Novel regimens and delivery systems in the pharmacological treatment of Alzheimer's disease

Drug delivery strategies for Alzheimer's disease treatment

INTRODUCTION

Current Alzheimer's disease (AD) therapy is based on the administration of the drugs donepezil, galantamine, rivastigmine and memantine. Until disease-modifying therapies become available, further research is needed to develop new drug delivery strategies to ensure ease of administration and treatment persistence.

AREAS COVERED

In addition to the conventional oral formulations, a variety of drug delivery strategies applied to the treatment of AD are reviewed in this paper, with a focus on strategies leading to simplified dosage regimens and to providing new pharmacological tools. Alternatives include extended release, orally disintegrating or sublingual formulations, intranasal or short- and long-acting intramuscular or transdermal forms, and nanotechnology-based delivery systems.

EXPERT OPINION

The advent of new research on molecular mechanisms of AD pathogenesis has outlined new strategies for therapeutic intervention; these include the stimulation of α-secretase cleavage, the inhibition of γ-secretase activity, the use of non-steroidal anti-inflammatory drugs, neuroprotection based on antioxidant therapy, the use of estrogens, NO synthetase inhibitors, and natural agents such as polyphenols. Unfortunately, these compounds might not help patients with end stage AD, but might hopefully slow or stop the disease process in its early stage. Nanotechnologies may prove to be a promising contribution in future AD drug delivery strategies, in particular drug carrier nano- or microsystems, which can limit the side effects of anti-Alzheimer drugs.

Amelioration of amyloid β-induced cognitive deficits by Zataria multiflora Boiss. essential oil in a rat model of Alzheimer's disease

INTRODUCTION

The limitations of current Alzheimer's disease (AD) therapeutics have prompted investigation into innovative therapeutics focused on antiinflammatory, antioxidant, and neuroprotective agents including those from medicinal plants. Numerous plants have been tested for their potential for alleviating symptoms of AD.

AIMS

Zataria multiflora Boiss. (ZM) a member of Lamiaceae family has been used in Iranian traditional medicine for its beneficial effects on mental abilities. Therefore, the effect of its essential oil was evaluated in a rat model of AD.

METHODS

Amyloid β-protein (Aβ) fragment 25-35 was injected bilaterally in the CA1 region of rats hippocampus and the effect of different doses of ZM essential oil (50, 100, or 200 μL/kg) on cognitive function was investigated in the Morris water maze. Acute toxicity of the essential oil was also studied.

RESULTS

The results showed increases in escape latency, traveled distance, heading angle, and decreases in target quadrant entries in Aβ-received groups as compared to the control group. This impairment was reversed by ZM essential oil. The results of acute toxicity testing revealed that the calculated LD50 (1264.9 μL/kg) is much higher than the therapeutic dose (100 μL/kg).

CONCLUSIONS

It seems that antioxidant, antiinflammatory, and anticholinesterase activities of ZM or its main constituents might contribute to its beneficial effects in this model. Our findings suggest that ZM may be a potentially valuable source of natural therapeutic agents for the treatment of AD. However, further investigations are necessary to establish its clinical efficacy and potential toxicity, before any recommendations concerning its use as a medication in the treatment of AD.

The ACTION study: methodology of a trial to evaluate safety and efficacy of a higher dose rivastigmine transdermal patch in severe Alzheimer's disease

BACKGROUND

Two sizes of rivastigmine patch (5 cm(2) and 10 cm(2)) are currently approved in the US and Europe, while a 20 cm(2) rivastigmine patch has also been tested. A 15 cm(2) rivastigmine patch may provide an optimal balance between efficacy and safety. Earlier studies have demonstrated the efficacy of rivastigmine in severe Alzheimer's disease (AD), and supported the use of a higher dose patch in AD.

OBJECTIVE

The ACTION (ACTivities of daily living and cognitION) trial (Study CENA713DUS44) is designed to evaluate the efficacy and safety of low-dose versus high-dose rivastigmine transdermal patch in patients with severe AD.

METHODS

ACTION is a prospective, randomized, parallel-group, double-blind, multicenter study of patients (aged ≥50 years) with severe AD and a Mini-Mental State Examination score of 3-12. Novartis began recruitment in July 2009 and is conducting the trial in the United States. Patients are randomized to receive either a 5 cm(2) (4.5 mg/24 h) or a 15 cm(2) rivastigmine patch (13.3 mg/24 h) for 24 weeks. Patients receiving the 15 cm(2) patch will be up-titrated over 8 weeks, via 5 and 10 cm(2) patches. The primary efficacy outcomes include activities of daily living (ADLs), assessed with the Alzheimer's Disease Cooperative Study - Activities of Daily Living - Severe Impairment Version (ADCS-ADL-SIV), and cognition, assessed with the Severe Impairment Battery (SIB). Secondary outcomes include behavior (Neuropsychiatric Inventory), global functioning (Alzheimer's Disease Cooperative Study - Clinical Global Impression of Change), response rates, and safety.

CONCLUSIONS

The ACTION trial examines the efficacy and tolerability of a 15 cm(2) rivastigmine patch over a 24-week period in patients with severe AD. This is a novel trial in the development of rivastigmine, as it uses a design that does not include a placebo arm, is recruiting patients with severe AD, and includes an ADL measure as a co-primary efficacy variable. CLINICAL REGISTRATION NUMBER: CENA713D US44.

Geriatric drug therapy: neglecting the inevitable majority

Demographic evolution will considerably increase the number of people aged 65 years and beyond in the coming decades. The elderly not only represent the most heterogeneous population, but also are a major user group for prescribed medicines, a predominance that will continue to further increase. Medicines and medication management are much more complex and challenging in the elderly and can only be addressed through a multidisciplinary approach. There is strong evidence that the elderly are able to properly manage their medication; however, their medications require different features than the standard medications used by adults. The elderly are exposed to several chronic disease conditions and their treatments, as well as experience age-related changes and limitations that need to be reflected in their medication management strategies. Geriatric drug therapy remains a multidisciplinary task. The health care industry, physicians, pharmacists, nurses and care givers provide and guide the patient's therapy according to individual needs, while the health care system and regulatory authorities build the necessary framework of support and resources.Any realistic and significant enhancement to the elderly patients' medicines and medication management needs to be addressed by all disciplines and stakeholders involved since the absence of any of the stakeholders in the overall process negatively impacts the achievable enhancement in geriatric drug therapy.

Neuroimmune pharmacology of neurodegenerative and mental diseases

Neuroimmune pharmacology is a newly emerging field that intersects with neuroscience, immunology, and pharmacology and that is seeking avenues for translational research and better understanding of disease mechanisms. It focuses on the immunity of the central nervous system (CNS) which is greatly influenced by endogenous effectors, such as cytokines and neurotransmitters, and by exogenous substances, including therapeutic compounds, infectious pathogens, and drugs of abuse. In this article, we attempt to raise awareness of the pivotal discovery of how those mediators affect the immunity of the CNS in both physiological conditions and processes of certain mental illnesses, including psychiatric disorders, neurodegenerative diseases, and cerebral dysfunctions due to drugs of abuse. The abnormality in cytokine networks, neurotransmitter homeostasis, and other immune responses may be involved in the neuropathology associated with those mental illnesses, and the therapeutic effects of the potential treatments can be attributed, at least partially, to their immunomodulatory activities. However, the resulting inflammatory cytokines from certain treatments frequently cause psychiatric complications. In addition, the poor neuropathological outcomes frequently found among drug abusers with HIV-1 infection appear to be related to the neurotoxic and immunomodulatory effects of the drugs used. Importantly, glial cells, especially microglia and astrocytes, are key players in the immunomodulatory activities in the CNS, and the functioning CNS is largely dependent upon the reciprocal interactions between neurons and glial cells. Therefore, glia-neuron interactions have become a critical issue for further understanding the disease mechanism. From this review, readers will gain insights into the new field of neuroimmune pharmacology, with a focus on the impacts of CNS immunity on the mental illnesses.

Memantine ER, a once-daily formulation for the treatment of Alzheimer's disease

IMPORTANCE OF THE FIELD

Alzheimer's disease is a progressive, degenerative brain disease. As the disease progresses, patients and caregivers face increasing problems with medication adherence. Given its relentlessly progressive nature, newer and more effective therapies for Alzheimer's disease are needed. Memantine 10 mg twice daily is the FDA-approved regimen for the treatment of moderate to severe Alzheimer's disease.

AREAS COVERED IN THIS REVIEW

The goal of this article is to review the once-daily memantine ER 28 mg formulation for the treatment of Alzheimer's disease, which, by simplifying the dosage regimen, decreases the problems of medication adherence. A new extended-release formulation has been developed to improve adherence and possibly efficacy without compromising an excellent tolerability and safety profile. There is also a possibility of dose-dependent improvement/superiority in cognitive, global and behavioral measures as well as in verbal fluency with higher-dose (28 mg/day) memantine.

WHAT THE READER WILL GAIN

Readers will become knowledgeable about this new dose and preparation of memantine. However, these advantages remain provisional and more research is needed to evaluate patient adherence, outcomes and caregiver burden related to twice-daily versus once-daily administration in patients with moderate to severe Alzheimer's disease.

TAKE HOME MESSAGE

A new, once-daily, higher-dose preparation of memantine seems to be well tolerated and may provide additional benefits for selected patients with Alzheimer's disease.