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

Patterns, determinants, and outcomes of early use of antidementia drugs: A 6-year multicenter cohort study in Thailand

BACKGROUND

Evidence on antidementia drugs (ADD) use in developing countries, where accessibility to ADD is challenging, is limited. Our aim was to examine prescribing patterns, factors, and outcomes associated with the early-ADD use (within 3 months from diagnosis) in people with dementia.

METHODS

A retrospective cohort study included individuals aged ≥ 60 years with dementia from three hospitals in Thailand between 2015 and 2020. Participants were categorized as non-ADD users, early-ADD users, and delayed users. ADD switching and one-year persistence were analyzed. Multivariable logistic regression was used to identify factors associated with early-ADD prescribing and its impact on clinical outcomes, including in-hospital death and hospitalization.

RESULTS

3,116 patients were included. The ADD prescription rate was 14.31 %, with 79.82 % of those being early-ADD users. Donepezil was the most prescribed (70.18 %). The one-year persistence rate of any ADD was 24.89 %. Factors associated with early-ADD use included the Civil Servant Medical Benefit Scheme, dyslipidemia, and dementia type. Early-ADD use was associated with reduced in-hospital death (adjusted odds ratio [aOR]=0.46, 95 % CI: 0.22-0.96, p = 0.038) and hospitalization (adjusted OR = 0.70 95 % CI: 0.51-0.97, p = 0.034) after controlling for age, sex, and Charlson Comorbidity Index.

CONCLUSION

ADD prescription rates were relatively low, with a one-year persistence rate of 25 %. Early-ADD use may improve clinical outcomes by reducing hospitalization and in-hospital mortality. These findings provide clinical features of ADD used in real-world settings and highlight the need for adherence to practice standards and strategies to promote ADD persistence among individuals with dementia.

Dual-target ligand discovery for Alzheimer's disease: triphenylphosphoranylidene derivatives as inhibitors of acetylcholinesterase and β-amyloid aggregation

Alzheimer disease (AD) is one of the major neurodegenerative diseases that could not be prevented or completely cured and may lead to death. Here, we target AChE and β-amyloid proteins. Synthesising new triphenylphosphporanylidene derivatives based on the surveyed literature and testing their biological activity revealed promising results especially for the acetyl triphenylphosphoranylidene derivative 8c, which showed good inhibitor activity against AChE enzyme with IC₅₀ in the nanomolar range (97.04 nM); on the other hand, it showed poor selectivity for AChE versus butyrylcholinesterase but with some futural structural modification, this selectivity can be improved. 8c showed MMP-2 IC₅₀ of 724.19 nM and Aβ_1-42 aggregation IC₅₀ of 302.36 nM. A kinetic study demonstrated that compound 8c uncompetitively inhibited AChE. Moreover, derivative 8c showed low cytotoxicity, good in vivo behavioural studies including Y-maze and passive avoidance tests with activity similar to that of donepezil. Finally, in silico studies for 8c predict its good penetration into BBB and good binding affinity in the AChE binding site.

Polypharmacy in Older Adults with Alzheimer’s Disease

The number of patients with Alzheimer’s disease is increasing annually. Most of these patients are older adults with comorbid physical illnesses, which means that they are often treated with a combination of medications for the disease they have and those for Alzheimer’s disease. Thus, older adults with Alzheimer’s disease are potentially at risk for polypharmacy. In addition, the drug interactions between Alzheimer’s disease medications and those for the treatment of physical illnesses may reduce their efficacy and increase side effects. This article reviews polypharmacy and drug interactions in elderly patients with Alzheimer’s disease, with a focus on psychotropic drugs.

Use of Drugs With Risk of Heart Rate-Related Problems is Common in Norwegian Dementia Patients Treated With Acetylcholinesterase Inhibitors: A Prevalence Study Based on the Norwegian Prescription Database

Background: Drugs commonly prescribed for heart rate control may induce adverse drug reactions in Alzheimer patients treated with acetylcholinesterase inhibitors (AChEIs). We have studied use of drugs with a known risk of Torsades de pointes (TdP) and drugs used to treat behavioral and psychological symptoms of dementia, as well as a combination of drugs with a known risk of TdP and drugs with a known heart rate-lowering effect, before and after initiating treatment with AChEIs.

Methods: The study applied data from the Norwegian Prescription Database for the period 2004–2016. Prescriptions of concomitant use of drugs in persistent users of AChEIs was studied in a follow-up period from 4 years before to 2 years after AChEI initiation in men and women of two age groups: 37–80 and 81–88 years.

Results: A small number of patients were prescribed haloperidol (∼1.5% The second year after AChEI initiation), digoxin/digitoxin (∼3%), and verapamil (∼1.3%), while a substantial proportion of the patients were prescribed betablockers (∼28%) and citalopram/escitalopram (∼17%). During follow-up, up to 6% of the study population were prescribed both betablockers and citalopram/citalopram in addition to AChEIs, a combination that increased over the follow-up period and was observed most frequently in women in the oldest age group.

Conclusions: A large proportion (∼44%) of patients treated with AChEIs were prescribed drugs that could cause bradycardic and prolonged time from the start of the Q wave to the end of the T wave (QT interval). Thus, action should be taken to reduce the combination of drugs with risk of bradycardia and prolonged QT interval. Medication review on a regular basis could be an option as an important risk-reducing intervention.

Adverse Drug Reactions of Acetylcholinesterase Inhibitors in Older People Living with Dementia: A Comprehensive Literature Review

The rising of global geriatric population has contributed to increased prevalence of dementia. Dementia is a neurodegenerative disease, which is characterized by progressive deterioration of cognitive functions, such as judgment, language, memory, attention and visuospatial ability. Dementia not only has profoundly devastating physical and psychological health outcomes, but it also poses a considerable healthcare expenditure and burdens. Acetylcholinesterase inhibitors (AChEIs), or so-called anti-dementia medications, have been developed to delay the progression of neurocognitive disorders and to decrease healthcare needs. AChEIs have been widely prescribed in clinical practice for the treatment of Alzheimer's disease, which account for 70% of dementia. The rising use of AChEIs results in increased adverse drug reactions (ADRs) such as cardiovascular and gastrointestinal adverse effects, resulting from overstimulation of peripheral cholinergic activity and muscarinic receptor activation. Changes in pharmacokinetics (PK), pharmacodynamics (PD) and pharmacogenetics (PGx), and occurrence of drug interactions are said to be major risk factors of ADRs of AChEIs in this population. To date, comprehensive reviews in ADRs of AChEIs have so far been scarcely studied. Therefore, we aimed to recapitulate and update the diverse aspects of AChEIs, including the mechanisms of action, characteristics and risk factors of ADRs, and preventive strategies of their ADRs. The collation of this knowledge is essential to facilitate efforts to reduce ADRs of AChEIs.

Discontinuation of cholinesterase inhibitor treatment in institutionalised patients with advanced dementia

OBJECTIVE

To evaluate the impact of discontinuation of treatment with cholinesterase inhibitors (ChEIs) on cognitive, behavioural and functional outcomes in patients with severe dementia.

METHODS

A prospective observational study in which the prescribing physician decides, depending on multidisciplinary assessment and following the recommendations of the clinical practice guidelines, whether to withdraw or continue ChEI treatment in institutionalised patients, with a follow-up of 3 months. Cognitive abilities were measured using the Mini-Mental State Examination (MMSE) and Reisberg's Global Deterioration Scale (GDS). Other measures were the behavioural and psychological symptoms of dementia (BPSD) according to the Neuropsychiatric Inventory (NPI), the activities of daily living using the Barthel index, the pharmacological and the non-pharmacological measures to treat the BPSD.

RESULTS

ChEI treatment was discontinued in 23 of 43 patients. After 3 months there were no differences in MMSE (p=0.441), GDS (p=0.976), NPI (p=0.882) or Barthel index (p=0.080) scores, or the establishing of new pharmacological measures (p=0.919) or non-pharmacological measures (p=0.832).

CONCLUSIONS

ChEI discontinuation in advanced stage dementia was not related to clinical deterioration in terms of cognitive function, BPSD, or functional status. Discontinuing ChEI treatment according to a multidisciplinary assessment and the recommendation of the guidelines appears to be a possible way of optimising pharmacotherapy without altering the main clinical evaluation scales.

Pharmacogenetic considerations when prescribing cholinesterase inhibitors for the treatment of Alzheimer's disease

INTRODUCTION

Cholinergic dysfunction, demonstrated in the late 1970s and early 1980s, led to the introduction of acetylcholinesterase inhibitors (AChEIs) in 1993 (Tacrine) to enhance cholinergic neurotransmission as the first line of treatment against Alzheimer's disease (AD). The new generation of AChEIs, represented by Donepezil (1996), Galantamine (2001) and Rivastigmine (2002), is the only treatment for AD to date, together with Memantine (2003). AChEIs are not devoid of side-effects and their cost-effectiveness is limited. An option to optimize the correct use of AChEIs is the implementation of pharmacogenetics (PGx) in the clinical practice.

AREAS COVERED

(i) The cholinergic system in AD, (ii) principles of AD PGx, (iii) PGx of Donepezil, Galantamine, Rivastigmine, Huperzine and other treatments, and (iv) practical recommendations.

EXPERT OPINION

The most relevant genes influencing AChEI efficacy and safety are APOE and CYPs. APOE-4 carriers are the worst responders to AChEIs. With the exception of Rivastigmine (UGT2B7, BCHE-K), the other AChEIs are primarily metabolized via CYP2D6, CYP3A4, and UGT enzymes, with involvement of ABC transporters and cholinergic genes (CHAT, ACHE, BCHE, SLC5A7, SLC18A3, CHRNA7) in most ethnic groups. Defective variants may affect the clinical response to AChEIs. PGx geno-phenotyping is highly recommended prior to treatment.

Pharmacogenomics of Cognitive Dysfunction and Neuropsychiatric Disorders in Dementia

Symptomatic interventions for patients with dementia involve anti-dementia drugs to improve cognition, psychotropic drugs for the treatment of behavioral disorders (BDs), and different categories of drugs for concomitant disorders. Demented patients may take >6-10 drugs/day with the consequent risk for drug-drug interactions and adverse drug reactions (ADRs >80%) which accelerate cognitive decline. The pharmacoepigenetic machinery is integrated by pathogenic, mechanistic, metabolic, transporter, and pleiotropic genes redundantly and promiscuously regulated by epigenetic mechanisms. CYP2D6, CYP2C9, CYP2C19, and CYP3A4/5 geno-phenotypes are involved in the metabolism of over 90% of drugs currently used in patients with dementia, and only 20% of the population is an extensive metabolizer for this tetragenic cluster. ADRs associated with anti-dementia drugs, antipsychotics, antidepressants, anxiolytics, hypnotics, sedatives, and antiepileptic drugs can be minimized by means of pharmacogenetic screening prior to treatment. These drugs are substrates, inhibitors, or inducers of 58, 37, and 42 enzyme/protein gene products, respectively, and are transported by 40 different protein transporters. APOE is the reference gene in most pharmacogenetic studies. APOE-3 carriers are the best responders and APOE-4 carriers are the worst responders; likewise, CYP2D6-normal metabolizers are the best responders and CYP2D6-poor metabolizers are the worst responders. The incorporation of pharmacogenomic strategies for a personalized treatment in dementia is an effective option to optimize limited therapeutic resources and to reduce unwanted side-effects.

The role of acetylcholinesterase inhibitors such as neostigmine and rivastigmine on chronic pain and cognitive function in aging: A review of recent clinical applications

Chronic pain in patients with Alzheimer's disease or dementia is a complex issue in the medical field; these patients suffer from the common causes of chronic pain, especially in geriatric medicine. To ensure the correct type and level of given treatment, medical care should be taken to avoid the contribution of chronic pain and cognitive impairment in the elderly population. Acetylcholinesterase inhibitors (AChE-Is) have been proven as an efficient therapeutic resource for significant improvement in dementia of Alzheimer's disease and chronic pain due to the fact that cholinergic deficit is considered as an early finding in cognitive impairment and persisting pain. Some AChE-Is are investigated here in terms of treatment of dementia and chronic pain management. Neostigmine has been used as an adjunct analgesic in the postoperative period and in combination with other analgesic medications in an intrathecal approach. Rivastigmine has, over the past ten years, become the approved agent for the management of dementia of mild to moderate Alzheimer's disease and has gained approval for treating different types of non-Alzheimer's dementia. In this review, we will focus on the two types of AChE-Is (rivastigmine and neostigmine) in the development of their clinical use and their respective mechanisms of actions on improving cognitive function and managing chronic pain.

Pleiotropy and promiscuity in pharmacogenomics for the treatment of Alzheimer's disease and related risk factors

Patients with Alzheimer's disease are current consumers of polypharmacy with a high risk for drug–drug interactions. Antidementia drugs and other pharmacological treatments for vascular risk factors associated with dementia exert pleiotropic effects which are promiscuously regulated by different gene products. The aim of this review is to highlight the influence of genes involved in pharmacogenetics (i.e., pathogenic, mechanistic, metabolic, transporter and pleiotropic genes) as major determinants of response to treatment in Alzheimer's disease. Patients harboring poor or ultrarapid geno-phenotypes display more irregular profiles in drug efficacy and safety than extensive or intermediate metabolizers. Polymorphic variants of genes associated with lipid metabolism influence the therapeutic response to hypolipemic agents. Understanding these effects is very useful for optimizing polytherapy in dementia.

Pharmacogenetic considerations in the treatment of Alzheimer's disease

The practical pharmacogenetics of Alzheimer's disease (AD) is circumscribed to acetylcholinesterase inhibitors (AChEIs) and memantine. However, pharmacogenetic procedures should be applied to novel strategies in AD therapeutics including: novel AChEIs and neurotransmitter regulators, anti-Aβ treatments, anti-tau treatments, pleiotropic products, epigenetic drugs and combination therapies. Genes involved in the pharmacogenetic network are under the influence of the epigenetic machinery which regulates gene expression transcriptionally and post-transcriptionally, configuring the fundamentals of pharmacoepigenomics. Over 60% of AD patients present concomitant pathologies demanding additional treatments which increase the likelihood of drug-drug interactions. Lipid metabolism dysfunction is a pathogenic mechanism inherent to AD neurodegeneration. The therapeutic response to hypolipidemic compounds is influenced by the APOE and CYP genotypes. The development of novel compounds and the use of combination/multifactorial treatments require the implantation of pharmacogenomic procedures for the avoidance of ADRs and the optimization of therapeutics.

Prime Drug Interplay in Dental Practice

Drug interaction is a negative representation of pharmacotherapy. In order to provide the best patient care possible, a thorough knowledge of how the drug interactions occur is needed for proper application in practice. Possible interactions among current medication and drugs being prescribed should be considered always. A thorough understanding of the mechanism of interactions among drugs is a must for the health care practitioner. Considering the astounding number of drugs patients may be taking, this task seems discouraging. The count of possible interactions in dental practice are less due to few number of drugs utilized and brief period of therapy, but still notable number are to be considered. The aim of present preview is to consider the manifold and multiplex nature of pharmacological drug-drug interaction in the general dental practice setting.

Treatment of Overactive Bladder in the Elderly Female: The Case for Trospium, Oxybutynin, Fesoterodine and Darifenacin

Overactive bladder (OAB) is a common constellation of lower urinary tract storage symptoms that causes a significant impact on a person's quality of life. The elderly may be disproportionally impacted by these symptoms due to concomitant poor mobility, comorbid conditions such as diabetes and heart failure, and polypharmacy. While behavioral modification and pelvic floor muscle training should be considered first-line treatment options, pharmacotherapy remains the backbone of the therapeutic regimen. Trospium, oxybutynin, fesoterodine, and darifenacin all have unique properties that may confer certain advantages in the elderly population. The hydrophilicity and quaternary amine structure of trospium may limit its ability to cross the blood-brain barrier and thus minimize impact on cognition in the elderly. In its oral form, oxybutynin may have the most significant effect on cognition; however, the transdermal preparations may be favorable in the elderly population due to the ability to avoid first-pass metabolism and its limited antimuscarinic adverse effects. Fesoterodine may be the most extensively studied OAB medication in the elderly population. Darifenacin has a strong affinity for the M3 receptor in the bladder, while having a weak affinity for the M1 receptor commonly found in the brain. It must be noted that all muscarinic receptor antagonists are associated with common adverse effects to some degree, and frequent re-evaluation of the elderly patient is necessary to confirm the proper benefit-to-risk profile.

Potential drug-drug interactions in Alzheimer patients with behavioral symptoms

The use of multi drug regimens among the elderly population has increased tremendously over the last decade although the benefits of medications are always accompanied by potential harm, even when prescribed at recommended doses. The elderly populations are particularly at an increased risk of adverse drug reactions considering comorbidity, poly-therapy, physiological changes affecting the pharmacokinetics and pharmacodynamics of many drugs and, in some cases, poor compliance due to cognitive impairment and/or depression. In this setting, drug–drug interaction may represent a serious and even life-threatening clinical condition. Moreover, the inability to distinguish drug-induced symptoms from a definitive medical diagnosis often results in addition of yet another drug to treat the symptoms, which in turn increases drug–drug interactions. Cognitive enhancers, including acetylcholinesterase inhibitors and memantine, are the most widely prescribed agents for Alzheimer’s disease (AD) patients. Behavioral and psychological symptoms of dementia, including psychotic symptoms and behavioral disorders, represent noncognitive disturbances frequently observed in AD patients. Antipsychotic drugs are at high risk of adverse events, even at modest doses, and may interfere with the progression of cognitive impairment and interact with several drugs including anti-arrhythmics and acetylcholinesterase inhibitors. Other medications often used in AD patients are represented by anxiolytic, like benzodiazepine, or antidepressant agents. These agents also might interfere with other concomitant drugs through both pharmacokinetic and pharmacodynamic mechanisms. In this review we focus on the most frequent drug–drug interactions, potentially harmful, in AD patients with behavioral symptoms considering both physiological and pathological changes in AD patients, and potential pharmacodynamic/pharmacokinetic drug interaction mechanisms.

Opportunities in pharmacogenomics for the treatment of Alzheimer's disease

ABSTRACT 

In Alzheimer's disease (AD), approximately 10–20% of direct costs are associated with pharmacological treatment. Pharmacogenomics account for 30–90% variability in pharmacokinetics and pharmacodynamics. Genes potentially involved in the pharmacogenomics outcome include pathogenic, mechanistic, metabolic, transporter and pleiotropic genes. Over 75% of the Caucasian population is defective for the CYP2D6+2C9+2C19 cluster. Polymorphic variants in the APOE-TOMM40 region influence AD pharmacogenomics. APOE-4 carriers are the worst responders and APOE-3 carriers are the best responders to conventional treatments. TOMM40 poly T-S/S carriers are the best responders, VL/VL and S/VL carriers are intermediate responders and L/L carriers are the worst responders. The haplotype 4/4-L/L is probably responsible for early onset of the disease, a faster cognitive decline and a poor response to different treatments.

Anti-dementia drugs and co-medication among patients with Alzheimer's disease : investigating real-world drug use in clinical practice using the Swedish Dementia Quality Registry (SveDem)

BACKGROUND

There is a substantial risk of drug-interactions, adverse events, and inappropriate drug use (IDU) among frail Alzheimer's disease (AD) patients; however, there are few studies about co-medication and IDU in clinical settings.

OBJECTIVES

To investigate anti-dementia drugs, associated characteristics of cholinesterase inhibitors (ChEIs) and NMDA antagonists, co-medication, and IDU in a large population of outpatients with mild AD.

METHODS

In this cross-sectional analysis of medication characteristics, we analyzed data from the Swedish Dementia Quality Registry (SveDem) on 5,907 newly diagnosed AD patients who were registered in memory clinics. SveDem is a national quality registry in Sweden, which was established in 2007 to evaluate and improve dementia healthcare. Comparisons were performed concerning co-medications, use of ≥3 psychotropic drugs (IDU) and polypharmacy (≥5 drugs) based on anti-dementia treatment (ChEIs or NMDA antagonists). Information on baseline characteristics such as age, sex, living conditions, cognitive evaluation based on the Mini-Mental State Examination (MMSE) score, and diagnostic work-up was also evaluated.

RESULTS

The majority of the AD patients were in the mild stage of the disease. Overall, 4,342 (75.4 %) patients received any ChEI, 438 (7.6 %) used an NMDA antagonist and 74 (1.3 %) patients were treated with both. However, 907 (15.7 %) patients were not treated with any anti-dementia drug. While polypharmacy was seen in 33.5 % of patients, only 2.6 % concurrently used ≥3 psychotropic medications. Patients on ChEIs were significantly younger, had a higher MMSE score and were treated with a smaller number of medications (a proxy for overall co-morbidity). Co-medication with antipsychotics [3.3 vs. 7.6 %; adjusted odds ratio (OR) 0.55 (95 % CI 0.38-0.79)] and anxiolytics [5.8 vs. 10.9 %; adjusted OR 0.62 (95 % CI 0.46-0.84)] was significantly lower in the ChEI+ group than in those with no anti-dementia treatment.

CONCLUSION

Patients taking ChEIs were treated with less antipsychotics and anxiolytics than those not taking ChEIs. More research is warranted to elucidate whether use of ChEIs in clinical practice can reduce the need for psychotropic drugs in AD patients.

Cardiovascular pharmacodynamics of donepezil hydrochloride on the PR and QT intervals in patients with dementia

OBJECTIVE

Although several case reports suggested that donepezil hydrochloride can induce bradycardia or atrioventricular block, the details remain unclear. We implemented a study of the impact of donepezil hydrochloride administration on PR, RR, and QT intervals.

METHODS

The subjects were 18 patients who were diagnosed with either dementia or cognitive disorder (DSM-IV-TR) and were hospitalized between January 2011 and December 2012. After hospitalization, they were treated with donepezil hydrochloride. Clinical parameters and electrocardiograms before and after the administration of donepezil hydrochloride were retrieved from the patients' medical records.

RESULTS

After the administration of donepezil hydrochloride, the mean PR interval significantly increased from 177.3 ± 30.9 to 186.8 ± 38.4 ms (p<0.001). And the mean RR interval also significantly increased from 850.3 ± 112.5 to 886.7 ± 136.4 ms (p=0.014). The mean difference in the PR interval before and after the administration of donepezil hydrochloride was 9.5 ± 17.1 (range=-21.0-44.0) ms. The QT intervals were unaffected by the administration of donepezil hydrochloride.

CONCLUSIONS

Care should be taken when administering donepezil to patients with atrioventricular block, or patients taking other drugs that can prolong the PR interval. Copyright © 2014 John Wiley & Sons, Ltd.

Pharmacogenomics of Alzheimer's disease: novel therapeutic strategies for drug development

Alzheimer's disease (AD) is a major problem of health and disability, with a relevant economic impact on our society. Despite important advances in pathogenesis, diagnosis, and treatment, its primary causes still remain elusive, accurate biomarkers are not well characterized, and the available pharmacological treatments are not cost-effective. As a complex disorder, AD is a polygenic and multifactorial clinical entity in which hundreds of defective genes distributed across the human genome may contribute to its pathogenesis. Diverse environmental factors, cerebrovascular dysfunction, and epigenetic phenomena, together with structural and functional genomic dysfunctions, lead to amyloid deposition, neurofibrillary tangle formation, and premature neuronal death, the major neuropathological hallmarks of AD. Future perspectives for the global management of AD predict that genomics and proteomics may help in the search for reliable biomarkers. In practical terms, the therapeutic response to conventional drugs (cholinesterase inhibitors, multifactorial strategies) is genotype-specific. Genomic factors potentially involved in AD pharmacogenomics include at least five categories of gene clusters: (1) genes associated with disease pathogenesis; (2) genes associated with the mechanism of action of drugs; (3) genes associated with drug metabolism (phase I and II reactions); (4) genes associated with drug transporters; and (5) pleiotropic genes involved in multifaceted cascades and metabolic reactions. The implementation of pharmacogenomic strategies will contribute to optimize drug development and therapeutics in AD and related disorders.

Deterioration in donepezil-induced PR prolongation after a coadministration of memantine in a patient with Alzheimer's disease

The side effects and interaction of memantine and donepezil hydrochloride when used concomitantly are currently unknown. We encountered a case of a 77-year-old female with Alzheimer's disease in which the concomitant use of memantine exacerbated the prolonged electrocardiogram PR interval which appeared while donepezil hydrochloride was being orally administered. In terms of the cardiac circulation system side effects caused by donepezil hydrochloride and memantine, bradycardia has been reported. However, clinicians should be also aware of PR prolongation associated with the concomitant use of donepezil and memantine.

The impact of Medicare prescription drug coverage on the use of antidementia drugs

Background

Cholinesterase inhibitors and memantine are prescribed to slow the progression dementia. Although the efficacy of these drugs has been demonstrated, their effectiveness, from the perspective of patients and caregivers, has been questioned. Little is known about whether the demand for cholinesterase inhibitors and memantine are sensitive to out-of-pocket cost. Using the 2006 implementation of Medicare Part D as a natural experiment, this study examines the impact of changes in drug coverage on use of cholinesterase inhibitors and memantine by comparing use before and after Medicare Part D implementation among older adults who did and did not experience a change in coverage.

Methods

Retrospective analyses of claims data from 35,102 community-dwelling Medicare beneficiaries in Pennsylvania aged 65 or older. Beneficiaries were continuously enrolled in a Medicare Advantage plan from 2004 to 2007. Outcome variables were any use of donepezil (Aricept®), galantamine (Razadyne®), rivastigmine (Exelon®), tacrine (Cognex®), or memantine (Namenda®) each year and the number of 30-day prescriptions filled for these drugs. Independent variables included type of drug benefit pre–Part D (No coverage, $150 cap, $350 cap, and No cap as the reference group), time period, and their interaction. Sensitivity analyses were conducted to test if there are differences in use by drug class or if beneficiaries with a diagnosis of dementia pre–Part D experienced an increase in use post–Part D.

Results

The No coverage group had a 38% increase in the odds ratio of any use of antidementia medications (P = 0.0008) post–Part D relative to the No cap group. All four coverage groups had significant increases in number of 30-day prescriptions (P < 0.001) over the study period. In adjusted models that included the sub-sample with any use pre–Part D, the No coverage group had a 36% increase in prescriptions (P = 0.002) and the $350 cap group had a 15% increase (P = 0.003) after adjusting for trends in the No cap group. Results from the sensitivity analysis for the sub-sample with a diagnosis of dementia pre–Part D show that each group had significant increases in 30-day prescriptions compared to the No cap control group (P < 0.05).

Conclusions

Use of cholinesterase inhibitors and memantine in our sample increased and a greater increase in use was observed among Medicare beneficiaries who experienced improvements in drug coverage under Medicare Part D.

Long-term effects of rivastigmine treatment on the need for psychotropic medications in nursing home patients with Alzheimer's disease : results of a 52-week open-label study

BACKGROUND AND OBJECTIVE

Neuropsychiatric symptoms and behavioural disturbances occur in most patients with Alzheimer's disease (AD), are a source of stress for caregivers, and are the primary cause of patient institutionalisation. These symptoms often are treated with psychotropic medications. However, adverse drug interactions, adverse effects and nursing home regulations make reducing the use of psychotropic medications in elderly AD patients an important goal of therapy. Fifty-two-week data including data from a 26-week prospective open-label, multicentre study and its 26-week open-label extension were analysed.

PATIENTS AND METHODS

173 patients with moderate to severe AD residing in nursing homes were treated with rivastigmine 1.5-6mg twice daily. In the study, psychotropic drug use and behavioural symptoms were measured at baseline and at 52 weeks.

RESULTS

Results showed that 40% of patients who were receiving psychotropic medications at baseline had discontinued use or reduced their dose of psychotropic medications at week 52. Furthermore, significant improvements were observed from baseline in 10 of the 12 behavioural domains of the Nursing Home version of the Neuropsychiatric Inventory, including delusions (mean change from baseline -2.0; p = 0.002), hallucinations (mean change -3.1; p < 0.001), anxiety (mean change -1.1; p = 0.014), and euphoria (mean change -3.2; p = 0.006).

CONCLUSION

These data suggest favourable tolerability, behavioural and pharmacoeconomic outcomes in nursing home residents with AD who are treated with rivastigmine.

Concurrent administration of atypical antipsychotics and donepezil: drug interaction study in rats

Psychotic and behavioral symptoms are common in patients with dementia. Thus, it is rational to assume that patients with dementia would gain benefit from combination therapy of an antipsychotic agent and a cognitive enhancer. Antipsychotics are not approved by the US FDA in elderly patients with dementia but their use is still prevalent in other population. In the current study, we investigate the effect of atypical antipsychotics on acetylcholine modulation by donepezil. In addition, the plasma pharmacokinetics on concurrent administration of these drugs was studied. Acetylcholine modulation was carried out in the ventral hippocampus of Sprague-Dawley rats using brain microdialysis technique. In a parallel group of animals, pharmacokinetic parameters were evaluated on administration of donepezil (5.0 mg kg(-1), ip) alone and in combination with olanzapine, clozapine, or quetiapine. Donepezil produced 348% increase in hippocampal acetylcholine levels. Coadministration of olanzapine and donepezil produced 393% increase in extracellular acetylcholine, and the effect was supported by a significantly (p < 0.05) decreased clearance of donepezil in plasma. Whereas, other plasma pharmacokinetic parameters of donepezil "AUC(0-24h), T (1/2) and T (max)" were moderately altered after this combination treatment. Concurrent administrations of clozapine or quetiapine with donepezil produced a non-significant change in acetylcholine levels in comparison to donepezil alone. The plasma pharmacokinetics of donepezil was unaltered. Results from this preclinical investigation indicate that extrapyramidal side effects may precipitate upon coadministration of donepezil with olanzapine. Care must be exercised by physicians and caregivers while administering these two drugs together.

Nationwide drug-dispensing data reveal important differences in adherence to drug label recommendations on CYP2D6-dependent drug interactions

AIMS

The study aimed to investigate the clinical adherence to drug label recommendations on important drug-drug interactions (DDIs). Dispensing data on drug combinations involving selective serotonin reuptake inhibitor (SSRI) antidepressants could help to identify areas for intensified medical education.

METHODS

This was a retrospective, cross-sectional analysis of individual dispensing data regarding all individuals > or =15 years old in Sweden. The study analysed the prescribing and dispensing of CYP2D6 drugs (metoprolol, donepezil, galantamine, codeine, tamoxifen) together with CYP2D6-blocking SSRIs (paroxetine/fluoxetine) or SSRIs without significant CYP2D6 inhibition (citalopram/escitalopram/sertraline), and the related prescribing of CYP2D6-independent comparator drugs (atenolol, rivastigmine, propoxyphene, anastrozole). Odds were calculated between each CYP2D6 drug and the corresponding comparator drug in patients on fluoxetine/paroxetine and citalopram/escitalopram/sertraline, respectively. The odds ratio (OR) was calculated by dividing the obtained odds in patients on fluoxetine/paroxetine by the corresponding odds in patients on citalopram/escitalopram/sertraline.

RESULTS

Compared with patients that were dispensed citalopram/escitalopram/sertraline, patients dispensed fluoxetine/paroxetine had lower prescribing rates of metoprolol (adjusted OR 0.80; 95% confidence interval 0.76, 0.85), donepezil (0.65; 0.49, 0.86) and galantamine (0.58; 0.41, 0.81). In contrast, the use of prodrugs codeine (compared woth propoxyphene) or tamoxifen (compared with anastrozole) was similar among patients on fluoxetine/paroxetine and citalopram/escitalopram/sertraline (adjusted OR 1.03; 0.94, 1.12 and 1.29; 0.96, 1.73, respectively).

CONCLUSIONS

Clinically important DDIs that are associated with impaired bioactivation of prodrugs might be more easily neglected in clinical practice compared with DDIs that cause drug accumulation and symptomatic adverse drug reactions.

Pharmacological approaches to methamphetamine dependence: a focused review

Methamphetamine dependence is a serious worldwide public health problem with major medical, psychiatric, socioeconomic and legal consequences. Various neuronal mechanisms implicated in methamphetamine dependence have suggested several pharmacological approaches. A literature search from a range of electronic databases (PubMed, EMBASE, PsycInfo, the NIDA research monograph index and the reference list of clinicaltrials.gov) was conducted for the period from January 1985 to October 2009. There were no restrictions on the identification or inclusion of studies in terms of publication status, language and design type. A variety of medications have failed to show efficacy in clinical trials, including a dopamine partial agonist (aripiprazole), GABAergic agents (gabapentin) and serotonergic agents (SSRI, ondansetron, mirtazapine). Three double-blind placebo-controlled trials using modafinil, bupropion and naltrexone have shown positive results in reducing amphetamine or methamphetamine use. Two studies employing agonist replacement medications, one with d-amphetamine and the other with methylphenidate, have also shown promise. Despite the lack of success in most studies to date, increasing efforts are being made to develop medications for the treatment of methamphetamine dependence and several promising agents are targets of further research.

Pharmacogenomic Biomarkers in Neuropsychiatry: The Path to Personalized Medicine in Mental Disorders

Neuropsychiatric disorders and dementia represent a major cause of disability and high cost in developed societies. Most disorders of the central nervous system (CNS) share some common features, such as a genomic background in which hundreds of genes might be involved, genome-environment interactions, complex pathogenic pathways, poor therapeutic outcomes, and chronic disability.

Recent advances in genomic medicine can contribute to accelerate our understanding on the pathogenesis of CNS disorders, improve diagnostic accuracy with the introduction of novel biomarkers, and personalize therapeutics with the incorporation of pharmacogenetic and pharmacogenomic procedures to drug development and clinical practice.

The pharmacological treatment of CNS disorders, in general, accounts for 10–20% of direct costs, and less than 30–40% of the patients are moderate responders to conventional drugs, some of which may cause important adverse drugs reactions (ADRs). Pharmacogenetic and pharmacogenomic factors may account for 60–90% of drug variability in drug disposition and pharmacodynamics. Approximately 60–80% of CNS drugs are metabolized via enzymes of the CYP gene superfamily; 18% of neuroleptics are major substrates of CYP1A2 enzymes, 40% of CYP2D6, and 23% of CYP3A4; 24% of antidepressants are major substrates of CYP1A2 enzymes, 5% of CYP2B6, 38% of CYP2C19, 85% of CYP2D6, and 38% of CYP3A4; 7% of benzodiazepines are major substrates of CYP2C19 enzymes, 20% of CYP2D6, and 95% of

CYP3A4. About 10–20% of Caucasians are carriers of defective CYP2D6 polymorphic variants that alter the metabolism of many psychotropic agents. Other 100 genes participate in the efficacy and safety of psychotropic drugs. The incorporation of pharmacogenetic/ pharmacogenomic protocols to CNS research and clinical practice can foster therapeutics optimization by helping to develop cost-effective pharmaceuticals and improving drug efficacy and safety. To achieve this goal several measures have to be taken, including: (a) educate physicians and the public on the use of genetic/ genomic screening in the daily clinical practice; (b) standardize genetic testing for major categories of drugs; (c) validate pharmacogenetic and pharmacogenomic procedures according to drug category and pathology; (d) regulate ethical, social, and economic issues; and (e) incorporate pharmacogenetic and pharmacogenomic procedures to both drugs in development and drugs in the market to optimize therapeutics.

Drug therapy in Alzheimer disease: an update for the oral health care provider

Alzheimer disease (AD) is a progressive neurologic disorder that manifests as memory loss, personality changes, global cognitive dysfunction, and functional impairment. As the United States population continues to age, the prevalence of AD will rise. Accordingly, oral health care providers will be more likely to treat patients affected by this disease; therefore, it is necessary to understand the pharmacologic agents used for the management of AD. This article provides an update of the available drug therapies for AD and discusses their implications on the oral and dental health of patients.

Clinically relevant pharmacokinetic drug interactions with second-generation antidepressants: an update

BACKGROUND

The second-generation antidepressants include selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), and other compounds with different mechanisms of action. All second-generation antidepressants are metabolized in the liver by the cytochrome P450 (CYP) enzyme system. Concomitant intake of inhibitors or inducers of the CYP isozymes involved in the biotransformation of specific antidepressants may alter plasma concentrations of these agents, although this effect is unlikely to be associated with clinically relevant interactions. Rather, concern about drug interactions with second-generation antidepressants is based on their in vitro potential to inhibit > or = 1 CYP isozyme.

OBJECTIVE

The goal of this article was to review the current literature on clinically relevant pharmacokinetic drug interactions with second-generation antidepressants.

METHODS

A search of MEDLINE and EMBASE was conducted for original research and review articles published in English between January 1985 and February 2008. Among the search terms were drug interactions, second-generation antidepressants, newer antidepressants, SSRIs, SNRIs, fluoxetine, paroxetine, fluvoxamine, sertraline, citalopram, escitalopram, venlafaxine, duloxetine, mirtazapine, reboxetine, bupropion, nefazodone, pharmacokinetics, drug metabolism, and cytochrome P450. Only articles published in peer-reviewed journals were included, and meeting abstracts were excluded. The reference lists of relevant articles were hand-searched for additional publications.

RESULTS

Second-generation antidepressants differ in their potential for pharmacokinetic drug interactions. Fluoxetine and paroxetine are potent inhibitors of CYP2D6, fluvoxamine markedly inhibits CYP1A2 and CYP2C19, and nefazodone is a substantial inhibitor of CYP3A4. Therefore, clinically relevant interactions may be expected when these antidepressants are coadministered with substrates of the pertinent isozymes, particularly those with a narrow therapeutic index. Duloxetine and bupropion are moderate inhibitors of CYP2D6, and sertraline may cause significant inhibition of this isoform, but only at high doses. Citalopram, escitalopram, venlafaxine, mirtazapine, and reboxetine are weak or negligible inhibitors of CYP isozymes in vitro and are less likely than other second-generation antidepressants to interact with co-administered medications.

CONCLUSIONS

Second-generation antidepressants are not equivalent in their potential for pharmacokinetic drug interactions. Although interactions may be predictable in specific circumstances, use of an antidepressant with a more favorable drug-interaction profile may be justified.

Steady-state pharmacokinetics of rivastigmine in patients with mild to moderate Alzheimer's disease not affected by co-administration of memantine: an open-label, crossover, single-centre study

BACKGROUND AND OBJECTIVE

It has been shown that combining memantine and a cholinesterase inhibitor, which each affect different neurotransmitter systems, may offer further improvements in efficacy over either treatment alone in patients with Alzheimer's disease. The present study was conducted to determine if memantine has any effects on the steady-state pharmacokinetics of rivastigmine in patients with mild to moderate Alzheimer's disease.

METHODS

Rivastigmine-treated Alzheimer's disease patients who had been maintained on a fixed regimen of twice-daily rivastigmine for >or=2 months were eligible to enter the study. Sixteen patients (seven males and nine females, age range 64-88 years, weight range 51.8-104 kg) were enrolled in this open-label, crossover study, which consisted of a 28-day screening period, a 36-hour baseline period, and a 35-day combination treatment phase. The patients spent the baseline period and day 35 at the study centre, where plasma samples for pharmacokinetic evaluation were taken at specified time intervals over a 10-hour time period. In addition, 10-hour (evening pre-dose) memantine plasma samples were taken on days 21, 34 and 35.

RESULTS

The combination of memantine (10 mg twice daily) with rivastigmine (1.5-6 mg twice daily) was safe and well tolerated. At each dose level of rivastigmine, the area under the concentration-time curve (AUC) values of rivastigmine and its metabolite as well as the metabolite-to-parent AUC ratios were unaffected by co-administration of memantine, confirming the absence of a meaningful pharmacokinetic drug-drug interaction.

CONCLUSION

Under the study conditions, the extent of systemic exposure to rivastigmine and its metabolite NAP226-90 at steady state did not appear to be affected by concomitant administration of memantine.

Dementia in fragile X-associated tremor/ataxia syndrome (FXTAS): comparison with Alzheimer's disease

Neurocognitive deficits in fragile X-associated tremor/ataxia syndrome (FXTAS) involve attentional control, working memory, executive functioning, and declarative and procedural learning. To date, no studies comparing FXTAS with other dementias have been done. We characterize the dementia in FXTAS, comparing it with Alzheimer's disease. Retrospective chart review of 68 adults (50 men, 18 women) with FXTAS. 20 men with FXTAS dementia were matched by age, gender, and education to patients with mild Alzheimer's dementia (AD). Neuropsychological measures were compared between the two groups: Boston Naming Test (BNT), phonemic fluency (Controlled Oral Word Association Test), digit span forward (DSF) and backward (DSB). Comparisons were based on analysis of covariance and t-tests to assess significant differences between groups. 50% of men with FXTAS and no women were cognitively impaired. On mean scores of verbal fluency (22.83 in FXTAS vs. 28.83 in AD, P = 0.112), working memory (DSB, 4.80 in AD vs. 5.41 in FXTAS, P = 0.359), and language (BNT, 48.54 in AD vs. 54.20 in FXTAS, P = 0.089), there were no significant differences. Digit span forward, measuring attention, was significantly higher in subjects with FXTAS dementia (8.59, vs. 7.10 in AD, P = 0.010). Individuals with FXTAS have significant cognitive deficits, on the order of those in AD although the cognitive profiles in these dementias are not similar. Further research is needed to outline the neuropsychiatric profile in FXTAS and the correlation of genetic markers with the progression and severity of cognitive loss.

Evaluation of the cardiovascular and subjective effects of rivastigmine in combination with methamphetamine in methamphetamine-dependent human volunteers

Acetylcholine (ACh) has been implicated in the reinforcing and locomotor-activating effects produced by methamphetamine (Meth). Of interest, recent data suggest that acetylcholinesterase (AChE) inhibitors attenuate Meth-seeking behaviour in rats. We conducted this study in order to determine the safety (adverse events, mood changes, cardiovascular effects) and preliminary efficacy (subjective effects) of the AChE inhibitor rivastigmine (Riv) when tested in combination with Meth. Twenty-three non-treatment-seeking Meth-dependent participants resided in an in-patient unit at UCLA for 2mg i.v.) and Meth (day 5, 30mg, n=7) or Riv (1.5mg, n=9). On day 11, the subjects received saline and Meth infusions again (randomized to either 11:30 or 14:30 hours), under double-blind conditions. The data analyses compared across-study measures of adverse events and mood, and a post-randomization analysis of cardiovascular and subjective effects (on day 11). The data reveal that rivastigmine was not associated with increased adverse events or alterations in mood. As expected, acute Meth exposure (30mg, significantly attenuated Meth-induced increases in diastolic blood pressure, and self-reports of and (p<0.05). Taken together, the findings in the current report suggest that pharmacological manipulations that enhance brain ACh warrant continued investigation as potential treatments for Meth addiction.

Pharmacogenetic basis for therapeutic optimization in Alzheimer's disease

Alzheimer's disease is a major health problem in developed countries. Approximately 10-15% of direct costs in dementia are attributed to pharmacological treatment, and only 10-20% of the patients are moderate responders to conventional antidementia drugs, with questionable cost effectiveness. The phenotypic expression of Alzheimer's disease is characterized by amyloid deposition in brain tissue and vessels (amyloid angiopathy), intracellular neurofibrillary tangle formation, synaptic and dendritic loss, and premature neuronal death. Primary pathogenic events underlying this neurodegenerative process include genetic factors involving more than 200 different genes distributed across the human genome, accompanied by progressive cerebrovascular dysfunction, and diverse environmental factors. Mutations in genes directly associated with the amyloid cascade (APP, PSEN1, PSEN2) are present in less than 5% of the Alzheimer's disease population; however, the presence of the epsilon4 allele of the apolipoprotein E gene (APOE) represents a major risk factor for more than 40% of patients with dementia. Genotype-phenotype correlation studies and functional genomics studies have revealed the association of specific mutations in primary loci and/or APOE-related polymorphic variants with the phenotypic expression of biological traits. It is estimated that genetics accounts for between 20% and 95% of the variability in drug disposition and pharmacodynamics. Recent studies indicate that the therapeutic response in Alzheimer's disease is genotype specific, depending on genes associated with Alzheimer's disease pathogenesis and/or genes responsible for drug metabolism (e.g. cytochrome P450 [CYP] genes). In monogenic studies, APOEepsilon4/epsilon4 genotype carriers are the worst responders to conventional treatments. Some cholinesterase inhibitors currently being use in the treatment of Alzheimer's disease are metabolized via CYP-related enzymes. These drugs can interact with many other drugs that are substrates, inhibitors or inducers of the CYP system, this interaction eliciting liver toxicity and other adverse drug reactions. CYP2D6 enzyme isoforms are involved in the metabolism of more than 20% of drugs used in CNS disorders. The distribution of the CYP2D6 genotypes in the European population of the Iberian peninsula differentiates four major categories of CYP2D6-related metabolizer types: (i) extensive metabolizers (EM) [51.61%]; (ii) intermediate metabolizers (IM) [32.26%]; (iii) poor metabolizers (PM) [9.03%]; and (iv) ultra-rapid metabolizers (UM) [7.10%]. PMs and UMs tend to show higher transaminase activity than EMs and IMs. EMs and IMs are the best responders, and PMs and UMs are the worst responders to pharmacologic treatments in Alzheimer's disease. At this early stage of the development of pharmacogenomic/pharmacogenetic procedures in Alzheimer's disease therapeutics, it seems very plausible that the pharmacogenetic response in Alzheimer's disease depends on the interaction of genes involved in drug metabolism and genes associated with Alzheimer's disease pathogenesis.

Pharmacogenomics and therapeutic prospects in dementia

Dementia is a major problem of health in developed countries. Alzheimer's disease (AD) is the main cause of dementia, accounting for 50-70% of the cases, followed by vascular dementia (30-40%) and mixed dementia (15-20%). Approximately 10-15% of direct costs in dementia are attributed to pharmacological treatment, and only 10-20% of the patients are moderate responders to conventional anti-dementia drugs, with questionable cost-effectiveness. Primary pathogenic events underlying the dementia process include genetic factors in which more than 200 different genes distributed across the human genome are involved, accompanied by progressive cerebrovascular dysfunction and diverse environmental factors. Mutations in genes directly associated with the amyloid cascade (APP, PS1, PS2) are only present in less than 5% of the AD population; however, the presence of the APOE-4 allele in the apolipoprotein E (APOE) gene represents a major risk factor for more than 40% of patients with dementia. Genotype-phenotype correlation studies and functional genomics studies have revealed the association of specific mutations in primary loci (APP, PS1, PS2) and/or APOE-related polymorphic variants with the phenotypic expression of biological traits. It is estimated that genetics accounts for 20-95% of variability in drug disposition and pharmacodynamics. Recent studies indicate that the therapeutic response in AD is genotype-specific depending upon genes associated with AD pathogenesis and/or genes responsible for drug metabolism (CYPs). In monogenic-related studies, APOE-4/4 carriers are the worst responders. In trigenic (APOE-PS1-PS2 clusters)-related studies the best responders are those patients carrying the 331222-, 341122-, 341222-, and 441112- genomic profiles. The worst responders in all genomic clusters are patients with the 441122+ genotype, indicating the powerful, deleterious effect of the APOE-4/4 genotype on therapeutics in networking activity with other AD-related genes. Cholinesterase inhibitors of current use in AD are metabolized via CYP-related enzymes. These drugs can interact with many other drugs which are substrates, inhibitors or inducers of the cytochrome P-450 system; this interaction elicits liver toxicity and other adverse drug reactions. CYP2D6-related enzymes are involved in the metabolism of more than 20% of CNS drugs. The distribution of the CYP2D6 genotypes differentiates four major categories of CYP2D6-related metabolyzer types: (a) Extensive Metabolizers (EM)(*1/*1, *1/*10)(51.61%); (b) Intermediate Metabolizers (IM) (*1/*3, *1/*4, *1/*5, *1/*6, *1/*7, *10/*10, *4/*10, *6/*10, *7/*10) (32.26%); (c) Poor Metabolizers (PM) (*4/*4, *5/*5) (9.03%); and (d) Ultra-rapid Metabolizers (UM) (*1xN/*1, *1xN/*4, Dupl) (7.10%). PMs and UMs tend to show higher transaminase activity than EMs and IMs. EMs and IMs are the best responders, and PMs and UMs are the worst responders to pharmacological treatments in AD. It seems very plausible that the pharmacogenetic response in AD depends upon the interaction of genes involved in drug metabolism and genes associated with AD pathogenesis. The establishment of clinical protocols for the practical application of pharmacogenetic strategies in AD will foster important advances in drug development, pharmacological optimization and cost-effectiveness of drugs, and personalized treatments in dementia.

The acetylcholinesterase inhibitor rivastigmine does not alter total choices for methamphetamine, but may reduce positive subjective effects, in a laboratory model of intravenous self-administration in human volunteers

A human laboratory model of intravenous methamphetamine self-administration may facilitate study of putative treatments for methamphetamine addiction. We conducted a double-blind, placebo-controlled, between groups investigation of the acetylcholinesterase (AChE) inhibitor rivastigmine in non-treatment-seeking volunteers who met criteria for methamphetamine abuse or dependence. Safety and subjective effects data derived from days 1-10 of this protocol are described in a separate publication. In this report, we describe self-administration outcomes in participants randomized to treatment with rivastigmine (0 mg, N=7; 1.5 mg, N=6; 3 mg, N=9); data that were collected on days 11-15 of the inpatient protocol. On day 11, participants sampled two infusions of methamphetamine (0 and 30 mg, i.v.). On days 12-15, participants made ten choices each day to receive an infusion of either methamphetamine (3 mg, IV) or saline or a monetary alternative ($0.05-$16). The study design allowed for evaluation of differences in behavior on days in which infusions were performed by the physician (experimenter-administered) versus by the participant using a PCA pump (self-administered), and when monetary alternatives were presented in either ascending or descending sequence. The data show that rivastigmine (1.5 and 3 mg), as compared to placebo, did not significantly alter total choices for methamphetamine (p=0.150). Importantly, the number of infusion choices was greater when methamphetamine was available then when saline was available (p<0.0001), and the number of money choices was greater when saline was available then when methamphetamine was available (p<0.0001). The total number of choices for methamphetamine was not altered as a function of a participant's preferred route of methamphetamine use (p=0.57), and did not differ significantly whether they were experimenter-administered or self-administered (p=0.30). In addition, total choices for methamphetamine were similar made when money was available in an ascending versus descending sequence (p=0.49). The participants' years of methamphetamine use, recent use of methamphetamine (in the past 30 days), or baseline craving (indexed here as "Desire") on the day of the self-administration task were not predictive of number of choices for methamphetamine. In a subset of participants (N=8) for which data was available, individual dose of methamphetamine (3 x 3 mg, i.v.) produced significant increases in positive subjective effects, and a preliminary analysis revealed that 3 mg rivastigmine was associated with reductions in these responses, as compared to placebo. In summary, the current report indicates that there were no effects of rivastigmine on total choices for methamphetamine, that there were low levels of methamphetamine self-administration but these were 8 times greater than saline, and that choice behavior was insensitive to alternative reinforcers. In addition, we showed that rivastigmine may reduce the positive subjective effects produced by methamphetamine during self-administration.

Pharmacogenomics in Alzheimer's disease

Pharmacological treatment in Alzheimer's disease (AD) accounts for 10-20% of direct costs, and fewer than 20% of AD patients are moderate responders to conventional drugs (donepezil, rivastigmine, galantamine, memantine), with doubtful cost-effectiveness. Both AD pathogenesis and drug metabolism are genetically regulated complex traits in which hundreds of genes cooperatively participate. Structural genomics studies demonstrated that more than 200 genes might be involved in AD pathogenesis regulating dysfunctional genetic networks leading to premature neuronal death. The AD population exhibits a higher genetic variation rate than the control population, with absolute and relative genetic variations of 40-60% and 0.85-1.89%, respectively. AD patients also differ in their genomic architecture from patients with other forms of dementia. Functional genomics studies in AD revealed that age of onset, brain atrophy, cerebrovascular hemodynamics, brain bioelectrical activity, cognitive decline, apoptosis, immune function, lipid metabolism dyshomeostasis, and amyloid deposition are associated with AD-related genes. Pioneering pharmacogenomics studies also demonstrated that the therapeutic response in AD is genotype-specific, with apolipoprotein E (APOE) 4/4 carriers the worst responders to conventional treatments. About 10-20% of Caucasians are carriers of defective cytochrome P450 (CYP) 2D6 polymorphic variants that alter the metabolism and effects of AD drugs and many psychotropic agents currently administered to patients with dementia. There is a moderate accumulation of AD-related genetic variants of risk in CYP2D6 poor metabolizers (PMs) and ultrarapid metabolizers (UMs), who are the worst responders to conventional drugs. The association of the APOE-4 allele with specific genetic variants of other genes (e.g., CYP2D6, angiotensin-converting enzyme [ACE]) negatively modulates the therapeutic response to multifactorial treatments affecting cognition, mood, and behavior. Pharmacogenetic and pharmacogenomic factors may account for 60-90% of drug variability in drug disposition and pharmacodynamics. The incorporation of pharmacogenetic/pharmacogenomic protocols to AD research and clinical practice can foster therapeutics optimization by helping to develop cost-effective pharmaceuticals and improving drug efficacy and safety.

Domain-specific improvement of cognition on memantine in patients with Alzheimer's disease treated with rivastigmine

OBJECTIVE

Cholinergic therapy is used in mild-to-moderate Alzheimer's disease (AD) and antiglutamatergic therapy in moderate-to-severe AD. Global scales, as commonly used in clinical trials, blur specifics of disease progression and drug effects. The objective was to assess combination therapy of rivastigmine plus memantine by specific neuropsychological tests in patients with mild-to-moderate AD.

METHODS

12-week-short multicenter open-label pilot study. Ninety patients with mild-to-moderate AD already on stable medication with rivastigmine (3-6 mg b.i.d.) additionally received memantine for 12 weeks. Subscales of the Alzheimer's Disease Assessment Scale (ADAS-cog), the Mini-Mental State Examination (MMSE) and additional neuropsychological tests (e.g. span tasks, semantic fluency) were assessed.

RESULTS

The scores in the ADAS-cog memory subscale, the MMSE score, and digit span and semantic fluency significantly improved on combination therapy.

CONCLUSION

Memory improvement was correlated with ADAS-cog memory score at baseline and inversely with age at onset of treatment. The data suggest that improvement on combination therapy results from an improvement of attention/executive function with secondary memory improvement, which will need to be confirmed in a subsequent double-blind study on a larger number of patients.

Alzheimer Disease and Its Management

Alzheimer disease is a progressive degenerative disorder of the brain characterized by a slow, progressive decline in cognitive function and behavior. As the disease advances, persons with Alzheimer disease have tough time with daily usage of things like using the phone, cooking, handling money, or driving the car. The disease is more common in elder population. It is estimated that Alzheimer disease affects 15 million people worldwide and approximately 4 million Americans. The clinical features of Alzheimer disease overlaps with common signs of aging, and other types of dementia, hence the diagnosis remains difficult. The neuropathologic hallmarks of the disorder are amyloid-rich senile plaques, neurofibrillary tangles, and neuronal degeneration. Drugs approved for treating Alzheimer disease include acetylcholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonist. Caregivers not getting adequate information about Alzheimer disease may believe that nothing can be done to manage its symptoms. Understanding the extent of Alzheimer disease related knowledge can assist disease management that result in improved disease management and reduced care costs. This article attempts to focus on some of the important recent developments in understanding and management of Alzheimer disease.

Alzheimer's disease

BACKGROUND

The authors review the clinical features, epidemiology, pathophysiology, medical management, dental findings and dental treatment of patients with Alzheimer's disease (AD).

STUDIES REVIEWED

The authors conducted MEDLINE searches for 2000 through 2005 using the terms "Alzheimer's disease," "geriatric," "epidemiology," "pathophysiology," "treatment" and "dentistry." Reports selected for further review included those published in English in peer-reviewed journals. The authors gave preference to articles reporting randomized, controlled trials.

RESULTS

AD is a progressive and fatal neurodegenerative disorder characterized by cognitive dysfunctions, particularly in learning and memory, and the emergence of behavioral abnormalities. Deficiencies in the cells responsible for storage and processing of information underlie the cognitive, functional and behavioral changes seen in patients with the disorder.

CLINICAL IMPLICATIONS

As the elderly population grows, increasing numbers of Americans with AD will require dental treatment. The prevalence of dental disease likely will be extensive, because of diminished salivary flow and patients' inability to perform appropriate oral hygiene techniques. Preventive dental education for the caregiver and use of saliva substitutes and anticaries agents by the patient are indicated.

Drug-associated disease: cytochrome P450 interactions

Critically ill patients generally are older, frequently have organ failure, and commonly receive multiple medications, all of which make them susceptible to adverse effects of drugs. Drug interactions are a common adverse effect, and many are predictable based on understanding the mechanisms that underlie drug interactions. This article identifies commonly used medications in critically ill patients and the associated drug interactions that may occur with emphasis on the cytochrome P450 enzyme system.

Rivastigmine for Alzheimer's disease

Alzheimer's disease is the most common form of neurodegenerative dementia and poses considerable health challenges to both patients and their families. Rivastigmine is a powerful slow-reversible, noncompetitive carbamate cholinesterase inhibitor that is approved for the treatment of mild-to-moderate Alzheimer's disease. Randomized, double-blind, placebo-controlled trials of up to 6 months duration have shown beneficial effects of rivastigmine compared with placebo in measures of cognition and global functioning. Less rigorous but growing data suggest that the beneficial effects may endure for up to 5 years, extend to more advanced stages of Alzheimer's disease and may occur in noncognitive domains, such as activities of daily living and the behavioral symptoms of Alzheimer's disease. Evidence from controlled studies also supports the use of rivastigmine for cognitive and behavioral symptoms in Alzheimer's disease associated with vascular risk factors, dementia with Lewy bodies and Parkinson's disease dementia. Early and continued treatment of Alzheimer's disease with rivastigmine maximizes the observed beneficial effects. The most prominent adverse effect of rivastigmine is centrally mediated cholinergic gastrointestinal events, which can be minimized by slower dose-escalation intervals and administration with a full meal. Therapeutic dosing is 6-12 mg/day given twice daily, with higher doses having the potential for greater benefits.