Oxcarbazepine, an antiepileptic agent

Madhuca indica oil-entrapped buoyant galactomannan hydrogel microspheres for controlling epileptic seizures

A stable Madhuca indica oil-in-water nanoemulsion (99-210 nm, zeta potential: > - 30 mV) was produced employing Tween 20 (surfactant) and Transcutol P (co-surfactant) (3:1). The nanoemulsion (oil: Smix = 3:7, 5:5, and 7:3) were subsequently incorporated into oxcarbazepine-loaded carboxymethylxanthan gum (DS = 1.23) dispersion. The hydrogel microspheres were formed using the ionic gelation process. Higher oil concentration had a considerable impact on particle size, drug entrapment efficiency, and buoyancy. The maximum 92 % drug entrapment efficiency was achieved with the microspheres having oil: Smix ratio 5:5. FESEM study revealed that the microspheres were spherical in shape and had an orange peel-like surface roughness. FTIR analysis revealed a hydrogen bonding interaction between drug and polymer. Thermal and x-ray examinations revealed the transformation of crystalline oxcarbazepine into an amorphous form. The microspheres had a buoyancy period of 7.5 h with corresponding release of around 83 % drug in 8 h in simulated stomach fluid, governed by supercase-II transport mechanism. In vivo neurobehavioral studies on PTZ-induced rats demonstrated that the microspheres outperformed drug suspension in terms of rotarod retention, number of crossings, and rearing activity in open field. Thus, Madhuca indica oil-in-water nanoemulsion-entrapped carboxymethyl xanthan gum microspheres appeared to be useful for monitoring oxcarbazepine release and managing epileptic seizures.

Effects of sodium valproate and levetiracetam on posterior segment parameters in children with epilepsy

PURPOSE

To evaluate changes in posterior segment parameters in pediatric patients with epilepsy using sodium valproate or levetiracetam monotherapy for at least 12 months.

METHODS

This study included 45 children with generalized epilepsy aged 6-17 years and 32 age- and gender-matched healthy subjects. The patients were assigned to three groups: Group 1 included patients using valproate monotherapy at a dose of 20-40 mg/kg/day, group 2 included patients using levetiracetam monotherapy at a dose of 20-40 mg/kg/day, and group 3 consisted of healthy controls. Peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell layer-inner plexiform layer (mGCIPL) thicknesses were measured using spectral-domain optical coherence tomography (OCT).

RESULTS

No significant differences were noted between the groups regarding age, gender distribution, visual acuity, spherical equivalent, and intraocular pressure (p > 0.05). The average and temporal, nasal, and superior quadrants RNFL values were significantly thinner in group 1 than in group 2 (p = 0.001, p = 0.023, p = 0.011, and p = 0.001, respectively) and group 3 (p < 0.001, p = 0.032, p < 0.001, and p = 0.001, respectively). The OCT parameters were similar in groups 2 and 3 (p > 0.05). A negative correlation was observed in group 1 between only the average mGCIPL and the treatment dose (r =  - 0.501). In group 2, no significant correlation was found between OCT parameters and the duration of epilepsy treatment, dose of treatment, and age at treatment onset values (p > 0.05).

CONCLUSION

These findings support that there is an association between sodium valproate treatment and the reduction of RNFL thickness in epilepsy. Levetiracetam treatment appears to be a safe option, but care should be taken regarding ocular side effects that may occur with long-term and high-dose use of sodium valproate.

Synthetic Potential of Regio- and Stereoselective Ring Expansion Reactions of Six-Membered Carbo- and Heterocyclic Ring Systems: A Review

Ring expansion reactions fascinate synthetic chemists owing to their importance in synthesizing biologically active compounds and their efficacy in medicinal chemistry. The present review summarizes a number of synthetic methodologies, including stereoselective and regioselective pathways adopted by scientists, for framing medium- to large-size carbo- and heterocycles involving lactams, lactone, azepine and azulene derivatives via ring expansion of six-membered carbo- and heterocycles that have been reported from 2007–2022. Numerous rearrangement and cycloaddition reactions involving Tiffeneau–Demjanov rearrangement, Aza–Claisen rearrangement, Schmidt rearrangement, Beckmann rearrangement, etc., have been described in this regard.

Development and Validation of a Highly Sensitive and Rapid LC-MS3 Strategy to Determine Oxcarbazepine and Its Active Metabolite in the Serum of Patients with Epilepsy and Its Application in Therapeutic Drug Monitoring

A sensitive and rapid bioanalytical method based on the LC-triple-stage fragmentation (LC-MS³) strategy on a hybrid triple quadrupole-linear ion trap mass spectrometer in combination with protein precipitation extraction for sample pretreatment has been developed and validated for the simultaneous determination of the antiepileptic drug oxcarbazepine (OXC) and its main active metabolite (MHD) in human serum. The separation was performed on a Waters XBridge BEH C18 column (2.5 µm, 2.1 × 50 mm) in isocratic elution with 0.1% formic acid in water and methanol (50:50, v:v) as the mobile phase. The run time for each sample was 2.0 min. The calibration curves ranging from 25 to 1600 ng/mL for OXC and from 0.5 to 32 μg/mL for MHD showed correlation coefficients (r) better than 0.99. All of the validation data, such as precision, accuracy and other parameters, fit the requirements of the current bioanalytical method validation guidelines. The LC-MS³ method for quantitation of OXC and MHD was compared with the LC-MRM based method. Passing–Bablok regression coefficients and Bland–Altman plots showed that the developed LC–MS³ method is a reliable method for quantitative analysis of OXC and MHD. The proposed LC-MS³ method was successfully applied to determine the serum concentrations of OXC and MHD to support a clinical study.

Physiologically-based pharmacokinetic modeling of oxcarbazepine and levetiracetam during adjunctive antiepileptic therapy in children and adolescents

Oxcarbazepine (OXZ) and levetiracetam (LEV) are two new generation anti‐epileptic drugs, often co‐administered in children with enzyme‐inducing antiepileptic drugs (EIAEDs). The anti‐epileptic effect of OXZ and LEV are linked to the exposure of OXZ’s active metabolite 10‐monohydroxy derivative (MHD) and (the parent) LEV, respectively. However, little is known about the confounding effect of age and EIAEDs on the pharmacokinetics (PKs) of MHD and LEV. To address this knowledge gap, physiologically‐based pharmacokinetic (PBPK) modeling was performed in the PK‐Sim software using literature data from children greater than or equal to 2 years of age. Age‐related changes in clearance (CL) of MHD and LEV were characterized, both in the presence (group 1) and absence (group 2) of concomitant EIAEDs. The drug‐drug interaction effect of EIAEDs was estimated as the difference in CL estimates between groups 1 and 2. PBPK modeling suggests that bodyweight normalized CL (ml/min/kg) is higher in younger children than their older counterparts (i.e., due to an influence of age). Concomitant EIAEDs further increase MHD’s CL to a fixed extent of 25% at any age, but EIAEDs’ effect on LEV’s CL increases with age from 20% (at 2 years) to 30% (at adolescence). Simulations with the maximum recommended doses (MRDs) revealed that children between 2 and 4 years and greater than 4 years, who are not on EIAEDs, are at risk of exceeding the reference exposure range for OXZ and LEV, respectively. This analysis demonstrates the use of PBPK modeling in understanding the confounding effect of age and comedications on PKs in children and adolescents.

Oxcarbazepine induces mitotic catastrophe and apoptosis in NRK-52E proximal tubular cells

Certain medicines including anticancer drugs, NSAIDs and antiepileptic drugs are known to cause drug-induced nephropathy. For example, antiepileptic drugs such as carbamazepine (CBZ) and valproic acid have been reported to cause damage to the proximal tubular cells. Although there has been a great deal of research concerning the nephrotoxicity of CBZ, little is known about that of oxcarbazepine (OXC), a derivative of CBZ. To investigate the molecular mechanism underlying renal proximal tubular cell death caused by OXC, we examined alterations in the gene expression profile of NRK-52E proximal tubular cells during OXC exposure. DNA microarray analysis revealed that the levels of genes related to mitotic processes including chromosomal and cytoplasmic segregation, progression to G2/M phase, and formation of the mitotic spindle are increased after exposure to 50 μM OXC for 6 h. Cell cycle analysis by flow cytometry showed that OXC at concentrations between 25 and 100 μM induces G2/M arrest. We also found that OXC significantly increases histone H3 phosphorylation, indicative of mitotic cells. These results imply that OXC induces cell cycle arrest at the mitotic phase. Immunofluorescence analysis showed monopolar spindles, which are formed in response to centrosome separation defects, in OXC-treated cells. We also show that OXC suppresses the phosphorylation of PLK1, which is involved not only in the activation of the kinesin family of motor proteins for centrosome separation and bipolar spindle assembly, but also in the cleavage of centrosomal proteins. Thus, our results indicate that OXC inhibits centrosome separation by reducing the activation of PLK1, which leads to the formation of an abnormal spindle and induces mitotic catastrophe and apoptosis in NRK-52E cells.

HLA Risk Alleles in Aromatic Antiepileptic Drug-Induced Maculopapular Exanthema

To characterize human leukocyte antigen (HLA) loci as risk factors in aromatic antiepileptic drug-induced maculopapular exanthema (AED-MPE). A case-control study was performed to investigate HLA loci involved in AED-MPE in a southern Han Chinese population. Between January 2007 and June 2019, 267 patients with carbamazepine (CBZ), oxcarbazepine (OXC), or lamotrigine (LTG) associated MPE and 387 matched drug-tolerant controls from six centers were enrolled. HLA-A/B/C/DRB1 genotypes were determined using sequence-based typing. Potential risk alleles were validated by meta-analysis using data from different populations and in silico analysis of protein-drug interactions. HLA-DRB1*04:06 was significantly associated with OXC-MPE (p = 0.002, p _c = 0.04). HLA-B*38:02 was associated with CBZ-MPE (p = 0.03). When pooled, HLA-A*24:02, HLA-A*30:01, and HLA-B*35:01 additionally revealed significant association with AED-MPE. Logistic regression analysis showed a multiplicative interaction between HLA-A*24:02 and HLA-B*38:02 in CBZ-MPE. Meta-analysis of data from different populations revealed that HLA-24*:02 and HLA-A*30:01 were associated with AED-MPE (p = 0.02 and p = 0.04, respectively). In silico analysis of protein-drug interaction demonstrated that HLA-A*24:02 and HLA-A*30:01 had higher affinities with the three aromatic AEDs than the risk-free HLA-A allele. HLA-DRB1*04:06 showed relatively specific high affinity with S-monohydroxy derivative of OXC. HLA-DRB1*04:06 is a specific risk allele for OXC-induced MPE in the Southern Han Chinese. HLA-A*24:02, possibly HLA-A*30:01, are common risk factors for AED-MPE. The multiplicative risk potential between HLA-A*24:02 and HLA-B*38:02 suggests that patients with two risk alleles are at greater risk than those with one risk allele. Inclusion of these HLA alleles in pre-treatment screening would help estimating the risk of AED-MPE.

Metabolic Forest: Predicting the Diverse Structures of Drug Metabolites

Adverse drug metabolism often severely impacts patient morbidity and mortality. Unfortunately, drug metabolism experimental assays are costly, inefficient, and slow. Instead, computational modeling could rapidly flag potentially toxic molecules across thousands of candidates in the early stages of drug development. Most metabolism models focus on predicting sites of metabolism (SOMs): the specific substrate atoms targeted by metabolic enzymes. However, SOMs are merely a proxy for metabolic structures: knowledge of an SOM does not explicitly provide the actual metabolite structure. Without an explicit metabolite structure, computational systems cannot evaluate the new molecule's properties. For example, the metabolite's reactivity cannot be automatically predicted, a crucial limitation because reactive drug metabolites are a key driver of adverse drug reactions (ADRs). Additionally, further metabolic events cannot be forecast, even though the metabolic path of the majority of substrates includes two or more sequential steps. To overcome the myopia of the SOM paradigm, this study constructs a well-defined system-termed the metabolic forest-for generating exact metabolite structures. We validate the metabolic forest with the substrate and product structures from a large, chemically diverse, literature-derived dataset of 20 736 records. The metabolic forest finds a pathway linking each substrate and product for 79.42% of these records. By performing a breadth-first search of depth two or three, we improve performance to 88.43 and 88.77%, respectively. The metabolic forest includes a specialized algorithm for producing accurate quinone structures, the most common type of reactive metabolite. To our knowledge, this quinone structure algorithm is the first of its kind, as the diverse mechanisms of quinone formation are difficult to systematically reproduce. We validate the metabolic forest on a previously published dataset of 576 quinone reactions, predicting their structures with a depth three performance of 91.84%. The metabolic forest accurately enumerates metabolite structures, enabling promising new directions such as joint metabolism and reactivity modeling.

Retinal ganglion cell complex and visual evoked potentials in levetiracetam treatment

PURPOSE

To examine central macular, RNFL (retinal nerve fibre layer), GCC (ganglion cell complex) thicknesses; and VEPs (visual evoked potential) in epileptic patients using levetiracetam for at least one year.

MATERIALS AND METHODS

Sixteen focal epileptic patients receiving levetiracetam monotherapy and 16 healthy subjects were included in the study. Central macular, RNFL and GCC thicknesses according to spectral domain OCT (optical coherence tomography); and VEPs parameters were compared between patients and healthy subjects.

RESULTS

The mean age of patient and control groups were 40 ± 16 and 38 ± 12 years respectively (p > 0.05). The patient group was on levetiracetam therapy for 64 ± 45 (12-168) months. Central macular thickness was thinner in the patient group (p = 0.008). There was no difference among groups regarding RNFL thicknesses. GCC thicknesses in all quadrants were similar among groups, except the superior quadrant; which was thinner in the patient group (p = 0.03). P100 amplitude in 30 min pattern was lower in the patient group (p = 0.04). N135 latency in 15 min (p = 0.03) and 7 min patterns (p = 0.01) was longer in the patient group.

CONCLUSION

Central macular and GCC thicknesses; and VEP parameters in patients receiving levetiracetam treatment may differ from healthy subjects.

Oxcarbazepine add-on for drug-resistant focal epilepsy

BACKGROUND

Epilepsy is a common neurological disorder. In approximately 30% of epilepsy cases, seizures are uncontrolled by one antiepileptic drug (AED). These people require treatment with a combination of multiple AEDs and are described as having drug-resistant epilepsy. Oxcarbazepine is a keto-analogue of carbamazepine, an established AED, and can be used as an add-on treatment for drug-resistant epilepsy.

OBJECTIVES

To assess the efficacy and tolerability of oxcarbazepine as an add-on treatment for people with drug-resistant focal epilepsy.

SEARCH METHODS

The following databases were searched on 24 September 2018: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL); Medline (Ovid) 1946 to 21 September 2018; ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). Originally, we also searched SCOPUS as a substitute for Embase, but this is no longer necessary, because randomised and quasi-randomised controlled trials in Embase are now included in CENTRAL.

SELECTION CRITERIA

Randomised controlled trials with parallel-group or cross-over design, recruiting people of any age with drug-resistant focal epilepsy. We accepted any level of blinding and trials could be placebo- or active-controlled.

DATA COLLECTION AND ANALYSIS

In accordance with the methodological procedures expected by the Cochrane Collaboration, two review authors independently assessed trial eligibility before extracting data and assessing risk of bias. We assessed the primary outcomes: median percentage seizure reduction per 28 days; 50% or greater reduction in seizure frequency; and adverse effects including ataxia, hyponatraemia, and somnolence. We assessed the secondary outcomes: seizure freedom; treatment withdrawal; cognitive effects; and quality of life. We used an intention-to-treat population for all primary analyses. We present results as risk ratios (RR) with 95% confidence intervals (CI), with the exception of adverse effects which we present with 99% CI.

MAIN RESULTS

We identified six eligible studies, involving 1593 participants. We judged that three studies were at unclear risk of bias and three were at high risk of bias. Bias mainly arose from lack of methodological details and from high attrition rates. Participants were aged 1 month to 65 years, with a diagnosis of drug-resistant focal epilepsy. All studies were either placebo- or alternative-dose-controlled with parallel-group design. The treatment period varied from 9 days to 26 weeks. The median percentage seizure reduction per 28 days (3 studies; moderate-certainty evidence) ranged from 26% to 83.3% for participants randomised to experimental oxcarbazepine compared to 7.6% to 28.7% for participants randomised to control treatment. Oxcarbazepine may increase the responder rate for 50% or greater reduction in seizure frequency compared to control treatment (RR 1.80, 95% CI 1.27 to 2.56; random-effects model; 6 studies; low-certainty evidence). For seizure freedom, the RR was 2.86 (95% CI 1.19 to 6.87; random-effects model; 5 studies; low-certainty evidence), suggesting an advantageous effectiveness of oxcarbazepine over control treatment. Treatment with oxcarbazepine was associated with an increased treatment withdrawal rate compared to control (RR 1.75, 95% CI 1.44 to 2.13; fixed-effect model; 6 studies; moderate-certainty evidence). The largest oxcarbazepine dose used, 2400 mg/d, was associated with a higher treatment withdrawal rate (RR 2.38, 95% CI 1.92 to 2.94; fixed-effect model; 2 studies) compared to control, than 1200 mg/d (RR 1.54, 95% CI 1.21 to 1.95; fixed-effect model; 3 studies) or 600 mg/d oxcarbazepine (RR 0.79, 95% CI 0.55 to 1.15; fixed-effect model; 1 study). Treatment with oxcarbazepine was associated with an increased incidence of multiple adverse effects including: ataxia (RR 2.54, 99% CI 0.86 to 7.54; random-effects model; 5 studies; moderate-certainty evidence); and somnolence (RR 2.03, 99% CI 1.17 to 3.54; random-effects model; 6 studies; low-certainty evidence). Hyponatraemia occurred more frequently with oxcarbazepine treatment but not significantly so (RR 2.53, 99% CI 0.27 to 23.85; fixed-effect model; 6 studies; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Oxcarbazepine might be effective at reducing seizure frequency when used as an add-on for drug-resistant focal epilepsy. The efficacy outcomes - 50% or greater seizure reduction and seizure freedom - were derived from low-certainty evidence. We are, therefore, uncertain whether the estimated effect size is representative of the true effect. In contrast, the evidence for median percentage seizure reduction and treatment withdrawal were of moderate certainty: thus, we are fairly certain of the effect estimates' reliability. Overall, we are unsure of the true efficacy of oxcarbazepine, but have concerns about its tolerability.

Unsymmetrically Substituted Dibenzo[b,f][1,5]-diazocine-6,12(5H,11H)dione-A Convenient Scaffold for Bioactive Molecule Design

A novel approach for the synthesis of unsymmetrically substituted dibenzo[b,f][1,5]diazocine-6,12(5H,11H)diones has been developed. This facile three-step method uses variously substituted 1H-benzo[d][1,3]oxazine-2,4-diones (isatoic anhydrides) and 2-aminobenzoic acids as a starting materials. The obtained products were further transformed into N-alkyl-, N-acetyl- and dithio analogues. Developed procedures allowed the synthesis of unsymmetrical dibenzo[b,f][1,5]diazocine-6,12(5H,11H)diones and three novel heterocyclic scaffolds: benzo[b]naphtho[2,3-f][1,5]diazocine-6,14(5H,13H)dione, pyrido[3,2-c][1,5]benzodiazocine-5,11(6H,12H)-dione and pyrazino[3,2-c][1,5]benzodiazocine-6,12(5H,11H)dione. For 11 of the compounds crystal structures were obtained. The preliminary cytotoxic effect against two cancer (HeLa, U87) and two normal lines (HEK293, EUFA30) as well as antibacterial activity were determined. The obtained dibenzo[b,f][1,5]diazocine(5H,11H)6,12-dione framework could serve as a privileged structure for the drug design and development.

Leaching behavior of pharmaceuticals and their metabolites in the soil environment

Pharmaceuticals constitute a significant group of emerging pollutants (EPs). The use of pharmaceuticals in animal breeding causes them to reach the soil environment in excrement and fertilizers. Depending on their chemical properties, pharmaceuticals can be sorbed to the soil or be washed out with rainfall and eventually be entered into groundwater. This paper evaluates the mobility of tramadol (TRA) and carbamazepine (CBZ), and two transformation products, O-desmethyltramadol (O-DMTRA) and 10,11-dihydro-10-hydroxycarbamazepine (10-OH-CBZ) in soils. Both pharmaceuticals are applied in human and animal treatment, which makes them enter the environment in native and metabolized form in high doses. Experiments were carried out in accordance with the OECD 106 procedure (batch tests) and DIN 19528:2009-01 procedure (percolation column test). The adsorption coefficients (K_d) for TRA, CBZ, O-DMTRA and 10-OH-CBZ were, respectively, 1.41 ± 0.10, 1.87 ± 0.06, 0.90 ± 0.03 and 0.37 ± 0.07 for sandy soil RS04, and 18.09 ± 0.78, 2.56 ± 0.05, 10.89 ± 0.17 and 0.56 ± 0.38  L kg^-1 for loamy soil RS06. The percolation column test was carried out for sandy soil RS04. The results obtained for TRA and O-DMTRA under static conditions indicated a high mobility of these compounds in soil, whereas the column leaching experiment showed that these compounds bind strongly to soil particles. A correlation between static and dynamic tests was observed in the case of CBZ and 10-OH-CBZ. These compounds will probably be characterized by a high or moderate mobility in soil.

Evaluation of hematologic profile may be needed for patients treated with oxcarbazepine

Purpose

The major side effects of treatment with oxcarbazepine (OXC) are skin rash and hyponatremia. Hematologic side effects are reported rarely. The aim of this study was to investigate the rate and types of the hematologic side effects of OXC.

Methods

The medical records of 184 patients diagnosed with epilepsy or movement disorder and on OXC monotherapy, at the Department of Pediatrics of Inje University Sanggye Paik Hospital from July 2001 to July 2018, were retrospectively reviewed.

Results

Of the 184 patients, 10 (5.4%) developed leukopenia in addition to pancytopenia and 2 (1.0%) developed pancytopenia. Leukopenia developed in 11 days to 14 years after OXC administration and was more frequent in males than in females (male vs. female, 9 vs. 1; Fisher exact test, P<0.05). Of the eight patients with leukopenia alone, 7 continued OXC treatment; 6 improved without intervention; 1 was lost to follow-up; and 1 received a reduced OXC dose, who improved after intervention. Pancytopenia developed within 2 months of initiation of OXC treatment. Both patients initially continued OXC. One improved within 1 month and continued treatment with OXC, but the other showed progression of the side effect, leading to the discontinuation of OXC and subsequent improvement within 1 month. There were no significant differences in the ages of the patients, OXC dose, and duration of OXC treatment between patients with and without these side effects of OXC (P >0.05, t -test).

Conclusion

OXC-induced leukopenia is not rare and may result in pancytopenia. Patients being treated with OXC should be regularly monitored for abnormal complete blood count profiles.

Vorapaxar and diplopia: Possible off-target PAR-receptor mismodulation

Vorapaxar, a novel antiplatelet thrombin PAR-1 inhibitor, has been evaluated in the successful TRA2P trial and the failed TRACER trial. The drug is currently approved for post myocardial infarction and peripheral artery disease indications with concomitant use of clopidogrel and/or aspirin. The FDA ruled that the vorapaxar safety profile is acceptable. However, both trials revealed excess diplopia (double vision) usually reversible after vorapaxar. The diplopia risk appears to be small (about 1 extra case per 1,000 treated subjects), but real. Overall, there were 10 placebo and 34 vorapaxar diplopia cases (p=0.018) consistent for TRACER (2 vs 13 cases; p=0.010) and for TRA2P (8 vs 21 cases; p=0.018). Hence, we review the FDA-confirmed evidence and discuss potential causes and implications of such a surprising adverse association, which may be related to off-target PAR receptor mismodulation in the eye.

Investigation and risk evaluation of the occurrence of carbamazepine, oxcarbazepine, their human metabolites and transformation products in the urban water cycle

Trace organic contaminants such as pharmaceuticals, personal care products and industrial chemicals are frequently detected in the urban water cycle, including wastewater, surface water and groundwater, as well as drinking water. These also include human metabolites (HMs), which are formed in the human body and then excreted via urine or feces, as well as transformation products (TPs) formed in engineered treatment systems and the aquatic environment. In the current study, the occurrence of HMs as well as their TPs of the anticonvulsants carbamazepine (CBZ) and oxcarbazepine (OXC) were investigated using LC tandem MS in effluents of wastewater treatment plants (WWTPs), surface water and groundwater. Highest concentrations were observed in raw wastewater for 10,11-dihydro-10,11-dihydroxycarbamazepine (DiOHCBZ), 10,11-dihydro-10-hydroxy-cabamazepine (10OHCBZ) and CBZ with concentrations ranging up to 2.7 ± 0.4, 1.7 ± 0.2 and 1.07 ± 0.06 μg L^-1, respectively. Predictions of different toxicity endpoints using a Distributed Structure-Searchable Toxicity (DSSTox) expert system query indicated that several HMs and TPs, in particular 9-carboxy-acridine (9-CA-ADIN) and acridone (ADON), may exhibit an increased genotoxicity compared to the parent compound CBZ. As 9-CA-ADIN was also detected in groundwater, a detailed investigation of the genotoxicity of 9-CA-ADIN is warranted. Investigations of an advanced wastewater treatment plant further revealed that the discharge of the investigated compounds into the aquatic environment could be substantially reduced by ozonation followed by granular activated carbon (GAC) filtration.

HLA-B*40:02 and DRB1*04:03 are risk factors for oxcarbazepine-induced maculopapular eruption

OBJECTIVE

Oxcarbazepine (OXC) is a widely used antiepileptic drug for the treatment of partial seizures that was developed through structural variation of carbamazepine. Although OXC has a lower risk of cutaneous adverse drug reactions (cADRs) than carbamazepine, cADRs ranging from maculopapular eruption (MPE) to the more severe Stevens-Johnson syndrome and toxic epidermal necrolysis still limit the use of OXC in some patients. A few human leukocyte antigen (HLA)-related genetic risk factors for carbamazepine-induced cADRs have been identified. However, the HLA-related genetic risk factors associated with OXC-induced cADRs are unknown.

METHODS

A total of 40 patients who experienced OXC-induced MPE and 70 patients who were tolerant to OXC treatment were included in the study. Genomic DNA was extracted from the peripheral blood of these patients, and high-resolution HLA genotyping was performed.

RESULTS

The HLA-B*40:02 and HLA-DRB1*04:03 alleles were significantly associated with OXC-induced MPE compared with the OXC-tolerant group (odds ratio [OR] 4.33, p = 0.018 and OR 14.64, p = 0.003, respectively) and the general Korean population (OR 4.04, p = 0.001 and OR 3.11, p = 0.019, respectively). The HLA-B*15:01 genetic frequency was significantly lower in the OXC-MPE group compared to the OXC-tolerant group (OR 0.18, p = 0.016) and the Korean population (OR 0.22, p = 0.030). The allele frequencies of well-known HLA-related risk factors for carbamazepine-induced cADRs (HLA-B*15:02, A*31:01 and B*15:11) were not different among the three groups.

SIGNIFICANCE

This study is the first to demonstrate an association of HLA-B*40:02 and HLA-DRB1*04:03 with OXC hypersensitivity using a large cohort of patients with OXC-induced MPE. These findings should be confirmed in future studies in different ethnic groups.

The Impact of Anti-Epileptic Drugs on Growth and Bone Metabolism

Epilepsy is a common neurological disorder worldwide and anti-epileptic drugs (AEDs) are always the first choice for treatment. However, more than 50% of patients with epilepsy who take AEDs have reported bone abnormalities. Cytochrome P450 (CYP450) isoenzymes are induced by AEDs, especially the classical AEDs, such as benzodiazepines (BZDs), carbamazepine (CBZ), phenytoin (PT), phenobarbital (PB), and valproic acid (VPA). The induction of CYP450 isoenzymes may cause vitamin D deficiency, hypocalcemia, increased fracture risks, and altered bone turnover, leading to impaired bone mineral density (BMD). Newer AEDs, such as levetiracetam (LEV), oxcarbazepine (OXC), lamotrigine (LTG), topiramate (TPM), gabapentin (GP), and vigabatrin (VB) have broader spectra, and are safer and better tolerated than the classical AEDs. The effects of AEDs on bone health are controversial. This review focuses on the impact of AEDs on growth and bone metabolism and emphasizes the need for caution and timely withdrawal of these medications to avoid serious disabilities.

Effective Treatment of Paroxysmal Nonkinesigenic Dyskinesia With Oxcarbazepine

Paroxysmal nonkinesigenic dyskinesia (PNKD) is a rare chronic disorder characterized by intermittent, non-movement-related involuntary movements. The response to currently available therapies is inconsistent and temporary. We describe here a patient with infantile-onset PNKD who failed a number of pharmaceutical agents used alone or in combination. Treatment with oxcarbazepine resulted in a substantial reduction in the frequency and severity of episodes. The patient has been followed for 4 years now, and the outcome of treatment is consistently favorable. Oxcarbazepine has been effective in managing the kinesigenic form of this disorder; however, its use has never been reported in PNKD to our knowledge. Oxcarbazepine is safer and better tolerated than most of the drugs currently used for treating PNKD, but blinded clinical trials are needed to verify its efficacy in the management of this debilitating, often difficult-to-treat disease.

Modeling Epoxidation of Drug-like Molecules with a Deep Machine Learning Network

Drug toxicity is frequently caused by electrophilic reactive metabolites that covalently bind to proteins. Epoxides comprise a large class of three-membered cyclic ethers. These molecules are electrophilic and typically highly reactive due to ring tension and polarized carbon-oxygen bonds. Epoxides are metabolites often formed by cytochromes P450 acting on aromatic or double bonds. The specific location on a molecule that undergoes epoxidation is its site of epoxidation (SOE). Identifying a molecule's SOE can aid in interpreting adverse events related to reactive metabolites and direct modification to prevent epoxidation for safer drugs. This study utilized a database of 702 epoxidation reactions to build a model that accurately predicted sites of epoxidation. The foundation for this model was an algorithm originally designed to model sites of cytochromes P450 metabolism (called XenoSite) that was recently applied to model the intrinsic reactivity of diverse molecules with glutathione. This modeling algorithm systematically and quantitatively summarizes the knowledge from hundreds of epoxidation reactions with a deep convolution network. This network makes predictions at both an atom and molecule level. The final epoxidation model constructed with this approach identified SOEs with 94.9% area under the curve (AUC) performance and separated epoxidized and non-epoxidized molecules with 79.3% AUC. Moreover, within epoxidized molecules, the model separated aromatic or double bond SOEs from all other aromatic or double bonds with AUCs of 92.5% and 95.1%, respectively. Finally, the model separated SOEs from sites of sp(2) hydroxylation with 83.2% AUC. Our model is the first of its kind and may be useful for the development of safer drugs. The epoxidation model is available at http://swami.wustl.edu/xenosite.

Reducing PEC uncertainty in coastal zones: a case study on carbamazepine, oxcarbazepine and their metabolites

Concentrations of the antiepileptic drugs carbamazepine (Cbz), oxcarbazepine (OxCz) and their main metabolites were predicted in a wastewater treatment plant (WTP) and in the vicinity of its submarine outfall located in a Mediterranean coastal zone. Refined predicted environmental concentrations (PECs) were calculated in effluents based on consumption data and human excretion rates. PECs were estimated in the sea using the hydrodynamic MARS 3D model integrating meteorological data, oceanic conditions (wind, tide, atmospheric pressure), freshwater and sewage inputs. Measured environmental concentrations (MECs) were compared to PECs to assess the estimation relevance. In the coastal zone, PEC and MEC were in the same magnitude range. Modeling of Cbz diffusion and advection just above the submarine outfall showed the influence of the thermocline during summer, with low diffusion of Cbz from the bottom to the surface. This work allowed understanding the dispersion of target compounds and deserved further development for a better acknowledgement of vulnerability at local scales.

Single centre 20 year survey of antiepileptic drug-induced hypersensitivity reactions

BACKGROUND

Epilepsy is a chronic neurological disease which affects about 1% of the human population. There are 50 million patients in the world suffering from this disease and 2 million new cases per year are observed. The necessary treatment with antiepileptic drugs (AEDs) increases the risk of adverse reactions. In case of 15% of people receiving AEDs, cutaneous reactions, like maculopapular or erythematous pruritic rash, may appear within four weeks of initiating therapy with AEDs.

METHODS

This study involved 300 epileptic patients in the period between September 1989 and September 2009. A cutaneous adverse reaction was defined as a diffuse rash, which had no other obvious reason than a drug effect, and resulted in contacting a physician.

RESULTS

Among 300 epileptic patients of Neurological Practice in Kielce (132 males and 168 females), a skin reaction to at least one AED was found in 30 patients. As much as 95% of the reactions occurred during therapies with carbamazepine, phenytoin, lamotrigine or oxcarbazepine. One of the patients developed Stevens-Johnson syndrome.

CONCLUSION

Some hypersensitivity problems of epileptic patients were obviously related to antiepileptic treatment. Among AEDs, gabapentin, topiramate, levetiracetam, vigabatrin, and phenobarbital were not associated with skin lesions, although the number of patients in the case of the latter was small.

A structurally diverse heterocyclic library by decoration of oxcarbazepine scaffold

A library of new heterocyclic systems was synthesized starting from oxcarbazepine (OXC, Trileptal^®, 10-oxo-10,11-dihydro-5H-dibenzo[b,f]azepine-5-carboxamide). The key for these transformations is the α-enolizable ketone present on the [d]-side of our starting material OXC, thus, an in depth investigation of the literature to find heteroannulation reactions for substrates carrying an α-enolizable ketone gave us a boost to discover an excellent derivatization strategy and [3+2], [4+2] and [4+1] approaches were successfully developed. Almost always a pre-functionalization was needed, but also the direct one-pot heterocycle construction was also explored.

Cutaneous reactions induced by oxcarbazepine in Southern Han Chinese: incidence, features, risk factors and relation to HLA-B alleles

PURPOSE

Oxcarbazepine (OXC) is a promising alternative for patients who cannot tolerate carbamazepine. Recently, however, it has been reported that OXC-induced cutaneous adverse drug reactions (cADRs) are prevalent and may lead to drug discontinuation. Additionally, these reactions are thought to be associated with HLA-B*1502. This study aims to investigate the incidence, features and risk factors of OXC-cADRs, and to explore their relation to HLA-B alleles in Southern Han Chinese.

METHODS

A prospective study was performed to investigate the incidence, features and risk factors of OXC-cADRs, in which 252 new users were recruited. To examine the association between OXC-cADRs and HLA-B alleles, 14 maculopapular eruption (MPE) cases, including 9 additional cases beyond this prospective observation, were genotyped by PCR-SSP and sequencing. Thirty-five OXC-tolerant patients served as controls.

RESULTS

Five patients (2.0%) developed an OXC-cADR, and all were mild MPE. History of other AED allergy (p=0.005, OR=121.23) and non-AED allergy (p=0.006, OR=59.92) were significant risk factors for OXC-cADRs in multivariate logistic regression analysis. Only one patient with OXC-MPE was positive for HLA-B*1502; and the frequency of HLA-B*1502 in OXC-MPE did not differ significantly from that in OXC-tolerant controls. Four HLA-B*1302 alleles were detected in OXC-MPE cases, which was significantly different from that in general population of southern Han Chinese (p=0.001, OR=7.83).

CONCLUSIONS

The incidence of OXC-induced cADRs was low, and no severe reactions occurred. Patients with a history of allergy are more susceptible to OXC-cADRs. No significant association between HLA-B*1502 and OXC-MPE was found. The associations between OXC-MPE and HLA alleles warrant further studies.

Oxcarbazepine versus carbamazepine in the treatment of paroxysmal kinesigenic dyskinesia

Paroxysmal kinesigenic dyskinesia (PKD) is an uncommon neurological disorder, consisting of brief attacks of involuntary movements triggered by sudden action. Patients with PKD generally respond positively to antiepileptic drugs. We compared the efficacy and tolerability of oxcarbazepine (OXC) and carbamazepine (CBZ) in the treatment of PKD, in order to find the optimal prescription. This retrospective study reviewed monotherapy use of CBZ or OXC in 28 patients with PKD during 2005-2011, dividing into two groups. The frequency and severity of attacks and adverse events were recorded. Ten patients in the OXC group and 12 in the CBZ group continued the therapy for more than 12 months. The 12-month retention rate was 76.92% and 80.00%. Both groups showed a marked reduction in attack frequency and the degree of reduction did not differ significantly between the groups. Side effects in patients with OXC included headache, diplopia, and elevated hepatic enzymes, while diplopia, nausea, and leukopenia were recorded in CBZ group. Another three cases were found with better tolerance when converted to OXC from CBZ for rash, drowsiness, diplopia, and nervousness. In conclusion, OXC and CBZ are similarly effective and tolerated in the treatment of PKD, however, more evidence from larger and blind prospective trials are needed.

Effects of oxcarbazepine on monoamines content in hippocampus and head and body shakes and sleep patterns in kainic acid-treated rats

The aim of this work was to analyze the effect of oxcarbazepine (OXC) on sleep patterns, "head and body shakes" and monoamine neurotransmitters level in a model of kainic-induced seizures. Adult Wistar rats were administered kainic acid (KA), OXC or OXC + KA. A polysomnographic study showed that KA induced animals to stay awake for the whole initial 10 h. OXC administration 30 min prior to KA diminished the effect of KA on the sleep parameters. As a measure of the effects of the drug treatments on behavior, head and body shakes were visually recorded for 4 h after administration of KA, OXC + KA or saline. The presence of OXC diminished the shakes frequency. 4 h after drug application, the hippocampus was dissected out, and the content of monoamines was analyzed. The presence of OXC still more increased serotonin, 5-hidroxyindole acetic acid, dopamine, and homovanilic acid, induced by KA.

Titrimetric and spectrophotometric assay of oxcarbazepine in pharmaceuticals using N-bromosuccinimide and bromopyrogallol red

Titrimetric and spectrophotometric methods are described for the determination of oxcarbazepine (OXC) in bulk drug and in tablets. The methods use N-bromosuccinimide (NBS) and bromopyrogallol red (BPR) as reagents. In titrimetry (method A), an acidified solution of OXC is titrated directly with NBS using methyl orange as indicator. Spectrophotometry (method B) involves the addition of known excess of NBS to an acidified solution of OXC followed by the determination of the unreacted NBS by reacting with BPR and measuring the absorbance of the unreacted dye at 460 nm. Titrimetry allows the determination of 6–18 mg of OXC and follows a reaction stoichiometry of 1 : 1 (OXC : NBS), whereas spectrophotometry is applicable over the concentration range of 0.8–8.0 μg mL⁻¹. Method B with a calculated molar absorptivity of 2.52 × 10⁴ L mol⁻¹ cm⁻¹ is the most sensitive spectrophotometric method ever developed for OXC. The optical characteristics such as limits of detection (LOD), quantification (LOQ), and Sandell's sensitivity values are also reported for the spectrophotometric method. The accuracy and precision of the methods were studied on intraday and interday basis. The methods described could usefully be applied to routine quality control of tablets containing OXC. No interference was observed from common pharmaceutical adjuvants. Statistical comparison of the results with a reference method shows an excellent agreement and indicates no significant difference in accuracy and precision. The reliability of the methods was further ascertained by recovery studies in standard addition procedure.

Pharmacologically active metabolites of currently marketed drugs: potential resources for new drug discovery and development

Biotransformation is the major clearance mechanism of therapeutic agents from the body. Biotransformation is known not only to facilitate the elimination of drugs by changing the molecular structure to more hydrophilic, but also lead to pharmacological inactivation of therapeutic compounds. However, in some cases, the biotransformation of drugs can lead to the generation of pharmacologically active metabolites, responsible for the pharmacological actions. This review provides an update of the kinds of pharmacologically active metabolites and some of their individual pharmacological and pharmacokinetic aspects, and describes their importance as resources for drug discovery and development.

Binding of licarbazepine enantiomers to mouse and human plasma proteins

Racemic licarbazepine (Lic) is the active metabolite of oxcarbazepine (OXC) and eslicarbazepine acetate (ESL), appearing in human plasma as S-licarbazepine (S-Lic) and R-licarbazepine (R-Lic). However, human metabolism of OXC and ESL to Lic differs in the S-Lic/R-Lic enantiomeric ratio observed in plasma. S-Lic appears in higher proportion after ESL administration than after OXC (95% versus 80%). Enantioselective pharmacokinetics of Lic enantiomers have been found in mice after their separate administration and in humans following OXC treatment. Since protein binding of drugs may be enantioselective and a determining factor of pharmacokinetics, the binding of S-Lic and R-Lic to mouse and human total plasma proteins and, specifically, to human serum albumin (HSA) and alpha(1)-acid glycoprotein (AGP) were herein investigated for the first time. Free and bound fractions of S-Lic and R-Lic were separated by ultrafiltration after previous in vitro incubation of spiked plasma samples and protein solutions with each enantiomer at 10, 25 and 50 microg/ml. The results revealed that the extent of binding of Lic enantiomers to total plasma proteins was 30% and independent of the drug concentration and species considered. The data also suggest that the binding of Lic enantiomers to HSA is greater than that to AGP. Moreover, absence of enantioselectivity in the binding of Lic enantiomers to mouse and human plasma proteins and to HSA and AGP is evident. In conclusion, these findings suggest that the enantioselectivity observed in vivo in the biodisposition of S-Lic and R-Lic is not dependent on their affinity to plasma proteins.

Oxcarbazepine: validation and application of an analytical method

Oxcarbazepine (OXC) is an important anticonvulsant and mood stabilizing drug. A pharmacopoeial monograph for OXC is not yet available and therefore the development and validation of a new analytical method for quantification of this drug is essential. In the present study, a UV spectrophotometric method for the determination of OXC was developed. The various parameters, such as linearity, precision, accuracy and specificity, were studied according to International Conference on Harmonization Guidelines. Batches of 150 mg OXC capsules were prepared and analyzed using the validated UV method. The formulations were also evaluated for parameters including drug-excipient compatibility, flowability, uniformity of weight, disintegration time, assay, uniformity of content and the amount of drug dissolved during the first hour.

[Therapeutic drug monitoring of oxcarbazepine]

Oxcarbazepine is an analogue of carbamazepine, used for the treatment of partial seizure with or without secondary generalization. The two forms R and S of the mono-hydroxylated derivatives (MHD) are responsible for most of the anti-convulsant activity and it is the concentrations of MHD that are relevant in therapeutic drug monitoring (TDM). Analysis of currently literature provides no well-established relationship between plasma concentration of MHD and efficiency or toxicity. Although there is not a validated therapeutic range, the residual concentrations of usually observed therapeutic MHD are situated between 12 and 30 mg/L. In certain pathological or physiological circumstances, the pharmacokinetic variability of the oxcarbazepine can be considerable, but this strong unpredictability does not nevertheless justify the TDM of the MHD. Based on the available evidence, TDM of MHD is not routinely warranted but may be possibly useful in specific situations such as pregnancy or renal insufficiency.

[Pharmacotherapy in bipolar disorders during childhood and adolescence]

OBJECTIVE

Bipolar disorders during childhood and adolescence are rare, but serious and highly recurrent disorders, often associated with negative outcome. Pharmacotherapy, including Lithium, other mood stabilizers and typical antipsychotic agents, is the first-line treatment in bipolar disorders and often necessary for many months or years.

METHOD

A computerized medline-search (Pubmed) was made for prospective studies and reviews of bipolar disorder in this age-group published during the last 10 years, which were then reviewed for their relevance.

RESULTS

Despite the widespread use of substances whose efficacy for adults is well-established, there is a substantial lack of empirical data regarding the efficacy and safety in the treatment of bipolar disorder in children and adolescents. Placebo-controlled studies are very rare, and the interpretation of the existing data is complicated by the diagnostic controversy about bipolar disorder in children. Side-effects are more common in children and adolescents than in adults.

CONCLUSIONS

Combination therapy may be favoured in cases of severe and psychotic bipolar disorder. Needed are more placebo-controlled studies and long-term studies on the efficacy and safety of mood stabilizers and atypical antipsychotic agents in the treatment of children and adolescents with bipolar disorder.

Aggravation of Seizures and/or EEG Features in Children Treated with Oxcarbazepine Monotherapy

PURPOSE

Exacerbation of epilepsy may occur following initiation of therapy with antiepileptic drugs (AEDs). The aim of this study is to analyze the clinical and EEG characteristics of a group of pediatric patients with worsening of seizures and/or EEG deterioration while on oxcarbazepine (OXC).

METHODS

A retrospective analysis of a clinical database was performed to identify patients with epilepsy treated with OXC over the past 3 years. History, neurological examination, and EEG findings were reviewed to identify any who had developed exacerbation of seizures or new abnormalities on EEG.

RESULTS

Of 290 patients on OXC, we identified 12 patients with new onset seizures, all with initial normal neurological exam and normal EEG, who developed either worsening of preexisting seizures, new seizure types, and/or EEG deterioration following introduction of OXC monotherapy. EEG changes were primarily characterized by new onset of generalized epileptiform activity not reported on the initial baseline EEG. Following substitution of OXC with a broad spectrum AED, significant improvement of seizure control and improvement in the EEG was observed.

CONCLUSIONS

These findings suggest that OXC can aggravate seizures and/or worsen EEG features in children. Following initiation of therapy with OXC, monitoring of patients with follow-up EEGs may be important, especially in patients who do not show adequate response to therapy.

Rash from Antiepileptic Drugs: Influence by Gender, Age, and Learning Disability

PURPOSE

Cutaneous adverse reactions from antiepileptic drugs (AEDs) are common, but have received little scientific attention from a clinical point of view. We wanted to study the incidence of skin reactions of current AEDs and to explore their relation to clinical parameters such as gender, age, and learning disability.

METHODS

Consecutive patients with epilepsy were studied retrospectively. A detailed survey of medical records concerning all treatment with AEDs was performed.

RESULTS

A total of 663 patients were included with altogether 2,567 exposures to 15 different AEDs. Skin reactions were found in 14% of the patients and in 5% of the exposures. Ninety-seven percent of the reactions occurred to either carbamazepine (CBZ, 11%), phenytoin (PHT, 8%), lamotrigine (LTG, 8%), oxcarbazepine (8%), or phenobarbital (2%). Skin reactions developed significantly more often in females than in males (19% vs. 8%), and significantly less often in patients with learning disability than in other patients (7% vs. 16%). These differences were significant for CBZ, PHT, and LTG when analyzed separately. Females displayed higher rash frequency during the reproductive years, while men experienced less frequent rash in the same phase of life.

CONCLUSIONS

Fertile females have a higher risk for skin reactions compared to males, probably due to hormonal factors. Patients with learning disability appeared to have a lower risk than other patients in this study. Hygiene factors may possibly be underlying.