Pregabalin for the treatment of generalized anxiety disorder: a novel pharmacologic intervention

Toxicological Relevance of Pregabalin in Heroin Users: A Two-Year Post-Mortem Population Study

Pregabalin (PGL) is a gabapentinoid used to treat epilepsy, neuropathic pain and generalized anxiety disorder. PGL is also misused by heroin users as it enhances the effects of heroin. While it is thought those who misuse PGL take it in amounts greater than the recommended therapeutic dose, it is unknown whether there is a significant difference between the amounts of PGL used by heroin users compared to non-heroin users. This study hypothesised that the PGL concentrations in post-mortem samples taken from heroin users positive for PGL would be higher than those in non-heroin users. Between 01.01.2016 and 31.12.2017, a routine drugs screen and a specific screen for PGL was carried out on femoral-vein bloods from 3,750 post-mortem Coroners' cases. Of the cases screened, 354 were heroin users, of which 264 cases were negative for gabapentinoids and therefore used as the control-heroin users group. PGL was positive in 229 cases, of which 69 were heroin users and 160 were non-heroin users. On comparing the PGL concentrations, statistically higher concentrations were observed in the heroin users compared to non-heroin users (P = 0.002). There was no correlation between the concentrations of PGL and morphine (from heroin) in the heroin users (P = 0.95), and the amount of heroin (morphine) consumed was not dependant on whether PGL was consumed or not (P = 0.98). The prevalence of anti-depressants, benzodiazepines, methadone and non-heroin related opioids were seen to be significantly higher in heroin users that were positive for PGL than the control-heroin users (P = < 0.001 for all drugs). This study suggests that heroin users are using greater amounts of PGL compared to non-heroin users; however, the magnitude of the difference in use may not be sufficient to conclude that heroin users are at substantially greater risk of pregabalin toxicity compared to non-heroin users. Results indicate that heroin users who take PGL are more likely to use multiple depressant drugs, hence increasing the risk of multi-drug toxicity and death in this population.

Management of treatment-resistant generalized anxiety disorder

Generalized anxiety disorder (GAD) is characterized by persistent and excessive worry. Around half of the patients treated for GAD will fail to respond to initial treatment. Treatment-resistant (or refractory) GAD is defined as failure to respond to at least 1 trial of antidepressant therapy at adequate dose and duration. Review of the literature indicates several potential medication classes and individual agents that can be used as augmentation strategies to treat residual symptoms when recommended therapy per clinical practice guidelines fails. A thorough literature search revealed 2 medication classes with the largest amount of data to support their use in treatment-resistant GAD treatment: gamma-aminobutyric acid–related agents and atypical antipsychotics. This article focuses on evidence-based recommendations for the use of these agents as adjunctive therapies for patients with treatment-resistant GAD. Different pharmacologic approaches to use these agents are demonstrated through 2 patient cases in which patients have failed first-line treatment options.

Metabolome modulatory effects of Kigelia africana (Lam.) Benth. fruit extracts on oxidative stress, hyperlipidaemic biomarkers in STZ-induced diabetic rats and antidiabetic effects in 3T3 L1 adipocytes

OBJECTIVES

The management of diabetes is considered a global problem, and a cure is yet to be discovered. This study investigated the modulatory effect of Kigelia africana fruit on oxidative stress and hyperlipidaemic biomarkers in STZ-induced diabetic rats, profiled phytoconstituents using GC-TOF-MS and evaluated antidiabetic effects on 3T3 L1 adipocytes.

METHODS

Thirty male Wistar rats (120-150 g) were divided into six groups (n = 5). Diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg) and treated with 100, 200 and 400 of hexane fraction of KA for 28 days. Immunohistochemical evaluation was carried out using avidin-biotin immunoperoxidase (ABI) method. Catalase and SOD activities as well as the levels of total protein, albumin, bilirubin, triglyceride, cholesterol, and high-density lipoprotein were measured.

KEY FINDINGS

The expressions of oxidative stress and hyperlipidaemic biomarkers alongside fasting blood glucose concentrations were remarkedly decreased in KA-treated diabetic rats. Moreover, there was a significant increase in endocrine cell distribution, area covered with increase in β-cell mass, composition and morphology of KA-treated animals. Additionally, there was constant up-regulation in 3T3 L1 adipocytes due to the presence of phytoconstituents.

CONCLUSION

Kigelia africana fruit can act as a modulatory agent due to its ameliorative effects against oxidative stress.

Valproate (depakine-chrono) in the acute treatment of outpatients with generalized anxiety disorder without psychiatric comorbidity: Randomized, double-blind placebo-controlled study

Objective

Anxiety disorders are highly prevalent in population of European countries. However, the effect of Valproate (depakine-chrono) on generalized anxiety disorder (GAD) has not been studied in a double-blind placebo-controlled design.

Method

Eighty patients (all men) were washout from the all medications. Each patient was randomized to receive either depakine-chrono (40 patients) for 6 weeks or matched placebo (40 patients) in a double-blind manner. Eligible participants, in addition to meeting the DSM-IV criteria for GAD and having a minimum score of 25 and more on the Hamilton Anxiety Scale, were required to be between 18 and 65 years. Response was defined as a 50% reduction in the Hamilton anxiety scale score. Response and side effects with depakine-chrono and placebo were compared by using analysis of variance (ANOVA) and chi-square tests. Six patients did not return for at least one subsequent assessment, leaving 74 patients (36 taking depakine-chrono and 38 taking placebo) in the valuables study group.

Results

Twenty six of the 36 depakine-chrono-treated participants responded by 6 weeks, versus six of the 38 placebo-treated participants (p< 0.001). The most common and problematic side effect in the depakine-chrono group was dizziness and nausea.

Conclusions

The authors believe this to be the first double-blind placebo-controlled randomization study to test the efficacy of a depakine-chrono in the management of anxiety disorders. They need to be replicated in a larger study group.

A comparison of the dimensionality of the Hamilton Rating Scale for anxiety and the DSM-5 Anxious-Distress Specifier Interview

The Hamilton Rating Scale for Anxiety (HAM-A) is one of the most widely used measures for assessing anxiety in research settings. However, it has been criticized for its inclusion of items that assess depressive symptoms. The DSM-5 Anxious Distress Specifier Interview (DADSI), developed as one assessment tool for measuring anxiety among depressed patients, demonstrates similar validity when compared with the HAM-A. However, its underlying factor structure has never been explored. The goal of the current study, therefore, was to compare the underlying factor structures of the HAM-A and the DADSI among clinically depressed (n = 576) and non-depressed (n = 146) patient samples. While two- and three-factor structures of the HAM-A fit similarly well among patients with a current major depressive episode, the three-factor structure-with anxiety and depressive symptoms forming separate factors-fit best among patients without a current major depressive episode. The DADSI was best represented by a single-factor model in both groups. The DADSI showed stronger associations with anxiety and somatic symptoms than with depressive symptoms of the HAM-A. These findings add to the characterization of the DADSI, and further highlight an important consideration for the use of HAM-A as a measure of anxiety in outcome studies.

An Insight into Gabapentin and Pregabalin in Scottish Prisoners

The aim of this study was to evaluate the prevalence and abuse potential of antiepileptic drugs (AEDs) among prison populations in Scotland, UK. Participants consisted of all admitted and released prisoners over a 1 month period who consented to provide samples. Urine samples were collected and analyzed by liquid chromatography coupled with triple quadrupole tandem mass spectrometry using a method validated for the simultaneous quantification of 21 AEDs in urine. A total of 904 samples were collected. The samples were also screened for drugs of abuse by using point-of-care testing kits. A total of 18% of the samples were positive for AEDs. Gabapentin (GBP) was identified in 118 samples (13%) and pregabalin (PRG) in 32 samples (3.5%). Interestingly, 12 samples contained both drugs (1.3%). The concentrations ranged from 0.5 to 1,100 mg/L (median, 15 mg/L) for GBP and from 0.5 to 440 mg/L (median, 7.3 mg/L) for PRG. Four samples were found to have concentrations &gt;400 mg/L, two samples for GBP and two samples for PRG. These concentrations are at least 20 times above the median concentrations. Other AEDs detected were levetiracetam (four samples), vigabatrin (four samples), lamotrigine (three samples), valproic acid (three samples), carbamazepine (two samples) and topiramate (one sample). Illicit or non-prescribed drugs were detected in 81% of urine samples of which 80% were from admitted prisoners and 20% from released prisoners. Benzodiazepines, opiates and cannabis were the most frequently detected drugs. Other drugs found in positive AED samples were methadone (26%), cocaine (18%), buprenorphine (17%), amphetamines (4%), methamphetamines (4%) and barbiturates (4%). This study shows a high prevalence of AEDs within the Scottish prison system, primarily due to GBP and PRG; however, due to the anonymity of the sample collection, it is unknown if these are prescribed or illicit drug ingestions.

Rising pregabalin use and misuse in Australia: trends in utilization and intentional poisonings

BACKGROUND AND AIMS

Pregabalin is a gamma-aminobutyric acid (GABA) analogue, used to treat neuropathic pain and epilepsy. Pregabalin was registered in Australia in 2005, and subsidized publically in 2013. We aimed to describe Australian patterns of pregabalin use and intentional poisoning, and identify people potentially at high risk of misuse.

DESIGN AND SETTING

Population-based retrospective cohort study of dispensings in the 10% sample of Australian Pharmaceutical Benefits Scheme (July 2012-February 2017); intentional poisoning calls to New South Wales Poisons Information Centre (NSWPIC) (2004-2016); intentional poisonings in two Australian toxicology service databases; and poisoning fatalities in NSW coronial records (2005-2016).

PARTICIPANTS

A total of 122 572 people dispensed pregabalin, people with intentional pregabalin overdoses managed by NSWPIC and the toxicology services and pregabalin-associated deaths referred to the NSW coroner.

MEASUREMENTS

Trends in dispensing, poisoning, death; demographics and patient characteristics, proportion of users at high risk of misuse (latent class analysis, LCA) and characteristics of high-risk users.

FINDINGS

Pregabalin dispensing increased by 73 424 per year [95% confidence interval (CI) = 61726-85 121 P < 0.001] between 2013 and 2016. NSWPIC received 1158 reports of intentional pregabalin poisonings, with a 53.8% increase per year, 2005-2016 (95% CI = 44.0-64.2%, P < 0.001). We identified 88 pregabalin-associated deaths, 57.8% yearly increase (95% CI = 30.0-91.6%, P < 0.001). Patients overdosing on pregabalin commonly co-ingested opioids, benzodiazepines and illicit drugs, and had high rates of psychiatric and substance use comorbidities; 14.7% of pregabalin users were classed by the LCA as at high risk of misuse, and were more likely to be younger, male, co-prescribed benzodiazepines or opioids, have more individual prescribers and higher pregabalin strengths dispensed.

CONCLUSIONS

There has been a dramatic increase in pregabalin use, poisonings and deaths in Australia since it became subsidized publicly in 2013. One in seven Australians dispensed pregabalin appears to be at high risk of misuse.

Developments in depression in epilepsy: screening, diagnosis, and treatment

INTRODUCTION

Depression is one of the most frequent comorbidities in epilepsy affecting between 17% and 22% of patients, but it is still underdiagnosed and undertreated. Areas covered: This paper discusses recent advances about screening, diagnosis, and treatment of depression in epilepsy taking into account the heterogeneity of clinical scenarios where depression can occur. Expert opinion: A number of screening instruments are now validated for adults with epilepsy, and their psychometric properties are discussed but the NDDI-E is the most practical and cost-effective. Challenges in diagnosing depression in epilepsy are discussed including reasons for the atypical features of mood disorders in epilepsy. Psychological treatments and/or SSRIs are indicated, but the level of evidence is still low. Even if there is no reason to hypothesise that internationally accepted guidelines of treatment of depression outside epilepsy may not be valid, rigorous studies are needed in order to have proper outcome measures. Epilepsy centers should have well-defined care pathways for depression in order to provide access to mental health support when needed.

Psychogenic Pruritus and Its Management

Chronic itching can be frustrating for patients and providers, and patients are not always willing to accept that their psychiatric health has an impact on their skin. Psychogenic pruritus is defined as itch not related to dermatologic or systemic causes. When a patient presents with pruritus, regardless of the presumed cause, the standard work-up should include a thorough history, dermatologic examination, and laboratory examinations or biopsies as needed. If no medical source is found, the provider must work in partnership with the patient to explore other causes and that may include acknowledging and treating underlying psychiatric conditions.

Use and safety of antiepileptic drugs in psychiatric inpatients-data from the AMSP study

The psychiatric utilization patterns and risks of antiepileptic drugs (AEDs) were assessed by using data from the drug safety programme Arzneimittelsicherheit in der Psychiatrie over the time period 1993-2013. In a total of 432,215 patients, the main indications for AED use were acute mania, schizoaffective disorder, and schizophrenic and organic psychoses. Valproic acid (VPA) was the most common substance across all of those groups, reaching administration rates of up to 50% since 2005, at which time carbamazepine (CBZ) administration consistently dropped below a rate of 10%. Lamotrigine (LTG) and pregabalin (PGB) increased in relevance after 2005 and 2010, respectively (with administration rates of up to 9%), whereas oxcarbazepine (OXC) was least prevalent (<3%). The mean rates of severe adverse drug reactions (ADRs) ranged from 6 cases per 1000 patients treated (VPA) to 19/1000 (OXC) and were significantly lower with treatment with VPA compared to OXC and CBZ. Hyponatremia was the leading ADR during treatment with OXC; severe allergic skin reactions were most often observed during treatment with CBZ and LTG, and severe oedema was most common during treatment with PGB. Severe hyponatremia induced by OXC was observed significantly more often in female patients than in male patients.

Early improvement with pregabalin predicts endpoint response in patients with generalized anxiety disorder: an integrated and predictive data analysis

Generalized anxiety disorder (GAD), a common mental disorder, has several treatment options including pregabalin. Not all patients respond to treatment; quickly determining which patients will respond is an important treatment goal. Patient-level data were pooled from nine phase II and III randomized, double-blind, short-term, placebo-controlled trials of pregabalin for the treatment of GAD. Efficacy outcomes included the change from baseline in the Hamilton Anxiety Scale (HAM-A) total score and psychic and somatic subscales. Predictive modelling assessed baseline characteristics and early clinical responses to determine those predictive of clinical improvement at endpoint. A total of 2155 patients were included in the analysis (1447 pregabalin, 708 placebo). Pregabalin significantly improved the HAM-A total score compared with the placebo at endpoint, treatment difference (95% confidence interval), -2.61 (-3.21 to -2.01), P<0.0001. Pregabalin significantly improved HAM-A psychic and somatic scores compared with placebo, -1.52 (-1.85 to -1.18), P<0.0001, and -1.10 (-1.41 to -0.80), P<0.0001, respectively. Response to pregabalin in the first 1-2 weeks (≥20 or ≥30% improvement in HAM-A total, psychic or somatic score) was predictive of an endpoint greater than or equal to 50% improvement in the HAM-A total score. Pregabalin is an effective treatment option for patients with GAD. Patients with early response to pregabalin are more likely to respond significantly at endpoint.

Efficacy of Pregabalin as Premedication for Post-Operative Analgesia in Vaginal Hysterectomy

Background

Pregabalin, a structural analogue of gamma amino butyric acid (GABA), is shown to be effective in treatment of several types of neuropathic pain, incisional injury, and inflammatory injury.

Objectives

The aim of the present study is to compare the efficacy of two doses (75 mg or 150 mg) of pregabalin with the administration of a placebo for post-operative analgesia in patients undergoing hysterectomy under spinal anesthesia.

Patients and Methods

A randomized, placebo-controlled trial was conducted on 135 patients undergoing vaginal hysterectomy under spinal anesthesia. The patients were divided in three groups of 45 patients each: group 0, placebo; group 1, 75 mg pregabalin; and group 2, 150 mg pregabalin; each treatment of which was administered one hour before surgery. The Ramsay sedation scale (RSS) was used for pre-operative assessment and the visual analog scale (VAS) was used to determine pain at rest and for cough on the first post-operative day. The time for the requirement of rescue analgesics on the first post-operative day was also assessed.

Results

The RSS scores were significantly higher in groups 1 and 2 as compared to the controls (P < 0.001). Postoperative VAS scores for pain both at rest and on cough were significantly reduced in groups 1 and 2 (P < 0.001). Rescue analgesic consumption decreased significantly in groups 1 and 2 (P < 0.001). The time at which rescue analgesia was administered (first dose) was 4.45 hours in group 0, 10.86 hours in group 1, and 16.82 hours in group 2 (P < 0.001).

Conclusions

Pregabalin administered as premedication provided significant postoperative pain relief and decreased the requirement of other parenteral analgesics. Pregabalin doses of 150 mg had a better analgesic profile, but the advantages of their use may be limited by side effects such as dizziness. Thus, it is concluded that pregabalin doses of 75 mg may be the optimal pre-emptive dose.

Cost-Effective Isolation of a Process Impurity of Pregabalin

Cost-effective isolation methods were developed on preparative HPLC, flash LC, and simulated moving bed (SMB) to prepare the process impurity, 3-(aminomethyl)-5-methylhex-4-enoic acid (4-ene impurity), of pregabalin. By a thorough experimental study on the different isolation techniques available, it was concluded that SMB was the most cost-effective. Hence, it was a continuous chromatography that utilized the advantage of SMB so that a high quantity of the impurity was generated in a short period of time. SMB was equipped with eight reversed-phased columns and was used to separate the process impurity of pregabalin. The effects of flow rate in zone 2 (Q2) and 3 (Q3), as well as switching time, on the operating performance parameters like purity, productivity, and desorbent consumption were studied. Operating conditions leading to more than 90% purity in the raffinate outlet stream were identified, together with those achieving optimal performance. All of these developed methods are novel, cost-effective, and can be applied to the isolation of other process- and stability-related impurities of pregabalin.

Glutamatergic agents for schizophrenia: current evidence and perspectives

Suboptimal outcomes in schizophrenia are a consequence of lacking insight into the etiology, biomarkers and treatment-relevant subgroups, the therapeutic restriction to dopaminergic-modulating antipsychotics that fail to significantly improve negative and cognitive symptoms, non-adherence, and, in the case of treatment-resistance, the underutilization of clozapine. Evidence suggests additional, extra-dopaminergic abnormalities in amino acid neurotransmission, particularly the glutamatergic system. Antidopaminergic antipsychotics modulate this system on several levels, as do mood stabilizers, including lamotrigine, topiramate and pregabaline. Recently, agonists at metabotropic glutamate receptors and glycine uptake inhibitors failed in large placebo-controlled trials for schizophrenia. Problems to overcome for successfully leveraging glutamatergic agents for schizophrenia are patient selection, focus on positive symptoms and late disease stages, and dose-response relationships. Because glutamate guides processes of brain development and maturation, clinical research should focus on the at-risk mental state or first-episode psychosis, address cognition and negative symptoms and use monotherapy designs in parallel to augmentation strategies.

Efficacy and safety of pregabalin in generalised anxiety disorder: A critical review of the literature

The aim of this review is to summarise the literature on the efficacy and safety of pregabalin for the treatment of generalised anxiety disorder (GAD). Of 241 literature citations, 13 clinical trials were identified that were specifically designed to evaluate the efficacy and safety of pregabalin in GAD, including 11 randomised double-blind trials and two open-label studies. Pregabalin efficacy has been consistently demonstrated across the licensed dose range of 150-600 mg/day. Efficacy has been reported for pregabalin monotherapy in elderly patients with GAD, patients with severe anxiety, and for adjunctive therapy when added to a selective serotonin reuptake inhibitor or serotonin-norepinephrine reuptake inhibitor in patients who have failed to respond to an initial course of antidepressant therapy. The two most common adverse events with pregabalin are somnolence and dizziness, both of which appear to be dose-related. Pregabalin appears to have a low potential for causing withdrawal symptoms when long-term therapy is discontinued; however, tapering over the course of at least one week is recommended. A review of available evidence indicates that pregabalin is a well-tolerated and consistently effective treatment for GAD, with a unique mechanism of action that makes it a useful addition to the therapeutic armamentarium.

Priapism associated with pregabalin

Priapism is a well-known cause of erectile dysfunction. There are a wide variety of causes, including hemoglobinopathy, neurological diseases, and drugs. We present a case report of an Asian man who presented with priapism that was continuous for 3 days after taking three doses of pregabalin for chronic back pain. Cavernous aspiration, phenylephrine injection, and a winter shunt all failed to achieve detumescence. The patient then presented to our institution on the 5^th day of his initial presentation, and an El-Ghorab shunt was performed, after which detumescence and pain relief were achieved. We suggest that pregabalin might induce tumescence through acting on the α2δ1 subunit of voltage-gated calcium channels in the penile smooth muscle or by presynaptic inhibition of noradrenaline release. Further studies are warranted regarding the action of pregabalin and its effect on penile physiology.

Pregabalin: a review of its use in adults with generalized anxiety disorder

Pregabalin (Lyrica(®)), a well established anxiolytic agent, has been approved in the EU for the treatment of generalized anxiety disorder (GAD) in adults. It has a distinct mechanism of action relative to other anti-anxiety agents (α2δ binding at presynaptic voltage dependent calcium channels leading to inhibition of excitatory neurotransmission), a rapid onset of effect (typically ≤1 week) and broad spectrum activity against both the psychic and somatic symptoms of GAD. In long-term studies, pregabalin maintained improvements in anxiety symptoms that occurred in response to short-term treatment and delayed the time to relapse of GAD compared with placebo. Common comorbidities of GAD, such as insomnia, gastrointestinal symptoms and subsyndromal depression, have no effect on the anxiolytic efficacy of, and moreover are specifically improved by, pregabalin. Treatment with pregabalin is generally well tolerated; the drug has an adverse event profile that includes dizziness, somnolence and weight gain. The potential for abuse of pregabalin is low; the risk of withdrawal symptoms is generally low when the drug is discontinued gradually (over 1 week). Alongside selective serotonin reuptake inhibitors (SSRIs) and serotonin-noradrenaline reuptake inhibitors (SNRIs), pregabalin is considered a first-line agent for the long-term treatment of GAD by the World Federation of Societies of Biological Psychiatry. It should be stressed, however, that definitive head-to-head studies comparing pregabalin with SSRI/SNRIs, including in patients with GAD and co-morbid major depressive disorder, are currently lacking. Recently, a study of SSRI/SNRI augmentation with pregabalin yielded positive results, while another study of switching from long-term benzodiazepine therapy to pregabalin was inconclusive; further investigations on these topics are warranted.

Depression and anxiety in people with epilepsy

Many recent epidemiological studies have found the prevalence of depression and anxiety to be higher in people with epilepsy (PWE) than in people without epilepsy. Furthermore, people with depression or anxiety have been more likely to suffer from epilepsy than those without depression or anxiety. Almost one-third of PWE suffer from depression and anxiety, which is similar to the prevalence of drug-refractory epilepsy. Various brain areas, including the frontal, temporal, and limbic regions, are associated with the biological pathogenesis of depression in PWE. It has been suggested that structural abnormalities, monoamine pathways, cerebral glucose metabolism, the hypothalamic-pituitary-adrenal axis, and interleukin-1b are associated with the pathogenesis of depression in PWE. The amygdala and the hippocampus are important anatomical structures related to anxiety, and γ-aminobutyric acid and serotonin are associated with its pathogenesis. Depression and anxiety may lead to suicidal ideation or attempts and feelings of stigmatization. These experiences are also likely to increase the adverse effects associated with antiepileptic drugs and have been related to poor responses to pharmacological and surgical treatments. Ultimately, the quality of life is likely to be worse in PWE with depression and anxiety than in PWE without these disorders, which makes the early detection and appropriate management of depression and anxiety in PWE indispensable. Simple screening instruments may be helpful for in this regard, particularly in busy epilepsy clinics. Although both medical and psychobehavioral therapies may ameliorate these conditions, randomized controlled trials are needed to confirm that.

Nutrients for prevention and treatment of mental health disorders

The choice of nutrients for review is based on clinical evidence of efficacy in neuropsychiatric disorders and biochemical effects that are neuroprotective or reparative. Vitamins, minerals, amino acids, and metabolites have been shown to augment antidepressants, improve symptoms in anxiety disorders, depression, neurodegenerative diseases, brain injury, ADHD, and schizophrenia, and to reduce medication side effects. Detection and correction of vitamin and mineral deficiencies can be essential for recovery. Generally low in adverse effects when taken in therapeutic doses, nutrients can be combined for greater benefits. Further studies are warranted to validate these promising treatments.

Evaluation of the effects of venlafaxine and pregabalin on the carbon dioxide inhalation models of Generalised Anxiety Disorder and panic

Previous studies have shown that subjective and objective symptoms of anxiety induced by 7.5% CO(2) inhalation can be attenuated by anxiolytics such as lorazepam and, to a lesser extent, paroxetine. Venlafaxine and pregabalin, two other licensed treatments for Generalised Anxiety Disorder, were used to further investigate the 7.5% and 35% CO(2) models of anxiety in healthy volunteers. Fifty-four participants were randomised to receive either placebo, venlafaxine or pregabalin. Study treatments were dosed incrementally over a three week period, to reach daily doses of 150 mg venlafaxine and 200mg pregabalin by the CO(2) challenge test day. Participants inhaled air 7.5% CO(2) for 20 minutes (single-blind presentation), and a non-blinded single vital capacity of 35% CO(2). Subjective ratings were recorded before and after each inhalation. Both 7.5% and 35% CO(2) inhalations produced the expected effects of increased ratings of symptoms of panic and anxiety, with increased blood pressure and heart rate. No significant treatment effects were found, although there were trends towards a reduction in feeling tense and nervous by both drugs compared with placebo during the 7.5% CO(2) challenge, and a reduction in alertness generally in the venlafaxine group compared with the pregabalin group. In contrast with the clear anxiolytic effects of benzodiazepines reported in several previous CO(2) studies, these findings suggest that the anxiogenic effects of CO(2) challenges are not significantly influenced by these serotonergic and GABAergic anxiolytics. This may be due to a lack of sensitivity of the CO(2) challenges in healthy volunteers to these drug types.

Exposure to predator odor and resulting anxiety enhances the expression of the α2 δ subunit of voltage-sensitive calcium channels in the amygdala

The α2 δ subunit of voltage-sensitive calcium channels (VSCCs) is the molecular target of pregabalin and gabapentin, two drugs marked for the treatment of focal epilepsy, neuropathic pain, and anxiety disorders. Expression of the α2 δ subunit is up-regulated in the dorsal horns of the spinal cord in models of neuropathic pain, suggesting that plastic changes in the α2 δ subunit are associated with pathological states. Here, we examined the expression of the α2 δ-1 subunit in the amygdala, hippocampus, and frontal cortex in the trimethyltiazoline (TMT) mouse model of innate anxiety. TMT is a volatile molecule present in the feces of the rodent predator, red fox. Mice that show a high defensive behavior during TMT exposure developed anxiety-like behavior in the following 72 h, as shown by the light-dark test. Anxiety was associated with an increased expression of the α2 δ-1 subunit of VSCCs in the amygdaloid complex at all times following TMT exposure (4, 24, and 72 h). No changes in the α2 δ-1 protein levels were seen in the hippocampus and frontal cortex of mice exposed to TMT. Pregabalin (30 mg/kg, i.p.) reduced anxiety-like behavior in TMT-exposed mice, but not in control mice. These data offer the first demonstration that the α2 δ-1 subunit of VSCCs undergoes plastic changes in a model of innate anxiety, and supports the use of pregabalin as a disease-dependent drug in the treatment of anxiety disorders.

Efficacy and safety of pregabalin in the treatment of alcohol and benzodiazepine dependence

INTRODUCTION

Both alcohol and benzodiazepine dependence (AD, BD) are severe and chronic conditions with devastating physical and mental health effects. The relative scarcity and controversial evidential status of available pharmacological interventions for the treatment of patients' acute withdrawal syndrome and/or relapse prevention call for the clinical investigation of novel safe and efficacious agents.

AREAS COVERED

We review published studies of pregabalin as monotherapy in the treatment of AD and BD in more than 450 patients. Available evidence includes four RCTs, two in AD with active comparator drugs (naltrexone, tiapride, and lorazepam) and one placebo-controlled, and one placebo-controlled in BD. We also review other available studies on pregabalin's potential to reduce benzodiazepine consumption, its side effects, especially cognitive, as well as extant reports on its liability for abuse.

EXPERT OPINION

Available evidence suggests that monotherapy with pregabalin, within the dosage range of 150 - 600 mg/d, is a promising "novel" option for the safe and efficacious relapse prevention of both AD and BD. However, its efficacy as monotherapy in the acute treatment of AD withdrawal syndrome is still controversial. Clinicians should be cautious in prescribing pregabalin to patients with a history of multiple substance recreational use, and monitor its effects on cognition at dosages above 450 mg/d. Further, well-designed clinical research is still needed for the eventual consolidation of pregabalin's place in the treatment of AD and BD.

Modulation of ion channels in clinical psychopharmacology: adults and younger people

This review focuses on the use of Na(+), Ca(2+) and Cl(-) channel modulators in psychiatric disease. Drugs that modulate ion channels have been used in psychiatry for more than a century, and in this review we critically evaluate clinical research that reports the therapeutic effects of drugs acting on GABA(A), voltage-gated Na(+) and voltage-gated Ca(2+) channels in pediatric and adult patients. As in other fields, the evidence underpinning the use of medicines in younger people is far less robust than for adults. In addition, we discuss some current developments and highlight clinical disorders in which current molecules could be further tested. Notable success stories, such as benzodiazepines (in sleep and anxiety disorders) and antiepileptics (in bipolar disorder), have been the result of serendipitous discoveries or refinements of serendipitous discoveries, as in all other major treatments in psychiatry. Genomic, high-throughput screening and molecular pharmacology discoveries may, however, guide further developments in the future. This could include increased research in promising targets that have been perceived as commercially risky, such as selective α-subunit GABA(A) receptors.

Dysfunctional neurotransmitter systems in fibromyalgia, their role in central stress circuitry and pharmacological actions on these systems

Fibromyalgia is considered a stress-related disorder, and hypo- as well as hyperactive stress systems (sympathetic nervous system and hypothalamic-pituitary-adrenal axis) have been found. Some observations raise doubts on the view that alterations in these stress systems are solely responsible for fibromyalgia symptoms. Cumulative evidence points at dysfunctional transmitter systems that may underlie the major symptoms of the condition. In addition, all transmitter systems found to be altered in fibromyalgia influence the body's stress systems. Since both transmitter and stress systems change during chronic stress, it is conceivable that both systems change in parallel, interact, and contribute to the phenotype of fibromyalgia. As we outline in this paper, subgroups of patients might exhibit varying degrees and types of transmitter dysfunction, explaining differences in symptomatoloy and contributing to the heterogeneity of fibromyalgia. The finding that not all fibromyalgia patients respond to the same medications, targeting dysfunctional transmitter systems, further supports this hypothesis.

A meta-analysis of the efficacy of pregabalin in the treatment of generalized anxiety disorder

OBJECTIVE

Generalized anxiety disorder (GAD) is a chronic anxiety disorder that leads to significant functional impairment and reduced quality of life. Pregabalin is a novel analogue of the inhibitory neurotransmitter gamma amino butyric acid, which has been proposed as a treatment for a range of conditions including GAD. This study examined the efficacy of pregabalin for GAD across published trials, using a meta-analytic method.

METHOD

This study examined the 7 published placebo-controlled trials of GAD using pregabalin, and, using meta-analytic techniques, we calculated the effect size of treatment with pregabalin (compared with placebo) on a total of 1352 people.

RESULTS

The overall effect size of pregabalin in the treatment of GAD was Hedges' g = 0.364, with an effect size of 0.349 on psychic anxiety symptoms and of 0.239 on somatic anxiety symptoms.

CONCLUSION

Pregabalin is an efficacious therapy for GAD, although effect sizes are smaller than those from earlier studies. Limitations and future research directions are discussed.

Pregabalin in zolpidem dependence and withdrawal

Several recent reports attest to zolpidem's strong potential for abuse, dependence, and severe withdrawal symptoms upon its discontinuation. We report, for the first time, on 1 case of heavy zolpidem abuse and dependence with severe withdrawal symptoms twice treated safely and successfully with pregabalin, a newer antiepileptic agent devoid of known strong potential for abuse and dependence.

Augmentation with pregabalin in schizophrenia

Anxiety is a core symptom of schizophrenia that elicits significant subjective burden of disease and contributes to treatment resistance in schizophrenia. Anxious syndromes might be attributed to incompletely remitted delusions, the negative syndrome, depressive episodes, panic attacks, social phobia, avoidance after hospitalization, and down-tapering of benzodiazepine medication. Pregabalin, an antagonist at the alpha2delta subunit of voltage-gated Ca channels, modulates several neurotransmitter systems and was found to alleviate anxiety in different mental disorders. In schizophrenia, this treatment option has not been evaluated before.Here, we report a case series of 11 schizophrenic patients who had treatment-resistant anxiety and received augmentation with pregabalin. This observational analysis reveals that the strategy was able to significantly reduce scores on the Hamilton anxiety scale; furthermore, we observed improvements of psychotic positive and negative symptoms and mood as assessed by Positive and Negative Syndrome Scale, Scale for the Assessment of Negative Symptoms, and Calgary Depression Scale for Schizophrenia. After augmentation, both a complete discontinuation of concomitant benzodiazepine treatment as well as a dose reduction of antipsychotics could be achieved. We did not observe pharmacokinetic interactions or adverse events.These observations suggest that treating anxious syndromes in schizophrenia with pregabalin can be effective and tolerable. Further investigations should differentiate schizophrenic subsyndromes of anxiety and evaluate benefits and risks of pregabalin in comparison to placebo and active competitors.

Pregabalin in the treatment of alcohol and benzodiazepines dependence

We review all available studies on the use of the newer anticonvulsant drug pregabalin (PGB) in the treatment of both alcohol dependence (AD) and benzodiazepine dependence (BD). In AD, the available evidence includes one open-label and one double-blind randomized studies, whereas in BD, only a few case reports and one open-label study are as yet available. In both conditions, PGB was found efficacious with significant improvement in withdrawal symptoms at the dosage ranges of 150-450 mg/day (AD) and 225-900 mg/day (BD). Moreover, its side effects were mild and transient. Despite the limited quality of the studies design, their findings suggest that PGB might constitute a novel efficacious and safe option in the treatment of both AD and BD.

Pregabalin in the treatment of chronic pain: an overview

Chronic 'pathological' pain is sustained by mechanisms of peripheral and central sensitization, which are being increasingly investigated at the molecular and cellular levels. The molecular determinants of nociceptive sensitization are natural targets for potential analgesic drugs used in the treatment of different forms of pain. Most of these determinants are common to all forms of chronic pain, and it is therefore not surprising that drugs specifically targeted for the treatment of neuropathic pain are effective in relieving nociceptive inflammatory pain and vice versa. The molecular mechanisms of sensitization that occur in peripheral nociceptors and the dorsal horns of the spinal cord are putative targets for context-dependent drugs, i.e. drugs that are able to discriminate between 'normal' and 'pathological' pain transmission. Among these, pregabalin and gabapentin bind to the alpha(2)delta subunit of voltage-sensitive Ca2+ channels, which sustain the enhanced release of pain transmitters at the synapses between primary afferent fibres and second-order sensory neurons under conditions of chronic pain. Pregabalin in particular represents a remarkable example of a context-dependent analgesic drug that acts at a critical step of nociceptive sensitization. Preclinical and clinical data suggest that pregabalin is more than a structural and functional analogue of gabapentin and may be effective in the treatment of nociceptive inflammatory pain that is resistant to gabapentin.

World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for the pharmacological treatment of anxiety, obsessive-compulsive and post-traumatic stress disorders - first revision

In this report, which is an update of a guideline published in 2002 (Bandelow et al. 2002, World J Biol Psychiatry 3:171), recommendations for the pharmacological treatment of anxiety disorder, obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD) are presented. Since the publication of the first version of this guideline, a substantial number of new randomized controlled studies of anxiolytics have been published. In particular, more relapse prevention studies are now available that show sustained efficacy of anxiolytic drugs. The recommendations, developed by the World Federation of Societies of Biological Psychiatry (WFSBP) Task Force for the Pharmacological Treatment of Anxiety, Obsessive-Compulsive and Post-traumatic Stress Disorders, a consensus panel of 30 international experts, are now based on 510 published randomized, placebo- or comparator-controlled clinical studies (RCTs) and 130 open studies and case reports. First-line treatments for these disorders are selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline reuptake inhibitors (SNRIs) and the calcium channel modulator pregabalin. Tricyclic antidepressants (TCAs) are equally effective for some disorders, but many are less well tolerated than the SSRIs/SNRIs. In treatment-resistant cases, benzodiazepines may be used when the patient does not have a history of substance abuse disorders. Potential treatment options for patients unresponsive to standard treatments are described in this overview. Although these guidelines focus on medications, non-pharmacological were also considered. Cognitive behavioural therapy (CBT) and other variants of behaviour therapy have been sufficiently investigated in controlled studies in patients with anxiety disorders, OCD, and PTSD to support them being recommended either alone or in combination with the above medicines.

Pregabalin for the management of partial epilepsy

Pregabalin is one of the latest antiepileptic drugs introduced for the treatment of partial epilepsy. Its efficacy and safety as adjunctive therapy in refractory partial epilepsy have been established in four double-blind placebo-controlled trials (n = 1396) and 4 long-term open-label studies (n = 1480). In 3 fixed-dose trials, the proportion of patients with a >/=50% reduction in seizure frequency across the effective dose-range (150-600 mg/day) ranged between 14% and 51%, with a clear dose-response relationship. Suppression of seizure activity could be demonstrated as early as day 2. The most frequently reported CNS-related adverse events included dizziness, somnolence, ataxia and fatigue, were usually mild or moderate, and tended to be dose related. In long-term studies, weight gain was reported as an adverse event by 24% of patients. When pregabalin dose was individualized to according to response within the 150 to 600 mg/day dose range, tolerability was considerably improved compared with use of a high-dose, fixed-dose regimen (600 mg/day) without titration. In long-term studies up to 4 years, no evidence of loss efficacy was identified. During the last year on pregabalin, 3.7% of patients were seizure-free. Pregabalin appears to be a useful addition to the therapeutic armamentariun for the management of refractory partial epilepsy.

The medical treatment of obsessive-compulsive disorder and anxiety

Selective serotonin reuptake inhibitors (SSRIs) are first-line pharmacotherapy treatments for obsessive-compulsive disorder (OCD). Clomipramine is effective in OCD but associated with more adverse events. Typically, higher doses of antidepressants are required for OCD. Up to 50% of patients do not respond to initial treatment of OCD. Treatment options for nonresponders include augmentation of antidepressants with atypical antipsychotics, among other strategies. First-line treatments for anxiety disorders include SSRIs, serotonin norepinephrine reuptake inhibitors, and pregabalin. Tricyclic antidepressants are equally effective as SSRIs, but are less well tolerated. In treatment-resistant cases, benzodiazepines may be used when the patient does not have a history of dependency and tolerance. Other treatment options include irreversible and reversible monoamine oxidase inhibitors, the atypical antipsychotic quetiapine, and other medications. Cognitive-behavioral therapy has been sufficiently investigated in controlled studies of OCD and anxiety disorders and is recommended alone or in combination with the above medications.

Effects of pregabalin on visceral pain responses and colonic compliance in rats

BACKGROUND AND PURPOSE

Pregabalin, which binds to the alpha2-delta subunit of voltage-gated calcium channels, increased the threshold for pain during colorectal distension (CRD) in irritable bowel syndrome (IBS) patients. We tested the effects of oral pregabalin on the visceral pain-related viscerosomatic and autonomic cardiovascular responses to CRD and colonic compliance in rats.

EXPERIMENTAL APPROACH

The activity of the abdominal musculature (viscerosomatic response), monitored by electromyography and intracolonic manometry, and changes in blood pressure and heart rate, monitored by telemetry, were assessed simultaneously in conscious rats during CRD.

KEY RESULTS

Pregabalin (10-200 micromol kg(-1), p.o.) inhibited dose dependently the viscerosomatic response to phasic, noxious CRD (12 distensions at 80 mm Hg). At 200 mumol kg(-1), pregabalin also reduced the increase in blood pressure and heart rate associated with noxious CRD. Moreover, pregabalin (200 micromol kg(-1), p.o.) reduced the visceromotor response to ascending phasic CRD (10-80 mm Hg) and significantly increased the threshold pressure for response. During phasic CRD (2-20 mm Hg), pregabalin (200 micromol kg(-1), p.o.) increased intracolonic volume, resulting in a shift to the left of the pressure-volume relationship curve, indicative of an increase of compliance.

CONCLUSIONS AND IMPLICATIONS

Pregabalin reduced the viscerosomatic and autonomic responses associated with CRD-induced visceral pain and increased colonic compliance in rats. These observations confirm the analgesic activity of pregabalin on visceral pain and support the translational value of the CRD model to humans. Ligands for the alpha2-delta subunit might represent interesting compounds for the treatment of visceral pain disorders, such as IBS.

Incensole acetate, an incense component, elicits psychoactivity by activating TRPV3 channels in the brain

Burning of Boswellia resin as incense has been part of religious and cultural ceremonies for millennia and is believed to contribute to the spiritual exaltation associated with such events. Transient receptor potential vanilloid (TRPV) 3 is an ion channel implicated in the perception of warmth in the skin. TRPV3 mRNA has also been found in neurons throughout the brain; however, the role of TRPV3 channels there remains unknown. Here we show that incensole acetate (IA), a Boswellia resin constituent, is a potent TRPV3 agonist that causes anxiolytic-like and antidepressive-like behavioral effects in wild-type (WT) mice with concomitant changes in c-Fos activation in the brain. These behavioral effects were not noted in TRPV3(-/-) mice, suggesting that they are mediated via TRPV3 channels. IA activated TRPV3 channels stably expressed in HEK293 cells and in keratinocytes from TRPV3(+/+) mice. It had no effect on keratinocytes from TRPV3(-/-) mice and showed modest or no effect on TRPV1, TRPV2, and TRPV4, as well as on 24 other receptors, ion channels, and transport proteins. Our results imply that TRPV3 channels in the brain may play a role in emotional regulation. Furthermore, the biochemical and pharmacological effects of IA may provide a biological basis for deeply rooted cultural and religious traditions.

[Treatment of generalized anxiety disorders]

Generalized anxiety disorder (GAD) is a condition that is common in the general population and in general practice; it is disabling and often unrecognized. Its recognition is difficult because of the need to differentiate between normal anxiety and the other psychiatric disorders with which it is often associated. The primary drugs used for GAD are the antidepressants that have been authorized for this indication (venlafaxine XR, paroxetine, and escitalopram). Although benzodiazepines are effective, their prescription is limited by the disadvantages associated with their long-term use. Drug treatment of GAD must continue for a sufficiently long period (at least 6 months) to minimize the chance of a relapse. Cognitive and behavioral therapies (CBT) are as effective as antidepressants. They are often desirable, but their limited availability impedes their use as a first-line treatment.