower level of memantine (5 and 25 mg/kg) could antagonize the dichlorvos-evoked down-regulation of [(3)H]MK-801 binding to NMDA receptor in rat brain [Bmax value: (0.55 +/- 0.07) and (0.64 +/- 0.07) pmol/mg pro; Kd value: (38.68 +/- 4.54) and (32.58 +/- 3.90) nmol/L respectively] while higher dose of memantine (45 mg/kg), the Bmax (0.45 +/- 0.06) pmol/mg pro and Kd (22.88 +/- 4.42) nmol/L of NMDA receptor were significantly decreased (P < 0.01). CONCLUSION: Memantine in certain dose range could protect against the down-regulation of NMDA receptor in rat brain, and alleviate organophosphorus poisoning symptoms to some extent. The recovery of AChE activity inhibition wasn't involved in the treatment with memantine on dichlorvos poisoning, therefore, atropine and a proper AChE reactivator (an oxime) should be used clinically.

Acetylcholinesterase↗

[Clinical efficacy and safety of akatinol memantine in treatment of mild to moderate Alzheimer disease: a donepezil-controlled, randomized trial].

OBJECTIVE: To evaluate the clinical efficacy and safety of akatinol memantine in the treatment of patients with mild to moderate Alzheimer disease (AD). METHODS: One hundred patients with diagnosis of possible or probable AD and Mini Mental State Examination total scores between 10 and 26 from 6 centers in two cities of China were randomly divided into two groups: akatinol memantine group (n = 50, given akatinol memantine 5 mg/d in first week, 10 mg/d in second week, 15 mg/d in third week and 20 mg/d from fourth to sixteenth week); donepezil group (n = 50, donepezil 5 mg/d). Different scales were used to evaluated cognitive function (MMSE), activity of daily life and behavior and mood (Blessed-Roth scale) as well as the severity of dementia (GDS). Safety evaluation was conducted every 4 weeks. RESULTS: In comparison with the baseline data, there were significant improvements in cognition assessed with MMSE on 16th week in akatinol memantine group (P = 0.000) and donepezil group (P = 0.000) respectively; There also were significant improvements in activity of daily life, behavior and mood assessed by Blessed-Roth scale in akatinol memantine group (P = 0.000) and donepezil group (P = 0.000) on 8th week and 16th week. However there was no improvements in the change of the basic habit of life assessed with the Part II of Blessed-Roth scale (P > 0.05), and nor an improvements in the serious level of dementia assessed with GDS (P > 0.05). In comparison with the data in donepezil group, there were no improvement in the change of MMSE score, Blessed-Roth scale score and GDS score in akatinol memantine group on 16th week (P > 0.05). Mild and transient adverse events were observed in 6% of akatinol memantine group. CONCLUSION: As a safe and effective medicine, akatinol memantine, which has a similar effect as donepezil for AD, can remarkably improve the cognition, behavior, and mood of AD patients.

Aged↗

Drug forecast: memantine, prototype of a new approach to treatment of dementia.

OBJECTIVE: To review the first clinically useful N-methyl-D-aspartate (NMDA) inhibitor for the treatment of dementia, memantine. DATA SOURCE: A MEDLINE/PUBMED search was conducted to identify pertinent studies, case reports, letters, and reviews in the English language. All articles published from 1950 to March 2003 were reviewed. Additional references were obtained from the bibliographies of these articles. STUDY SELECTION: All studies evaluating any aspect of memantine in humans. DATA SYNTHESIS: The excitatory amino acid neurotransmitter glutamate is felt to play a role in neuroinflammation and destruction of cholinergic neurons associated with dementia. Memantine is an NMDA receptor antagonist which partially blocks glutamatergic neurotransmission in the central nervous system (CNS). It is a selective, moderate affinity, noncompetitive receptor blocker that rapidly associates with and dissociates from the NMDA receptor. Memantine, that is usually dosed once or twice daily, is predominantly eliminated as unchanged drug via the renal route (renal clearance accounts for 90% of total body clearance). Use of memantine is associated with significant improvements in a number of cognitive, functional, and behavioral assessment scales used in the evaluation of cognition-enhancing drugs in dementia. Adverse effects of memantine are generally referable to the CNS and include depression, insomnia, akathisia, agitation, dizziness, drowsiness, restlessness, and hyperexcitability. CONCLUSION: Although there is no cure for dementia, memantine may delay disease progression and improve functioning to a clinically significant extent. However, efficacy has not been consistent within trials and no comparative data with acetylcholinesterase inhibitors (AchEI) are available. In addition, there are no controlled data available regarding combination memantine-AchEI therapy. Further study data are awaited.

Journal Article↗

A responder analysis of memantine treatment in patients with Alzheimer disease maintained on donepezil.

OBJECTIVE: The objective of this study was to examine the clinical utility of memantine for moderate-to-severe Alzheimer disease (AD) using responder analyses. METHOD: Data from a previously published 24-week, randomized, double-blind, placebo-controlled trial of 10 mg memantine twice a day in patients with moderate-to-severe AD (N = 404) on stable donepezil therapy were evaluated using three sets of responder criteria. Response rates were calculated and analyzed for the intention-to-treat population using a generalized estimating equations model. The following outcomes were examined separately and in combination: the Alzheimer's Disease Cooperative Study-Activities of Daily Living 19-Item Inventory (ADCS-ADL19), Severe Impairment Battery (SIB), Clinician's Interview-Based Impression of Change Plus Caregiver Input (CIBIC-Plus), and Neuropsychiatric Inventory (NPI). RESULTS: When treatment response required cognitive improvement relative to baseline, memantine yielded higher response rates than placebo. When treatment response was defined as stabilization of individual outcomes, memantine resulted in significantly higher response rates than placebo for all outcomes, with number needed to treat (NNT) ranging from 8-10. More conservative definitions of response that required simultaneous stabilization on multiple outcome measures again favored memantine treatment for six of 10 combinatorial definitions. CONCLUSIONS: These responder analyses may assist clinicians in evaluating the impact of memantine in a relevant clinical scenario, i.e., in patients with AD previously stabilized on a cholinesterase inhibitor. The current results indicate that in this setting, memantine produces both improvement and stabilization of symptoms, across multiple outcomes, and thus provides a clinically important treatment benefit for patients with moderate-to-severe AD.

Activities of Daily Living↗

Activities of daily living in moderate-to-severe Alzheimer disease: an analysis of the treatment effects of memantine in patients receiving stable donepezil treatment.

In moderate-to-severe Alzheimer disease (AD), there are significant losses of activities of daily living (ADL). In a recent prospective, randomized, placebo-controlled trial, memantine treatment lessened the overall functional decline in AD patients already on stable donepezil therapy. In this trial, patients (n=404) with Mini-Mental State Examination scores of 5 to 14 receiving stable donepezil treatment were randomized to double-blind treatment with memantine (10 mg b.i.d.; n=203) or placebo (n=201). A primary outcome measure was the 19-item Alzheimer's Disease Cooperative Study--Activities of Daily Living Inventory (ADCS-ADL(19)). To further evaluate the treatment effects of memantine on function, we performed post hoc analyses of ADCS-ADL(19) data from this trial, including ADL items and new subscales derived from factor analysis. Using mixed model analyses, patients receiving memantine had statistically significant less decline in total ADCS-ADL(19) scores compared with placebo. An item analysis revealed statistically significant benefits of memantine on grooming, toileting, conversing, watching television, and being left alone. Statistically significant improvements were noted in subscales evaluating higher-level functions and connectedness/autonomy with memantine compared with placebo. These post hoc analyses in moderate-to-severe AD patients receiving stable donepezil treatment suggest that memantine may impact overall functional levels, and some of the cognitive processing underlying ADL performance.

Activities of Daily Living↗

High doses of memantine (1-amino-3,5-dimethyladamantane) induce seizures in kindled but not in non-kindled rats.

Memantine (1-amino-3,5-dimethyladamantane) has previously been shown to attenuate or block chemically or electrically induced seizures in rodents at doses of 5-20 mg/kg i.p., suggesting that the drug might have potential utility in the treatment of seizures. In the present study, the effects of memantine were examined in amygdala-kindled and non-kindled rats. In fully kindled rats, i.e. a model of focal seizures with secondary generalization, memantine exerted no effects on seizure parameters at 5 mg/kg i.p., but reduced seizure severity and duration at 10 mg/kg. The threshold for induction of afterdischarges recorded from the amygdala was not altered after administration of 10 mg/kg. At 20 mg/kg, memantine induced spontaneous motor seizures in amygdala-kindled rats. No motor seizures were observed in non-kindled rats, but in both kindled and non-kindled animals memantine, 20 mg/kg, induced spikes in the electroencephalogram. Additional dose-dependent behavioural alterations observed after memantine included hyperactivity, ataxia and stereotypies, which may relate to the dopaminomimetic properties of the drug. The results demonstrate that kindled rats are more sensitive to central nervous system stimulating effects of memantine than non-kindled rats, which could relate to an impairment of inhibitory processes and/or alterations in synaptic transmission mediated by excitatory amino acids in the kindled brain.

Amantadine↗

Effects of the NMDA antagonist memantine on human methamphetamine discrimination.

RATIONALE: The discriminative stimulus effects of N-methyl- D-aspartate (NMDA) antagonists have been assessed in laboratory animals. To date, no published study has assessed their ability to alter methamphetamine-related discriminative stimulus effects in humans. OBJECTIVE: This study investigated the discriminative stimulus, subjective (e.g. "Good Drug Effect"), psychomotor performance, and cardiovascular effects (e.g. blood pressure) of oral methamphetamine following acute oral memantine (a non-competitive NMDA antagonist) in humans. METHODS: Initially, participants were trained to discriminate 10 mg methamphetamine from placebo using a standard two-response procedure (drug versus placebo). Then, the effects of memantine (0, 40 mg) on methamphetamine discrimination were examined across several methamphetamine doses (0, 5, 10, 20 mg) using a novel-response procedure (drug versus placebo versus novel). RESULTS: Following placebo pretreatment, 10 mg methamphetamine produced 99% methamphetamine-appropriate responding and placebo produced 75% placebo-appropriate responding. Following memantine pretreatment, participants responded as if they had been given a novel compound, although memantine did not significantly alter most subjective-effects ratings following methamphetamine. Memantine alone produced "positive" subjective effects and novel drug-appropriate responding. CONCLUSION: These data indicate that the memantine-methamphetamine combination produced novel discriminative stimulus effects and that memantine produced some stimulant-like subjective effects.

Adult↗

Acute effects of memantine in combination with alcohol in moderate drinkers.

RATIONALE: Alcohol effects in humans involve N-methyl- d-aspartate (NMDA) receptor-mediated glutamatergic neurotransmission. It has been proposed that NMDA receptor antagonists may be effective in the treatment of alcohol dependence. OBJECTIVE: This study evaluated the acute effects of memantine, an NMDA receptor antagonist, on the subjective, physiological, and performance effects of alcohol in moderate (10-30 drinks per week) alcohol drinkers. METHODS: Eighteen volunteers without alcohol dependence were tested using a double-blind design with three 3-day long inpatient phases separated by at least a 2-week wash-out period. Memantine (0, 15, and 30 mg) was administered 4 h before alcohol (1.5 g/l body water), which was given in four divided doses every 20 min. RESULTS: Pretreatment with memantine attenuated the craving for alcohol before alcohol administration, but not after alcohol was given. Memantine increased the dissociative effects of alcohol, without altering its sedative, stimulant, and overall intoxicating effects. Memantine also did not affect alcohol-induced impairment in performance, physiological changes, or pharmacokinetics. Memantine increased subjective reports of dissociation, confusion, and stimulation, and impaired motor coordination on the balance task. CONCLUSIONS: Memantine was well tolerated in combination with alcohol. The findings suggest that NMDA receptor neurotransmission may be involved in alcohol craving and alcohol-induced subjective dissociative effects.

Adult↗

A retrospective study of memantine in children and adolescents with pervasive developmental disorders.

RATIONALE: There are no drugs that have been shown to effectively treat the core social impairment of autism. OBJECTIVES: The purpose of this study was to examine the effectiveness and tolerability of memantine for social impairment in children and adolescents with pervasive developmental disorders (PDDs). MATERIALS AND METHODS: Medical records of 18 patients with PDDs consecutively treated with open-label memantine were retrospectively reviewed. The data reviewed included prospectively obtained assessments of severity (S) and improvement (I) using the Clinical Global Impressions Scale (CGI). Pretrial and follow-up parent ratings were also available on six patients using the Aberrant Behavior Checklist (ABC). RESULTS: Eighteen patients (15 male, 3 female; mean age=11.4 years, range 6-19 years) received memantine (mean dosage=10.1 mg/day, range 2.5-20 mg/day) over a mean duration of 19.3 weeks (range 1.5-56 weeks). Eleven of 18 (61%) patients were judged responders to memantine based on a rating of "much improved" or "very much improved" on the CGI-I. Significant improvement was also seen on the CGI-S. Improvement was primarily seen clinically in social withdrawal and inattention. Adverse effects occurred in 7 of 18 (39%) patients and led to drug discontinuation in 4 of 18 (22%) patients. Thirteen of 18 (72%) patients received stable doses of concomitant medications during the memantine trial. CONCLUSIONS: In this open-label retrospective study, memantine was effective in a number of patients with PDDs. Controlled studies are warranted to further assess the efficacy and safety of memantine in PDDs.

Adolescent↗

Reduction of edema and infarction by Memantine and MK-801 after focal cerebral ischaemia and reperfusion in rat.

N-methyl-D-aspartate (NMDA) receptor antagonists have been found to be protective after cerebral ischemia. However most of these drugs have limited value as neuroprotectives in clinical therapy because of their side effects. Memantine is a noncompetitive NMDA receptor antagonist and it has been used for the treatment of various cerebral disorders with relatively few side effects. We investigated the beneficial effects of Memantine and compared its effect with MK-801 in a temporary focal cerebral ischemia model. As cerebral ischemia model three hours middle cerebral artery occlusion (MCAO) with intraluminal thread and three hours reperfusion was used. 78 male Spraque-Dawley rats were divided into three groups as follows: Control (Saline), treatment 1 (MK-801), and treatment 2 (Memantine) groups. In the treated groups, 15 minutes after MCAO, MK-801 and Memantine were administered in amounts of 1 mg/kg and 10 mg/kg intraperitoneally respectively. After a 3 hour period of reperfusion, the animals were examined for neurological deficits and then killed. The following values were measured; cerebral water content, blood brain barrier (BBB) permeability at the core and periphery of the ischemic hemisphere and contralateral hemisphere and infarct volumes. The severity of neurological deficit (p < 0.001) and infarct volume (p < 0.001) was reduced in both Memantine and MK-801 treated groups compared with saline treated groups. Memantine attenuated brain edema formation and BBB permeability at the periphery (p < 0.01), MK-801 both at the core (p < 0.05) and the periphery (p < 0.01) of the ischemia. These results demonstrated that the NMDA receptor antagonists Memantine and MK-801 were neuroprotective when given 15 min after MCAO in temporary focal cerebral ischemia.

Animals↗

Memantine reduces striatal cell death with decreasing calpain level in 3-nitropropionic model of Huntington's disease.

Huntington's disease has an increase in the activated calpain, which is enhanced by the NMDA receptor activation. We investigated the neuroprotective effect of memantine in 3-nitropropionic acid (3NP)-induced striatal degeneration model. Either memantine (20 mg/kg/day) or PBS was intraperitoneally administered for five days with 3NP continuous infusion. In the memantine-treated group, the striatal lesion volume, the number of TUNEL+ cells, and Fluoro-Jade C+ degenerating neurons were all decreased. Memantine increased Bcl-xl and decreased Bax level. Memantine also exerted an inhibitory effect on the micro-calpain level and decreased the huntingtin proteolytic fragments. Those rats treated with memantine showed less degree of weight loss at 5 days. Subsequently, memantine was found to have neuroprotective effects and save striatal cells with decreasing calpain levels in the 3NP model of Huntington's disease.

Animals↗