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Background: Postmarketing surveillance studies (PMS) are an important tool for evaluating a drug’s effectiveness and safety in clinical practice. To our knowledge, no PMS on memantine monotherapy for moderately-severe-to-severe Alzheimer’s disease (AD) according to National Institute of Neurological and Communicative Disorders and Stroke — Alzheimer’s Disease and Related Disorders Association criteria has been conducted to date. Objective: The Lombardy Health Office, Italy, promoted this PMS to evaluate the effectiveness and safety of memantine in the treatment of moderately-severe-to-severe AD in clinical practice. Methods: A total of 451 patients with moderately-severe-to-severe AD (mean age 77 ± 7 years; 72% female), free of cholinergic medication, received memantine (standard titration to 10 mg twice daily). After 6 months of therapy, treatment effectiveness was evaluated according to two definitions of response (‘no deterioration’ and ‘improvement’), as measured by changes in baseline scores on the Clinical Global Impression of Change, Mini-Mental State Examination, Neuropsychiatric Inventory and Activities of Daily Living scales. The safety measure was the frequency of adverse events (AEs). Results: At 6-month assessment, 26.8% of subjects showed no deterioration and 3.8% showed improvement. In those showing no deterioration, response to treatment at the 3-month assessment was associated with a greater probability of a response at 6 months (adjusted odds ratio = 8.54; 95% CI 4.54, 16.05). Seventy patients (15.5%) experienced at least one AE and 39 (8.6%) discontinued treatment prematurely because of an AE. Of those who experienced an AE, 27 (38.6%) manifested behavioural and psychological symptoms of dementia. Conclusion: The proportion of responders to memantine treatment in this PMS was similar to that reported in a previous randomized clinical trial (26.8% vs 29%, respectively). The proportion of patients who discontinued treatment prematurely because of an AE (8.6%) was similar to that reported in two previous randomized clinical trials (10% and 12.4%). This PMS provides additional evidence that both the effectiveness and the tolerability of memantine may be transferred into real world medicine, where AD patients receiving treatment are not selected according to strict criteria.

The aim of this study is to evaluate memantine effectiveness on behavioural and psychological symptoms of dementia (BPSD) in clinical practice and to identify variables that may predict the therapy effects. The effects of memantine on behaviour were analysed in the database of a post-marketing surveillance study promoted by the Lombardy Region Health Office and involving 43 Alzheimer's disease (AD) Units. From July to December 2005, 399 moderately severe-to-severe AD patients free of cholinergic medications were enrolled, treated with memantine and followed-up for 6 months. BPSD were assessed in a subgroup of 297 patients [mean age 77 ± 8 years; 73% females; mean neuropsychiatric inventory (NPI) score 28 ± 24] for whom the 12-item NPI subscores at baseline, and at 3 and 6 months were available. The 12 BPSD were clustered as follows: affect, physical behaviour, psychosis and hypomania. The main outcome measure was the proportion of individual cluster responders at 6 months of therapy. The proportion of individual cluster responders was 30% affect, 24% physical behaviour, 29% psychosis, 27% hypomania. Patients taking 20 mg memantine daily during the study period had a statistically significant higher probability to experience behavioural improvement than those who discontinued treatment or did not complete memantine titration (affect OR 9.0; 95% CI 3.8-21.6; physical behaviour OR 17.8; 95% CI 5.9-53.6; psychosis OR 23.6; 95% CI 5.1-110.8). The logistic regression analysis was not applicable to the hypomania subsyndrome because of the low cluster prevalence. The standard 20 mg daily memantine treatment regimen was found to be associated with a modest 6-month behavioural improvement in the affect, physical behaviour and psychosis domains in 24-30% of patients.

Lignin peroxidase catalyses the H2O2-induced oxidation of 4-methoxybenzyltrimethylsilane by an electron transfer mechanism. The intermediate radical cation undergoes preferentially Ca–H deprotonation to give 4-methoxybenzaldehyde whereas Ca–Si bond cleavage is a minor fragmentation pathway and leads to 4-methoxybenzyl alcohol. Similar results are obtained in the oxidation catalysed by the water soluble model compound 5,10,15,20-tetra(N-methyl-4-pyridyl)porphyrinatoiron(III) pentachloride. Instead, in the oxidation promoted by the genuine one-electron transfer oxidant potassium dodecatungstocobalt(III)ate Ca–Si bond cleavage is the exclusive fragmentation process of the intermediate radical cation. It is suggested that in the enzymatic and biomimetic oxidations of 4-methoxybenzyltrimethylsilane the deprotonation of the intermediate radical cation is promoted by the reduced form [PorFe+.(IV)=O] of the active oxidant, which is an iron-oxo porphyrin radical cation.

The oxygen atom transfer-electron transfer (ET) mechanistic dichotomy has been investigated in the oxidation of a number of aryl sulfides by H2O2 in acidic (pH 3) aqueous medium catalysed by the water soluble iron(III) porphyrin 5, 10, 15, 20-tetraphenyl-21H, 23H-porphine-p,p’,p’’,p’’’-tetrasulfonic acid iron (III) chloride (FeTPPSCl). Under these reaction conditions, the iron-oxo complex porphyrin radical cation, P+·Fe(IV)=O, should be the active oxidant. When the oxidation of a series of paraÓX substituted phenyl alkyl sulfides (X = OCH3, CH3, H, Br, CN) was studied the corresponding sulfoxides were the only observed product and the reaction yields as well as the reactivity were little influenced by the nature of X as well as by the bulkiness of the alkyl group. Labelling experiments using H218O or H218O2 clearly indicated that the oxygen atom in the sulfoxides comes exclusively from the oxidant. Moreover, no fragmentation products were observed in the oxidation of a benzyl phenyl sulfide whose radical cation is expected to undergo cleavage of the b C-H and C-S bonds. These results would seem to suggest a direct oxygen atom transfer from the iron-oxo complex to the sulfide. However, competitive experiments between thioanisole (E°= 1.49 V vs NHE in H2O) and N,N-dimethylaniline (E°= 0.97 V vs NHE in H2O) resulted in exclusive N-demethylation, whereas the oxidation of N-methylphenothiazine (10, E°= 0.95 V vs NHE in CH3CN) and N,N-dimethyl-4-methylthioaniline (11, E°= 0.65 V vs NHE in H2O) produced the corresponding sulfoxide with complete oxygen incorporation from the oxidant. Since an ET mechanism must certainly hold in the reactions of 10 and 11, the oxygen incorporation experiments indicate that the intermediate radical cation, once formed, has to react with PFe(IV)=O (the reduced form of the iron-oxo complex which is formed by the ET step) in a fast oxygen rebound. Thus, an ET step followed by a fast oxygen rebound is also suggested for the other sulfides investigated in this work.