Carbamazepine and valproate for the treatment of bipolar disorder: a review of the literature

Effects of exogenous melatonin on sleep and circadian rhythm parameters in bipolar disorder with comorbid delayed sleep-wake phase disorder: An actigraphic study

The present study evaluates the effect of exogenous melatonin (exo-MEL) on sleep and circadian parameters in patients with bipolar disorder (BD) and delayed sleep-wake phase disorder (DSWPD). BD euthymic patients (n = 83, mean age = 45.13 ± 13.68, males 56%) were evaluated for chronotype (reduced Morningness-Eveningness Questionnaire [rMEQ]), sleep quality (Pittsburgh Sleep Quality Index), sleep and circadian parameters (actigraphic monitoring). Patients that fulfilled criteria for DSWPD (n = 25) were treated for three months with exo-MEL 2 mg administered approximately 4 h before the sleep onset time (SOT) actigraphically-determined at baseline. Sleep and circadian parameters at baseline (T0) and after the exo-MEL treatment (T1) were compared using paired Wilcoxon test. In patients that completed the treatment (n = 19), the rMEQ score increased between T0 (median = 8.0 [IQR = 7.0, 11.0]) and T1 (median = 13.5 [IQR = 9.3, 15.0], p-value = 0.006), the SOT was advanced between T0 (median = 00:55 [IQR = 00:25, 01:39] and T1 (median = 00:09 [IQR = 23:41, 01:04], p-value = 0.039), the sleep efficiency and total sleep time increased (T0: median = 84.4 [IQR = 81.3, 89.4]; T1 (median = 90.3 [IQR = 85.5, 92.9] %, p-value = 0.01, and T0: median = 7.20 [IQR = 6.15, 8.15]; T1: median = 7.7 [IQR = 7.0, 9.3] hours, p-value = 0.04, respectively). These results indicate that in BD with comorbid DSWPD, the self-reported chronotype, the sleep onset time, and sleep efficiency and duration were modified after a personalized treatment with exo-MEL, suggesting its potential efficacy in improving sleep patterns in BD. The absence of proper control groups and of treatment randomization constitute limitations of our study and further randomized controlled trials are required to confirm our results.

Long-Term Treatment of Bipolar Disorder with Valproate: Updated Systematic Review and Meta-analyses

LEARNING OBJECTIVE

After participating in this activity, learners should be better able to:• Evaluate the evidence regarding the effectiveness of long-term treatment of bipolar disorder with valproate.

BACKGROUND

Prophylactic treatment is critical for bipolar disorder (BD) patients. Valproate is commonly used for this purpose but lacks regulatory approval and carries appreciable risks.

METHODS

Systematic literature searching through June 2020 sought prospective trials lasting ≥12 months with adults diagnosed with BD to support comparisons of risk of new illness episodes with valproate versus placebo or other agents.

RESULTS

Included were 13 reports involving 9240 subjects treated for an average of 29.1 months (range, 12-124) in 21 trials: 9 were blinded, randomized trials (RCTs) of valproate versus placebo (n = 3), lithium (5), or olanzapine (1); 2 were unblinded RCTs versus lithium (1) or quetiapine (1); and 10 were open-label trials versus lithium (5), quetiapine (2), carbamazepine (1), lamotrigine (1), or olanzapine (1). Random-effects meta-analysis found valproate superior to placebo in 3 trials (odds ratio [OR] = 0.42 [95% confidence level (CI), 0.30-0.60]; p < .0001). In 11 trials, protective effects with valproate and lithium were similar (OR = 1.20 [CI, 0.81-1.79]; p = .36), as well in 5 comparisons versus antipsychotics quetiapine and olanzapine (OR = 0.96 [CI, 0.66-1.40]; p = .84), and 2 versus other mood-stabilizing anticonvulsants (carbamazepine and lamotrigine) (OR = 1.30 [CI, 0.75-2.26]; p = .34). Valproate was nonsignificantly more effective versus new mania than depression (χ2 = 3.03; p = .08).

CONCLUSIONS

Valproate was more effective than placebo in preventing new BD episodes of mania or depression, and not significantly different from lithium, second-generation antipsychotics, or other anticonvulsants. Overall benefits were nonsignificantly greater versus mania than bipolar depression.

Carbamazepine Toxicity Masquerading as Complex Febrile Seizures in a Pediatric Patient

Carbamazepine is an antiepileptic drug that can cause seizures in overdose. In certain patient populations, this may be misdiagnosed as a seizure disorder. We describe a case of a 20-month-old female who presented with fever and seizure-like activity who was initially thought to have complex febrile seizures. Further historical information prompted carbamazepine level to be checked, which was found to be 29 mcg/ml (therapeutic range of 4–12 mcg/ml). Her carbamazepine levels downtrended with multidose activated charcoal. Her condition improved, and she was discharged without evidence of permanent neurologic sequelae. This case illustrates that xenobiotic exposure should often be considered, even if historical clues are not present, as they can often present as other conditions leading to misdiagnosis and delayed treatment.

Sodium valproate in pregnancy: what are the risks and should we use a shared decision-making approach?

BACKGROUND

Despite significant teratogenic risks, sodium valproate is still widely prescribed in many countries to women of childbearing age, as a mood stabiliser in bipolar disorder and also in epilepsy. The UK has recently banned valproate use in women who are not in a pregnancy prevention programme. Whilst this ruling reflects prevailing clinical practice, it also highlights an ongoing debate about when (if ever) a woman who is or could become pregnant should be allowed to choose to take valproate.

MAIN BODY

We review the benefits and harms of drugs available for bipolar disorder and epilepsy in women of childbearing age, with a particular focus on teratogenic risk. We speculate on hypothetical rare situations in which potential benefits of valproate may outweigh potential harms in such women. We also review the literature on shared decision-making - on which there is now a NICE guideline and numerous evidence-based decision tools. Drawing on previous work by experts in shared decision-making, we offer a list of 'frequently asked questions' and a matrix of options to support conversations with women about continuing or discontinuing the drug in (or in anticipation of) pregnancy. We also consider whether shared decision-making is an appropriate paradigm when considering whether to continue a teratogenic drug.

CONCLUSION

We conclude that because valproate in pregnancy remains the subject of such debate, there is scope for further research - not only into the relative efficacy and safety of alternatives to it - but also into the dynamics of communication and shared decision-making in this situation.

Effect of valproic acid on dementia onset in patients with bipolar disorder

BACKGROUND

Valproic acid (VPA) is widely used for treating patients with bipolar disorder; however, it has adverse effects on cognitive function. This study investigated the effect of VPA on the risk of dementia in patients with bipolar disorder.

METHODS

We analyzed data from Taiwan's Longitudinal Health Insurance Database 2010. Patients with bipolar disorder who were prescribed VPA for 28 days or at least once per month for 3 consecutive months after the index date were classified as the VPA-treated group, whereas those who did not receive VPA were classified as the VPA-untreated group. Both groups were tracked until the end of 2013 or until loss to follow-up to identify new-onset dementia events. Multivariable Cox proportional hazards models were used to estimate the hazard ratio (HR) of subsequent dementia associated with VPA treatment after adjustment for confounding variables.

RESULTS

The study comprised 5158 patients with bipolar disorder. The multivariable-adjusted HR for newly diagnosed dementia was 1.73 (95% confidence interval [CI], 1.24-2.41, P=0.001) for the VPA-treated group compared with the VPA-untreated group after adjustment for potential confounders. The VPA-treated group had a higher risk than did the VPA-untreated group after propensity score adjustment (HR=1.95, 95% CI=1.42-2.67, P<0.001).

LIMITATION

Certain variables that may affect the incidence of dementia were unavailable in the claims database and thus could not be considered.

CONCLUSION

Treating bipolar disorder with VPA increases the risk of dementia by 73-95%.

The effects of valproic acid on appetitive and aversive instrumental learning in adult rats

Antiepileptic medications are the frontline treatment for seizure conditions. However, these medications are not without cognitive side effects. Previously, our laboratory reported learning deficits in phenytoin and carbamazepine-treated rats. In the experiment reported here, the effects of valproic acid (VPA) have been studied using the same instrumental training tasks. VPA-treated rats displayed a severe deficit in acquiring a tone-signaled avoidance response. This deficit was attenuated in animals that had prior training in an appetitive context. Thus, this deficit is specific to learning in an aversive context, and does not result from difficulties in transferring associations from an appetitive to aversive context. Learning transfer deficits were previously observed in rats treated with phenytoin, and to a lesser extent, carbamazepine. On the other hand, rats treated with VPA fail to suppress inappropriate responsiveness across aversive training whether they had undergone prior appetitive training or not.

Carbamazepine Prevents Hippocampal Neurodegeneration in Mice Lacking the Neuroprotective Protein, Carboxypetidase E

Carboxypeptidase E (CPE) has recently been described as a neuroprotective protein, and in mice devoid of CPE, a complete loss of the hippocampal CA3 neurons is observed. The pattern of loss is characteristic of that caused by status epilepticus. We therefore set out to determine when this loss occurred, what might induce it and if it could be prevented. We found that the hippocampus was intact in 4 week old CPE knock out (KO) mice that had not undergone weaning. However, weaning of 2 or 3 week old CPE KO mice, which involves maternal separation (emotional stress) and ear tagging and tail snipping for genotyping (physical stress), resulted in degeneration of the CA3 neurons by 3 and 4 weeks of age, respectively, while the wild-type mice were unaffected. Moreover, the physical stress caused a more severe neurodegeneration phenotype than the emotional stress of the maternal separation alone. Daily treatment with carbamazepine, an antiepileptic agent, in 2 week old CPE KO mice for 2 weeks prevented the neurodegeneration, despite the weaning process at 3 weeks. No further neurodegeneration was observed 3 weeks post weaning in carbamazepine treated mice. These results showed that degeneration of the CA3 neurons in the hippocampus, previously observed in 6 week old CPE KO mice, is not due to a developmental defect, but caused by physical and emotional stress during the weaning process. This degeneration was prevented by carbamazepine suggesting that the stress associated with weaning caused epileptic-like events in the CPE KO mice.

Gabapentin's minimal action on markers of rat brain arachidonic acid metabolism agrees with its inefficacy against bipolar disorder

In rats, FDA-approved mood stabilizers used for treating bipolar disorder (BD) selectively downregulate brain markers of the arachidonic acid (AA) cascade, which are upregulated in postmortem BD brain. Phase III clinical trials show that the anticonvulsant gabapentin (GBP) is ineffective in treating BD. We hypothesized that GBP would not alter the rat brain AA cascade. Chronic GBP (10 mg/kg body weight, injected i.p. for 30 days) compared to saline vehicle did not significantly alter brain expression or activity of AA-selective cytosolic phospholipase A(2) (cPLA(2)) IVA or secretory (s)PLA(2) IIA, activity of cyclooxygenase-2, or prostaglandin E(2) or thromboxane B(2) concentrations. Plasma esterified and unesterified AA concentration was unaffected. These results, taken with evidence of an upregulated AA cascade in the BD brain and that approved mood stabilizers downregulate the rat brain AA cascade, support the hypothesis that effective anti-BD drugs act by targeting the brain AA cascade whereas ineffective drugs (such as GBP) do not target this pathway, and suggest that the rat model might be used for screening new anti-BD drugs.

Effect of valproic acid through regulation of NMDA receptor-ERK signaling in sleep deprivation rats

Although the effect of mood stabilizer valproic acid (VPA) through multiple signaling pathways has been shown, its therapeutic mechanism is still largely unknown. We investigated the effect of VPA (200 mg/kg, every 12 h) in sleep deprivation (SD) rats (72 h), the manic-like animal model, focusing on the N-methyl-D: -aspartic acid (NMDA) receptor and signaling mediators of synaptic plasticity such as extracellular signal-regulated protein kinase (ERK), cAMP response element-binding protein (CREB), B cell chronic lymphocytic leukemia/lymphoma 2 (BCL2), and brain-derived neurotrophic factor (BDNF). SD reduced the expression of the NR2B subunit of the NMDA receptor in the frontal cortex and hippocampus but did not affect the expression of NR1 and NR2A subunits. In comparison, VPA inhibited the SD-induced reduction of NR2B expression in both brain regions. In addition, SD attenuated ERK phosphorylation in the frontal cortex and hippocampus, whereas VPA prevented the attenuation. VPA also protected the SD-induced decrease of CREB phosphorylation, BCL2 expression, and BDNF expression in the frontal cortex but not in the hippocampus. These results indicate that VPA could regulate NMDA receptor-ERK signaling in SD rats, preventing the SD-induced decrease of the expression of NR2B subunit and the activation of ERK signaling mediators such as ERK, CREB, BCL2, and BDNF.

Effect of prolonged phenytoin administration on rat brain gene expression assessed by DNA microarrays

Preliminary clinical trials have recently shown that phenytoin, an antiepileptic drug, may also be beneficial for treatment of bipolar disorder. To examine molecular mechanisms of action of phenytoin as a potential mood stabilizer, DNA microarrays were used to study the effect of phenytoin on gene expression in the hippocampus and frontal cortex of Sprague-Dawley rats. While our particular interest is in bipolar disorder, this is the first DNA microarray study on the effect of phenytoin in brain tissue, in general. As compared with control rats, treated rats had 508 differentially expressed genes in the hippocampus and 62 in the frontal cortex. Phenytoin modulated the expression of genes which may affect neurotransmission, e.g. glutamate decarboxylase 1 (Gad1) and gamma-aminobutyric acid A receptor, alpha 5 (Gabra5). Phenytoin also exerted an effect on neuroprotection-related genes, namely the survival-promoting and antioxidant genes v-akt murine thymoma viral oncogene homolog 1 (Akt1), FK506 binding protein 12-rapamycin associated protein 1 (Frap1), glutathione reductase (Gsr) and glutamate cysteine ligase catalytic subunit (Gclc). The expression of genes potentially associated with mechanisms of mood regulation such as adenylate cyclase-associated protein 1 (Cap1), Glial Fibrillary Acidic Protein (Gfap) and prodynorphin (Pdyn) was also altered. Some of the above genes are regarded as targets of classical mood stabilizers and their modulation supports the clinical observation that phenytoin may have mood-stabilizing effects. The results may provide new insights regarding the mechanism of action of phenytoin and genes found differentially expressed following phenytoin administration may play a role in the pathophysiology of either bipolar disorder or epilepsy.

The management of individuals with bipolar disorder: a review of the evidence and its integration into clinical practice

Bipolar disorder is a common, debilitating, chronic illness that emerges early in life and has serious consequences such as long-term unemployment and suicide. It confers considerable functional disability to the individual, their family and society as a whole and yet it is often undetected, misdiagnosed and treated poorly. In the past decade, many new treatment strategies have been trialled in the management of bipolar disorder with variable success. The emerging evidence, for pharmacological agents in particular, is promising but when considered alone does not directly translate to real-world clinical populations of bipolar disorder. Data from drug trials are largely based on findings that identify differences between groups determined in a time-limited manner, whereas clinical management concerns the treatment of individuals over the life-long course of the illness. Considering the findings in the context of the individual and their particular needs perhaps best bridges the gap between the evidence from research studies and their application in clinical practice. Specifically, only lithium and valproate have moderate or strong evidence for use across all three phases of bipolar disorder. Anticonvulsants, such as lamotrigine, have strong evidence in maintenance; whereas antipsychotics largely have strong evidence in acute mania, with the exception of quetiapine, which has strong evidence in bipolar depression. Maintenance data for antipsychotics is emerging but at present remains weak. Combinations have strong evidence in acute phases of illness but maintenance data is urgently needed. Conventional antidepressants only have weak evidence in bipolar depression and do not have a role in maintenance therapy. Therefore, this paper summarizes the efficacy data for treating bipolar disorder and also applies clinical considerations to these data when formulating recommendations for the management of bipolar disorder.

Is anticonvulsant treatment of mania a class effect? Data from randomized clinical trials

Our aim was to evaluate the efficacy and tolerability of anticonvulsant agents for the treatment of acute bipolar mania and ascertain if their effects on mania are a "class" effect. We conducted a systematic review of randomized controlled trials (RCTs) with placebo or active comparator, in acute bipolar mania in order to summarize available data on anticonvulsant treatment of mania/mixed episodes. We searched (PubMed/MEDLINE) with the combination of the words "acute mania" and "clinical trials" with each one of the following words: "anticonvulsants/antiepileptics,""valproic/valproate/divalproex,""carbamazepine,""oxcarbazepine,""lamotrigine,""gabapentin,""topiramate,""phenytoin,""zonisamide,""retigabine,""pregabalin,""tiagabine,""levetiracetam,""licarbazepine,""felbamate," and "vigabatrin." Original articles were found until November 1, 2008. Data from 35 randomized clinical trials suggested that not all anticonvulsants are efficacious for the treatment of acute mania. Valproate showed greater efficacy in reducing manic symptoms, with response rates around 50% compared to a placebo effect of 20-30%. It appears to have a more robust antimanic effect than lithium in rapid cycling and mixed episodes. As valproate, the antimanic effects of carbamazepine have been demonstrated. Evidences did not support the efficacy of the gabapentin, topiramate as well as lamotrigine as monotherapy in acute mania and mixed episodes. Oxcarbazepine data are inconclusive and data regarding other anticonvulsants are not available. Anticonvulsants are not a class when treating mania. While valproate and carbamazepine are significantly more effective than placebo, gabapentin, topiramate, and lamotrigine are not. However, some anticonvulsants may be efficacious in treating some psychiatric comorbidities that are commonly associated to bipolar illness.

Medicating mood with maintenance in mind: bipolar depression pharmacotherapy

OBJECTIVES

Bipolar depression is a core feature of bipolar disorder, a phase in which many patients spend the majority of time and one that confers a significant degree of burden and risk. The purpose of this paper is to briefly review the evidence base for the pharmacotherapy of bipolar depression and to discuss the recommendations for its optimal management.

METHODS

A detailed literature review was undertaken with a particular emphasis on pharmacological treatment strategies for bipolar depression across the acute and maintenance phases of the illness. Electronic library and Web-based searches were performed using recognised tools (MEDLINE, PubMED, EMBASE and PsychINFO) to identify the pertinent literature. A summary of the evidence base is outlined and then distilled into broad clinical recommendations to guide the pharmacological management of bipolar depression.

RESULTS

Partitioning treatment into acute and maintenance therapy is difficult based on the paucity of current evidence. The evidence from treatment trials favours the use of lithium and lamotrigine as first-line treatment in preference to valproate, and indicates that, for acute episodes, quetiapine and olanzapine have perhaps achieved equivalence at least in terms of efficacy. However, the effectiveness of the atypical antipsychotics in maintenance therapy is constrained by the potential for significant side effects of individual agents and the lack of both long-term research data and clinical experience in treating bipolar disorder as compared to other agents. Conversely, lithium and the anticonvulsants are generally slower to effect symptomatic change, and this limits their usefulness.

CONCLUSIONS

There has been a tendency for research trials of bipolar depression to differentiate the illness cross-sectionally into the acute and maintenance phases of bipolar depression; however, in clinical terms, bipolar depression invariably follows a longitudinal course in which the phases of illness are inextricably linked, and useful acute treatments are typically continued in maintenance. Therefore, when medicating mood in acute bipolar depression it is imperative to keep maintenance in mind as it is this aspect of treatment that determines long-term success.

Comparative in vivo bioequivalence and in vitro dissolution of two valproic acid sustained-release formulations

Objective

A study was conducted to establish the bioequivalence between different sustained-release formulations of valproic acid (Depakene R and Selenica R), which were developed in Japan.

Materials and methods

The clinical investigation was designed in a randomized, crossover fashion with a single dose given to 12 healthy subjects. The subjects were administered a single 600 mg dose of valproic acid in one of two formulations. Serial venous blood samples were obtained over 72 hours after each administration to measure valproic acid in serum by enzyme immunoassay (EIA). In addition, a dissolution test was performed. Each sample was analyzed by an high-performance liquid chromatography to determine the dissolution rate of valproic acid.

Results

No difference in maximum concentration or area under the curve was found between the two formulations. The time to maximum concentration of the new formation was significantly delayed compared with the conventional formulation (10.8 ± 1.7 versus 17.6 ± 1.8 hours, p < 0.001). Apparent clearance or elimination half-life did not differ between the two formulations. An in vitro dissolution study showed that Depakene R was significantly more dissoluble than Selenica R.

Conclusion

Based on the results, the present study demonstrated a significant difference between the two sustained-release formulations in the absorption profile, and also demonstrated that the bioavailability of valproic acid in the two formulations was similar but absorption speed (lag time) was very different.

Chronic administration of valproic acid reduces brain NMDA signaling via arachidonic acid in unanesthetized rats

Evidence that brain glutamatergic activity is pathologically elevated in bipolar disorder suggests that mood stabilizers are therapeutic in the disease in part by downregulating glutamatergic activity. Such activity can involve the second messenger, arachidonic acid (AA, 20:4n - 6). We tested this hypothesis with regard to valproic acid (VPA), when stimulating glutamatergic N-methyl-D: -aspartate (NMDA) receptors in rat brain and measuring AA and related responses. An acute subconvulsant dose of NMDA (25 mg/kg i.p.) or saline was administered to unanesthetized rats that had been treated i.p. daily with VPA (200 mg/kg) or vehicle for 30 days. Quantitative autoradiography following intravenous [1-(14)C]AA infusion was used to image regional brain AA incorporation coefficients k*, markers of AA signaling. In chronic vehicle-pretreated rats, NMDA compared with saline significantly increased k* in 41 of 82 examined brain regions, many of which have high NMDA receptor densities, and also increased brain concentrations of the AA metabolites, prostaglandin E(2) (PGE(2)) and thromboxane B(2) (TXB(2)). VPA pretreatment reduced baseline concentrations of PGE(2) and TXB(2), and blocked the NMDA induced increases in k* and in eicosanoid concentrations. These results, taken with evidence that carbamazepine and lithium also block k* responses to NMDA in rat brain, suggest that mood stabilizers act in bipolar disorder in part by downregulating glutamatergic signaling involving AA.

Structure-activity relationship and substrate-dependent phenomena in effects of ginsenosides on activities of drug-metabolizing P450 enzymes

Ginseng, a traditional herbal medicine, may interact with several co-administered drugs in clinical settings, and ginsenosides, the major active components of ginseng, may be responsible for these ginseng-drug interactions (GDIs). Results from previous studies on ginsenosides' effects on human drug-metabolizing P450 enzymes are inconsistent and confusing. Herein, we first evaluated the inhibitory effects of fifteen ginsenosides and sapogenins on human CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 enzymes by using commercially available fluorescent probes. The structure-activity relationship of their effects on the P450s was also explored and a pharmacophore model was established for CYP3A4. Moreover, substrate-dependent phenomena were found in ginsenosides' effects on CYP3A4 when another fluorescent probe was used, and were further confirmed in tests with conventional drug probes and human liver microsomes. These substrate-dependent effects of the ginsenosides may provide an explanation for the inconsistent results obtained in previous GDI reports.

Association of MDR1 C3435T polymorphism with bipolar disorder in patients treated with valproic acid

P-glycoprotein (P-gp), an efflux transporter protein, is an ABC transporter encoded by the multidrug resistance 1 gene (MDR1, ABCB1). The common synonymous C3435T polymorphism in exon 26 is reported to associate with lower P-gp functional expression and drug uptake. Many extended pharmacogenomics, functional, and complex disease association studies focused mainly on this polymorphism. We investigated the association of exon 26 C3435T genetic variants of MDR1 gene with susceptibility to bipolar disorder and serum valproic acid concentration. Totally, 104 patients meeting DSM-IV criteria for bipolar disorder and 169 controls were admitted to the study. There was statistically significant difference between the genotypes of bipolar patients (CT 91.2%, TT 6.8%, and CC 2%) and controls (CT 52.7%, TT 26%, CC 21.3%) although their allelic distribution was similar. The serum valproic acid concentrations of the patients with CT, TT and CC genotypes were 72.92 +/- 20.55, 80.47 +/- 14.01 and 68.29 +/- 12.17 microg/ml, respectively, and there was no significant difference between the C3435T genotypes.

Different serum concentrations of steady-state valproic acid in two sustained-release formulations

Recently a new sustained-release formulation of valproic acid has been developed in Japan. The sustained-release mechanism of the new formulation was different from the conventional formulation. The aim of the present study was to compare the pharmacokinetic characteristics of valproic acid in two sustained-release formulations. Different sustained-release formulations of valproic acid (Depakene R and Selenica R) were administered in a randomized cross-over fashion in repeated doses in 24 psychiatric patients. After > or = 4 weeks administration of valproic acid once daily, blood samples were taken just before (0 h) and 8, 12, 24 h after the morning dose. Blood sampling was performed in the same manner in the same patients 4 weeks after switching from one to the other formulation of valproic acid. Serum concentrations of valproic acid at 0 h (50.7 +/- 19.4 vs 44.9 +/- 21.8 microg/mL, P < 0.05) and 24 h (52.3 +/- 19.54 vs 6.2 +/- 22.2 microg/mL, P < 0.05) were significantly higher during Selenica R than during Depakene R treatment, whereas the serum concentration of valproic acid at 8 h (49.7 +/- 19.2 vs 62.4 +/- 25.6 microg/mL, P < 0.01) was significantly lower during Selenica R treatment than during Depakene R treatment. Serum concentrations of valproic acid at 12 h were not different. The present study demonstrated that steady-state serum concentrations were different because of the different dissolution profiles. When a prescription for valproic acid is switched from one drug to the other, prescribers should be aware that the therapeutic drug monitoring data are not consistent.

Rats bred for susceptibility to depression-like phenotypes have higher kainic acid-induced seizure mortality than their depression-resistant counterparts

Epidemiological evidence suggests that epilepsy and depression are comorbid diseases. In fact, depression is the most common neuropsychiatric disorder associated with epilepsy, particularly temporal lobe epilepsy, and individuals with a history of depression are at a higher risk for developing epilepsy than the general population. Despite the epidemiological evidence for this link, there has been little experimental evidence to support the connection or elucidate possible underlying mechanisms. In an effort to address this problem and develop an animal model of epilepsy and depression comorbidity, we assessed seizure susceptibility and severity parameters in rats selectively bred for either susceptibility (the SwLo, SUS, and HYPER lines) or resistance (the SwHi, RES, and MON RES lines) to depression-like phenotypes. We found that rats bred for susceptibility to depression-like phenotypes experienced higher mortality following kainic acid-induced seizures than their resistant counterparts. In contrast, most line differences were not recapitulated when flurothyl was used to elicit seizures. Stress reduced kainic acid-induced mortality rates in all lines except the HYPER rats, supporting previously established indications that the stress response of HYPER rats is abnormal. These combined results support a neurobiological link between epilepsy and depression, advancing us towards an animal model of their comorbidity.

GSK-3 is a viable potential target for therapeutic intervention in bipolar disorder

Bipolar disorder is a serious psychiatric condition that has been treated for over 50 years with lithium. Lithium is a well established glycogen synthase kinase-3 (GSK-3) inhibitor, suggesting that manipulating GSK-3 may have therapeutic value in treating bipolar disorder. GSK-3 is regulated by a wide variety of mechanisms including phosphorylation, binding with protein complexes, phosphorylation state of its substrates, cellular localization and autoregulation, thus providing a wide number of potential therapeutic mechanisms. Mounting evidence suggests that GSK-3 regulation can be used to manage bipolar disorder symptoms. Although GSK-3 mutations have not been detected amongst the general bipolar population, they have been correlated with females with bipolar II and most of the drugs used for successful bipolar disorder treatment regulate GSK-3. These drugs produce a weak anti-depressant-like and a strong anti-mania-like effect in a wide range of animal models tested, mirroring their utility in treating bipolar disorder symptoms. Taken together, the evidence suggests that targeting GSK-3 may be a means to control the symptoms of bipolar disorder.