Topiramate augmentation in treatment-resistant obsessive-compulsive disorder: a retrospective, open-label case series

Glutamatergic Synaptic Dysfunction and Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric condition estimated to afflict 1-3% of the world population. The estimated financial impact in the treatment and management of OCD is in the billions of dollars annually in the US alone. At present there is a marked lack of evidence on the specific causes of OCD. Current hypotheses largely focus on the serotonin (5-HT) system on the basis of the effectiveness of selective serotonin reuptake inhibitors (SSRIs) in alleviating symptoms of patients with OCD, yet a considerable fraction of patients are non-responsive or minimally responsive to these agents. Despite this fact, SSRIs have remained the primary pharmacological treatment avenue for OCD. In recent years, multiple lines of evidence have implicated glutamatergic synaptic dysfunction within the cortico-striatal-thalamo-cortical (CSTC) brain circuit in the etiology of OCD and related disorders, thereby prompting intensified effort in the development and evaluation of agents that modulate glutamatergic neurotransmission for the treatment of OCD. With this in mind, here we review the following topics with respect to synaptic dysfunction and the neural circuitry underlying OCD: (1) evidence supporting the critical involvement of the CSTC circuit, (2) genetic studies supporting the involvement of glutamatergic dysfunction, (3) insights from genetic animal models of OCD, and (4) preliminary findings with glutamatergic neurotransmission-modulating agents in the treatment of OCD. Given the putative mechanistic overlap between OCD and the broader OC-spectrum of disorders, unraveling the synaptic basis of OCD has potential to translate into more effective treatments for an array of poorly understood human disorders.

The role of anticonvulsant drugs in anxiety disorders: a critical review of the evidence

Antiepileptic drugs (AEDs) have been successfully used in the treatment of mood disturbances, leading clinicians and researchers to investigate their use in other psychiatric disorders. This article reviews the literature about the potential efficacy of AEDs in anxiety disorders. An updated MEDLINE search (January 1970 to September 2006) using the terms "panic disorder," "agoraphobia," "posttraumatic stress disorder," "obsessive-compulsive disorder," "generalized anxiety disorder," "social phobia," "phobia," "carbamazepine," "phenobarbital," "phenytoin," "valproate," "lamotrigine," "topiramate," "vigabatrin," "tiagabine," "gabapentin," "levetiracetam," and "pregabalin" showed more than 70 articles and 38 published studies. Only articles published in English were reviewed. We have assigned level 1 of evidence to meta-analysis and replicated randomized controlled trials, level 2 to at least 1 randomized controlled trial, level 3 to uncontrolled trials with 10 or more subjects, and level 4 to anecdotal case reports. The strongest evidence has been demonstrated for pregabalin in social phobia and generalized anxiety disorder, lamotrigine in posttraumatic stress disorder, and gabapentin in social anxiety. The available data about gabapentin in panic disorder are somewhat mixed, and more definitive conclusion would require additional studies. This review suggests that AEDs can be an alternative treatment in some anxiety disorders. Further investigation is needed to determine in what circumstances they should be used in individuals who are partially responsive or nonresponsive to conventional therapy.

An update on the pharmacological treatment of obsessive-compulsive disorder

The purpose of this article is to introduce the reader to an updated evidence-based drug treatment algorithm to be employed in patients with obsessive-compulsive disorder (OCD). Relevant studies were identified through a comprehensive review and classified according to the type of patients enrolled, the quality of the study design and the invasiveness, availability and complexity of the therapeutic approach. When ineffective, therapeutic trials with first-line strategies (such as the selective serotonin re-uptake inhibitors [SSRIs] and venlafaxine) should be followed by treatment approaches such as clomipramine, augmentation with antipsychotics or pindolol, SSRI megadoses or cognitive behavioral therapy. These therapeutic strategies are expected to help most patients with OCD. Additional approaches include intravenous clomipramine, oral morphine, 'heroic drug strategies', deep brain stimulation and functional neurosurgery. Independent studies are urgently needed to help identify the most promising drug treatment sequences for OCD.

The treatment of generalized anxiety disorder with pregabalin, an atypical anxiolytic

A constellation of pharmacologic treatments for generalized anxiety disorder (GAD) have been developed over the past five decades, although each has a number of potential drawbacks in clinical practice. This review addresses one potentially new pharmacologic treatment for generalized anxiety disorder, the gamma-aminobutyric acid analogue pregabalin. We review the mechanism of action, and pharmacokinetic and pharmacodynamic properties of pregabalin as well as the results of 5 double-blind, placebo-controlled trials of pregabalin in the treatment of generalized anxiety disorder (GAD). Based entirely on data from these industry-sponsored (Pfizer), multi-site clinical trials in patients with GAD, pregabalin appears to be generally well tolerated and has rapid onset of action (approximately 1 week), comparable efficacy to benzodiazepines and lower discontinuation rates compared with other pharmacologic treatments. Thus in GAD, a disorder that is often suboptimally responsive to traditional psychotherapeutic and psychopharmacologic interventions - secondary to poor efficacy, tolerability, and/or side-effects - pregabalin may have a primary role in GAD patients, especially in those with certain psychiatric comorbidities or individuals who are on multi-drug regimens for medical comorbidities.

Topiramate prescribing patterns among medicaid patients: Diagnosis, comorbidities, and dosing

BACKGROUND

Routine clinical practice data are useful for payers and formulary decision makers to make sound decisions regarding coverage policy. Based on a literature search, there has been scant research into topiramate prescribing patterns among Medicaid patients.

OBJECTIVE

The aim of this study was to describe diagnoses, demographic characteristics, additional co-existing diagnoses, and dosing among Medicaid patients prescribed topiramate.

METHODS

This descriptive, retrospective database analysis used data from South Carolina (SC) and Texas (TX) ambulatory Medicaid claims dated October 1, 2003, to December 31, 2004. Patients whose data were eligible for inclusion in the study were enrolled in Medicaid during the study period, had >or=2 topiramate prescriptions, were aged <65 years, and had evidence of a topiramate treatment-related diagnosis (possible diagnoses were identified through literature search and drug compendiums). Four cohorts were defined: (1) epilepsy only; (2) migraine only; (3) epilepsy and migraine; and (4) nonepilepsy/nonmigraine. Demographic characteristics, diagnoses, comorbidities, and daily dose of topiramate were summarized using descriptive statistics. The initial study analysis (period 1) was a 180-day window comprising the 90 days before and after the first available topiramate prescription claim was filed. A second, 360-day analysis (period 2) was completed comprising the 180 days before and after the index topiramate prescription date.

RESULTS

In the 180-day analysis, 2216 SC and 4766 TX Medicaid patients met the selection criteria. Cohort classification percentages were 32.3% and 39.6% (epilepsy only), 29.7% and 16.4% (migraine only), 10.7% and 9.2% (epilepsy and migraine), and 27.3% and 34.9% (nonepilepsy/nonmigraine) for SC and TX, respectively. Mean (SD) ages were 29.9 (15.9) (SC) and 27.1 (16.1) (TX) years. In the nonepilepsy/nonmigraine cohort, the most common diagnoses were bipolar disorder and depression. The median daily doses in the epilepsy-only cohort were 175 mg/d in the SC group and 200 mg/d in the TX group. In the migraine-only cohort, the median daily dose was 100 mg/d in SC and TX. Results for the 360-day analysis were similar.

CONCLUSIONS

In this descriptive study using data from 2 Medicaid populations, the majority of patients using topiramate had a diagnosis of epilepsy and/or migraine. Median dosages ranged from 175 to 200 mg/d in patients with epilepsy and 100 mg/d in those with migraine. Depression was a common comorbidity in the migraine cohort and the nonepilepsy/nonmigraine cohort.