Validation of a suite of ERP and QEEG biomarkers in a pre-competitive, industry-led study in subjects with schizophrenia and healthy volunteers

OBJECTIVE

Complexity and lack of standardization have mostly limited the use of event-related potentials (ERPs) and quantitative EEG (QEEG) biomarkers in drug development to small early phase trials. We present results from a clinical study on healthy volunteers (HV) and patients with schizophrenia (SZ) that assessed test-retest, group differences, variance, and correlation with functional assessments for ERP and QEEG measures collected at clinical and commercial trial sites with standardized instrumentation and methods, and analyzed through an automated data analysis pipeline.

METHODS

81 HV and 80 SZ were tested at one of four study sites. Subjects were administered two ERP/EEG testing sessions on separate visits. Sessions included a mismatch negativity paradigm, a 40 Hz auditory steady-state response paradigm, an eyes-closed resting state EEG, and an active auditory oddball paradigm. SZ subjects were also tested on the Brief Assessment of Cognition (BAC), Positive and Negative Syndrome Scale (PANSS), and Virtual Reality Functional Capacity Assessment Tool (VRFCAT).

RESULTS

Standardized ERP/EEG instrumentation and methods ensured few test failures. The automated data analysis pipeline allowed for near real-time analysis with no human intervention. Test-retest reliability was fair-to-excellent for most of the outcome measures. SZ subjects showed significant deficits in ERP and QEEG measures consistent with published academic literature. A subset of ERP and QEEG measures correlated with functional assessments administered to the SZ subjects.

CONCLUSIONS

With standardized instrumentation and methods, complex ERP/EEG testing sessions can be reliably performed at clinical and commercial trial sites to produce high-quality data in near real-time.

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).

A Phase 1B, randomized, double blind, placebo controlled, multiple-dose escalation study of NSI-189 phosphate, a neurogenic compound, in depressed patients

We wanted to examine tolerability and efficacy of NSI-189, a benzylpiperizine-aminiopyridine neurogenic compound for treating major depressive disorder (MDD). This was a Phase 1B, double blind, randomized, placebo controlled, multiple-dose study with three cohorts. The first cohort received 40 mg q.d. (n=6) or placebo (n=2), the second cohort 40 mg b.i.d. (n=6) or placebo (n=2), and the third cohort 40 mg t.i.d. (n=6) or placebo (n=2). Twenty-four patients with MDD were recruited, with the diagnosis and severity confirmed through remote interviews. Eligible patients received NSI-189 or placebo for 28 days in an inpatient setting with assessments for safety, pharmacokinetics (PK) and efficacy. Outpatient follow-up visits were conducted until day 84 (±3). NSI-189 was relatively well tolerated at all doses, with no serious adverse effects. NSI-189 area under the curve increased in a dose-related and nearly proportional manner across the three cohorts, with a half-life of 17.4-20.5 h. The exploratory efficacy measurements, including Symptoms Of Depression Questionnaire (SDQ), Montgomery-Asberg Depression Scale (MADRS), Clinical Global Impressions-Improvement (CGI-I), and The Massachusetts General Hospital (MGH) Cognitive and Physical Functioning Questionnaire (CPFQ) showed a promising reduction in depressive and cognitive symptoms across all measures for NSI-189, with significant improvement in the SDQ and CPFQ, and a medium to large effect size for all measures. These improvements persisted during the follow-up phase. In summary, NSI-189 shows potential as a treatment for MDD in an early phase study. The main limitation of this preliminary study was the small sample size of each cohort.

Multiple-Dose Plasma Pharmacokinetic and Safety Study of LY450108 and LY451395 (AMPA Receptor Potentiators) and Their Concentration in Cerebrospinal Fluid in Healthy Human Subjects

The objective of this study was to measure the steady-state cerebrospinal fluid (CSF) concentration of LY450108 and LY451395 (positive modulators of AMPA receptors) in healthy subjects after the administration of 1 mg and 5 mg. Secondary objectives included the evaluation of safety, pharmacokinetics, and steady-state ratio of plasma:CSF concentrations of LY450108 and LY451395 after multiple dosing. This study was an open-label, multiple oral dose study evaluating 1 mg and 5 mg LY450108 and 1 mg and 5 mg LY451395 in 12 (3 subjects per dosing group) healthy subjects, aged 18 to 49 years. Twelve healthy male subjects completed the study. LY450108 and LY451395 were quantifiable in CSF after 1-mg and 5-mg multiple-dose administrations with plasma:CSF ratio of 82:1 and 44:1, respectively. LY450108 and LY451395 1 mg and 5 mg were measured in the CSF. Single and multiple oral doses of LY450108 and LY451395 were determined to be safe and well tolerated in healthy subjects.

Pharmacokinetics and pharmacodynamics of the novel daily rivastigmine transdermal patch compared with twice-daily capsules in Alzheimer's disease patients

A transdermal patch has been developed for the cholinesterase inhibitor rivastigmine. This study investigated the pharmacokinetics and pharmacodynamics of rivastigmine and NAP226-90, and compared drug exposure between patch and capsule administrations. This was an open-label, parallel-group study in Alzheimer's disease patients randomized to receive either capsule (1.5-6 mg Q12H, i.e., 3-12 mg/day) or patch (5-20 cm2) in ascending doses through four 14-day periods. The patch showed lower Cmax (ca. 30% lower at 20 cm2, 19.5 versus 29.3 ng/ml), longer tmax (8.0 versus 1.0 h), and greater AUC (ca. 1.8-fold at 20 cm2, 345 versus 191 ng x h/ml) compared with the 6 mg Q12H capsule dose, with markedly less fluctuation between peak and trough plasma levels (80% at 20 cm2 versus 620% at 1.5 mg Q12H). Plasma butyrylcholinesterase inhibition rose slowly after patch administration, whereas two distinct peaks were seen after capsule administration. Average exposure with the 10 cm2 patch was comparable to the highest capsule dose (6 mg Q12H, i.e., 12 mg/day).

Review of the pharmacokinetics, pharmacogenetics, and drug interaction potential of antidepressants: focus on venlafaxine

Improving outcomes for patients with depression involves selecting the best possible drug therapy. Considerations relevant to drug product selection include: 1) pharmacokinetic issues such as half-life and time to steady-state, and protein binding; 2) pharmacodynamic drug-drug interactions; and 3) drug metabolism-related drug interactions. A comparison of selected antidepressants with an emphasis on venlafaxine's similarities and differences is presented. Based on these parameters, selecting an antidepressant medication, such as venlafaxine, that has a low potential for drug interactions at the Cytochrome P450 (CYP) enzyme system, and is easy to monitor and dose, facilitate successful treatment of patients. Venlafaxine has been evaluated in clinical studies that demonstrate low to negligible drug interaction potential at CYP2D6, CYP1A2, CYP2C19, and CYP3A4. Its short half-life and time to steady-state, when coupled with the extended release characteristics of the preferred dosage formulation allow for once daily dosing and rapid attainment of therapeutic effects. The CYP3A4 system is involved in both first-pass metabolism and systemic clearance of medications. Drug interactions at this isoenzyme have proven to be of high clinical relevance ranging from cardiovascular toxicity and death with commonly used drugs such as cisapride, to subtherapeutic levels of cyclosporine or protease inhibitors leading to transplant rejection or HIV relapse. Reasons for the under detection and reporting of drug interaction mediated adverse events include healthcare system structure, the poor return to follow up of non-adherent patients, the need for greater education and training of clinicians to recognize drug-related adverse events, and the reluctance of patients to spontaneously communicate about the unpleasant effects of their medication.

Branded versus generic clozapine: bioavailability comparison and interchangeability issues

Clozapine has been the treatment of choice for patients with refractory schizophrenia. Generic clozapine has recently become available, because of a waiver of the usual criteria for establishing bioequivalence. However, there are biopharmaceutical, bioavailability, and clinical concerns related to the generic formulation raised by both clinicians and academic researchers. We conducted a prospective, randomized, crossover study to evaluate steady-state pharmacokinetics, pharmacodynamics, and tolerability of generic clozapine (Zenith Goldline Pharmaceuticals) versus Clozaril (Novartis Pharmaceuticals) in schizophrenic patients. A preliminary report of the pertinent bioavailability results is presented here. Despite comparable mean plasma concentration-time curves, significant differences were found in the primary pharmacokinetic parameters of the 2 formulations in almost 40% of patients. Such intraindividual differences raise the issue of average bioequivalence versus individual bioequivalence and the implication for interchangeability of different clozapine formulations. The decision to switch a patient from branded to generic clozapine should be made on an individual basis with special emphasis on clinical outcome, and patients should be monitored closely during the transition.

Effect of venlafaxine versus fluoxetine on metabolism of dextromethorphan, a CYP2D6 probe

Two antidepressants, venlafaxine and fluoxetine, were evaluated in vivo for their effect on cytochrome P450 2D6 (CYP2D6) activity, measured by the ratio of dextromethorphan, a sensitive CYP2D6 marker, to its metabolite dextrorphan (i.e., DM:DT) excreted in urine after DM coadministration. Twenty-eight healthy extensive metabolizers of CYP2D6 received either venlafaxine (37.5 mg bid for 7 days, then 75 mg bid until Day 28) or fluoxetine (20 mg daily for 28 days); 26 completed the study. Plasma concentrations of both drugs and their active metabolites were determined. DM:DTs were evaluated at baseline (Day 0), on Days 7 and 28 of dosing, and 2 weeks after drug discontinuation (Day 42). Steady-state drug and metabolite levels were achieved in both groups by Day 28. Mean DM:DTs for venlafaxine and fluoxetine differed statistically significantly (p < 0.001) on Days 7, 28, and 42. Comparisons of DM:DT as a percentage of baseline values showed that DM:DT increased 1.2-fold for venlafaxine and 9.1-fold for fluoxetine on Day 7 (p < 0.001) and increased 2.1-fold for venlafaxine and 17.1-fold for fluoxetine on Day 28 (p < 0.001). Inhibition of CYP2D6 metabolism persisted for 2 weeks after discontinuation of fluoxetine, unlike the case with venlafaxine. These in vivo results confirm in vitro data demonstrating significantly weaker inhibition of CYP2D6 with venlafaxine than with fluoxetine. This suggests that clinically significant interactions involving CYP2D6 inhibition could occur between fluoxetine and drugs metabolized by CYP2D6 but may be less likely to occur with venlafaxine.

Sleep disorders: assisting patients to a good night's sleep

Sleep is an active process consisting of macro- and microarchitectural rhythms, chronobiology, and neurochemical changes. Disruptions in sleep chronobiology, which may occur in shift workers and the elderly or due to jet lag, often respond to exogenous melatonin. Insomnia requires careful evaluation to determine contributions of comorbid medical conditions and drug effects. Treatment options include sleep hygiene principles and sedative hypnotic therapy. Zaleplon and zolpidem, short-acting benzodiazepines selective for omega-1 GABA receptors, are effective first-line agents for initiating sleep.

CYP2D6 inhibition by fluoxetine, paroxetine, sertraline, and venlafaxine in a crossover study: intraindividual variability and plasma concentration correlations

The authors report the CYP2D6 inhibitory effects of fluoxetine, paroxetine, sertraline, and venlafaxine in an open-label, multiple-dose, crossover design. Twelve CYP2D6 extensive metabolizers were phenotyped, using the dextromethorphan/dextrorphan (DM/DX) urinary ratio, before and after administration of fluoxetine 60 mg (loading dose strategy), paroxetine 20 mg, sertraline 100 mg, and venlafaxine 150 mg. Paroxetine, sertraline, and venlafaxine sequences were randomized with 2-week washouts between treatments; fluoxetine was the last antidepressant (AD) administered. Comparing within groups, baseline DM/DX ratios (0.017) were significantly lower than DM/DX ratios after treatment (DM/DXAD) with fluoxetine (0.313, p < 0.0001) and paroxetine (0.601, p < 0.0001) but not for sertraline (0.026, p = 0.066) or venlafaxine (0.023, p = 0.485). Between groups, DM/DXAD ratios were significantly higher for fluoxetine and paroxetine compared to sertraline and venlafaxine. No differences between DM/DXAD ratios were found for fluoxetine and paroxetine although more subjects phenocopied to PM status after receiving the latter (42% vs. 83%; chi 2 = 4.44, p = 0.049, df = 1). Similarly, no differences between DM/DXAD ratios were found for sertraline and venlafaxine. Of note, the DM/DXAD for 1 subject was much lower after treatment with paroxetine (0.058) compared to fluoxetine (0.490), while another subject exhibited a much lower ratio after treatment with fluoxetine (0.095) compared to paroxetine (0.397). Significant correlations between AD plasma concentration and DM/DXAD were found for paroxetine (r2 = 0.404, p = 0.026) and sertraline (r2 = 0.64, p = 0.002) but not fluoxetine or venlafaxine. In addition, DM/DXAD correlated with baseline isoenzyme activity for paroxetine, sertraline, and venlafaxine groups. These results demonstrate the potent, but variable, CYP2D6 inhibition of fluoxetine and paroxetine compared to sertraline and venlafaxine. CYP2D6 inhibition may be related, in part, to dose, plasma concentration, and baseline isoenzyme activity, and these correlations merit further investigation.

Pharmacologic and pharmacokinetic considerations in choosing an antipsychotic

Recent advances in our understanding of schizophrenia along with neuroscience insights into antipsychotic medication mechanisms of action have led to a renaissance in new drug development, including an expanded therapeutic spectrum encompassing more of the symptoms encountered in schizophrenia. Atypical antipsychotics, or new generation therapies, also demonstrate greater selectivity for therapeutic actions than for extrapyramidal symptoms (EPS). Our modern armamentarium of drugs spans a wide range of pharmacologies, and it is more accurate to envision shades of gray rather than a black-and-white description for typical versus atypical properties of medications. As our paradigms for antipsychotic efficacy have shifted, a reexploration of the "older" neuroleptics is warranted to determine if they possess pharmacologic attributes that might have been overlooked during the era of high-dose neuroleptic therapy. Loxapine appears to be in the center of this spectrum, somewhere between haloperidol and risperidone. Dosing implications for drugs with a more even serotonin-2A (5-HT2A) receptor and dopamine-2 (D2) receptor blocking effect are discussed. Loxapine might have a window of partial atypicality at doses < or = 50 mg/day. These lower doses might have potential as both monotherapy in responsive patients with persistent psychotic disorders and as an adjunctive treatment in partially responding patients on concurrent atypical antipsychotic treatments. The pharmacologic properties of loxapine within its usable dosage range are quite complex and are the net sum of the parent's plus metabolites' contributions (demethylation and hydroxylation by cytochrome P450 enzymes). These pharmacologic effects include alpha-adrenergic blockade, inhibition of the noradrenergic transporter protein (reuptake inhibition), and antimuscarinic effects. Drug interactions and cigarette smoking might alter the parent-to-metabolite concentration ratios, affecting the relative atypicality of this antipsychotic therapy. Moreover, with the intramuscular formulation, which does not undergo first-pass metabolism, the parent compound of loxapine, i.e., not its metabolites, is predominantly detected in the plasma of patients, reducing the likelihood for EPS during emergency interventions in patients with positive symptoms. Further study is warranted to determine loxapine's place in our treatment of schizophrenia.

CYP2D6 status of extensive metabolizers after multiple-dose fluoxetine, fluvoxamine, paroxetine, or sertraline

The aim of this study was to evaluate the CYP2D6 inhibitory effects of four selective rerotonin re-uptake inhibitors (SSRIs). Thirty-one healthy subjects were phenotyped as extensive metabolizers using the dextromethorphan/dextrorphan (DM/DX) urinary ratio as a marker for CYP2D6 activity before and after 8 days of administration of fluoxetine 60 mg (loading dose strategy), fluvoxamine 100 mg, paroxetine 20 mg, or sertraline 100 mg in a parallel-group design. Statistical analysis was performed on log-transformed DM/DX ratios because of variability within and between treatment groups. DM/DX ratios before (DM/DX(BL)) and after (DM/DX(SSRI)) were compared within and between the four SSRI groups. DM/DX(BL) ratios were not significantly different between the four SSRI treatment groups. Comparing within groups, significant differences between DM/DX(BL) and DM/DX(SSRI) were found for the fluoxetine (p < 0.001; ratio values, 0.020 vs. 0.364) and paroxetine (p = 0.0005, ratio values 0.029 vs. 1.085) but not for the fluvoxamine or sertraline groups. Comparing between groups, significant differences in DM/DX(SSRI) ratios were found for fluoxetine versus sertraline (p = 0.0019, DM/DX = 0.364 vs. 0.057), fluoxetine versus fluvoxamine (p < 0.0001, DM/DX = 0.364 vs. 0.019), paroxetine versus sertraline (p = 0.0026, DM/DX = 1.085 vs. 0.057), and paroxetine versus fluvoxamine (p < 0.0001, DM/DX = 1.085 vs. 0.019). No significant differences were noted between the two potent CYP2D6 inhibitors, fluoxetine and paroxetine, or the two weakest inhibitors, fluvoxamine and sertraline. Five subjects in the fluoxetine and four subjects in the paroxetine groups changed to poor metabolizer phenotype (DM/DX > or = 0.3) after treatment. Although CYP2D6 inhibitory effects of fluvoxamine and sertraline did not yield significant differences from baseline, some subjects exhibited DM/DX ratio increases of 150 to 200%. One paroxetine-treated subject did not exhibit any CYP2D6 inhibition. SSRI dose and plasma concentration may be correlated with the extent of CYP2D6 inhibition and should be further investigated.

A pharmacoeconomic model of outpatient antipsychotic therapy in "revolving door" schizophrenic patients

BACKGROUND

The discrepancy between supply and demand in health care today requires that psychiatrists and other providers of patient care expand their traditional role from one of patient advocate to one of allocator of care. In this new role, the care provider must consider not only the efficacy and safety of a therapeutic regimen, but also its impact on society in terms of quality of life and cost-effectiveness.

METHOD

A variety of pharmacoeconomic analysis methodologies have been used to assess the economic and quality of life consequences of alternate treatment strategies. A clinical decision analysis model that takes into account compliance rates and associated rehospitalization was used to compare the direct treatment costs associated with alternate outpatient neuroleptic strategies for "revolving door" schizophrenic patients. The antipsychotic treatment options considered were traditional oral neuroleptics (e.g., haloperidol), depot neuroleptics (e.g., haloperidol decanoate), and "atypical" oral agents (e.g., risperidone).

RESULTS

The results of this decision analysis model (based on a set of reasonable outcome probabilities and costs) suggest that, under five sets of cost and outcome assumptions, switching to the depot route in a patient with a history of relapse and rehospitalization may reduce total direct treatment costs by approximately $650 to $2600/year compared with an atypical agent and approximately $460 to $1150/year compared with a traditional oral neuroleptic. Under a sixth set of assumptions-namely, a compliance rate with atypical oral drug (80%) equal to that with the depot agent and an average wholesale price of the atypical drug 25% lower than current wholesale price-the atypical oral drug treatment option would be approximately $700 less than treatment with a depot agent, and $1860 less than treatment with a traditional neuroleptic.

CONCLUSION

The decision analysis model presented here indicates that, under a variety of assumptions, switching a revolving door patient to a depot medication for outpatient maintenance therapy could result in lower total direct treatment costs over the first year. This finding was consistent, although to varying degrees, under differing probability and cost assumptions. The proposed model can be used in other clinical circumstances, such as treatment-refractory patients or those with severe negative symptoms, as well as with other associated outcome probabilities and costs. Application of this model in different clinical scenarios associated with different outcome probabilities and treatment costs, however, may well provide different results.