A Framework for Developing Pharmacotherapy for Agitation in Alzheimer's Disease: Recommendations of the ISCTM* Working Group

Dementia is characterized by a significant decline in one of several cognitive domains such as memory, language and executive function, affecting independence and representing a significant deterioration from a previous level of functioning (1). Alzheimer’s Disease (AD) represents the most common form of dementia and contributes up to 70% of the almost 50 million dementia cases worldwide, a number that is projected to double in 20 years (2).

The Patient in Your Alzheimer's Disease Study May be in Another: Duplication and Deception in Clinical Trials of Alzheimer's Disease

Duplicate and deceptive subjects, a significant issue in CNS studies, are not often considered in Alzheimer's Disease (AD) clinical trials. However, AD patients and their study partners may be motivated to take advantage of different mechanisms of action, increase odds of receiving active treatment, and/or obtain financial compensation, which may lead them to participate in multiple studies. CTSdatabase reviewed memory loss subjects (n=1087) from January 2017 through May 2019 to determine how many attempted to screen at multiple sites. 117 subjects (10.8%) visited more than one site within two years. When these potential AD subjects went to additional sites, it was predominantly for non-memory indications (often MDD or schizophrenia). For those that participated in studies, the rate of duplication approached 4% of screened AD subjects. This data indicates that significant numbers of AD subjects attempt to enroll at multiple sites, which confounds efficacy and safety signals in clinical trials.

A Randomized, Double-blind, Placebo-controlled Trial of the Efficacy and Safety of Levomilnacipran ER 40-120mg/day for Prevention of Relapse in Patients with Major Depressive Disorder

OBJECTIVE

Major depressive disorder is often chronic, with relapse and recurrence common. Levomilnacipran extended-release is a potent and selective serotonin and reuptake inhibitor approved in the United States for treatment of major depressive disorder in adults. The objective of this study (NCT01085812) was to evaluate the efficacy, safety, and tolerability of levomilnacipran extended-release in the prevention of relapse in patients with major depressive disorder.

DESIGN

A 24-week Phase III randomized, double-blind, controlled trial comparing levomilnacipran extended-release 40-120mg/day with placebo for relapse prevention in patients with major depressive disorder who had responded to 12-week, open-label treatment with levomilnacipran extended-release. Statistical power was calculated on the assumption that 38 percent of placebo and 20 percent of levomilnacipran extended-release patients would relapse.

SETTING

Thirty-six outpatient study centers throughout the United States and Canada.

PARTICIPANTS

Of 348 patients who met randomization criteria and entered double-blind treatment, three discontinued prior to treatment, 112 were randomized to placebo, and 233 to levomilnacipran extended-release.

PRIMARY OUTCOME

Time to relapse was analyzed using the Cox proportional hazard-regression model with treatment group and baseline Montgomery-Åsberg Depression Rating Scale score as explanatory variables. Safety was also evaluated.

RESULTS

Time to relapse was longer for levomilnacipran extended-release versus placebo (hazard ratio [95% confidence interval] = 0.68 [0.40][1.17]), but the treatment difference was not statistically significant (P=0.165). A relatively low percentage of patients from either group relapsed (placebo=20.5%, levomilnacipran extended-release=13.9%).

CONCLUSION

This study did not detect between-treatment group differences, potentially due to lower than expected relapse rates in the placebo group. Levomilnacipran extended-release was generally well tolerated.

A randomized evaluation of the effects of six antipsychotic agents on QTc, in the absence and presence of metabolic inhibition

Many drugs have been associated with QTc prolongation and, in some cases, this is augmented by concomitant administration with metabolic inhibitors. The effects of 6 antipsychotics on the QTc interval at and around the time of estimated peak plasma/serum concentrations in the absence and presence of metabolic inhibition were characterized in a prospective, randomized study in which patients with psychotic disorders reached steady-state on either haloperidol 15 mg/d (n = 27), thioridazine 300 mg/d (n = 30), ziprasidone 160 mg/d (n = 31), quetiapine 750 mg/d (n = 27), olanzapine 20 mg/d (n = 24), or risperidone 6-8 mg/d increased to 16 mg/d (n = 25/20). Electrocardiograms (ECGs) were done at estimated Cmax at steady-state on both antipsychotic monotherapy and after concomitant administration of appropriate cytochrome P-450 (CYP450) inhibitor(s). Mean QTc intervals did not exceed 500 milliseconds in any patient taking any of the antipsychotics studied, in the absence or presence of metabolic inhibition. The mean QTc interval change was greatest in the thioridazine group, both in the presence and absence of metabolic inhibition. The presence of metabolic inhibition did not significantly augment QTc prolongation associated with any agent. Each of the antipsychotics studied was associated with measurable QTc prolongation at steady-state peak plasma concentrations, which was not augmented by metabolic inhibition. The theoretical risk of cardiotoxicity associated with QTc prolongation should be balanced against the substantial clinical benefits associated with atypical antipsychotics and the likelihood of other toxicities.

An 8-week multicenter, parallel-group, double-blind, placebo-controlled study of sertraline in elderly outpatients with major depression

OBJECTIVE

There have been few placebo-controlled trials of selective serotonin reuptake inhibitors for depressed elderly patients. This placebo-controlled study of sertraline was designed to confirm the results of non-placebo-controlled trials.

METHOD

The subjects were outpatients age 60 years or older who had a DSM-IV diagnosis of major depressive disorder and a total score on the 17-item Hamilton Depression Rating Scale of 18 or higher. The patients were randomly assigned to 8 weeks of double-blind treatment with placebo or a flexible daily dose of 50 or 100 mg of sertraline. The primary outcome variables were the Hamilton scale and Clinical Global Impression (CGI) scales for severity and improvement.

RESULTS

A total of 371 patients assigned to sertraline and 376 assigned to placebo took at least one dose. At endpoint, the patients receiving sertraline evidenced significantly greater improvements than those receiving placebo on the Hamilton depression scale and CGI severity and improvement scales. The mean changes from baseline to endpoint in Hamilton score were -7.4 points (SD=6.3) for sertraline and -6.6 points (SD=6.4) for placebo. The rate of CGI-defined response at endpoint was significantly higher for sertraline (45%) than for placebo (35%), and the time to sustained response was significantly shorter for sertraline (median, 57 versus 61 days). There were few discontinuations due to treatment-related adverse events, 8% for sertraline and 2% for placebo.

CONCLUSIONS

Sertraline was effective and well tolerated by older adults with major depression, although the drug-placebo difference was not large in this 8-week trial.

First clinical evaluation of ganstigmine in patients with probable Alzheimer's disease

The objective of this study was to evaluate the safety, tolerability, maximum tolerated dose, pharmacokinetics, and pharmacodynamics of five fixed doses of ganstigmine (CHF 2819) in patients with probable Alzheimer's disease (AD). This randomized, double-blind, placebo-controlled trial evaluated five dose levels (5, 7.5, 10, 12.5, and 15 mg) administered orally once daily for 7 days. Adverse events and continuous telemetry were collected on successive panels of six patients (five active, one placebo). Acetylcholinesterase, butyrylcholinesterase, and plasma drug levels were measured. A total of 29 patients were randomized and 18 completed the study. A total of seven patients, including five of five in the 12.5-mg panel, discontinued because of adverse events. Four patients were withdrawn administratively from the first panel while an episode of atrial fibrillation (the only serious adverse event) was investigated. This panel was then repeated. Mild, transient headache or nausea were the most commonly reported adverse events. Multiple moderate adverse events in the 12.5-mg panel (including nausea, vomiting, and anorexia) led to the decision not to proceed with a 15-mg panel. Ten milligrams was determined to be the maximum tolerated dose. Ganstigmine exhibited nonlinear pharmacokinetics, was absorbed rapidly, and reached peak concentrations within 1 hour. Acetylcholinesterase inhibition was dose dependent and lasted as long as 24 hours. Ganstigmine, a novel cholinesterase inhibitor, was well tolerated within a dosing range of 5 to 10 mg. Once-daily dosing is supported by data on acetylcholinesterase inhibition.

Estimation of the absolute bioavailability of rivastigmine in patients with mild to moderate dementia of the Alzheimer's type

OBJECTIVE

To investigate the bioavailability of rivastigmine, an approved therapy for patients with mild to moderate dementia of the Alzheimer's type, at the highest approved single dose of 6 mg.

DESIGN AND SETTING

Randomised, two-period crossover, single-centre, non-blinded, inpatient study.

PATIENTS AND PARTICIPANTS

Eleven patients (five females and six males) with mean age 69.5 years.

METHODS

The 6 mg oral dose was compared with a 2 mg intravenous dose of rivastigmine infused over a 1-hour period. Plasma concentrations of rivastigmine and its metabolite NAP 226-90 were measured with a gas chromatographic/mass spectrometric method.

RESULTS

Following oral administration of a single 6 mg capsule, rivastigmine is rapidly absorbed with an average time to peak plasma concentration of about 1 hour and an average peak concentration of about 25.6 g/L. By a noncompartmental approach, the absolute bioavailability of the 6 mg oral dose of rivastigmine was 71.7% when compared with a 2mg intravenous infusion normalised for dose. By using a population pharmacokinetic model with Michaelis-Menten elimination, absolute bioavailability was estimated at 60.2%. The average terminal elimination half-life of rivastigmine ranged from 1.4 to 1.7 hours for both treatments. Plasma concentrations of the major metabolite, NAP 226-90, formed by the hydrolysis of rivastigmine by cholinesterase are lower than those of the parent compound following oral and intravenous administration.

CONCLUSION

A noncompartmental approach and a compartmental approach based on a population pharmacokinetic model with Michaelis-Menten elimination yielded comparable values, 71.7% and 60.2% respectively, for the absolute bioavailability of a single 6 mg oral dose of rivastigmine. Comparison with previous studies confirmed that the oral form of the drug exhibits increased bioavailability with increasing dose, consistent with its nonlinear pharmacokinetics..

Pharmacokinetics and pharmacodynamics of the triptan antimigraine agents: a comparative review

The current approach to antimigraine therapy comprises potent serotonin 5-HT1B/1D receptor agonists collectively termed triptans. Sumatriptan was the first of these compounds to be developed, and offered improved efficacy and tolerability over ergot-derived compounds. The development of sumatriptan was quickly followed by a number of 'second generation' triptan compounds, characterised by improved pharmacokinetic properties and/or tolerability profiles. Triptans are believed to effect migraine relief by binding to serotonin (5-hydroxy-tryptamine) receptors in the brain, where they act to induce vasoconstriction of extracerebral blood vessels and also reduce neurogenic inflammation. Although the pharmacological mechanism of the triptans is similar, their pharmacokinetic properties are distinct. For example, bioavailability of oral formulations ranges between 14% (sumatriptan) and 74% (naratriptan), and their elimination half-life ranges from 2 hours (sumatriptan and rizatriptan) to 25 hours (frovatriptan). Clearly, such diverse pharmacokinetic properties will influence the effectiveness of the compounds and favour the prescription of one over another in different patient populations. This article reviews the pharmacological properties of the triptans (time to peak plasma concentration, half-life, bioavailability and receptor binding) and relates these properties to efficacy and time of onset. It also considers the effects of concomitant medication, food, age and disease on the pharmacokinetics of the compounds. In addition, the relative merits, such as headache recurrence, tolerability and route of administration, are discussed. Finally, the performance of the triptans is considered in the context of direct head-to-head comparative trials that have assessed the efficacy profile of the compounds.

Beta-amyloid therapies in Alzheimer's disease

Neurones in the brain produce beta-amyloid fragments from a larger precursor molecule termed the amyloid precursor protein (APP). When released from the cell, these protein fragments may accumulate in extracellular amyloid plaques and consequently hasten the onset and progression of Alzheimer's disease (AD). A beta fragments are generated through the action of specific proteases within the cell. Two of these enzymes, beta- and gamma-secretase, are particularly important in the formation of A beta as they cleave within the APP protein to give rise to the N-terminal and C-terminal ends of the A beta fragment, respectively. Consequently, many researchers are investigating therapeutic approaches that inhibit either beta- or gamma-secretase activity, with the ultimate goal of limiting A beta; production. An alternative AD therapeutic approach that is being investigated is to employ anti-A beta antibodies to dissolve plaques that have already formed. Both of these approaches focus on the possibility that accrual of A beta leads to neuronal degeneration and cognitive impairment characterised by AD and test the hypothesis that limiting A beta deposition in neuritic plaques may be an effective treatment for AD.

Placebo-controlled study of gabapentin treatment of panic disorder

A randomized, double-blind, placebo-controlled, parallel-group study was conducted to evaluate the efficacy and safety of gabapentin in relieving the symptoms of panic disorder. One hundred three patients were randomly assigned to receive double-blind treatment with either gabapentin (dosed flexibly between 600 and 3,600 mg/day) or placebo for 8 weeks. No overall drug/placebo difference was observed in scores on the Panic and Agoraphobia Scale (PAS) (p = 0.606). A post hoc analysis was used to evaluate the more severely ill patients as defined by the primary outcome measure (PAS score > or = 20). In this population, the gabapentin-treated patients showed significant improvement in the PAS change score (p = 0.04). In patients with a PAS score of 20 or greater, women showed a greater response than men regardless of treatment. Adverse events were consistent with the known side effect profile of gabapentin and included somnolence, headache, and dizziness. One patient experienced a serious adverse event during the study. No deaths were reported. The results of this study suggest that gabapentin may have anxiolytic effects in more severely ill patients with panic disorder.