Clinical significance of pharmacokinetic interactions between antiepileptic and psychotropic drugs

N-Formyl-Methionyl-Leucyl-Phenylalanine Plays a Neuroprotective and Anticonvulsant Role in Status Epilepticus Model

Status epilepticus (SE) is described as continuous and self-sustaining seizures, which triggers hippocampal neurodegeneration, inflammation, and gliosis. N-formyl peptide receptor (FPR) has been associated with inflammatory process. N-formyl-methionyl-leucyl-phenylalanine (fMLP) peptide plays an anti-inflammatory role, mediated by the activation of G-protein-coupled FPR. Here, we evaluated the influence of fMLP peptides on the behavior of limbic seizures, memory consolidation, and hippocampal neurodegeneration process. Male Wistar rats (Rattus norvegicus) received microinjections of pilocarpine in hippocampus (H-PILO, 1.2 mg/μL, 1 μL) followed by fMLP (1 mg/mL, 1 μL) or vehicle (VEH, saline 0.9%, 1 μL). During the 90 min of SE, epileptic seizures were analyzed according to the Racine's Scale. After 24 h of SE, memory impairment was assessed by the inhibitory avoidance test and the neurodegeneration process was evaluated in hippocampal areas. There was no change in latency and number of wet dog shake (WDS) after administration of fMLP. However, our results showed that the intrahippocampal infusion of fMLP reduced the severity of seizures, as well as the number of limbic seizures. In addition, fMLP infusion protected memory dysfunction followed by SE. Finally, the intrahippocampal administration of fMLP attenuated the process of neurodegeneration in both hippocampi. Taken together, our data suggest a new insight into the functional role of fMLP peptides, with important implications for their potential use as a therapeutic agent for the treatment of brain disorders, such as epilepsy. Schematic drawing on the neuroprotective and anticonvulsant role of fMLP during status epilepticus. Initially, a cannula was implanted in hippocampus and pilocarpine/saline was administered into the hippocampus followed by fMLP/saline (A-C). fMLP reduced seizure severity and neuronal death in the hippocampus, as well as protecting against memory deficit (D).

Drug-drug interactions between antiseizure medications and antipsychotic medications: a narrative review and expert opinion

INTRODUCTION

Antiseizure medications (ASMs) and antipsychotic drugs are frequently coadministered with the potential for drug-drug interactions. Interactions may either be pharmacokinetic or pharmacodynamic, resulting in a decrease or increase in efficacy and/or an increase or decrease in adverse effects.

AREAS COVERED

The clinical evidence for pharmacokinetic and pharmacodynamic interactions between ASMs and antipsychotics is reviewed based on the results of a literature search in MEDLINE conducted in April 2023.

EXPERT OPINION

There is now extensive published evidence for the clinical importance of interactions between ASMs and antipsychotics. Enzyme-inducing ASMs can decrease blood concentrations of many of the antipsychotics. There is also evidence that enzyme-inhibiting ASMs can increase antipsychotic blood concentrations. Similarly, there is limited evidence showing that antipsychotic drugs may affect the blood concentrations of ASMs through pharmacokinetic interactions. There is less available evidence for pharmacodynamic interactions, but these can also be important, as can displacement from protein binding. The lack of published evidence for an interaction should not be interpreted as meaning that the given interaction does not occur; the evidence is building continually. There is no substitute for careful patient monitoring and sound clinical judgment.

Pharmacokinetic Interactions Between Antiseizure and Psychiatric Medications

Antiseizure medications and drugs for psychiatric diseases are frequently used in combination. In this context, pharmacokinetic interactions between these drugs may occur. The vast majority of these interactions are primarily observed at a metabolic level and result from changes in the activity of the cytochrome P450 (CYP). Carbamazepine, phenytoin, and barbiturates induce the oxidative biotransformation and can consequently reduce the plasma concentrations of tricyclic antidepressants, many typical and atypical antipsychotics and some benzodiazepines. Newer antiseizure medications show a lower potential for clinically relevant interactions with drugs for psychiatric disease. The pharmacokinetics of many antiseizure medications is not influenced by antipsychotics and anxiolytics, while some newer antidepressants, namely fluoxetine, fluvoxamine and viloxazine, may inhibit CYP enzymes leading to increased serum concentrations of some antiseizure medications, including phenytoin and carbamazepine. Clinically relevant pharmacokinetic interactions may be anticipated by knowledge of CYP enzymes involved in the biotransformation of individual medications and of the influence of the specific comedication on the activity of these CYP enzymes. As a general rule, these interactions can be managed by careful evaluation of clinical response and, when indicated, individualized dosage adjustments guided by measurement of drugs serum concentrations, especially if pharmacokinetic interactions may cause any change in seizure control or signs of toxicity. Further studies are required to improve predictions of pharmacokinetic interactions between antiseizure medications and drugs for psychiatric diseases providing practical helps for clinicians in the clinical setting.

Role of Modulation of Hippocampal Glucose Following Pilocarpine-Induced Status Epilepticus

Status epilepticus (SE) is defined as continuous and self-sustaining seizures, which trigger hippocampal neurodegeneration, mitochondrial dysfunction, oxidative stress, and energy failure. During SE, the neurons become overexcited, increasing energy consumption. Glucose uptake is increased via the sodium glucose cotransporter 1 (SGLT1) in the hippocampus under epileptic conditions. In addition, modulation of glucose can prevent neuronal damage caused by SE. Here, we evaluated the effect of increased glucose availability in behavior of limbic seizures, memory dysfunction, neurodegeneration process, neuronal activity, and SGLT1 expression. Vehicle (VEH, saline 0.9%, 1 μL) or glucose (GLU; 1, 2 or 3 mM, 1 μL) were administered into hippocampus of male Wistar rats (Rattus norvegicus) before or after pilocarpine to induce SE. Behavioral analysis of seizures was performed for 90 min during SE. The memory and learning processes were analyzed by the inhibitory avoidance test. After 24 h of SE, neurodegeneration process, neuronal activity, and SGLT1 expression were evaluated in hippocampal and extrahippocampal regions. Modulation of hippocampal glucose did not protect memory dysfunction followed by SE. Our results showed that the administration of glucose after pilocarpine reduced the severity of seizures, as well as the number of limbic seizures. Similarly, glucose after SE reduced cell death and neuronal activity in hippocampus, subiculum, thalamus, amygdala, and cortical areas. Finally, glucose infusion elevated the SGLT1 expression in hippocampus. Taken together our data suggest that possibly the administration of intrahippocampal glucose protects brain in the earlier stage of epileptogenic processes via an important support of SGLT1.

Bilateral pedal edema associated with lurasidone: a case report

Lurasidone, an atypical antipsychotic, is currently approved for treatment of schizophrenia and bipolar depression. Little is known about whether lurasidone might also cause pedal edema. A 55-year-old female patient had been diagnosed with bipolar I disorder from the age of 26. She had been prescribed escitalopram and quetiapine 300 mg/day for her persistent depressive mood. Later, she took lurasidone plus escitalopram to treat depressive episode. Consequently, she developed mild bilateral swelling over the lower legs and ankles. After lurasidone was discontinued, the bilateral pedal edema was completely resolved, and no further recurrence of edema occurred. Resolution of the edema after discontinuation of lurasidone indicates that the edema may have been caused by lurasidone. Caution should be needed when prescribing lurasidone for patients, as pedal edema may affect patients' adherence to the prescription.

Inhibiting Epileptiform Activity in Cognitive Disorders: Possibilities for a Novel Therapeutic Approach

Cognitive impairment is a common and seriously debilitating symptom of various mental and neurological disorders including autism, attention deficit hyperactivity disorder, multiple sclerosis, epilepsy, and neurodegenerative diseases, like Alzheimer's disease. In these conditions, high prevalence of epileptiform activity emerges as a common pathophysiological hallmark. Growing body of evidence suggests that this discrete but abnormal activity might have a long-term negative impact on cognitive performance due to neuronal circuitries' remodeling, altered sleep structure, pathological hippocampo-cortical coupling, and even progressive neuronal loss. In animal models, epileptiform activity was shown to enhance the formation of pathological amyloid and tau proteins that in turn trigger network hyperexcitability. Abolishing epileptiform discharges might slow down the cognitive deterioration. These findings might provide basis for therapeutic use of antiepileptic drugs in neurodegenerative cognitive disorders. The aim of our review is to describe the data on the prevalence of epileptiform activity in various cognitive disorders, to summarize the current knowledge of the mechanisms of epileptic activity in relation to cognitive impairment, and to explore the utility of antiepileptic drugs in the therapy of cognitive disorders. We also propose future directions for drug development and novel therapeutic interventions targeting epileptiform discharges in these disorders.

Modulation of Glucose Availability and Effects of Hypo- and Hyperglycemia on Status Epilepticus: What We Do Not Know Yet?

Status epilepticus (SE) can lead to serious neuronal damage and act as an initial trigger for epileptogenic processes that may lead to temporal lobe epilepsy (TLE). Besides promoting neurodegeneration, neuroinflammation, and abnormal neurogenesis, SE can generate an extensive hypometabolism in several brain areas and, consequently, reduce intracellular energy supply, such as adenosine triphosphate (ATP) molecules. Although some antiepileptic drugs show efficiency to terminate or reduce epileptic seizures, approximately 30% of TLE patients are refractory to regular antiepileptic drugs (AEDs). Modulation of glucose availability may provide a novel and robust alternative for treating seizures and neuronal damage that occurs during epileptogenesis; however, more detailed information remains unknown, especially under hypo- and hyperglycemic conditions. Here, we review several pathways of glucose metabolism activated during and after SE, as well as the effects of hypo- and hyperglycemia in the generation of self-sustained limbic seizures. Furthermore, this study suggests the control of glucose availability as a potential therapeutic tool for SE.

Evidence of Progenitor Cell Lineage Rerouting in the Adult Mouse Hippocampus After Status Epilepticus

Cell lineage in the adult hippocampus comprises multipotent and neuron-committed progenitors. In the present work, we fate-mapped neuronal progenitors using Dcx-CreERT2 and CAG-CAT-EGFP double-transgenic mice (cDCX/EGFP). We show that 3 days after tamoxifen-mediated recombination in cDCX/EGFP adult mice, GFP+ cells in the dentate gyrus (DG) co-expresses DCX and about 6% of these cells are proliferative neuronal progenitors. After 30 days, 20% of GFP+ generated from these progenitors differentiate into GFAP+ astrocytes. Unilateral intrahippocampal administration of the chemoconvulsants kainic acid (KA) or pilocarpine (PL) triggered epileptiform discharges and led to a significant increase in the number of GFP+ cells in both ipsi and contralateral DG. However, while PL favored the differentiation of neurons in both ipsi- and contralateral sides, KA stimulated neurogenesis only in the contralateral side. In the ipsilateral side, KA injection led to an unexpected increase of astrogliogenesis in the Dcx-lineage. We also observed a small number of GFP+/GFAP+ cells displaying radial-glia morphology ipsilaterally 3 days after KA administration, suggesting that some Dcx-progenitors could regress to a multipotent stage. The boosted neurogenesis and astrogliogenesis observed in the Dcx-lineage following chemoconvulsants administration correlated, respectively, with preservation or degeneration of the parvalbuminergic plexus in the DG. Increased inflammatory response, by contrast, was observed both in the DG showing increased neurogenesis or astrogliogenesis. Altogether, our data support the view that cell lineage progression in the adult hippocampus is not unidirectional and could be modulated by local network activity and GABA-mediated signaling.

Pharmacological Augmentation in Unipolar Depression: A Guide to the Guidelines

BACKGROUND

Pharmacological augmentation is a recommended strategy for patients with treatment-resistant depression. A range of guidelines provide advice on treatment selection, prescription, monitoring and discontinuation, but variation in the content and quality of guidelines may limit the provision of objective, evidence-based care. This is of importance given the side effect burden and poorer long-term outcomes associated with polypharmacy and treatment-resistant depression. This review provides a definitive overview of pharmacological augmentation recommendations by assessing the quality of guidelines for depression and comparing the recommendations made.

METHODS

A systematic literature search identified current treatment guidelines for depression published in English. Guidelines were quality assessed using the Appraisal of Guidelines for Research and Evaluation II tool. Data relating to the prescription of pharmacological augmenters were extracted from those developed with sufficient rigor, and the included recommendations compared.

RESULTS

Total of 1696 records were identified, 19 guidelines were assessed for quality, and 10 were included. Guidelines differed in their quality, the stage at which augmentation was recommended, the agents included, and the evidence base cited. Lithium and atypical antipsychotics were recommended by all 10, though the specific advice was not consistent. Of the 15 augmenters identified, no others were universally recommended.

CONCLUSIONS

This review provides a comprehensive overview of current pharmacological augmentation recommendations for major depression and will support clinicians in selecting appropriate treatment guidance. Although some variation can be accounted for by date of guideline publication, and limited evidence from clinical trials, there is a clear need for greater consistency across guidelines to ensure patients receive consistent evidence-based care.

Treatment-related transient splenial lesion of the Corpus Callosum in patients with neuropsychiatric disorders: a literature overview with a case report

Introduction: Transient-localized lesions of the splenium of the corpus callosum (SCC) have been described in various clinical conditions, some of them being attributed to the withdrawal of psychotropic drugs. The pathophysiology of the lesion reflects cytotoxic edema and reversible demyelination.Areas covered: The present article aimed at reviewing cases of transient SCC lesion exclusively related to changes in pharmacotherapy. It also reports the original case of a patient receiving a complex psychopharmacological therapy who developed a transient SCC lesion investigated by magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and pharmacogenetic profiling.Expert opinion: To date, only one review on the subject has been published, analyzing 22 cases of transient SCC lesion arising in epileptic patients on antiepileptic therapy. It hypothesized that the nature of the lesion is a cytotoxic edema and the cases described in the subsequent 14 years seem to support this hypothesis. The authors reported the case of an Italian-Egyptian patient who developed a transient SCC lesion after the rapid withdrawal of Carbamazepine and Lurasidone. The lesion completely disappeared from the MRI performed after 1 month. Patient's ethnic group and its pharmacogenetic profile were considered as possible causes of altered drug metabolism and, likely, of the SCC lesion.

The unmasking of hidden severe hyponatremia after long-term combination therapy in exacerbated bipolar patients: a case series

Hyponatremia is occasionally unmasked in psychiatric patients during hospitalization after routine blood and urinary tests, and correlates in most cases with an inappropriate secretion of antidiuretic hormone, mainly due to iatrogenic factors. Only a few studies have regarded the combination of psychotropic drugs as triggers of chronic, asymptomatic hyponatremia in bipolar patients, who require to be hospitalized because of the exacerbation of their mental illness. We presented three clinical cases of patients affected by a long-term psychiatric disorder and under polypharmacotherapy for several months. After excluding other potential factors, we hypothesized that pharmacological treatment with a mood stabilizer (oxcarbazepine) associated with a benzodiazepine (delorazepam), a second-generation antipsychotic (olanzapine) or an antidepressant (fluvoxamine), triggered severe hyponatremia ([Na+] ≤125 mEq/L), serum hypo-osmolarity, and elevated inappropriate urine osmolarity added to more diluted sodium concentration. When we discontinued the treatment, clinical conditions of our patients improved, despite the previous administration of hypertonic saline jointly with water restriction. Psychiatrists should consider that bipolar patients on long-term polypharmacotherapy may present a higher risk of severe hyponatremia not clinically detectable. Consequently, routine laboratory tests should be periodically repeated as they represent the only available tool to unmask such electrolyte imbalances.

Drug interactions in maternal intensive care: prevalence, risk factors, and potential risk medications

Objective:

To characterize severe potential drug interactions in maternal intensive care, and to determine their frequency, risk factors and potential risk medications.

Methods:

An observational and longitudinal study conducted between December 2014 and December 2015 in a maternal intensive care unit. Clinical data were collected and severe potential drug interactions were identified on pregnant inpatients. The drug interactions were classified by type, prevalence and exposure rate. A multivariate logistic regression model was used to identify the severe potential drug interactions and the related drugs (p<0.05).

Results:

A total of 95.1% of patients were exposed to, at least, one potential drug interaction; in that, 91.7% 33.9% were related to, respectively, moderate and severe potential drug interactions. The patients were exposed, on average, on 69.2% of days they were in the intensive care unit. The main drugs involved in more severe drug interactions were magnesium sulfate, metoclopramide, propranolol and diazepam.

Conclusion:

The severe potential drug interactions were observed in almost all patients of the study, and, approximately one third of those interactions were related to greater severity and resulted in exposure during long hospital stay. The higher number of prescribed drugs and its previous use of medications at home increase the occurrence of severe potential drug interactions.

Antiepileptic Drugs and Accumulation of Hospital Days Among Persons With Alzheimer's Disease

OBJECTIVES

To compare the accumulation of hospital days between initiators and noninitiators of antiepileptic drugs (AEDs) among persons with Alzheimer's disease (AD).

DESIGN

Exposure-matched cohort study.

SETTING AND PARTICIPANTS

Persons newly diagnosed with AD in 2005-2011 (n = 70,718) and initiating AED use identified from Finnish health care registers. For each AED initiator, 1 noninitiator matched on age, sex, and time since AD diagnosis was selected. Persons with epilepsy were excluded from the study.

METHODS

Association between AED initiation or use of individual AEDs and accumulation of hospital days during a 2-year follow-up was assessed using negative binomial model.

RESULTS

AED initiators (n = 4432) were hospitalized on average for 43.7 (SD: 88.3) days and matched noninitiators for 32.2 (SD: 71.3) days during the 2-year follow-up. Altogether, 27.3% of the AED initiators and 35.6% of the noninitiators had no hospital days during the study period. Number of accumulated hospital days during the follow-up was 31% higher [adjusted incidence rate ratio (aIRR): 1.31, 95% confidence interval (CI): 1.19-1.43] among AED initiators than the noninitiators. Hospital days due to diseases of the nervous system excluding dementia (aIRR: 2.72, 95% CI: 1.72-4.31), musculoskeletal system (aIRR: 2.49, 95% CI: 1.73-3.58), respiratory system (aIRR: 1.89, 95% CI: 1.47-2.43), and mental and behavioral disorders excluding dementia (aIRR: 1.96, 95% CI: 1.02-3.79) were more common among the AED initiators than noninitiators. Among pregabalin (aIRR: 0.65, 95% CI: 0.56-0.77), gabapentin (aIRR: 0.66, 95% CI: 0.49-0.88), and clonazepam (aIRR: 0.73, 95% CI: 0.55-0.96) initiators, the number of accumulated hospital days was 27% to 35% lower than the days accumulated among the initiators of valproic acid.

CONCLUSIONS AND IMPLICATIONS

AED initiators had more hospital days than noninitiators. Pregabalin and gabapentin were associated with a lower number of hospital days than valproic acid. Further research is needed on the reasons for these findings.

Psychotropic use and risk of stroke among patients with bipolar disorders: 10-year nationwide population based study

OBJECTIVES

To investigate the association between psychotropic agents (including antipsychotics, antidepressants and mood stabilizers) and risk of stroke among patients with bipolar disorders.

METHODS

We conducted a disease risk score-matched nested case-control study and identified patients with bipolar disorders (ICD-9 codes: 296.0x, 296.1x, 296.4x, 296.5x, 296.6x, 296.7x, 296.80, 296.81 or 296.89) from the National Health Insurance Research Database in Taiwan. Among them, we identified 1232 cases (981 were ischemic stroke and 251 were hemorrhagic stroke) and 5314 disease risk score-matched controls. Conditional logistic regression model equations were applied to determine the effect of psychotropic agents on stroke risk among patients with bipolar disorders.

RESULTS

The results indicated that overall use of psychotropic agents was associated with an increased risk of stroke (adjusted odds ratio [AOR] = 1.82; 95% confidence interval [CI]: 1.56-2.13). When classifying psychotropic agents into antipsychotics, antidepressants and mood stabilizers, respectively, a significant positive association was found for users of antipsychotics (AOR = 1.98; 95% CI = 1.53-2.56), antidepressants (AOR = 1.44; 95% CI = 1.16-1.79), and mood stabilizers (AOR = 1.89; 95% CI = 1.22-2.93). Combined use of psychotropic agents was associated with higher risk of stroke than monotherapy (AOR = 2.62; 95% CI = 1.98-3.45).

DISCUSSIONS

The results support our hypothesis that psychotropic use is associated with increased risk of stroke among patients with bipolar disorders. The stroke risks are higher among patients with polypharmacy than those with monotherapy. These findings warrant further investigation to confirm and replicate the findings using different methodologies and populations, and to mitigate residual confounding.

Diagnosing and treating depression in epilepsy

At least one third of patients with active epilepsy suffer from significant impairment of their emotional well-being. A targeted examination for possible depression (irrespective of any social, financial or personal burdens) can identify patients who may benefit from medical attention and therapeutic support. Reliable screening instruments such as the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) are suitable for the timely identification of patients needing help. Neurologists should be capable of managing mild to moderate comorbid depression but referral to mental health specialists is mandatory in severe and difficult-to-treat depression, or if the patient is acutely suicidal. In terms of the therapeutic approach, it is essential first to optimize seizure control and minimize unwanted antiepileptic drug-related side effects. Psychotherapy for depression in epilepsy (including online self-treatment programs) is underutilized although it has proven effective in ten well-controlled trials. In contrast, the effectiveness of antidepressant drugs for depression in epilepsy is unknown. However, if modern antidepressants are used (e.g. SSRI, SNRI, NaSSA), concerns about an aggravation of seizures and or problematic interactions with antiepileptic drugs seem unwarranted. Epilepsy-related stress ("burden of epilepsy") explains depression in many patients but acute and temporary seizure-related states of depression or suicidality have also been reported. Limbic encephalitits may cause isolated mood alteration without any recognizable psychoetiological background indicating a possible role of neuroinflammation. This review will argue that, overall, a bio-psycho-social model best captures the currently available evidence relating to the etiology and treatment of depression as a comorbidity of epilepsy.

Pharmacokinetic/pharmacodynamic considerations for epilepsy - depression comorbidities

INTRODUCTION

Epilepsy may be frequently associated with psychiatric disorders and its co-existence with depression usually results in the reduced quality of life of patients with epilepsy. Also, the efficacy of antiepileptic treatment in depressed patients with epilepsy may be significantly reduced.

AREAS COVERED

Results of experimental studies indicate that antidepressants co-administered with antiepileptic drugs may either increase their anticonvulsant activity, remain neutral or decrease the protective action of antiepileptic drugs in models of seizures. Apart from purely pharmacodynamic interactions, pharmacokinetic mechanisms have been proven to contribute to the final outcome. We report on clinical data regarding the pharmacokinetic interactions of enzyme-inducing antiepileptic drugs with various antidepressants, whose plasma concentration may be significantly reduced. On the other hand, antidepressants (especially selective serotonin reuptake inhibitors) may influence the metabolism of antiepileptics, in many cases resulting in the elevation of plasma concentration of antiepileptic drugs.

EXPERT OPINION

The preclinical data may provide valuable clues on how to combine these two groups of drugs - antidepressant drugs neutral or potentiating the anticonvulsant action of antiepileptics are recommended in this regard. Avoidance of antidepressants clearly decreasing the convulsive threshold or decreasing the anticonvulsant efficacy of antiepileptic drugs (f.e. bupropion or mianserin) in patients with epilepsy is recommended.

Conscious Intravenous Sedation in Dentistry: A Review of Current Therapy

Several sedation options are used to minimize pain, anxiety, and discomfort during oral surgery procedures. Minimizing or eliminating pain and anxiety for dental care is the primary goal for conscious sedation. Intravenous conscious sedation is a drug-induced depression of consciousness during which patients respond purposefully to verbal commands. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate as well as cardiovascular function. Patients must retain their protective airway reflexes, and respond to and understand verbal communication. The drugs and techniques used must therefore carry a broad margin of safety.

Effect of carbamazepine or phenytoin therapy on blood level of intravenously administered midazolam: a prospective cohort study

Dental treatment of intellectually disabled patients is frequently performed under general anesthesia or sedation. Many of these patients have epilepsy and are medicated with antiepileptic drugs (AEDs). Carbamazepine (CBZ) and phenytoin (PHT) are known to promote the metabolism of midazolam, and the blood levels of midazolam in patients medicated with CBZ or PHT may be different from those in healthy individuals. In this study, we clarified the influences of CBZ and PHT on the blood level of intravenously administered midazolam in patients medicated with CBZ or PHT. The subjects were divided into the following groups: not medicated with AEDs (control group), medicated with only CBZ or PHT (mono CBZ/PHT group), and medicated with CBZ or PHT or both and other AEDs (poly CBZ/PHT group). General anesthesia was achieved using midazolam, propofol, and remifentanil, and then the blood midazolam level was measured at 10, 30, and 60 min after intravenous midazolam administration. According to the results, the blood midazolam level was significantly lower in the mono and poly CBZ/PHT groups than in the control group. This finding suggests that intravenously administered midazolam may have a weaker effect in patients medicated with CBZ or PHT.

Key issues in addressing the comorbidity of depression and pediatric epilepsy

Depression is a common comorbidity associated with epilepsy. However, the etiology of depression is difficult to establish given the heterogeneity in both epilepsy and depression. Nevertheless, the co-occurrence is so common that a bidirectional relationship between depression and epilepsy has been theorized. Persons with temporal lobe seizure foci and partial-onset epilepsy may be more vulnerable to the development of depression. In pediatrics, depression differs but may be readily identified by understanding nuances of mood states and variability of neurovegetative symptom presentation. Although no clear treatment guidance exists in the context of epilepsy, antidepressants have been relatively well studied in pediatrics and are effective and well tolerated. Anticonvulsant drugs may also improve depressive symptoms though clinical research is lacking in pediatrics. Treatment of depression may independently improve outcome for epilepsy and for quality of life. Future studies will clarify etiologies of depression in the context of epilepsy and improve the evidence base for treatment outcomes.

The effects of antiepileptic inducers in neuropsychopharmacology, a neglected issue. Part I: A summary of the current state for clinicians

The literature on inducers in epilepsy and bipolar disorder is seriously contaminated by false negative findings. This is part i of a comprehensive review on antiepileptic drug (AED) inducers using both mechanistic pharmacological and evidence-based medicine to provide practical recommendations to neurologists and psychiatrists concerning how to control for them. Carbamazepine, phenobarbital and phenytoin, are clinically relevant AED inducers; correction factors were calculated for studied induced drugs. These correction factors are rough simplifications for orienting clinicians, since there is great variability in the population regarding inductive effects. As new information is published, the correction factors may need to be modified. Some of the correction factors are so high that the drugs (e.g., bupropion, quetiapine or lurasidone) should not co-prescribed with potent inducers. Clobazam, eslicarbazepine, felbamate, lamotrigine, oxcarbazepine, rufinamide, topiramate, vigabatrin and valproic acid are grouped as mild inducers which may (i)be inducers only in high doses; (ii)frequently combine with inhibitory properties; and (iii)take months to reach maximum effects or de-induction, definitively longer than the potent inducers. Potent inducers, definitively, and mild inducers, possibly, have relevant effects in the endogenous metabolism of (i)sexual hormones, (ii) vitamin D, (iii)thyroid hormones, (iv)lipid metabolism, and (v)folic acid.

Pharmacokinetic and pharmacodynamic interactions between antiepileptics and antidepressants

INTRODUCTION

Antiepileptic-antidepressant combinations are frequently used by clinicians; their pharmacokinetic (PK) and pharmacodynamic (PD) drug interactions (DIs) have not been well studied but are frequently likely to be clinically relevant.

AREAS COVERED

This article provides a comprehensive review of PK DIs between antiepileptics and antidepressants. In the absence of PD DI studies, PD information on pharmacological mechanisms and studies on efficacy and safety of individual drugs are reviewed.

EXPERT OPINION

The clinical relevance of the inductive properties of carbamazepine, phenytoin, phenobarbital and primidone and the inhibitory properties of valproic acid and some antidepressants are well understood; correction factors are provided if appropriate DI studies have been completed. More PK studies are needed for: i) antiepileptics with potent inductive effects for all recently approved antidepressants; ii) high doses of mild CYP3A4 inducers, such as clobazam, eslicarbazepine, oxcarbazepine, rufinamide and topiramate for reboxetine and vilazodone; iii) valproate as a possible inhibitor, mild inducer or both a mild inducer and competitive inhibitor of some antidepressants; and iv) inhibitory effects of long-term fluoxetine use on clobazam, lacosamide, phenobarbital, primidone, carbamazepine, felbamate, tiagabine and zonisamide. Possible synergistic or additive beneficial PD DIs in generalized anxiety disorder, chronic pain, migraine prophylaxis, weight control and menopausal symptoms need study.

Interaction of valproic acid and the antidepressant drugs doxepin and venlafaxine: analysis of therapeutic drug monitoring data under naturalistic conditions

Valproic acid and the antidepressants doxepin and venlafaxine are frequently used psychotropic drugs. In the literature, an influence of valproic acid on serum levels of antidepressants has been described, although studies have focused on amitriptyline. The authors assessed their therapeutic drug monitoring (TDM) database for patients receiving a combination of doxepin or venlafaxine and valproic acid and compared these samples with matched controls without valproic acid comedication in terms of the serum concentration of antidepressants. The mean dose-corrected serum concentration of doxepin+N-doxepin in 16 patients who received valproic acid comedication was higher (2.171±1.482 ng/ml/mg) than that in the matched controls (0.971±0.857 ng/ml/mg, P<0.003). We also found a significant correlation between valproic acid serum level and dose-corrected doxepin+N-doxepin serum level (Spearman's ρ r=0.602, P<0.014). The mean dose-corrected serum level of venlafaxine+O-desmethylvenlafaxine in 41 patients who received valproic acid comedication did not differ significantly from that of the matched controls (P<0.089), but there was a significant difference between both groups in the dose-corrected serum level of O-desmethylvenlafaxine (1.403±0.665 vs. 1.102±0.444, P<0.017). As a consequence, if a combination of valproic acid with doxepin or venlafaxine is administered, cautious dosing is advisable and TDM should be performed.

Intravenous bupropion: a previously undocumented method of abuse of a commonly prescribed antidepressant agent

Bupropion is an antidepressant commonly prescribed as a smoking cessation aid. It has effects on dopamine and norepinephrine, and can lower seizure threshold, particularly in overdose. Several cases of recreational use of bupropion via nasal insufflation have been reported in the literature. Here we describe a first case of intravenous bupropion dependence, with no evidence of resulting seizure activity. This addiction was sustained in part under the the premise of seeking smoking cessation aid. Pharmacokinetic interactions are explored, and the literature with respect to buproprion abuse is reviewed. We propose that bupropion may have stimulant effects amenable to abuse that vary with route of administration. Health care providers may wish to exercise additional caution when prescribing bupropion to unfamiliar patients.

Interaction of valproic acid and amitriptyline: analysis of therapeutic drug monitoring data under naturalistic conditions

Amitriptyline (AMI) and valproic acid (VPA) are common psychotropic drugs which are frequently used in psychiatry and also administered in neurology or anesthesia in the absence of a psychiatric indication. On the basis of the case of a 73-year-old man with therapy-resistant major depressive episode who experienced anticholinergic delirium after adding VPA to AMI, we retrospectively analyzed therapeutic drug monitoring data of the years 2008 to 2010. We assessed cases receiving a combination of AMI and VPA, and obtained a control sample of AMI patients without VPA which were matched for sex, age, daily dose, and comedication. Both samples were compared regarding the serum levels of AMI and nortriptyline (NOR) as well as the ratio of NOR and AMI with the Mann-Whitney U test. The combination of AMI and VPA led to a remarkable increase of AMI and NOR serum levels. When comparing 33 patients who received comedication with VPA versus 33 matched controls, the total concentration by combining mean AMI and NOR serum levels (237.1 [119.9] vs 126.4 [52.8] ng/mL) and NOR/AMI ratio (1.300 [0.905] vs 0.865 [0.455]) was significantly higher. Both AMI and VPA are widely prescribed drugs. A combination of both is common for psychiatric or neurologic patients. A cautious dosing of AMI with VPA comedication is advisable, and therapeutic drug monitoring should be performed because this combination may lead to a remarkable increase of AMI and NOR serum levels.

The treatment of depressive disorders in epilepsy: what all neurologists should know

One of every three patients with epilepsy (PWE) will experience a depressive disorder in the course of their life, often associated with anxiety symptoms or a full blown anxiety disorder. Clearly, the high prevalence of these psychiatric comorbidities calls for their early identification and management. This article provides practical strategies in the management of depressive episodes in PWE. Contrary to long-held beliefs, the use of antidepressant drugs are safe in PWE when used at therapeutic doses. Antidepressant drugs of the selective serotonin reuptake inhibitor (SSRI) or serotonin-norepinephrine reuptake inhibitor (SNRI) families are the first line of therapy in depressive disorders, and failure to achieve complete symptom remission after a trial of an SSRI or SNRI at optimal doses should be followed by a second trial with a drug from the other antidepressant family. In developing countries, antidepressant drugs of these two antidepressant families are not always available, and tricyclic antidepressants (TCAs) are the drugs of choice. Although there are no differences in efficacy among the three families of antidepressants, TCAs have a lower tolerability and higher toxicity, with greater mortality risk associated with cardiotoxic effects in overdoses. Cognitive behavior therapy is another treatment modality that has been shown to be effective in the treatment of depressive disorders in patients with and without epilepsy. Its use should be considered together with pharmacotherapy or by itself.

Why and How the Old Neuroleptic Thioridazine Cures the XDR-TB Patient

This mini-review provides the entire experimental history of the development of the old neuroleptic thioridazine (TZ) for therapy of antibiotic resistant pulmonary tuberculosis infections. TZ is effective when used in combination with antibiotics to which the initial Mycobacterium tuberculosis was resistant. Under proper cardiac evaluation procedures, the use of TZ is safe and does not produce known cardiopathy such as prolongation of QT interval. Because TZ is cheap, it should be considered for therapy of XDR and TDR-Mtb patients in economically disadvantaged countries.

Brain tumor-related epilepsy

In patients with brain tumor (BT), seizures are the onset symptom in 20-40% of patients, while a further 20-45% of patients will present them during the course of the disease. These patients present a complex therapeutic profile and require a unique and multidisciplinary approach. The choice of antiepileptic drugs is challenging for this particular patient population because brain tumor-related epilepsy (BTRE) is often drug-resistant, has a strong impact on the quality of life and weighs heavily on public health expenditures.In BT patients, the presence of epilepsy is considered the most important risk factor for long-term disability. For this reason, the problem of the proper administration of medications and their potential side effects is of great importance, because good seizure control can significantly improve the patient's psychological and relational sphere. In these patients, new generation drugs such as gabapentin, lacosamide, levetiracetam, oxcarbazepine, pregabalin, topiramate, zonisamide are preferred because they have fewer drug interactions and cause fewer side effects. Among the recently marketed drugs, lacosamide has demonstrated promising results and should be considered a possible treatment option. Therefore, it is necessary to develop a customized treatment plan for each individual patient with BTRE. This requires a vision of patient management concerned not only with medical therapies (pharmacological, surgical, radiological, etc.) but also with emotional and psychological support for the individual as well as his or her family throughout all stages of the illness.

Clinically relevant drug interactions in anxiety disorders

OBJECTIVE

Certain drugs used in the treatment of patients with anxiety disorders can interact with other psychotropic drugs and with pharmacological treatments for physical illnesses. There is a need for an updated comparative review of clinically relevant drug interactions in this area.

DESIGN

Relevant literature on drug interactions with medications used in the treatment of anxiety disorders was identified through a search in MEDLINE and EMBASE.

RESULTS

Drug interactions involving medications used to treat anxiety disorders may be pharmacokinetic, such as enzyme inhibition or induction in the cytochrome P450 system and transporter-mediated drug interactions, or pharmacodynamic, such as additive effects in causing drowsiness or additive effects at neurotransmitter receptors. Certain selective serotonin reuptake inhibitors (fluoxetine, fluvoxamine, and paroxetine) are particularly liable to be potentially involved in untoward pharmacokinetic interactions.

CONCLUSIONS

The potential for drug interactions with medications used in anxiety disorders should be the cause of clinical concern, particularly in elderly individuals. However, the liability for harmful drug interactions may be anticipated, and the risk reduced. Although not all interactions are clinically relevant, careful monitoring of clinical response and possible interactions is essential.

Effect of valproate on olanzapine plasma concentrations in patients with bipolar or schizoaffective disorder

The effect of valproate on the steady-state plasma concentrations of olanzapine was investigated in 18 patients with bipolar or schizoaffective disorder. Additional valproate, at a dose ranging from 600 to 2000 mg/d, was administered for 4 weeks to patients stabilized on olanzapine (5-20 mg/d). During valproate coadministration, mean plasma olanzapine concentrations decreased significantly from 32.9 +/- 9.7 ng/mL at baseline to 27.4 +/- 9.8 ng/mL at week 2 (P = 0.02), and to 26.9 +/- 9.2 ng/mL at week 4 (P = 0.001). Smoking also decreased plasma olanzapine concentrations. Valproate coadministration with olanzapine was well tolerated and no patient showed a worsening of his or her psychopathological condition. These findings indicate that valproate, at doses of up to 2000 mg/d, is associated with a minimal, presumably not clinically significant, decrease in plasma olanzapine concentrations, possibly as a result of induction of olanzapine metabolism. New studies are needed to confirm that valproate could have mild inductive effects.

Protease inhibitor levels in hair strongly predict virologic response to treatment

OBJECTIVE

Antiretroviral (ARV) therapies fail when behavioral or biologic factors lead to inadequate medication exposure. The currently available methods to assess ARV exposure are limited. Levels of ARVs in hair reflect plasma concentrations over weeks to months, and may provide a novel method for predicting therapeutic responses.

DESIGN/METHODS

The Women's Interagency HIV Study, a prospective cohort of HIV-infected women, provided the basis for developing and assessing methods to measure commonly prescribed protease inhibitors (lopinavir/ritonavir and atazanavir) in small hair samples. We examined the association between hair protease inhibitor levels and initial virologic responses to therapy in multivariate logistic regression models.

RESULTS

ARV concentrations in hair were strongly and independently associated with treatment response for 224 women starting a new protease inhibitor-based regimen. For participants initiating lopinavir/ritonavir, the odds ratio (OR) for virologic suppression was 39.8 [95% confidence interval (CI) = 2.8-564] for those with lopinavir hair levels in the top tertile (>1.9 ng/mg) compared to the bottom (3.4 ng/mg) compared to the lowest (

CONCLUSION

Protease inhibitor levels in small hair samples were the strongest independent predictor of virologic success in a diverse group of HIV-infected adults. This non-invasive method for determining ARV exposure may have particular relevance for the epidemic in resource-poor settings due to the ease of collecting and storing hair.

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Key Words

• hair levels
• therapeutic drug monitoring
• antiretroviral exposure
• virologic response
• protease inhibitors
• atazanavir
• lopinavir
• wihs cohort

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MESH Headings

• Adult
• Atazanavir Sulfate
• CD4 Lymphocyte Count
• Drug Monitoring/methods
• Epidemiologic Methods
• Female
• HIV Infections/drug therapy
• HIV Infections/metabolism
• HIV Infections/virology
• HIV Protease Inhibitors/pharmacokinetics
• HIV Protease Inhibitors/therapeutic use
• Hair/metabolism
• Humans
• Lopinavir
• Middle Aged
• Oligopeptides/pharmacokinetics
• Oligopeptides/therapeutic use
• Patient Compliance
• Pyridines/pharmacokinetics
• Pyridines/therapeutic use
• Pyrimidinones/pharmacokinetics
• Pyrimidinones/therapeutic use
• Ritonavir/pharmacokinetics
• Ritonavir/therapeutic use
• Specimen Handling/methods
• Treatment Outcome
• Viral Load

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Grants

• M01 RR000079 NCRR NIH HHS
• UO1-AI-34994 NIAID NIH HHS
• UO1-AI-34989 NIAID NIH HHS
• U01 AI035004 NIAID NIH HHS
• K23 AI067065 NIAID NIH HHS
• UO1-CH-32632 OID CDC HHS
• U01 AI034989 NIAID NIH HHS
• M01 RR000071 NCRR NIH HHS
• UO1-AI-34993 NIAID NIH HHS
• U01 AI034994 NIAID NIH HHS
• K23 AI067065-03 NIAID NIH HHS
• UO1-AI-42590 NIAID NIH HHS
• U01 AI034993 NIAID NIH HHS
• K23 A1067065 PHS HHS
• MO1-RR-00083 NCRR NIH HHS
• U01 AI031834 NIAID NIH HHS
• UO1-AI-35004 NIAID NIH HHS
• K23 AI067065-02 NIAID NIH HHS
• U01 AI042590-12 NIAID NIH HHS
• MO1-RR-00079 NCRR NIH HHS
• UO1-AI-31834 NIAID NIH HHS
• M01 RR000083 NCRR NIH HHS
• MO1-RR-00071 NCRR NIH HHS
• U01 AI042590 NIAID NIH HHS

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Affiliation(s)

Monica Gandhi Department of Medicine, University of California, San Francisco, San Francisco, California, USA.
Niloufar Ameli
Peter Bacchetti
Stephen J Gange
Kathryn Anastos
Alexandra Levine
Charles L Hyman
Mardge Cohen
Mary Young
Yong Huang
Ruth M Greenblatt

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Moclobemide monotherapy vs. combined therapy with valproic acid or carbamazepine in depressive patients: a pharmacokinetic interaction study

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Moclobemide (MCB) undergoes extensive both presystemic and systemic metabolism that can be affected by concomitant drugs. Valproic acid (VPA) and carbamazepine (CBZ) have been found to interact with psychotropic medications of all classes and many other drugs; VPA acts as a broad-spectrum inhibitor, and CBZ as a potent inducer of a variety of drug-metabolizing enzymes. There have been no previous studies designed to investigate a potential pharmacokinetic (PK) interaction between MCB and VPA or CBZ; however, these agents are likely to be used concomitantly for the treatment of depressive disorders.

WHAT THIS STUDY ADDS

VPA does not significantly affect PK or metabolism of MCB at steady state. CBZ significantly decreases MCB exposure. This effect is time-dependent, being more pronounced after 3-5 weeks of co-administration.

AIM

To assess the impact of valproic acid (VPA) and carbamazepine (CBZ) on moclobemide (MCB) pharmacokinetics (PK) and metabolism at steady state in depressive patients.

METHODS

Twenty-one inpatients with recurrent endogenous depression received MCB (150 mg t.i.d.), either as monotherapy or in combination with VPA (500 mg b.i.d.) or CBZ (200 mg b.i.d.) in a nonrandomized manner. Steady-state plasma PK parameters of MCB and its two metabolites, Ro 12-8095 and Ro 12-5637, were derived. Clinical assessments of treatment efficacy were performed weekly using standard depression rating scales.

RESULTS

CBZ, but not VPA, was associated with decreases in the MCB AUC by 35% [from 7.794 to 5.038 mg h l(-1); 95% confidence interval (CI) -4.84863, -0.66194; P = 0.01] and C(max) by 28% (from 1.911 to 1.383 mg l(-1); 95% CI -0.98197, -0.07518; P < 0.05), and an increase in its oral clearance by 41% (from 0.323 to 0.454 l h(-1) kg(-1); 95% CI 0.00086, 0.26171; P < 0.05) after 4 weeks of co-administration. MCB through concentrations were also decreased, on average by 41% (from 0.950 to 0.559 mg l(-1); 95% CI -0.77479, -0.03301; P < 0.05). However, the efficacy in this group of patients was not inferior to the controls, for several possible reasons. Overall tolerability of all study medications was good.

CONCLUSIONS

VPA does not significantly affect PK or metabolism of MCB, whereas CBZ time-dependently decreases MCB exposure, probably by inducing metabolism of MCB and its major plasma metabolite. The actual clinical relevance of the observed MCB-CBZ PK interaction needs to be further evaluated in a more comprehensive study.

Pharmacodynamic and pharmacokinetic interactions of psychotropic drugs with antiepileptic drugs

Co-morbid psychiatric disorders are relatively frequent in patients with epilepsy. The prevalence rates of mood and anxiety disorders, psychotic disorders and attention deficit/hyperactivity disorder have been found to be significantly higher in patients with epilepsy than in the general population. While co-morbid psychiatric disorders have frequently been considered as complications of the seizure disorder, there is an increasing body of literature that points to a complex relationship between psychiatric and seizure disorders. Because of this, it is crucial that clinicians consider the presence of co-morbid psychiatric disorders when planning the treatment of patients with epilepsy. Having a clear understanding of the pharmacodynamic and pharmacokinetic interactions between antiepileptic drugs and psychotropic drugs is of the essence to avert unnecessary adverse events and loss of efficacy of psychotropic drugs. This chapter provides a practical review on the use of psychotropic drugs for the treatment of these psychiatric co-morbidities in patients with epilepsy.

Phenytoin intoxication in a clozapine-related prolonged seizure

Phenytoin is a first-line drug for the treatment of status epilepticus. We report a case of phenytoin intoxication after intravenous phenytoin loading in a patient with clozapine-related seizures. To our knowledge, this is the first description of phenytoin intoxication due to CYP2C9 inhibition by clozapine. This case report is important because it supports the use of a lower intravenous loading dose of phenytoin in patients with clozapine-related status epilepticus.

Efficacy, safety and early response of paliperidone extended-release tablets (paliperidone ER): results of a 6-week, randomized, placebo-controlled study

BACKGROUND

Paliperidone extended-release tablet (paliperidone ER) is an oral psychotropic agent developed for schizophrenia treatment. Paliperidone (9-OH-risperidone, metabolite of risperidone), when used with OROS technology has a unique pharmacokinetic profile undergoing limited hepatic metabolism.

METHODS

The efficacy and safety of once-daily paliperidone ER (3 mg, 9 mg and 15 mg) were compared with placebo in 618 patients with acute schizophrenia in a 6-week, multicenter, double-blind, randomized, parallel-group study. An assay sensitivity group with known efficacy was included to confirm trial validity (olanzapine 10 mg).

RESULTS

All doses of paliperidone ER demonstrated significant improvements in PANSS total and PANSS factors scores (p<0.05) and in personal and social functioning (p<0.001) compared with placebo. Symptom improvement has been observed at the first observation assessment (Day 4) (p<0.001) compared with placebo, suggesting a rapid onset of action for paliperidone ER. Paliperidone ER was associated with a low incidence of treatment-emergent adverse events. The incidence of movement disorder-related adverse events and rating scale scores were similar in the paliperidone ER 3 mg and placebo groups and increased with dose. Increases in prolactin plasma levels and dose-related increases in body weight (<2 kg) were observed; there were no significant changes in serum lipid or glucose levels.

CONCLUSION

In this study, all doses of paliperidone ER were effective in significantly improving the symptoms of schizophrenia and personal and social functioning and were generally well tolerated. As such, paliperidone ER may provide a valuable new treatment option for patients with schizophrenia.

The effect of adjunctive mood stabilizers on antipsychotic utilization pattern and health resource utilization for Medicaid enrollees with schizophrenia

BACKGROUND

Prescribing adjunctive mood stabilizers to manage schizophrenia is prevalent, despite the lack of substantial evidence to support the long-term use of this treatment regimen.

OBJECTIVE

The objective of this study was to assess the impact of using adjunctive mood stabilizers on antipsychotic utilization, total health expenditures, inpatient hospitalizations, long-term care stays, and emergency room (ER) visits for patients with schizophrenia.

METHODS

Georgia Medicaid claims from 1999 through 2001 were analyzed to identify recipients diagnosed with schizophrenia (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]: 295. XX). The treatment groups consisted of subjects who received combination therapy of mood stabilizers and antipsychotics (including both atypical and typical medications), while the comparison group consisted of subjects who were on antipsychotic medications without exposure to the mood stabilizers under investigation. Four treatment groups (valproate, lithium, carbamazepine, and combination mood stabilizer therapy) were formed based on the mood stabilizers patient received. Differences in annual health care use and expenditures were estimated between propensity score matched treatment and comparison groups controlling for comorbidity, prior utilization, demographic, and health provider specialty.

RESULTS

During the 1-year observation period, subjects in treatment groups filled an average of 200-days supply of adjunctive mood stabilizers. These adjunctive mood stabilizer recipients had significantly longer antipsychotic treatment durations than the subjects who did not have exposure to mood stabilizers (valproate + antipsychotic vs. antipsychotic only, net difference: 56.47 days, p < 0.0001; lithium + antipsychotic vs. antipsychotic only, net difference: 90.25 days, p < 0.0001; carbamazepine + antipsychotic vs. antipsychotic only, net difference: 41.27 days, p = 0.0439; multiple mood stabilizers + antipsychotic vs. antipsychotic only, net difference: 83.14 days, p < 0.0001). The intensive pharmacotherapy associated with treatment groups resulted in $900-$1300 higher pharmacy costs than the comparison groups (valproate + antipsychotic vs. antipsychotic only, net difference: $1218.43, p < 0.0001; lithium + antipsychotic vs. antipsychotic only, net difference: $985.79, p = 0.0015; carbamazepine + antipsychotic vs. antipsychotic only, net difference: $911.63, p = 0.0497; multiple mood stabilizers + antipsychotic vs. antipsychotic only, net difference: $1281.91, p < 0.0047). However, there were no statistically significant differences for total health expenditures, hospitalizations, emergency room visits, and nursing home admissions between propensity-matched treatment and control groups.

CONCLUSIONS

There were no differences in health care costs or utilization of ER, long-term care, and inpatient services between schizophrenia patients who did and did not receive adjunctive mood stabilizer; however, longer antipsychotic treatment durations were observed in patients receiving adjunctive mood stabilizers. Interpretation of these results is limited by the unknown selection bias between the treatment and the comparison groups and the relatively small number of patients in some treatment groups. The development of a better-controlled study to further evaluate this treatment regimen is warranted.

Metabolic drug interactions with newer antipsychotics: a comparative review

Newer antipsychotics introduced in clinical practice in recent years include clozapine, risperidone, olanzapine, quetiapine, sertindole, ziprasidone, aripiprazole and amisulpride. These agents are subject to drug-drug interactions with other psychotropic agents or with medications used in the treatment of concomitant physical illnesses. Most pharmacokinetic interactions with newer antipsychotics occur at the metabolic level and usually involve changes in the activity of the major drug-metabolizing enzymes involved in their biotransformation, i.e. the cytochrome P450 (CYP) monooxygenases and/or uridine diphosphate-glucuronosyltransferases (UGT). Clozapine is metabolized primarily by CYP1A2, with additional contribution by other CYP isoforms. Risperidone is metabolized primarily by CYP2D6 and, to a lesser extent, CYP3A4. Olanzapine undergoes both direct conjugation and CYP1A2-mediated oxidation. Quetiapine is metabolized by CYP3A4, while sertindole and aripiprazole are metabolized by CYP2D6 and CYP3A4. Ziprasidone pathways include aldehyde oxidase-mediated reduction and CYP3A4-mediated oxidation. Amisulpride is primarily excreted in the urine and undergoes relatively little metabolism. While novel antipsychotics are unlikely to interfere with the elimination of other drugs, co-administration of inhibitors or inducers of the major enzymes responsible for their metabolism may modify their plasma concentrations, leading to potentially significant effects. Most documented metabolic interactions involve antidepressant and anti-epileptic drugs. Of a particular clinical significance is the interaction between fluvoxamine, a potent CYP1A2 inhibitor, and clozapine. Differences in the interaction potential among the novel antipsychotics currently available may be predicted based on their metabolic pathways. The clinical relevance of these interactions should be interpreted in relation to the relative width of their therapeutic index. Avoidance of unnecessary polypharmacy, knowledge of the interaction profiles of individual agents, and careful individualization of dosage based on close evaluation of clinical response and, possibly, plasma drug concentrations are essential to prevent and minimize potentially adverse drug interactions in patients receiving newer antipsychotics.

Effect of Topiramate on Plasma Concentrations of Clozapine, Olanzapine, Risperidone, and Quetiapine in Patients With Psychotic Disorders

OBJECTIVES

To investigate the effect of topiramate on the steady-state plasma concentrations of the second-generation antipsychotics--clozapine, olanzapine, risperidone, and quetiapine--in patients with schizophrenia or bipolar disorder.

METHODS

Thirty-eight outpatients on long-term treatment with clozapine (250-500 mg/d, n = 10), olanzapine (10-20 mg/d, n = 12), risperidone (3-6 mg/d, n = 9), or quetiapine (200-600 mg/d, n = 7) received adjunctive topiramate, gradually titrated up to a final dosage of 200 mg/d for 6 weeks. Pharmacokinetic assessments were made at baseline and at the end of treatment weeks 4 and 8 at topiramate dosages of 100 and 200 mg/d, respectively.

RESULTS

Plasma concentrations of clozapine and its metabolite (norclozapine), olanzapine, risperidone and its metabolite (9-hydroxy-risperidone), and quetiapine were not significantly modified during concomitant administration of topiramate. Adjunctive topiramate therapy was well tolerated in all groups.

CONCLUSIONS

These findings indicate that topiramate, at the dosages recommended for use as a mood stabilizer, does not affect the plasma levels of the new antipsychotics-clozapine, olanzapine, risperidone, and quetiapine.

Currently available antiepileptic drugs

Many new antiepileptic drugs (AEDs) have become available over the past 15 years. At the same time, the emphasis on treating patients with epilepsy has grown from stopping seizures to avoiding side effects and maximizing quality of life. This review summarizes currently available AEDs, and presents general treatment principles and guidelines for AED selection. Unfortunately, despite the increased treatment options of today, seizure freedom without side effects remains unattainable for too many patients with epilepsy. Consequently, there remains a significant need for further development of new therapies.