Oxcarbazepine

The Effect of Neuropsychiatric Drugs on the Oxidation-Reduction Balance in Therapy

The effectiveness of available neuropsychiatric drugs in the era of an increasing number of patients is not sufficient, and the complexity of neuropsychiatric disease entities that are difficult to diagnose and therapeutically is increasing. Also, discoveries about the pathophysiology of neuropsychiatric diseases are promising, including those initiating a new round of innovations in the role of oxidative stress in the etiology of neuropsychiatric diseases. Oxidative stress is highly related to mental disorders, in the treatment of which the most frequently used are first- and second-generation antipsychotics, mood stabilizers, and antidepressants. Literature reports on the effect of neuropsychiatric drugs on oxidative stress are divergent. They are starting with those proving their protective effect and ending with those confirming disturbances in the oxidation-reduction balance. The presented publication reviews the state of knowledge on the role of oxidative stress in the most frequently used therapies for neuropsychiatric diseases using first- and second-generation antipsychotic drugs, i.e., haloperidol, clozapine, risperidone, olanzapine, quetiapine, or aripiprazole, mood stabilizers: lithium, carbamazepine, valproic acid, oxcarbazepine, and antidepressants: citalopram, sertraline, and venlafaxine, along with a brief pharmacological characteristic, preclinical and clinical studies effects.

Plasma exosomes proteome profiling discovers protein markers associated with the therapeutic effect of Chaihu-Longgu-Muli decoction on temporal lobe epilepsy

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) uses Chaihu-Longgu-Muli decoction (CLMD) to alleviate disease, clear away heat, calm the mind, and temper excitation. It has been widely used for the therapy of neuropsychiatric disorders including epilepsy, dementia, anxiety, insomnia, and depression for several centuries in China.

AIM OF THE STUDY

This study aims to analyze differentially expressed proteins (DEPs) in the plasma exosomes of patients with temporal lobe epilepsy (TLE) and after the Chaihu-Longgu-Muli Decoction (CLMD) therapy and to explore the biomarkers of TLE and the potential targets of CLMD in treating TLE.

MATERIALS AND METHODS

The plasma exosomes of normal people and patients with TLE before the treatment of oxcarbazepine (OXC) and combined treatment of OXC and CLMD (OXC.CLMD) were harvested. The exosomes were separated from plasma through ultracentrifugation and then identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and flow cytometry. The DEPs were analyzed by proteomics and then subjected to gene ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The protein level of key genes was detected using Western blot. A lithium chloride-pilocarpine-induced epilepsy rat model was established and treated with OXC alone, OXC. CLMD, and CLMD alone (low dose and high dose). Neuronal injury in the hippocampal dentate gyrus and ribosomal protein L6 (RPL6) expression in the brain tissues were detected using H&E staining, Nissl staining, and Western blot.

RESULTS

The proteomic analysis showed several DEPs were present among plasma exosomes in the four groups; DEPs were enriched in epilepsy-related function and pathway. Four key proteins were screened, including RPL6, Nucleolin (NCL), Apolipoprotein A1 (APOA1), and Lactate Dehydrogenase A (LDHA). Among them, RPL6, NCL, and LDHA protein levels were downregulated and APOA1 protein level was upregulated in the plasma exosomes of TLE patients. After OXC and OXC. CLMD treatment, the protein level of RPL6, NCL, and LDHA was increased, and the APOA1 protein level was decreased. Moreover, the RPL6 protein level was further elevated after OXC. CLMD treatment than that after OXC treatment. In the TLE rat model, neuronal degeneration and necrosis in the hippocampal dentate gyrus increased and RPL6 expression level decreased. After the treatment with OXC, OXC. CLMD, and CLMD alone, the degeneration and necrosis of neurons decreased, and the RPL6 expression level was increased; RPL6 upregulation was remarkably obvious after CLMD treatment.

CONCLUSIONS

RPL6, NCL, LDHA and APOA1 are the DEPs in the plasma exosomes of patients with TLE before and after therapy. RPL6 might be a potential biomarker of CLMD in treating TLE.

Neuroprotective Properties of Antiepileptics: What are the Implications for Psychiatric Disorders?

Since the discovery of the first antiepileptic compound, increasing attention has been paid to antiepileptic drugs (AEDs), and recently, with the understanding of the molecular mechanism underlying cells death, a new interest has revolved around a potential neuroprotective effect of AEDs. While many neurobiological studies in this field have focused on the protection of neurons, growing data are reporting how exposure to AEDs can also affect glial cells and the plastic response underlying recovery; however, demonstrating the neuroprotective abilities of AEDs remains a changeling task. The present work aims to summarize and review the literature available on the neuroprotective properties of the most commonly used AEDs. Results highlighted how further studies should investigate the link between AEDs and neuroprotective properties; while many studies are available on valproate, results for other AEDs are very limited and the majority of the research has been carried out on animal models. Moreover, a better understanding of the biological basis underlying neuro-regenerative defects may pave the way for the investigation of further therapeutic targets and eventually lead to an improvement in the actual treatment strategies.

A Combined Experimental and Computational Study of Novel Benzotriazinone Carboxamides as Alpha-Glucosidase Inhibitors

Diabetes is a chronic metabolic disorder of the endocrine system characterized by persistent hyperglycemia appears due to the deficiency or ineffective use of insulin. The glucose level of diabetic patients increases after every meal and medically recommended drugs are used to control hyperglycemia. Alpha-glucosidase inhibitors are used as antidiabetic medicine to delay the hydrolysis of complex carbohydrates. Acarbose, miglitol, and voglibose are commercial drugs but patients suffer side effects of flatulence, bloating, diarrhea, and loss of hunger. To explore a new antidiabetic drug, a series of benzotriazinone carboxamides was synthesized and their alpha-glucosidase inhibition potentials were measured using in vitro experiments. The compounds 14k and 14l were found to be strong inhibitors compared to the standard drug acarbose with IC50 values of 27.13 ± 0.12 and 32.14 ± 0.11 μM, respectively. In silico study of 14k and 14l was carried out using molecular docking to identify the type of interactions developed between these compounds and enzyme sites. Both potent compounds 14k and 14l exhibited effective docking scores by making their interactions with selected amino acid residues. Chemical hardness and orbital energy gap values were investigated using DFT studies and results depicted affinity of 14k and 14l towards biological molecules. All computational findings were found to be in good agreement with in vitro results.

Repurposing Carbamazepine To Treat Gonococcal Infection in Women: Oral Delivery for Control of Epilepsy Generates Therapeutically Effective Levels in Vaginal Secretions

Neisseria gonorrhoeae has developed resistance to all previous antibiotics used for treatment. This highlights a crucial need for novel antimicrobials to treat gonococcal infections. We previously showed that carbamazepine (Cz), one of the most commonly prescribed antiepileptic drugs, can block the interaction between gonococcal pili and the I-domain region of human complement receptor 3 (CR3)-an interaction that is vital for infection of the female cervix. We also show that Cz can completely clear an established N. gonorrhoeae infection of primary human cervical cells. In this study, we quantified Cz in serum, saliva, and vaginal fluid collected from 16 women who were, or were not, regularly taking Cz. We detected Cz in lower reproductive tract mucosal secretions in the test group (women taking Cz) at potentially therapeutic levels using a competitive ELISA. Furthermore, we found that Cz concentrations present in vaginal fluid from women taking this drug were sufficient to result in a greater than 99% reduction (within 24 h) in the number of viable gonococci recovered from ex vivo, human, primary cervical cell infections. These data provide strong support for the further development of Cz as a novel, host-targeted therapy to treat gonococcal cervicitis.

Adverse Fetal and Neonatal Outcomes following in-utero exposure to Oxcarbazepine: A Systematic Review and Meta-Analysis

AIM

This systematic review aims to assess the safety profile of oxcarbazepine during pregnancy.

METHODS

Observational studies that included women who took oxcarbazepine anytime during pregnancy were included in our systematic review. The review did not include non-English articles, reviews, meta-analyses, case reports, and animal studies. Different online sources such as MEDLINE, Cochrane library, Virtual Health Library, etc. were searched for published and unpublished literature. Assessment of the risk of bias in observational studies was done using the Newcastle-Ottawa Scale. The meta-analyses were performed using a random-effect model. GRADE was used for the evaluation of the quality of evidence for the primary outcomes.

RESULTS

We included 19 cohort studies with a total number of 5,071,137 patients, of which 2,450 were exposed to oxcarbazepine either as monotherapy or polytherapy. The summary odds ratio (OR) was 1.69 (95% CI, 0.95-2.98) for congenital malformations following in-utero exposure to oxcarbazepine as compared to the control group of unexposed patients [seven studies (n=625)], and was 1.19 (95% CI, 0.67-2.12) when compared to those following lamotrigine (LTG) exposure during pregnancy [3 studies (n=591)]. In total, three studies (n=770) reported the association between in-utero oxcarbazepine exposure and fetal/perinatal deaths. The meta-analysis yielded a summary OR of 3.33 (95% CI, 1.70-6.51).

SIGNIFICANCE

Our systematic review will help healthcare providers and guideline developers regarding the treatment of epilepsy and other neurological disorders during pregnancy. More cohort studies with a higher sample size concerning oxcarbazepine use in pregnant patients are required to truly assess the in-utero safety profile of the drug.

Current role of carbamazepine and oxcarbazepine in the management of epilepsy

Epilepsy is one of the most common neurological disorders, affecting approximately 50 million people worldwide. Despite a dramatic increase in treatment options over the past 30 years, it still ranks fourth in the world's disease burden. There are now close to 30 antiepileptic drugs (AEDs), with more than two thirds introduced to the market after carbamazepine (CBZ) and one third after its derivative, oxcarbazepine (OXC). Following the introduction of these newer AEDs, the role of CBZ and OXC in the therapeutic armamentarium for seizure control and effective epilepsy management needs to be reviewed. The main guidelines list both CBZ and OXC as first-line options or second-line alternatives for the treatment of focal-onset epilepsy and primary generalized tonic-clonic seizures. While evidence suggests that overall AEDs have similar efficacy, some newer AEDs may be better tolerated than CBZ. In line with this, there have been changes in treatment patterns, with many variations across different countries. However, CBZ remains among the two or three most prescribed drugs for focal epilepsy in many countries, and is widely used across Europe, Africa, South America, and Asia, where it represents a good compromise between cost, availability, and effectiveness. OXC is among the first-choice options for the initial treatment of focal-onset seizures in several countries, including the US and China, where the oral suspension is commonly prescribed. This review provides guidance on the optimal use of these two drugs in clinical practice, including in children, the elderly, and in pregnancy.

Antiepileptic drugs as analgesics/adjuvants in inflammatory pain: current preclinical evidence

Inflammatory pain is the most common type of pain that is treated clinically. The use of currently available treatments (classic analgesics - NSAIDs, paracetamol and opioids) is limited by insufficient efficacy and/or side effects/tolerance development. Antiepileptic drugs (AEDs) are widely used in neuropathic pain treatment, but there is substantial preclinical evidence on their efficacy against inflammatory pain, too. In this review we focus on gabapentinoids (gabapentin and pregabalin) and dibenzazepine AEDs (carbamazepine, oxcarbazepine, and recently introduced eslicarbazepine acetate) and their potential for relieving inflammatory pain. In models of somatic, visceral and trigeminal inflammatory pain, that have a translational value for inflammatory conditions in locomotor system, viscera and head/face, AEDs have demonstrated analgesic activity. This activity was mostly consistent, dependent on the dose and largely independent on the site of inflammation and method of its induction, nociceptive stimuli, species, specific drug used, its route of administration and dosing schedule. AEDs exerted comparable efficacy with classic analgesics. Effective doses of AEDs are lower than toxic doses in animals and, when expressed as equivalent human doses, they are largely overlapping with AEDs doses already used in humans for treating epilepsy/neuropathic pain. The main mechanism of antinociceptive/antihyperalgesic action of gabapentinoids in inflammatory pain models seems to be α₂δ-dependent suppression of voltage-gated calcium channels in primary sensory neurons that leads to reduced release of neurotransmitters in the spinal/medullar dorsal horn. The suppression of NMDA receptors via co-agonist binding site primarily at spinal sites, activation of various types of K⁺ channels at spinal and peripheral sites, and activation of noradrenergic and serotonergic descending pain modulatory pathways may also contribute. Inhibition of voltage-gated sodium channels along the pain pathway is probably the main mechanism of antinociceptive/antihyperalgesic effects of dibenzazepines. The recruitment of peripheral adrenergic and purinergic mechanisms and central GABAergic mechanisms may also contribute. When co-administered with classic/other alternative analgesics, AEDs exerted synergistic/additive interactions. Reviewed data could serve as a basis for clinical studies on the efficacy/safety of AEDs as analgesics/adjuvants in patients with inflammatory pain, and contribute to the improvement of the treatment of various inflammatory pain states.

Pharmacokinetic Properties of New Antiepileptic Drugs

Eight new antiepileptic drugs (AEDs) have been approved for use within the United States within the past decade. They are felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, and zonisamide. These afford clinicians with more options to increase efficacy and tolerability in the treatment of patients with epilepsy. Pharmacokinetic properties and drug interactions with other AEDs and other medications taken for comorbidities are individually discussed for each of these new agents. Drug concentrations are not routinely monitored for these newer agents, and there have been few studies designed to investigate their concentration-effect relationships. For most of these medications, the concentrations observed in responders and nonresponders overlap considerably and levels associated with efficacy are often associated with adverse events, complicating the definition of target ranges. Also, epilepsy manifests itself sporadically causing difficulty in clinically monitoring efficacy of medications. Therapeutic drug monitoring provides for the individualization of treatment for these agents, which is important because they demonstrate significant variability in inter- and intraindividual pharmaco-kinetic properties. Therapeutic drug monitoring also allows for identification of noncompliance, drug interactions, and toxicity. Current knowledge of the relationships between efficacy, toxicity, and drug concentrations is discussed.

Oxcarbazepine extended-release formulation in epilepsy

Oxcarbazepine (OXC) is a 10-keto-analogue of carbamazepine, which was developed and labeled as a follow-up antiepileptic drug, that was intended to overcome some of the pharmacological drawbacks of carbamazepine with similar efficacy. The main advantage is the nonoxidative metabolic pathway that allows a lower enzyme-induction profile and fewer drug interactions. OXC is rapidly and extensively reduced by cytosolic hepatic enzymes to its monohydroxylated derivative (MHD), thus OXC may be regarded as a prodrug with MHD representing the active antiepileptic agent. The immediate-release (IR) formulation of OXC (Trileptal(®), Timox(®)) has an almost complete bioavailibilty. It is rapidly absorbed and reaches peak concentrations after 1-3 h. MHD peak concentrations are measured within 4-12 h. Elimination half-life in healthy subjects is 1-5 h for OXC and 7-20 h for MHD. The OXC plasma concentration peak may have been responsible for side effects, such as dizziness, vertigo, coordination problems or blurred vision, which appeared more often with this formulation in individual cases than with the formulation available prior to 2000, or with another formulation that has been distributed in Scandinavian countries. Both possibilities offer a profile approaching the characteristics of an extended-release (ER) formulation. ER OXC was labeled in Germany in 2008 (Apydan(®) extent, Desitin Arzneimittel GmbH, Hamburg, Germany). Under steady-state conditions, Phase I studies show bioequivalence between IR and ER OXC. With ER OXC, OXC plasma peak concentrations and both OXC and MHD peak-trough fluctuations are markedly reduced. In clinical trials, comparisons between IR OXC twice daily versus ER OXC once daily failed to show significant differences; efficacy tended to be better with IR OXC, whereas OXC ER showed insignificant tolerability advantages. Another study is currently ongoing to compare the tolerability of both formulations under twice-daily administration conditions in patients with difficult-to-treat epilepsies who require a dosage increase of OXC and who are randomized to IR or ER OXC.

Oxcarbazepine for acute affective episodes in bipolar disorder

BACKGROUND

Oxcarbazepine, a keto derivative of the 'mood stabiliser' carbamazepine, may have efficacy in the treatment of acute episodes of bipolar disorder. Potentially, it may offer pharmacokinetic advantages over carbamazepine.

OBJECTIVES

To review the efficacy and acceptability of oxcarbazepine compared to placebo and other agents in the treatment of acute bipolar episodes including mania, mixed episodes and depression.

SEARCH METHODS

Electronic databases were searched up to 2 September 2011. Specialist journals and conference proceedings were handsearched. Authors, experts in the field and pharmaceutical companies were contacted requesting information on published and unpublished trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) which compared oxcarbazepine with placebo or alternative agents, where the stated intent of intervention was the acute treatment of bipolar affective disorder were sought. Participants with bipolar disorder of either sex and of all ages were included.

DATA COLLECTION AND ANALYSIS

Data were extracted from the original reports individually by two review authors. For dichotomous data, odds ratios (ORs) were calculated with 95% confidence intervals (CI). Continuous data were analysed using standardised mean differences (with 95% CI).

MAIN RESULTS

Seven studies were included in the analysis (368 participants in total). All were on mania, hypomania, mixed episodes or rapid-cycling disorder. Overall, their methodological quality was relatively low.There was no difference in the primary outcome analysis - a fall of  50% or more on the Young Mania Rating Scale (YMRS) - between oxcarbazepine and placebo (N=1, n=110, OR =2.10, 95% CI 0.94 to 4.73) in one study, conducted in children; no studies were available in adult participants.In comparison with other mood stabilisers, there was no difference between oxcarbazepine and valproate as an antimanic agent using the primary outcome (50% or more fall in YMRS, OR=0.44, 95% CI 0.10 to 1.97, 1 study, n=60, P=0.273) or the secondary outcome measure (differences in YMRS between the two groups, SMD=0.18, 95% CI -0.24 to 0.59, 2 studies, n=90, P=0.40). No primary or secondary efficacy outcome measures were found comparing oxcarbazepine with lithium monotherapy.As an adjunctive treatment to lithium, oxcarbazepine reduced depression rating scale scores more than carbamazepine in a group of manic participants on the Montgomery-Åsberg Depression Rating Scale (MADRS) (SMD=- 1.12, 95% CI -1.71 to -0.53, 1 study, n=52, P=0.0002) and on the Hamilton Depression Rating Scale (HDRS) (SMD=- 0.77, 95% CI -1.35 to -0.20, 1 study, n=52, P=0.008).There was a higher incidence of adverse effects, particularly neuropsychiatric, in participants randomised to oxcarbazepine compared to those on placebo (1 study, n=115, 17% to 39% of participants on oxcarbazepine had at least one such event compared to 7% to 10% on placebo).There was no difference in adverse events rates between oxcarbazepine and other mood stabilisers or haloperidol.

AUTHORS' CONCLUSIONS

Currently, there are insufficient trials of adequate methodological quality on oxcarbazepine in the acute treatment of bipolar disorder to inform us on its efficacy and acceptability. Studies predominantly examine the treatment of mania: there are data from subgroup analysis on mixed affective, hypomania and rapid-cycling states.From the few studies included in this review, oxcarbazepine did not differ in efficacy compared to placebo in children and adolescents. It did not differ from other active agents in adults. It may have a poorer tolerability profile compared to placebo. No data were found on outcomes relevant to patients and clinicians, such as length of hospital admission.  There is a need for adequately powered randomised controlled trials of good methodological quality to inform us of the therapeutic potential of oxcarbazepine across the spectrum of acute episodes in bipolar disorder.

Diagnosis and management of trigeminal neuropathic pains

SUMMARY Trigeminal neuropathic pains have presented diagnostic and therapeutic challenges to providers. In addition, knowledge of pathophysiology, current classification systems, taxonomy and phenotyping of these conditions are incomplete. While trigeminal neuralgia is the most identifiable and studied, other conditions are being recognized and require distinct management approaches. Furthermore, other facial pain conditions such as atypical odontalgia and burning mouth syndrome are now considered to have neuropathic elements in their etiology. This article reviews current knowledge on the pathophysiology, diagnosis and management of neuropathic pain conditions involving the trigeminal nerve, to include: trigeminal neuralgia, trigeminal neuropathic pain (with traumatically induced neuralgia and atypical odontalgia) and burning mouth syndrome. Treatment modalities are reviewed based on current and best available evidence. Trigeminal neuralgia is managed with anticonvulsant drugs as the first line, with surgical options providing variable results. Trigeminal neuropathic pain is managed medically based on the guidelines for other neuropathic pain conditions. Burning mouth syndrome is also treated with a number of neuropathic medications, both topical and systemic. In all these conditions, patients need to be thoroughly educated about their condition, involved in its management, and be provided with supportive and adjunctive treatment resources.

Headaches due to external compression

Headache is one of the most common types of recurrent pain in medical practice. Although nearly everyone has occasional headaches, there are well-defined headache disorders that vary in incidence and prevalence. Among the unusual headache syndromes, headache due to external compression is a poorly studied headache considered to arise as a result of continued stimulation of cutaneous nerves by the application of pressure over the scalp or forehead. The wearing of bands around the head, specifically goggles (such as those worn for swimming), tight hats, or even professional helmets have been described as causative factors. The pain is often constant and more severe at the location where the object is pressing the head. In predisposed patients (ie, those with migraine), external compression may lead to a more severe migrainous headache if the stimulus is prolonged. The mechanism responsible is the compression of trigeminal or occipital nerves branches. The headache resolves after pressure is relieved, or is prevented by avoiding the precipitating cause. Drugs are rarely used.

Medical management of trigeminal neuropathic pains

IMPORTANCE OF THE FIELD

Although trigeminal neuralgia has traditionally been considered the prime neuralgic condition in the face region, other forms of neuropathic pain are now being more frequently recognized and require recognition and a different management approach.

AREAS COVERED IN THIS REVIEW

This review principally covers medical management of trigeminal neuralgia; but also included is glossopharyngeal neuralgia, trigeminal neuropathic pain (atypical odontalgia) and burning mouth syndrome. Systematic reviews and guidelines will be discussed.

WHAT THE READER WILL GAIN

An update will be provided of drug therapy for these relatively rare facial pains.

TAKE HOME MESSAGE

Trigeminal neuralgia continues to be best managed using anticonvulsant drugs, the primary ones being carbamazepine and oxcarbazepine; baclofen may be helpful and, of the newly emerging drugs, pregabalin has potential. Glossopharyngeal neuralgia remains managed in the same way as trigeminal neuralgia. Trigeminal neuropathic pain is probably best managed according to guidelines used for the management of neuropathic pain, which include the use of tricyclic antidepressants, gabapentin, pregabalin, duloxetine, venalafaxine and topical lidocaine. Burning mouth syndrome is a neuropathic pain managed initially with topical clonazepam and then with other neuropathic drugs. Patients need to be involved in their management.

Therapy of trigeminal neuralgia secondary to multiple sclerosis

Trigeminal neuralgia occurs in approximately 1-2% of patients suffering from multiple sclerosis. Its pathophysiology is common to idiopathic forms and resides in altered properties of the sensory axonal membrane at the root entry zone into the pons, leading to parossistic firing. Antiepileptic drugs of the sodium channel blocker type, such as carbamazepine, lamotrigine, and phenytoin are highly effective in controlling pain. However, side effects on the CNS may, at higher doses, severely worsen the already impaired neurologic conditions in multiple sclerosis patients. Baclofen, a presynaptic muscle relaxant is also beneficial in trigeminal pain. Whatever the drug, habituation and loss of efficacy are likely to occur sooner or later. Symptomatic, neurolesive surgery is indicated in cases resistant or intolerant to medical therapy. Radiofrequency thermorhizotomy, either monitored by trigeminal evoked potentials or not, is the recommended procedure, as it may be considered the most reliable as far as localization and degree of lesion are concerned.

Synergistic interactions between paracetamol and oxcarbazepine in somatic and visceral pain models in rodents

BACKGROUND

Combination therapy is a valid approach in pain treatment, in which a reduction of doses could reduce side effects and still achieve optimal analgesia. We examined the effects of coadministered paracetamol, a widely used non-opioid analgesic, and oxcarbazepine, a relatively novel anticonvulsant with analgesic properties, in a rat model of paw inflammatory hyperalgesia and in a mice model of visceral pain and determined the type of interaction between components.

METHODS

The effects of paracetamol, oxcarbazepine, and their combinations were examined in carrageenan-induced (0.1 mL, 1%) paw inflammatory hyperalgesia in rats and in an acetic acid-induced (10 mg/kg, 0.75%) writhing test in mice. In both models, drugs were coadministered in fixed-dose fractions of the 50% effective dose (ED(50)), and type of interaction was determined by isobolographic analysis.

RESULTS

Paracetamol (50-200 mg/kg peroral), oxcarbazepine (40-160 mg/kg peroral), and their combination (1/8, 1/4, 1/3, and 1/2 of a single drug ED(50)) produced a significant, dose-dependent antihyperalgesia in carrageenan-injected rats. In the writhing test in mice, paracetamol (60-180 mg/kg peroral), oxcarbazepine (20-80 mg/kg peroral), and their combination (1/16, 1/8, 1/4, and 1/2 of a single drug ED(50)) significantly and dose dependently reduced the number of writhes. In both models, isobolographic analysis revealed a significant synergistic interaction between paracetamol and oxcarbazepine, with a >4-fold reduction of doses of both drugs in combination, compared with single drugs ED(50).

CONCLUSIONS

The synergistic interaction between paracetamol and oxcarbazepine provides new information about combination pain treatment and should be explored further in patients, especially with somatic and/or visceral pain.

Evaluation of bone turnover in epileptic children using oxcarbazepine

This study evaluated the effects of oxcarbazepine monotherapy on bone turnover in prepubertal and pubertal children. Thirty-four newly diagnosed pediatric patients with normal bone mineral density, serum biochemical markers of bone formation, and hormonal markers participated. Levels of 25-hydroxyvitamin D were significantly decreased after therapy compared with baseline values. Levels of gamma-glutamyl transferase, phosphorus, alkaline phosphatase, osteocalcin, parathyroid hormone, and calcitonin had increased. However, only changes in osteocalcin and gamma-glutamyl transferase levels were statistically significant compared with baseline values. Drug-induced osteopenia was evident in 3 patients with z scores of bone-mineral density less than -2.0, whereas these patients had z scores of less than -1.5 before treatment. Although 18 months of oxcarbazepine treatment exerted slightly adverse effects on bone metabolism, the effect seems insignificant in children with normal bone-mineral density. Although alterations in bone metabolism do not always suffice to explain the decrease in bone-mineral metabolism, we think that patients with osteopenia before the initiation of oxcarbazepine therapy should be followed carefully, especially in long-term treatment.

Parent drug and/or metabolite? Which of them is most appropriate to establish bioequivalence of two oral oxcarbazepine formulations in healthy volunteers?

The bioequivalence of two 600-mg oxcarbazepine oral formulations (Aurene, Ivax Argentina, [test]; and Trileptal, Novartis Laboratories, [reference]) were assessed through the simultaneous determination of oxcarbazepine and the active metabolite 10,11-dyhydro-10-hydroxy-carbamazepine derivative (MHD). 12 healthy male volunteers received a single oral dose of 600 mg of each formulation, in a balanced, randomized, paired, crossover design, with a 7-day wash out period. Oxcarbazepine and MHD concentrations were established at 0.5,1, 1.5, 2, 3, 4, 6, 8, 24 and 48 h post dose by high performance liquid chromatography (HPLC). The regression coefficient determined for oxcarbazepine calibration curves was 0.9933 +/- 0.0236; and for MHD, was 0.9897 +/- 0.0017. The working range for both oxcarbazepine and its metabolite was from 0.1 to 10.0 microg/ml. The quantification limit was 0.1 microg/ml. The 90% confidence interval (CI) geometric mean for oxcarbazepine C(max), AUC(0-48 h) and AUC(0-infinity) ratios (test : reference) were 74.1-146.2%, 85.6-171.5% and 89.6-169.8%, respectively, and the 90% CI geometric mean for MHD C(max), AUC(0-48 h) and AUC(0-infinity) ratios (test : reference) were 84.0-122.3, 93.2-117.9 and 96.5-116.7, respectively. These results established the bioequivalence of two oxcarbazepine formulations from MHD kinetic data used in 12 healthy volunteers, while it was not possible to establish bioequivalence with oxcarbazepine. MHD quantification is preferred to that of the oxcarbazepine in order to assess bioequivalence, as the metabolite is responsible for the antiepileptic activity, presents linear kinetics in the therapeutic range, has lower intra-individual variability and higher plasma levels and half life than the parent drug.

Oxcarbazepine--efficacy and tolerability during treatment of alcohol withdrawal: a double-blind, randomized, placebo-controlled multicenter pilot study

OBJECTIVE

Alcohol withdrawal syndrome (AWS) is a serious complication of alcohol dependence and often requires intensive medical treatment. Antiepileptic drugs (AEDs) have been shown to be as efficacious in the treatment of AWS in several controlled trials as benzodiazepines and superior to placebo in relieving alcohol withdrawal symptoms. Oxcarbazepine (OXC), a newer anticonvulsive drug, has a favorable safety profile over carbamazepine (CBZ) and other older AEDs due to its excellent efficacy and better side-effect profile.

METHODS

The efficacy and tolerability of OXC versus placebo were investigated in 50 inpatients during a 6-day treatment of alcohol withdrawal in a 4-site, double-blind, randomized, placebo-controlled pilot study. The amount of rescue medication of clomethiazole (CLO) capsules needed was chosen as the primary variable. The data were collected between May 2003 and September 2004.

RESULTS

No initial differences were found regarding sociodemographic data and alcohol-related parameters, indicating successful randomization. No differences were found in the need for rescue medication CLO, decrease of withdrawal symptoms, or craving for alcohol between the OXC and the placebo group. Subjectively experienced side effects, normalization of vegetative parameters, craving, or improvement of psychopathological parameters were not different between the groups.

CONCLUSION

Despite the negative finding, which may be attributable to the design of the study, OXC still poses an interesting alternative to CBZ and other drugs because other studies have found it not only as efficient but also as having no addictive potential, while additionally possessing an anti-craving effect. Therefore, well-designed investigations with larger cohorts are required to further elucidate this issue.

High and low dosage oxcarbazepine versus naltrexone for the prevention of relapse in alcohol-dependent patients

INTRODUCTION

Oxcarbazepine (OXC) reduces high-voltage-activated calcium currents, thus reducing glutamatergic transmission at corticostriatal synapses. This effect on NMDA glutamatergic transmission may play a role against the increased glutamatergic transmission determined by alcohol withdrawal. To investigate the efficacy and safety of OXC in relapse prevention we compared OXC at different dosages with Naltrexone (NAL) in a 90 days randomised open-label trial. Craving and psychiatric symptoms improvements were the secondary endpoints.

METHODS

Eighty-four detoxified alcohol dependent subjects currently meeting clinical criteria for alcohol dependence were randomised into three groups: 27 patients received 50 mg of naltrexone, 29 received 1500-1800 mg of oxcarbazepine (OXC high), 28 patients 600-900 mg of oxcarbazepine (OXC low). Craving (VAS; OCDS) and withdrawal (AWRS) rating scales were applied; psychiatric symptoms were evaluated through the SCL-90-R.

RESULTS

A significantly larger number of subjects remained alcohol free in the OXC high group (58.6%) with respect to both the OXC low (42.8%) and the NAL groups (40.7%). Comparing the OCDS total scores at the end of the treatment, the improvement was significantly greater for the NAL group with respect to the OXC low group. The reduction of the Hostility-Aggression subscore of the SCL-90-R was significantly greater in the OXC high group than that of the other groups. Dual diagnosis patients had a better outcome when treated with OXC high.

DISCUSSION

OXC at a dosage of 1500-1800 mg/day might be beneficial in terms of alcohol relapse prevention. The low dosage formulation did not show the same trend, but it still remain in the same range as NAL. The mechanism involved in the efficacy of oxcarbazepine in relapse prevention could be less related to craving and more connected to the treatment of the comorbid psychiatric symptomatology and the alcohol protracted withdrawal syndrome.

Development and validation of a high performance liquid chromatographic method for the determination of oxcarbazepine and its main metabolites in human plasma and cerebrospinal fluid and its application to pharmacokinetic study

An isocratic reversed-phase HPLC-UV procedure for the determination of oxcarbazepine and its main metabolites 10-hydroxy-10,11-dihydrocarbamazepine and 10,11-dihydroxy-trans-10,11-dihydrocarbamazepine in human plasma and cerebrospinal fluid has been developed and validated. After addition of bromazepam as internal standard, the analytes were isolated from plasma and cerebrospinal fluid by liquid-liquid extraction. Separation was achieved on a X-TERRA C18 column using a mobile phase composed of 20 mM KH(2)PO(4), acetonitrile, and n-octylamine (76:24:0.05, v/v/v) at 40 degrees C and detected at 237 nm. The described assay was validated in terms of linearity, accuracy, precision, recovery and lower limit of quantification according to the FDA validation guidelines. Calibration curves were linear with a coefficient of variation (r) greater than 0.998. Accuracy ranged from 92.3% to 106.0% and precision was between 2.3% and 8.2%. The method has been applied to plasma and cerebrospinal fluid samples obtained from patients treated with oxcarbazepine, both in monotherapy and adjunctive therapy.

Efficacy, safety, and tolerability of oxcarbazepine monotherapy

OBJECTIVE

This prospective, open-label, multicenter study evaluated the efficacy and tolerability of oxcarbazepine as monotherapy in patients with partial seizures who switched from their current antiepileptic drug (AED) monotherapy because of lack of efficacy or poor tolerability.

METHOD

Patients (>or=12 years old) experiencing 2-40 seizures per month while receiving an AED were included. During a 16-week treatment phase, oxcarbazepine was initiated (8-10mg/kg for children; 600 mg/day for adults) and titrated up over 4 weeks while the existing AED was tapered off. Improvement in seizure frequency (defined as >or=50% reduction compared with baseline) was evaluated for all patients, as well as the subgroups of patients switched due to poor tolerability or lack of efficacy.

RESULTS

Overall, 52% of patients experienced a 50% reduction in seizure frequency, 35% had a >or=75% reduction, and 18% were seizure-free. The most frequent (>10%) adverse events were dizziness, nausea, headache, somnolence, and fatigue. Overall, 17% of patients prematurely withdrew because of an adverse event; 62% of these withdrawals occurred during the conversion period.

CONCLUSION

Oxcarbazepine as monotherapy may be a favorable treatment option for patients with partial seizures or poor tolerability of their existing monotherapy regimen.

Prevention of early postoperative seizures in patients with primary brain tumors: preliminary experience with oxcarbazepine

Early postoperative seizures are defined as those that appear within the first week after surgery and are a well-known and feared complication in patients with supratentorial brain tumors. Few studies have investigated the value of pharmacological prophylaxis in the prevention of postoperative seizures in these patients and their outcome has not been consistent. Furthermore, the efficacy of the new generation of antiepileptic agents in the prophylaxis of perioperative seizures has not been assessed so far. We analyzed the data related to 150 patients harboring supratentorial brain gliomas with the aim to assess the efficacy of oxcarbazepine in preventing the occurrence or the recurrence of early postoperative seizures and its tolerability when it is rapidly titrated. Only four patients (2.7%) experienced seizures within the first week after surgery. Patients did not report disturbances during the titration phase. Regarding adverse events in the first week, six patients (4%) showed minor skin rash. Persistent symptomatic hyponatremia never occurred. Our data showed that oxcarbazepine can be a good alternative to traditional antiepileptic agents in the prevention of perioperative seizures being efficacy, ease of use (rapid titration in 3 days, not requiring close plasma concentration monitoring) and good tolerability (no major side effects during titration and during the first postoperative week) the key factors. Moreover, oxcarbazepine can be a valid choice when long-term therapy is required because of the low interaction with other drugs and the low hematological side effects.

A pilot clinical trial of oxcarbazepine in adults with attention-deficit hyperactivity disorder

Despite the increasing recognition of attention-deficit hyperactivity disorder (ADHD) in adults, there is a paucity of controlled pharmacological trials. Recent reports have suggested the potential usefulness of mood stabilizing drugs for ADHD. To this end, the authors completed a pilot study with oxcarbazepine for the treatment of adults with ADHD. This was an open pilot study of oxcarbazepine (300-1,500 mg daily dosage) in adults who met DSM-IV criteria for ADHD. The treatment period was 8 weeks. Of the 9 subjects enrolled in the study (4 men, 5 women), 8 patients could be included in the analysis. At the endpoint of the active treatment, a significantly high proportion of subjects was considered improved while receiving oxcarbazepine. ADHD symptom checklist scores (ADHD-IV rating scale, Conners ADHD adult rating scale, ADHD self-rating [ADHD-SR] scale) showed significant reduction during the treatment period. Treatment with oxcarbazepine was relatively well tolerated; dizziness, sedation and nausea were the most frequently reported adverse effects. The results of this investigation indicate that oxcarbazepine may be a potentially useful agent for the treatment of ADHD in adults. However, placebo-controlled randomized trials are needed to provide evidence.

The effects of alpha2-adrenoceptor agents on anti-hyperalgesic effects of carbamazepine and oxcarbazepine in a rat model of inflammatory pain

In this study, the effects of yohimbine (alpha2-adrenoceptor antagonist) and clonidine (alpha2-adrenoceptor agonist) on anti-hyperalgesia induced by carbamazepine and oxcarbazepine in a rat model of inflammatory pain were investigated. Carbamazepine (10-40 mg/kg; i.p.) and oxcarbazepine (40-160 mg/kg; i.p.) caused a significant dose-dependent reduction of the paw inflammatory hyperalgesia induced by concanavalin A (Con A, intraplantarly) in a paw pressure test in rats. Yohimbine (1-3 mg/kg; i.p.) significantly depressed the anti-hyperalgesic effects of carbamazepine and oxcarbazepine, in a dose- and time-dependent manner. Both drug mixtures (carbamazepine-clonidine and oxcarbazepine-clonidine) administered in fixed-dose fractions of the ED50 (1/2, 1/4 and 1/8) caused significant and dose-dependent reduction of the hyperalgesia induced by Con A. Isobolographic analysis revealed a significant synergistic (supra-additive) anti-hyperalgesic effect of both combinations tested. These results indicate that anti-hyperalgesic effects of carbamazepine and oxcarbazepine are, at least partially, mediated by activation of adrenergic alpha2-receptors. In addition, synergistic interaction for anti-hyperalgesia between carbamazepine and clonidine, as well as oxcarbazepine and clonidine in a model of inflammatory hyperalgesia, was demonstrated.

Algorithm for neuropathic pain treatment: an evidence based proposal

New studies of the treatment of neuropathic pain have increased the need for an updated review of randomized, double-blind, placebo-controlled trials to support an evidence based algorithm to treat neuropathic pain conditions. Available studies were identified using a MEDLINE and EMBASE search. One hundred and five studies were included. Numbers needed to treat (NNT) and numbers needed to harm (NNH) were used to compare efficacy and safety of the treatments in different neuropathic pain syndromes. The quality of each trial was assessed. Tricyclic antidepressants and the anticonvulsants gabapentin and pregabalin were the most frequently studied drug classes. In peripheral neuropathic pain, the lowest NNT was for tricyclic antidepressants, followed by opioids and the anticonvulsants gabapentin and pregabalin. For central neuropathic pain there is limited data. NNT and NNH are currently the best way to assess relative efficacy and safety, but the need for dichotomous data, which may have to be estimated retrospectively for old trials, and the methodological complexity of pooling data from small cross-over and large parallel group trials, remain as limitations.

The anti-hyperalgesic effects of carbamazepine and oxcarbazepine are attenuated by treatment with adenosine receptor antagonists

The antinociceptive effects of carbamazepine and oxcarbazepine, and the influence of caffeine, were examined in a paw pressure test in rats. Carbamazepine (10-40 mg/kg; intraperitoneal, i.p.) and oxcarbazepine (40-160 mg/kg; i.p.) caused a significant dose-dependent reduction of the paw inflammatory hyperalgesia induced by concanavalin A (Con A), intraplantarly (i.p1.). A comparable pattern of antinociceptive effect of carbamazepine and oxcarbazepine was observed; the only difference is their potency, in that carbamazepine was about three times more potent than oxcarbazepine. Caffeine (5-20mg/kg; i.p.), a non-selective adenosine receptor antagonist, significantly depressed the antinociceptive effects of carbamazepine and oxcarbazepine, in a dose- and time-dependent manner. Also, a significant depression of the antinociceptive effects of carbamazepine and oxcarbazepine was observed by pretreatment with 1,3-dipropyl-8-cyclopentylxantine (DPCPX, 0.4 and 0.8 mg/kg; i.p.), an adenosine A(1) receptor antagonist. These findings indicate that, in a paw inflammatory hyperalgesia in rats, the antinociceptive effects of both drugs are, at least partially, mediated by adenosine A(1) receptors. In conclusion, the present study suggests the potential clinical importance of carbamazepine and oxcarbazepine in the treatment of inflammatory pain. In addition, caffeine consumption could possibly depress the analgesic effects of both anticonvulsive drugs.

Efficacy of Oxcarbazepine in the Treatment of Painful Diabetic Neuropathy

OBJECTIVES

To evaluate the safety, tolerability, and efficacy of oxcarbazepine in the treatment of painful diabetic neuropathy.

METHODS

This was an open-label, 9-week trial, consisting of a 1-week prospective Screening Phase followed by an 8-week Treatment Phase. Treatment with oxcarbazepine was initiated at 150 mg/day, and the daily dose was doubled on a weekly basis and titrated to tolerability over 4 weeks, up to 1200 mg/day. This was followed by a 4-week fixed-dose Maintenance Phase, during which patients were maintained on oxcarbazepine at 1200 mg/day or highest tolerated dose. The primary efficacy variable was the change in the weekly pain rating assessed on the Visual Analog Scale (VAS) of the short-form McGill Pain Questionnaire between the Screening Phase and the Treatment Phase. All analyses were performed on the intent-to-treat population.

RESULTS

Thirty patients were enrolled in the trial. The mean daily oxcarbazepine dose during the Maintenance Phase was 814 mg. The mean VAS score dropped from 66.3 during the Screening Phase to 34.3 at the end of the trial (P = 0.0001), for a mean reduction of 48.3%. In addition, there were significant improvements in the total pain score and present pain intensity. Oxcarbazepine was well tolerated, with the most common adverse events consisting of drowsiness and dizziness.

DISCUSSION

The results suggest that oxcarbazepine administered as monotherapy is an efficacious and safe option for the symptomatic treatment of pain associated with symmetrical diabetic neuropathy. These results will need to be confirmed in large, double-blind, placebo-controlled, randomized clinical trials.

Adjunctive oxcarbazepine in comorbid anxiety and affective disorder with hyponatremic seizure: case analysis and literature review

Rational polypharmacy is required for management of refractory psychiatric disorders. Antiepileptic drugs are increasingly used as primary or adjunctive agents in the treatment of affective, schizoaffective, anxiety, and impulse control disorders. In this case report, the authors present the first case of hyponatremic seizure associated with oxcarbazepine in adjunctive treatment of comorbid affective/anxiety disorders.

Oxcarbazepine: clinical experience with hospitalized psychiatric patients

BACKGROUND

Oxcarbazepine (10-keto-carbamazepine) appears to be better tolerated and simpler to use than carbamazepine. It has antimanic effects but, as its potential clinical usefulness and tolerability in broad samples of psychiatric patients remain to be tested, we reviewed both the pharmacology of oxcarbazepine and our early experience with this new agent among psychiatric inpatients.

METHODS

We reviewed medical records of all inpatients given oxcarbazepine in the first 15 months of its use at McLean Hospital. Data analyzed included dosing, presenting illnesses, other medications, clinical changes, and adverse effects.

RESULTS

Oxcarbazepine was given to 56 inpatients (1.3% of admissions; 31 women, 25 men) presenting with depression (n = 23), mania (n = 19), or psychosis (n = 14). The discharge daily dose for the 43 patients (76%) taking oxcarbazepine was 831 mg/day, 34% higher in men than women, and fell by 9 mg/year-of-age. Oxcarbazepine was the only putative mood-stabilizing agent given at discharge in 19 of 43 cases (44%). It was discontinued in 20% of patients for apparent inefficacy, and 4% for adverse effects. Changes in CGI and GAF scores were similarly high across illnesses, and unrelated to days of use of oxcarbazepine or its dose.

CONCLUSIONS

Oxcarbazepine was well tolerated and simpler to use clinically than its precursor carbamazepine. This agent should be studied in controlled trials to test its efficacy in specific types of major psychiatric disorders, and particularly for long-term maintenance treatment in bipolar disorder.

Sustained efficacy and long-term safety of oxcarbazepine: one-year open-label extension of a study in refractory partial epilepsy

PURPOSE

To evaluate the long-term efficacy, tolerability, and safety of oxcarbazepine (OXC) in medically refractory partial epilepsy.

METHODS

This study is the open-label extension phase that followed a multicenter, randomized, double-blind, dose-response clinical study of OXC monotherapy in patients with medically refractory partial epilepsy. We analyzed the efficacy, tolerability, and safety of OXC during the first 48 weeks of open-label therapy. To evaluate efficacy, we compared the change in seizure frequency throughout the 48 weeks of treatment with OXC with the baseline seizure frequency that preceded the double-blind phase of the core study by an intent-to-treat and completer analysis. Safety and tolerability were evaluated by using an intent-to-treat analysis.

RESULTS

Of the 87 patients enrolled in the double-blind study, 76 patients participated in the open-label extension phase. Fifty-five (72%) patients completed 48 weeks of open-label treatment on a median OXC dose of 2,400 mg/day. Based on an intent-to-treat analysis, the median reduction in seizure frequency was 47%(p = 0.0054); the 50 and 75% responder rates were 46.1 and 25.0%, respectively, with 6.6% of patients remaining seizure free. The completer analysis yielded comparable efficacy results. OXC was well tolerated, with 13% of patients exiting because of adverse events. The six most common adverse events, irrespective of their causal relation to OXC, were dizziness, headache, fatigue, diplopia, nausea, and rash. For the most part, these adverse events tended to be transient.

CONCLUSIONS

The efficacy of OXC is sustained with good safety and tolerability profiles during long-term treatment of patients with medically refractory partial epilepsy.

Rationale and evidence for the use of oxcarbazepine in neuropathic pain

Oxcarbazepine is a second-generation antiepileptic drug (AED) with proven efficacy in managing partial epileptic seizures, with or without secondary generalization, in adults and children. The overlap between the underlying pathophysiologic mechanisms of some epilepsy models and neuropathic pain models supports the rationale for using certain AEDs in the treatment of neuropathic pain. Several AEDs have reportedly produced analgesia in a range of neuropathic pains, including painful diabetic neuropathy (PDN) and post-herpetic neuralgia. Increasing evidence suggests that oxcarbazepine can provide significant analgesia in several neuropathic pain conditions, including trigeminal neuralgia and PDN, and is also may be effective in treating neuropathic pain refractory to other AEDs, such as carbamazepine and gabapentin. The analgesic effects of oxcarbazepine, and its generally improved safety and tolerability profile compared with other standard AEDs, suggests that oxcarbazepine will be an important addition to the neuropathic pain armamentarium. The rationale and evidence to support the efficacy of oxcarbazepine are presented here.

Safety and tolerability of oxcarbazepine in elderly patients with epilepsy

Despite the high incidence of seizures and epilepsy in the elderly, the tolerability and safety of anticonvulsants are rarely evaluated in this patient population. We compared the safety and tolerability of oxcarbazepine in a cohort of 52 patients aged 65 years and older and a group of 1574 adult patients ranging in age between 18 and 64 years. There was no significant difference between the two groups with respect to premature discontinuation due to adverse events. The four most common adverse events experienced by patients in the elderly group, irrespective of their causal relationship to oxcarbazepine, were vomiting (19%), dizziness (17%), nausea (17%), and somnolence (15%). Three patients developed an asymptomatic hyponatremia, with at least one serum sodium level below 125mEq/L. Elderly patients on concomitant natriuretic drugs were significantly more likely to develop serum sodium levels below 135mEq/L. The results indicate that oxcarbazepine is safe to use in elderly patients and that its tolerability in this age group is similar to that of younger adult patients.

Liquid chromatographic determination of oxcarbazepine and its metabolites in plasma of epileptic patients after solid-phase extraction

A method based on high-performance liquid chromatography with UV detection in combination with solid-phase extraction for sample pretreatment has been developed for the simultaneous analysis of the antiepileptic drug oxcarbazepine and its main metabolites in human plasma. The extraction of the analytes from plasma samples was carried out by means of a selective solid-phase extraction procedure using hydrophilic-lipophilic balance cartridges. The separation was obtained on a reversed-phase column (C(18), 150x4.6 mm I.D., 5 micrometer) using a phosphate buffer-acetonitrile-methanol-triethylamine mixture (final apparent pH* 3.5) as the mobile phase. Under these chromatographic conditions, oxcarbazepine and its metabolites 10,11-dihydro-10-hydroxycarbamazepine, 10,11-dihydro-10,11-dihydroxycarbamazepine and the internal standard are baseline separated in less than 9 min. The extraction yield values were >94% for all analytes and the precision, expressed by the RSD%, was in the low percentage range. For the entire method, including sample pre-treatment and HPLC determination, the linearity of the calibration lines, expressed by the linear correlation coefficient, was better than 0.995; the limit of quantitation was 15 ng ml(-1). The method was applied to plasma samples from patients undergoing chronic treatment with oxcarbazepine, both in monotherapy and in polytherapy. Based on the analytical parameters precision, accuracy, limit of quantitation and analysis time the method is suitable for routine application in therapeutic drug monitoring.