Lamotrigine in mood disorders

SUMMARY

Lamotrigine is an anticonvulsant drug with good efficacy and safety in the treatment of epilepsy. There is now substantial evidence that lamotrigine is also useful in treating resistant depression, rapid cycling bipolar affective disorder, depressive episodes in bipolar affective disorder and in the maintenance phase or prophylaxis of bipolar affective disorder. There are possible roles in managing mood changes in borderline personality disorder, reducing chronic pain and treating schizoaffective disorder.

The general range of doses found effective in affective disorders is from 50 to 300?mg daily.

Clinical use seems to involve a titration of dose upwards over several weeks until the desired ! effect is obtained.

However, further definitive double-blind, randomised controlled trials against gold standard treatments are required.

Lamotrigine has a preferable side-effect profile compared to standard agents for bipolar affective disorder such as lithium or carbamazepine. Further research is certainly warranted and, given its tolerability, could point to lamotrigine as the treatment of choice for some affective disorders.     

Lamotrigine: a review of its use in bipolar disorder

Lamotrigine (Lamictal), a phenyltriazine derivative, is a well established anticonvulsant agent that has shown efficacy in the prevention of mood episodes in adult patients with bipolar I disorder. The mechanism of action of the drug in patients with bipolar disorder may be related to the inhibition of sodium and calcium channels in presynaptic neurons and subsequent stabilisation of the neuronal membrane. Lamotrigine monotherapy significantly delayed time to intervention with additional pharmacotherapy or electroconvulsive therapy for any new mood episode (mania, hypomania, depression and mixed episodes), compared with placebo, in two large, randomised, double-blind trials of 18 months' duration. Additionally, lamotrigine was significantly superior to placebo at prolonging time to intervention for depression. These effects of lamotrigine were demonstrated in both recently manic/hypomanic and recently depressed patients. Lamotrigine showed efficacy in delaying manic/hypomanic episodes in pooled data only, although lithium was superior to lamotrigine on this measure. Two of four double-blind, short-term studies have shown lamotrigine to be more effective than placebo in the treatment of patients with treatment-refractory bipolar disorder or those with bipolar depression. Lamotrigine has not demonstrated efficacy in the treatment of acute mania.Lamotrigine was generally well tolerated in maintenance studies with the most common adverse events being headache, nausea, infection and insomnia. Incidences of diarrhoea and tremor were significantly lower in lamotrigine- than in lithium-treated patients. The incidence of serious rash with lamotrigine treatment was 0.1% in all studies of bipolar disorder and included one case of mild Stevens-Johnson syndrome. Lamotrigine did not appear to cause bodyweight gain. The dosage of lamotrigine is titrated over a 6-week period to 200 mg/day to minimise the incidence of serious rash. Adjustments to the initial and target dosages are required if coadministered with valproate semisodium or carbamazepine. CONCLUSION: Lamotrigine has been shown to be an effective maintenance therapy for patients with bipolar I disorder, significantly delaying time to intervention for any mood episode. Additionally, lamotrigine significantly delayed time to intervention for a depressive episode and showed limited efficacy in delaying time to intervention for a manic/hypomanic episode, compared with placebo. Although not approved for the short-term treatment of mood episodes, lamotrigine has shown efficacy in the acute treatment of patients with bipolar depression but has not demonstrated efficacy in the treatment of acute mania. Lamotrigine is generally well tolerated, does not appear to cause bodyweight gain and, unlike lithium, generally does not require monitoring of serum levels.     

拉莫三嗪治疗双相情感障碍的研究进展

拉莫三嗪作为心境稳定剂治疗双相情感障碍已经应用于临床。在2013年最新的CANMAT指南中新增了拉莫三嗪单药或联合其他药物的治疗方案,提示目前应用拉莫三嗪治疗双相情感障碍已受到广泛关注。本文综述了近几年拉莫三嗪在治疗双相情感障碍各亚型中的临床研究、安全性及应用前景,为双相障碍的治疗提供新观点及新思路。     

Spotlight on lamotrigine in bipolar disorder

Lamotrigine (Lamictal), a phenyltriazine derivative, is a well established anticonvulsant agent that has shown efficacy in the prevention of mood episodes in adult patients with bipolar I disorder. The mechanism of action of the drug in patients with bipolar disorder may be related to the inhibition of sodium and calcium channels in presynaptic neurons and subsequent stabilisation of the neuronal membrane. Lamotrigine monotherapy significantly delayed time to intervention with additional pharmacotherapy or electroconvulsive therapy for any new mood episode (mania, hypomania, depression and mixed episodes), compared with placebo, in two large, randomised, double-blind trials of 18 months' duration. Additionally, lamotrigine was significantly superior to placebo at prolonging time to intervention for depression. These effects of lamotrigine were demonstrated in both recently manic/hypomanic and recently depressed patients. Lamotrigine showed efficacy in delaying manic/hypomanic episodes in pooled data only, although lithium was superior to lamotrigine on this measure. Two of four double-blind, short-term studies have shown lamotrigine to be more effective than placebo in the treatment of patients with treatment-refractory bipolar disorder or those with bipolar depression. Lamotrigine has not demonstrated efficacy in the treatment of acute mania. Lamotrigine was generally well tolerated in maintenance studies with the most common adverse events being headache, nausea, infection and insomnia. Incidences of diarrhoea and tremor were significantly lower in lamotrigine- than in lithium-treated patients. The incidence of serious rash with lamotrigine treatment was 0.1% in all studies of bipolar disorder and included one case of mild Stevens-Johnson syndrome. Lamotrigine did not appear to cause bodyweight gain. The dosage of lamotrigine is titrated over a 6-week period to 200 mg/day to minimise the incidence of serious rash. Adjustments to the initial and target dosages are required if coadministered with valproate semisodium or carbamazepine. CONCLUSION: Lamotrigine has been shown to be an effective maintenance therapy for patients with bipolar I disorder, significantly delaying time to intervention for any mood episode. Additionally, lamotrigine significantly delayed time to intervention for a depressive episode and showed limited efficacy in delaying time to intervention for a manic/hypomanic episode, compared with placebo. Although not approved for the short-term treatment of mood episodes, lamotrigine has shown efficacy in the acute treatment of patients with bipolar depression but has not demonstrated efficacy in the treatment of acute mania. Lamotrigine is generally well tolerated, does not appear to cause bodyweight gain and, unlike lithium, generally does not require monitoring of serum levels.     

Potential mechanisms of action of lamotrigine in the treatment of bipolar disorders

Based on the mood-stabilizing properties of carbamazepine and valproate, new anticonvulsants have been explored for use in bipolar disorders. One such agent, lamotrigine, has a novel clinical profile in that it may "stabilize mood from below," as it appears to maximally impact depressive symptoms in bipolar disorders. In this paper, we review the mechanisms of action of lamotrigine in an effort to understand the basis of its distinctive clinical use in the management of bipolar disorders as well as its diverse antiseizure effects. We consider lamotrigine mechanisms, emphasizing commonalities and dissociations among actions of lamotrigine, older mood stabilizers, and other anticonvulsants. Although ion channel effects, especially sodium channel blockade, may importantly contribute to antiseizure effects, such actions may be less central to lamotrigine thymoleptic effects. Antiglutamatergic and neuroprotective actions are important candidate mechanisms for lamotrigine psychotropic effects. Lamotrigine has a variable profile in kindling and contingent tolerance experiments and does not appear to have robust gamma-aminobutyric acid or monoaminergic actions. Lamotrigine intracellular signaling effects warrant investigation. Although lamotrigine mechanisms overlap those of other mood-stabilizing anticonvulsants, important dissociations suggest candidate mechanisms, which could contribute to lamotrigine's distinctive psychotropic profile.     

Chronic lamotrigine does not alter the turnover of arachidonic acid within brain phospholipids of the unanesthetized rat: implications for the treatment of bipolar disorder

Rationale Drugs that are effective in treating the manic phase of bipolar disorder (lithium, carbamazepine, and valproate) upon chronic administration to rats decrease the turnover of arachidonic acid in their brain phospholipids. Lamotrigine may not be effective in the manic phase, but is effective in delaying the depressive phase and for treating rapid cycling bipolar disorder. Thus, lamotrigine provides a pharmacological tool to differentiate if downregulation of arachidonic acid turnover is specific to drugs effective in the manic phase of bipolar disorder. Materials and methods To test this hypothesis, rats were administered lamotrigine (10 mg kg⁻¹ day⁻¹) or vehicle intragastrically once daily for 42 days. In the unanesthetized rat, [1-¹⁴C]arachidonic acid was infused intravenously and arterial blood plasma was sampled until the animal was killed at 5 min, and its microwaved brain was subjected to chemical and radiotracer analysis. Results Using equations from our fatty acid model, we found that chronic lamotrigine compared with vehicle did not alter the net incorporation rate of plasma arachidonic acid into brain phospholipids, nor did it alter the turnover of arachidonic acid within brain phospholipids. Conclusion Chronic lamotrigine, which is effective in the depressive phase or rapid cycling bipolar disorder does not alter brain arachidonic acid turnover in the unanesthetized rat. These results are consistent with the hypothesis that drugs effective in treating the manic phase of bipolar disorder decrease brain arachidonic acid turnover.     

Safety and tolerability of mood-stabilising anticonvulsants in the elderly

The authors review current research on the safety and tolerability of anticonvulsant medications used for individuals over the age of 60 years with affective disorders, agitation and other psychiatric disorders. Three anticonvulsants currently approved in the US for treatment of bipolar affective disorder are reviewed: valproate, lamotrigine and extended-release carbamazepine. The authors discuss the pharmacokinetics, pharmacodynamics, drug-drug interactions and the impact of ageing for each drug. There are few studies of anticonvulsant medications in elderly patients with bipolar disorder or other psychiatric conditions. Therefore, the authors summarise adverse events of greatest prevalence and/or greatest severity based on data derived predominately from studies of geriatric patients with epilepsy and/or other non-psychiatric indications. Guidelines are offered for the safe use of these medications in the elderly, based on research literature.     

Lamotrigine in the treatment of bipolar disorder

Lamotrigine has undergone a remarkable series of systematic studies since 1994 that now establish it as an efficacious, well-tolerated treatment in bipolar disorder. Its efficacy principally addresses both acute and maintenance phase benefits on depressive symptomatology. These benefits have been demonstrated in placebo-controlled studies, rapid cycling patients, bipolar I and II patients and monotherapy as well as in combination therapy, although this has been less well studied. The drug is exceptionally well-tolerated in long-term treatment, although initial dosing requires gradual dosage escalation to avoid the risk of inducing serious rashes with features within the spectrum of Stevens–Johnson syndrome. Administration with valproate requires a slower dosage titration, whereas, as with many drugs, administration with carbamazepine requires a more rapid dosage increase. In contrast to marketed antidepressants, lamotrigine appears not to induce manic or hypo-manic episodes, nor to increase cycling frequency. This combination of properties makes it a first-choice treatment for acute bipolar depression and continuation treatment, especially, but not limited to, prophylaxis against recurrent depression and depressive symptoms. Lamotrigine appears not to have acute antimanic properties. A small number of studies suggest a broader spectrum of efficacy, including in some axis I disorders that are comorbidly associated with bipolar disorder.     

Lamotrigine in the treatment of bipolar disorder

Lamotrigine has undergone a remarkable series of systematic studies since 1994 that now establish it as an efficacious, well-tolerated treatment in bipolar disorder. Its efficacy principally addresses both acute and maintenance phase benefits on depressive symptomatology. These benefits have been demonstrated in placebo-controlled studies, rapid cycling patients, bipolar I and II patients and monotherapy as well as in combination therapy, although this has been less well studied. The drug is exceptionally well-tolerated in long-term treatment, although initial dosing requires gradual dosage escalation to avoid the risk of inducing serious rashes with features within the spectrum of Stevens-Johnson syndrome. Administration with valproate requires a slower dosage titration, whereas, as with many drugs, administration with carbamazepine requires a more rapid dosage increase. In contrast to marketed antidepressants, lamotrigine appears not to induce manic or hypo-manic episodes, nor to increase cycling frequency. This combination of properties makes it a first-choice treatment for acute bipolar depression and continuation treatment, especially, but not limited to, prophylaxis against recurrent depression and depressive symptoms. Lamotrigine appears not to have acute antimanic properties. A small number of studies suggest a broader spectrum of efficacy, including in some axis I disorders that are comorbidly associated with bipolar disorder.     

Safety and tolerability of lamotrigine for bipolar disorder.

Tolerability and safety are important considerations in optimising pharmacotherapy for bipolar disorder. This paper reviews the tolerability and safety of lamotrigine, an anticonvulsant recommended in the 2002 American Psychiatric Association guidelines as a first-line treatment for acute depression in bipolar disorder and one of several options for maintenance therapy. This paper reviews the tolerability and safety of lamotrigine using data available from a large programme of eight placebo-controlled clinical trials of lamotrigine enrolling a total of nearly 1800 patients with bipolar disorder. This review is the first to collate all the safety information from these clinical trials, including data from four unpublished studies. The results these trials in which 827 patients with bipolar disorder were given lamotrigine as monotherapy or adjunctive therapy for up to 18 months for a total of 280 patient-years of exposure demonstrated that lamotrigine is well-tolerated with an adverse-event profile generally comparable with that of placebo. The most common adverse event with lamotrigine was headache. Lamotrigine did not appear to destabilise mood and was not associated with sexual adverse effects, weight gain, or withdrawal symptoms. Few patients experienced serious adverse events with lamotrigine, and the incidence of withdrawals because of adverse events was low. Serious rash occurred rarely (0.1% incidence) in the clinical development programme including both controlled and uncontrolled clinical trials. These findings - considered in the context of data showing lamotrigine to be effective for bipolar depression - establish lamotrigine as a well-tolerated addition to the psychotropic armamentarium.     

Gabapentin and lamotrigine in bipolar disorder.

The utility of gabapentin and lamotrigine for the treatment of bipolar disorder is reviewed. Bipolar disorder is characterized by extreme mood fluctuations, including mania, hypomania, depression, and mixed episodes. Extrapolation of postulated mechanisms of anticonvulsant activity in bipolar disorder has led to the use of the newer anticonvulsants gabapentin and lamotrigine for therapy. Both agents appear promising on the basis of limited (often anecdotal) evidence. They may prove effective in patients with difficult cases of bipolar disorder, such as patients with rapid cycling, mixed episodes, and illness refractory to other treatments. Lamotrigine may offer a much-needed treatment alternative for bipolar depression and could be found effective for acute mania, but the need for slow dosage adjustment and the risk of rash may limit overall clinical utility. Gabapentin may offer significant advantages for acute mania: The dosage can be adjusted rapidly, adverse effects are generally minimal, the therapeutic index is high, there is no required laboratory monitoring, and there is minimal potential for interactions with other psychotropics. Until the results of randomized controlled trials are known, however, these two agents should be reserved for patients with bipolar disorder unresponsive to traditional therapies and for patients who cannot tolerate traditional agents. Preliminary evidence indicates that gabapentin and lamotrigine may be useful for the treatment of bipolar disorder.     

The effects of lamotrigine on the pharmacokinetics of lithium

AIMS: The treatment of bipolar disorder often includes use of multiple drug therapies. Lithium is one of the most commonly used treatments, but has a narrow therapeutic window. Lamotrigine, an established antiepileptic drug, is emerging as a potentially important new therapy in the treatment of bipolar disorder. The objective of this two-treatment crossover study was to determine whether lamotrigine affects lithium pharmacokinetics. METHODS: Twenty healthy adult men completed the study. Subjects took 2 g lithium gluconate anhydrous every 12 h in the morning and evening for 5 days and in the morning of day 6, with or without 100 mg lamotrigine once daily in the morning for 6 days. Blood and urine samples were collected on day 6 of both treatments to characterize the pharmacokinetics of lithium using noncompartmental methods. RESULTS: The geometric least-square mean ratio for renal clearance of lithium between the combination treatment and lithium alone treatment was 0.93 (95% confidence interval 0.85-1.02). Both treatments were well tolerated. CONCLUSIONS: Lamotrigine does not cause significant change in the pharmacokinetics of lithium.     

Lack of pharmacokinetic interaction between lamotrigine and olanzapine in healthy volunteers

STUDY OBJECTIVE: To investigate the potential drug-drug interaction between lamotrigine, an antiepileptic agent used to treat bipolar disorders, and olanzapine, an atypical antipsychotic drug also used to treat bipolar disorders, both of which are metabolized by the uridine diphosphate glucuronosyltransferase system. DESIGN: Prospective cohort study. SETTING: University center for clinical research. SUBJECTS: Fourteen nonsmoking, healthy volunteers. INTERVENTION: Subjects received lamotrigine 25 mg/day for 5 days, then 50 mg/day for 10 days to achieve steady-state concentrations. On day 15, blood samples were obtained before and 0.5, 1, 2, 3, 4, 6, 8, 10, 12, and 24 hours after the dose. Lamotrigine 50 mg/day was then given for an additional 3 days. On the next day, lamotrigine 50 mg and olanzapine 5 mg were coadministered. Blood samples were obtained at the same times as before and at 48, 72, and 96 hours after dosing. MEASUREMENTS AND MAIN RESULTS: Blood samples were assayed for lamotrigine and olanzapine concentrations by means of high-performance liquid chromatography. Olanzapine did not significantly affect lamotrigine disposition, as we observed no differences in the area under the concentration-time curve from 0-24 hours or in lamotrigine plasma concentrations at baseline or at 24 hours. For lamotrigine, the mean time to reach maximum concentration was significantly prolonged during olanzapine coadministration (mean +/- SD 1.9 +/- 1.3 vs 4.0 +/- 3.0 hrs, p = 0.025), possibly because of the anticholinergic properties associated with olanzapine. Mild sedation was the only adverse effect that occurred during lamotrigine and olanzapine coadministration. CONCLUSION: Lamotrigine and olanzapine can safely be combined in healthy volunteers at the low doses studied, without a clinically significant interaction. When prescribing high doses of olanzapine and lamotrigine for bipolar disorder, patients must be carefully monitored.     

Lamotrigine prevents ketamine but not amphetamine-induced deficits in prepulse inhibition in mice

Rationale Lamotrigine, a broad-spectrum anticonvulsant known to block brain sodium channels, is effective in the treatment of persons with bipolar disorder, perhaps by virtue of its ability to reduce glutamate release. Furthermore, lamotrigine decreases the perceptual abnormalities produced by the N-methyl-d-aspartate (NMDA) antagonist ketamine in humans, similar to the effects of the atypical antipsychotic clozapine. Acutely manic bipolar patients, like persons with schizophrenia, Tourette's, and obsessive compulsive disorder, exhibit decreases in sensorimotor gating, as measured by prepulse inhibition of the startle response (PPI). Objective We assessed the ability of lamotrigine to reduce the PPI–disruptive effects of ketamine and the dopaminergic agent amphetamine in two inbred mouse strains, C57BL/6J and 129SvPasIco. Methods Mice were tested in a standard PPI paradigm after administration of lamotrigine (0, 6.7, 13, or 27 mg/kg) or a combination of lamotrigine (27 mg/kg) and either d-amphetamine (10 mg/kg) or ketamine (100 mg/kg). Results In the 129SvPasIco mice, lamotrigine reversed the ketamine-induced PPI deficit, without altering PPI in control mice. In C57BL/6J mice, however, 27 mg/kg lamotrigine generally increased PPI in both control and ketamine-treated mice. Lamotrigine did not ameliorate the amphetamine-induced PPI deficit in either strain. Conclusions In conclusion, lamotrigine can increase PPI on its own and prevent ketamine-induced, but not amphetamine-induced, disruptions of PPI. These results suggest that lamotrigine may exert its effects on PPI through the glutamatergic system.     

Newer antiepileptic drugs in bipolar disorder: rationale for use and role in therapy

Antiepileptic drugs (AEDS) are used regularly in the treatment of patients with bipolar disorders. Carbamazepine and valproic acid (sodium valproate) are effective as antimanic treatments, and the success of these medications has prompted investigation of other AEDs as possible treatments in patients with mood disorders. Lamotrigine appears to be the most promising of the newer AEDs with respect to effects in mood disorders. Current evidence suggests efficacy of this drug both as monotherapy and as an adjunctive agent in bipolar depression, and studies are underway to clarify its efficacy in mood stabilisation and rapid cycling, as currently available data are equivocal. Use of gabapentin is not as well supported in the literature, although data from open trials using it as an adjunctive agent suggest that it may be helpful in patients with bipolar depression. There have been some open trials and case reports supporting the use of topiramate as an adjunctive agent for the treatment of mania; however, data from controlled trials are not yet available. Further controlled trials of lamotrigine, gabapentin or topiramate as monotherapy and adjunctive treatment are needed to clarify their potential roles in the treatment of patients with mood disorders.     

A placebo-controlled,cross-over trial of lamotrigine in depersonalization disorder

There is evidence to support the view that glutamate hyperactivity might be relevant to the neurobiology of depersonalization. We tested the efficacy of lamotrigine, which reduces glutamate release, as a treatment for patients with depersonalization disorder. A double-blind, placebo-controlled, cross-over design was used to evaluate 12 weeks of treatment of lamotrigine. Subjects comprised nine patients with DSM-IV depersonalization disorder. Changes on the Cambridge Depersonalization Scale and the Present State Examination depersonalization/derealization items were compared across the two cross-over periods. Lamotrigine was not significantly superior to placebo. None of the nine patients was deemed a responder to the lamotrigine arm of the cross-over. Lamotrigine does not seem to be useful as a sole medication in the treatment of depersonalization disorder.     

拉莫三嗪与喹硫平治疗双相抑郁的对照研究

目的比较拉莫三嗪(利必通)和喹硫平(思瑞康)治疗双相抑郁的疗效及安全性。方法对71例符合CCMD-3诊断双相障碍(目前为抑郁发作)的患者按随机、平行、对照的方法分为拉莫三嗪组和喹硫平组,观察8周,分别于第0、2、4、6、8周末用HAMD、CGI评价疗效,于第2、4、6、8周末用TESS评定不良反应,于第4、8周末用BRMS评定躁狂症状。结果拉莫三嗪组的痊愈率34.21%,有效率65.79%,喹硫平组的痊愈率39.39%,有效率69.70%。两组疗效比较无显著性差异(P>0.05),两组不良反应发生率相当。结论拉莫三嗪和喹硫平均可首选用于双相抑郁治疗,且安全性、不良反应相当。     

Acute and maintenance treatment with mood stabilizers

Treatment of bipolar disorder is complicated by the multiple phases of the illness, dimensional symptomatology that varies considerably across individuals, and a limited spectrum of activity for all mood stabilizers. Randomized, blinded, placebo-controlled studies provide clear guidelines to the overall efficacy of treatments for mania. However, for secondary questions, such as the treatment to employ when lithium or valproate is inadequate as monotherapy, evidence is incomplete, and usually derived from both smaller and less well-designed studies. For mania, the spectrum of efficacy of valproate is broader than for other mood stabilizers. However, many patients obtain inadequate benefit from monotherapy regimens of all mood stabilizers. Recent studies indicate that for patients who develop mania while taking a mood stabilizer, combinations of an antipsychotic and a mood stabilizer yield greater improvement than does continuation of the mood stabilizer alone. Maintenance-treatment studies support the efficacy of lithium, valproate and lamotrigine, although with a different spectrum of benefits and limitations for each. Valproate and lithium provide greater benefits for prevention of manic relapses and control of manic symptomatology than for depression. Several studies indicate actual worsening in depressive aspects of bipolar disorder with lithium treatment. Lamotrigine appears effective in delaying relapse into a new episode, with most benefits limited to delaying time to depression. Lamotrigine has not shown anti-manic activity in placebo-controlled studies. In contrast to traditional antidepressant medications, lamotrigine has not been associated with induction of mania, or of rapid-cycling illness symptomatology. Recent studies reported that carbamazepine was inferior to valproate in acute mania, and inferior to lithium in maintenance treatment. Other putative mood stabilizers have to date yielded negative or inconclusive results in studies in mania. Systematic studies are needed to clarify treatment guidelines for youth with bipolar disorder, and for other special populations, e.g. pregnant women and the elderly.     

Anticonvulsants in the treatment of mood disorders: assessing current and future roles

Anticonvulsants are frequently used in the treatment of affective illnesses, especially for patients refractory to or intolerant of other treatments. The differential therapeutic roles of anticonvulsants, however, remain largely undetermined. The author reviews the available efficacy data for carbamazepine, oxcarbazepine, valproate, lamotrigine, gabapentin and topiramate. Valproate is efficacious in the monotherapy of acute manic presentations but confirmatory evidence of the efficacy of valproate in long-term maintenance has been elusive. Valproate and possibly carbamazepine, may provide a therapeutic advantage over lithium in non-classic bipolar conditions such as mixed mood states and rapid cycling conditions. Lamotrigine is unique among the anticonvulsants in its monotherapy efficacy for bipolar I depression. Emerging data also suggest a role for lamotrigine in the adjunctive treatment of depressive mixed states and rapid cycling conditions in the absence of prominent manic symptoms. Controlled trials have found gabapentin ineffective for acute mania and refractory bipolar conditions. The role of gabapentin in the treatment of other aspects of affective illness remains uncertain. Definitive statements regarding the differential psychotropic use of topiramate and oxcarbazepine are not possible, though active investigation is underway to better characterise the utility of topiramate. The author suggests that current diagnostic models utilised in controlled trials may limit identification of differential therapeutic benefits. Caution is advised in generalising from the ability or inability of an agent to demonstrate antimanic activity. Future studies of newer anticonvulsants should include dimensional perspectives and soft bipolar presentations, as the greatest contribution of the newer anticonvulsants may be in treatment of mood conditions other than acute mania.     

Bipolar comorbidity: from diagnostic dilemmas to therapeutic challenge

Comorbidity in bipolar disorder is the rule rather than the exception more than 60% of bipolar patients have a comorbid diagnosis and is associated with a mixed affective or dysphoric state; high rates of suicidality; less favourable response to lithium and poorer overall outcome. There is convincing evidence that rates of substance use and anxiety disorders are higher among patients with bipolar disorder compared to their rates in the general population. The interaction between anxiety disorders and substance use goes both ways: patients with bipolar disorder have a higher rate of substance use and anxiety disorder, and vice versa. Bipolar disorder is also associated with borderline personality disorder and ADHD, and to a lesser extent with weight gain. As more than 40% of bipolar patients have anxiety disorder, it is indicated that while diagnosing bipolar patients, systematic enquiry about different anxiety disorders is called for. This also presents a therapeutic challenge, since agents that effectively treat anxiety disorders are associated with the risk of induced mania. Therefore, the treating psychiatrist needs to carefully evaluate the potential benefit of treating the anxiety against the potential cost of inducing a manic episode. A possible solution would be to use, when possible, a non-pharmacological intervention, such as a cognitivebehavioural approach. Alternately, it is suggested that the clinician attempts to ensure that the patient receives adequate treatment with mood stabilizers before slowly and carefully attempting the addition of anti-anxiety compounds with a relatively lower risk of mania induction (e.g. SSRIs compared to TCAs).