Clinically significant drug interactions with cholinesterase inhibitors: a guide for neurologists

The anti-dementia drugs: myth, hype or reality?

The neurodegenerative diseases are in need of drugs that are capable of treating their many different presentations. Some drugs have recently been developed and approved by the authorities for use in Alzheimer's disease; their beneficial effects are no longer questionable. From the discussion about what to call these drugs (anti-dementia drugs?), it is apparent that pharmacology research has veered from pursuing the myth of the fountain of eternal youth back to the reality of the struggle for survival of neurons whenever they are attacked, long before the signs of dementia have developed (antiapoptotic drugs?). The neurosciences teach that there is a biology of cognition (hence a pharmacology of cognition), and that the brain is the permanent area of the confrontation between neurogenesis and apoptosis. Pharmacology has taken this new understanding on board, and has finally defined its objective as preventing the decline of the neuron as much as of cognitive performance. It remains for clinicians to confirm the authenticity of this worldwide project.

Adding memantine to rivastigmine therapy in patients with mild-to-moderate alzheimer's disease: results of a 12-week, open-label pilot study

OBJECTIVE

At present, inhibition of cholines-terase is the treatment of choice for subjects with mild-to-moderate Alzheimer's disease (AD). Memantine, a noncompetitive antagonist at N-methyl-d-aspartate receptors, is currently used to treat subjects with moderate-to-severe AD. The goal of this multicenter, open-label pilot study was to investigate whether combination therapy with memantine added to rivastigmine is safe and beneficial in subjects with mild-to-moderate AD.

METHOD

Patients with a DSM-IV diagnosis of dementia of the Alzheimer's type (N = 95), who were treated with rivastigmine (6-12 mg/day) for a maximum duration of 24 weeks prior to baseline, received memantine (5-20 mg/day) in combination with rivastigmine for 12 weeks. The primary efficacy variable was the change in the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) total score at the end of 12 weeks compared with baseline. The study was conducted between September 15, 2003, and May 27, 2004.

RESULTS

There was a statistically significant difference between baseline and week 12 for the ADAS-cog total score, showing a positive effect of combination therapy. Combination therapy did not evidence any unexpected safety concerns and was well-tolerated by most patients.

CONCLUSION

Memantine in combination with rivastigmine appears to be safe and beneficial in patients with mild-to-moderate AD. Our results need to be confirmed in a large, long-term, randomized, double-blind, placebo-controlled clinical trial.

Design, synthesis, and evaluation of novel bifunctional iron-chelators as potential agents for neuroprotection in Alzheimer's, Parkinson's, and other neurodegenerative diseases

Several novel antioxidant-iron chelators bearing 8-hydroxyoxyquinoline moiety were synthesized, and various properties related to their iron chelation, and neuroprotective action were investigated. All the chelators exhibited strong iron(III) chelating and high antioxidant properties. Chelator 9 (HLA20), having good permeability into K562 cells and moderate selective MAO-B inhibitory activity (IC50 110 microM), displayed the hightest protective effects against differentiated P19 cell death induced by 6-hydroxydopamine. EPR studies suggested that Chelator 9 also act as radical scavenger to directly scavenge hydroxyl radical.

Pharmacotherapeutic approaches to the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD), a progressive degenerative disorder of the brain, is the most common cause of cognitive impairment in the elderly. The pharmacotherapy of AD is evolving rapidly. Cholinergic stabilization with cholinesterase-inhibitor (ChEI) therapy implies neuroprotection and a resultant slowing of disability and disease progression. The moderate-affinity N-methyl-d-aspartate (NMDA)-receptor antagonist memantine may block neural excitotoxicity.

OBJECTIVE

The purpose of this review was to examine the evidence for the responsiveness to pharmacotherapy of established AD; specifically, the extent to which the benefits of therapy have been proved, the extent to which currently available ChEIs support cholinergic neurotransmission, and the extent to which currently available ChEIs and memantine provide neuroprotection.

METHODS

Relevant studies were identified through a comprehensive search of MEDLINE for articles published between January 1999 and February 2004 using the terms Alzheimer's pharmacotherapy, cholinesterase inhibitor therapy, Alzheimer's disease, donepezil, rivastigmine, galantamine, glutamatergic system modifiers, and memantine; a search of the reference lists of identified articles; and a manual search of pertinent journals. Articles were selected that contained higher-level evidence, based on explicit validated criteria.

RESULTS

ChEI therapy was associated with quality-of-life improvements that included enhanced performance of activities of daily living, reduced behavioral disturbances, stabilized cognitive impairment, decreased caregiver stress, and delay in the first dementia-related nursing home placement. In large clinical trials in moderate to severe AD (a stage that is associated with distress for patients and caregiver burden, and for which other treatments are not available), memantine showed an ability to delay cognitive and functional deterioration. The combination of memantine and ChEI therapy was significantly more efficacious than ChEI therapy alone (P < 0.001) and was well tolerated.

CONCLUSIONS

The idea that AD is pharmacologically unresponsive appears to be changing. With the use of ChEI and NMDA-receptor antagonist therapy, the symptoms and outcomes of this devastating neurodegenerative disease can be improved and its course altered.

Symptomatic and Disease-Modifying Therapy for the Progressive Ataxias

BACKGROUND

The progressive ataxias are a diverse group of neurologic diseases that share features of degeneration of the cerebellum and its inflow/outflow pathways but differ in etiology, course, and associated noncerebellar system involvement. Some will have treatable causes, but for most, the pathophysiology is incompletely known.

REVIEW SUMMARY

Treatment strategies will include (1) definitive therapy when available, (2) symptomatic treatment and prevention of complications, and (3) rehabilitation and support resources. The physician will have to decide whether to introduce or approve the use of therapies based on as yet-unproven mechanisms or the use of complementary medicine approaches.

CONCLUSIONS

There are as yet no drugs that have been approved by the Food and Drug Administration for the treatment of the progressive ataxias and relatively few disease-modifying therapies, but symptomatic and rehabilitation interventions can greatly improve the quality of life of individuals with these disabling neurodegenerative disorders.