Carbamazepine Levels Research Articles

Population Pharmacokinetics of Perampanel in Chinese Pediatric and Adult Patients With Epilepsy.

Perampanel is a promising epilepsy treatment with an innovative mechanism of action. This study was performed to investigate the factors affecting perampanel clearance in a population pharmacokinetic (PPK) model of Chinese pediatric and adult patients with epilepsy. A total of 135 perampanel plasma concentrations from 125 patients with epilepsy were analyzed using the PPK model with nonlinear mixed-effects modeling. One-compartment and proportional residual models best described the pharmacokinetics of perampanel. Covariate effects on the model parameters were assessed using forward and backward elimination. Goodness-of-fit, bootstrapping, visual predictive checks, and normalized prediction distribution errors were used to evaluate the model. Monte Carlo simulations were conducted to assess the impact of covariate combinations on perampanel plasma concentrations at different dosages. In the final PPK model, body weight (BW), concomitant carbamazepine (CBZ), oxcarbazepine (OXC), and C-reactive protein (CRP) levels significantly influenced perampanel clearance. The interindividual clearance was calculated as follows: 0.84 × (BW/70)0.53 × eCBZ × eOXC × eCRP (CBZ = 0.98, when comedicated with carbamazepine; OXC = 0.43, when comedicated with oxcarbazepine; CRP = -0.69, when CRP >15 mg/L, otherwise = 0). The estimates (relative standard error) for clearance and apparent volume of distribution of the final model were 0.84 L/h (8.75%) and 64.35 L (19.78%), respectively. The model maintained its stability and effectiveness with moderate predictability. BW and CBZ, OXC, and CRP levels may influence perampanel clearance in both pediatric and adult patients with epilepsy according to a population pharmacokinetic model that included real-world data.

GENETIC INFLUENCE OF CYP3A4 (rs2740574) GENE POLYMORPHISM ON CARBAMAZEPINE PHARMACOKINETICS IN EPILEPSY PATIENTS FROM KHYBER PAKHTUNKHWA: A PROSPECTIVE STUDY

Objectives: This study examines CYP3A genotypes regulating CYP enzymes, specifically CYP3A4 rs2740574, in Pashtun epilepsy patients in Khyber Pakhtunkhwa, Pakistan. This study documents the pharmacogenomic effects of this single nucleotide polymorphism on carbamazepine serum levels and dose-adjusted levels. It aims to promote customized medicine by providing insights that could lead to more effective epilepsy treatments for this population. Methods: CYP3A4 (rs2740574) genotyping was performed on 223 patients using Sanger sequencing. DNA extraction was done by salting out method manually. In subsequent follow ups serum for separated for the detection of serum levels of Carbamazepine through HPLC. Finch TV identified gene polymorphisms, and HPLC examined their effects on plasma CBZ levels. Results: Both TC (CYP3A4 *1A/*1B) and TT (CYP3A4*1B) genotypes had higher mean doses from the first to the second follow-up, with no statistically significant difference. Carbamazepine plasma levels increased by 0.70 ± 2.55 mg/L and CDR decreased by 0.41 mg/L per mg/kg/day among TT genotype carriers in the 2nd follow up. TT & CT were 96.4% & 3.6% whereas wild CC (CYP3A4 *1A/*1A) genotype was not encountered in the study sample. Conclusion: Genotypes of the selected gene revealed a statistically insignificant correlation with Carbamazepine pharmacokinetics.

PROSPECTIVE STUDY ON GENETIC DETERMINANTS OF CARBAMAZEPINE RESPONSE: THE CYP3A5-RS15524 GENE POLYMORPHISM IN PASHTUN PATIENTS WITH EPILEPSY

Objective: To evaluate the impact of CYP3A5-rs15524 polymorphism on the pharmacokinetics and clinical response to carbamazepine (CBZ) monotherapy in Pashtun epilepsy patients. Materials and Methods: A longitudinal study was carried out among Pashtun patients with epilepsy in Khyber Pakhtunkhwa from October 2020 to April 2022. Participants were recruited from Lady Reading Hospital, while laboratory work was performed at the Pharmacology Department of Khyber Medical University, Peshawar. Patients were genotyped for the CYP3A5-rs15524 polymorphism using Sanger sequencing, with variants analyzed via Finch TV. The study correlated each genotype with clinical response and serum CBZ levels, which were measured using reversed-phase HPLC during each follow-up visit. Results: A sample of 223 patients was analyzed, including 63.2% males and 36.8% females. Generalized tonic-clonic (GTC) seizures comprised 82.5% of cases, while partial seizures accounted for 17.5%. Genotype analyses showed a significant improvement in CBZ response in subsequent follow-up. At 3rd month, the non-responders / responders were recorded to be 18.3% / 31.3% for AA, 44.6% / 16.9% for AG, and 63.3% / 18.2% for GG genotype carriers. At 6th month it was recorded as 9.5% / 53% for AA, 32.3% / 32.3% for AG, and 27.3% / 54% among GG carriers, demonstrating a highly significant differences in response (p-value=0.001). Highest and lowest plasma levels across both follow-ups were observed in AA & AG genotypes, respectively with a p-value less than 0.001. Conclusion: Our findings suggest that CYP3A5-rs15524 polymorphism may impact the pharmacokinetics and clinical response to carbamazepine in Pashtun patients with epilepsy. Clinical pharmacogenetic research has the potential to greatly enhance personalized treatment within our study population.

Investigation into the linearity of the Roche c 702 carbamazepine assay.

Carbamazepine is an anticonvulsant drug which is monitored in patients due to toxic side effects. At Manchester University NHS Foundation Trust (MFT), carbamazepine is measured using Roche's Kinetic Interaction of Microparticles in Solution (KIMS) method on the c 702 platform. The assay has an upper limit of linearity of 20mg/L. Samples with concentrations above this limit should be identified and manually diluted. However, a poor EQA return from UK NEQAS for Tox and TDM Distribution 456 has highlighted an issue with the Roche KIMS assay. Sample A of the distribution had a carbamazepine concentration of 36mg/L but was underreported by several Roche users. This indicated that the assay was not consistently identifying high concentration samples which required a dilution. In this investigation, fresh frozen plasma was spiked with carbamazepine concentrations ranging from 15 to 40mg/L. The spiked samples and EQA material were analysed at two clinical laboratories using the Roche KIMS assay. Samples spiked with concentrations 20-30mg/L were not consistently identified for dilution by the analyser. This was observed at both hospital sites. Spike samples and EQA with concentrations >30mg/L were correctly identified at both sites. The manual dilution policy has been changed at MFT, so all samples with a carbamazepine level ≥15mg/L will be manually diluted. The problem was reported to Roche who are investigating the issue further. We would suggest that other laboratories look at validating their dilution protocols.

Development of an HPLC method using relative molar sensitivity for the measurement of blood concentrations of nine pharmaceutical compounds

We developed a reliable high-performance liquid chromatographic analysis method using a relative molar sensitivity (RMS) technique that does not require an authentic, identical reference analyte material to quantify blood serum carbamazepine, phenytoin, voriconazole, lamotrigine, meropenem, mycophenolic acid, linezolid, vancomycin, and caffeine levels for routine blood concentration measurements. Carbamazepine and caffeine were also used as non-analyte reference materials to calculate the RMS of each analyte. The RMS was calculated from the ratio of the slope of the calibration equation (analyte/non-analyte reference material), then used to quantify analytes in control serum samples spiked with carbamazepine, phenytoin, voriconazole, meropenem, mycophenolic acid, linezolid or vancomycin. In addition, the concentrations of these six drugs in control serum samples determined by the proposed RMS method agreed well with that obtained using a conventional method. The proposed RMS method is a promising tool for the clinical determination of nine drugs, given the accuracy, precision, and efficiency of quantifying these analytes.

Environmentally Relevant Levels of Antiepileptic Carbamazepine Altered Intestinal Microbial Composition and Metabolites in Amphibian Larvae.

There is growing concern about the potential ecological risks posed by pharmaceutical residues in the aquatic environment. However, our understanding of the toxic effects of antiepileptic pharmaceuticals, such as carbamazepine (CBZ), on aquatic animal larvae is still limited. In this study, the tadpoles of the black-spotted pond frog (Pelophylax nigromaculatus) were exposed to environmentally relevant concentrations of CBZ (0.3 and 3.0 μg/L) for 30 days, and their growth, intestinal microbial composition, and metabolites were investigated to assess the potential toxic effects of CBZ in non-targeted aquatic organisms. Some tadpoles died during exposure, but there was no significant among-group difference in the survival and growth rates. CBZ exposure significantly altered the composition of tadpole intestinal microbiota. Relative abundances of some bacterial genera (e.g., Blautia, Prevotella, Bacillus, Microbacterium, etc.) decreased, while others (e.g., Paucibacter, etc.) increased in CBZ-exposed tadpoles. Interestingly, CBZ-induced alterations in some bacteria might not necessarily lead to adverse outcomes for animals. Meanwhile, small molecular intestinal metabolites related to energy metabolism, and antioxidant and anti-inflammatory activities were also altered after exposure. Taken together, environmentally relevant levels of CBZ might alter the metabolic and immune performances of amphibian larvae by modifying the abundance of some specific bacteria and the level of metabolites in their intestines, thereby potentially causing a long-term effect on their fitness.

Determination of carbamazepine in fingerprints: a feasibility study to evaluate adherence in epilepsy patients.

Background: Fingerprint drug concentrations can be used as a noninvasive and convenient alternative to evaluate adherence to pharmacotherapy. Methods: Fingerprints were applied over glass slides, extracted and analyzed by ultra-high performanceLC-MS/MS. The assay and drug adherence questionnaires were applied to 30 epilepsy patients. Results: The assay had linearity in the range 0.05-10ng fingerprint-1, with precision of 2.16-7.9% and accuracy of 95.0-102.8%. Carbamazepine (CBZ) levels in fingerprints were stable at 45°C for 15days. Concentrations in patient samples were 0.06-9.28ng fingerprint-1. A significant difference (p=0.003) was found between CBZ concentrations in fingerprints between patient groups divided as low and medium/high adherence. Conclusion: This method can potentially be applied to the identification of epilepsy patients with low adherence to CBZ pharmacotherapy.

Carbamazepine transmits immune effect by activation of gut-liver axis and TLR signaling pathway from parental zebrafish to offspring.

Carbamazepine (CBZ) has been identified in the aquatic environment as an emerging contaminant. Its immune effect across generations at environmentally relevant concentrations is little known. We aim to elucidate the effects of CBZ on the immune system in zebrafish (Danio rerio), hypothesizing the effects caused by CBZ exposure in the parental generation can be passed on to its offspring, leading to impairment of innate immune function and defense against pathogen weakened. A suite of bioassays (including a test with added lipopolysaccharide) was used to measure the effects of environmentally relevant levels of CBZ (1, 10, and 100 μg/l) on zebrafish at multiple biological levels, and across 2 successive generations (21 days exposure for F0; 5 and 21 days exposure or nonexposure for F1). The results showed that CBZ affected homeostasis in the immune system, caused liver vacuolization, increased the inflammation-related microbiota proportion in gut, and decreased reproduction, by induction of oxidative stress and modulation of Toll-like receptors (TLR) signaling pathway on gut-liver axis. The effects of exposure to CBZ over 21 days in F0 could be passed to the next generation. Intergenerational effects on TLR and antioxidant defense system were also observed in nonexposed F1 at 5 days post-fertilization (5 dpf), but diminished at 21 dpf. The finding provided evidence to unravel immune response by gut-liver axis mediated and oxidative stress under 4 test conditions. The study has raised a potential concern about the multigenerational immune effects of environmental pollutants and calls for a focus on the risk of synergetic pathogen infection.

Assessment of adherence to carbamazepine using plasma and saliva samples, a study from Jordan

Assessment of adherence to carbamazepine using plasma and saliva samples, a study from Jordan

The association of ABCB1 gene polymorphism with clinical response to carbamazepine monotherapy in patients with epilepsy.

Epilepsy is a common neurological disease but around 30% of patients fail to respond to antiepileptic drug (AED) treatment. Genetic variation of the ATP-binding cassette subfamily B, member 1 (ABCB1) gene, a drug efflux transporter may infer treatment resistance by decreasing gastrointestinal absorption and preventing AED entry into the brain. This study examined the impact of ABCB1 genetic variants on carbamazepine responsiveness. Genomic DNA was extracted from whole blood of 104 epileptic patients. Genotyping of 3 ABCB1 variants (c.C3435T, c.G2677T/A and c.C1236T) was undertaken using validated TaqMan allelic discrimination assays. Plasma carbamazepine levels were measured at 3 and 6months following the initial dose using high-performance liquid chromatography (HPLC) alongside clinical outcomes evaluation. Nonresponse to carbamazepine (CBZ) was associated significantly with the ABCB1 variants c.C3435T, c.G2677T/A, c.C1236T and TTT, TTC haplotypes (P < 0.05). There was no significant association between variants and plasma CBZ level (P > 0.05). Our results showed that variant alleles of the ABCB1 gene and TTT, TTC haplotypes were significantly associated with CBZ resistance without affecting the plasma level of carbamazepine. The findings of this study may help to predict patient's response to treatment ultimately it will improve the personalized and evidence based treatment choice of patients with epilepsy.

Distribution pattern of UGT1A6 and UGT2B7 gene polymorphism and its impact on the pharmacokinetics of valproic acid and carbamazepine: Prospective genetic association study conducted in Pakistani patients with epilepsy

Ethnic variation is one of the important factors in clinical practice that may affect the pharmacokinetics of drugs. The present study aims to determine the distribution pattern of UGT1A6 and UGT2B7 gene polymorphism and its possible impact on the metabolism of valproic acid (VPA) and carbamazepine (CBZ) in patients with epilepsy from Khyber Pakhtunkhwa region of Pakistan. After the enrollment of targeted patients, blood was collected for genotype analysis through Sanger sequencing. Plasma concentrations of VPA and CBZ were determined by reversed-phase high-performance liquid chromatography (HPLC) at the follow-up visit of third month from the initiation of therapy. The drug plasma levels were correlated with different genotypes of UGT1A6 and UGT2B7 to determine the impact of genetic polymorphism on the drug metabolism. Of the total 178 epileptic patients, 120 subjects were prescribed VPA monotherapy while 58 subjects were given CBZ monotherapy. The mean age of the subjects was recorded as 26.1 ± 13.5 years with a predominance of the male gender. Generalized tonic-clonic (GTC) was the most prevalent type of seizure (82%) followed by partial seizure. Genotype analysis revealed that the frequency of homozygous and heterozygous variants of the targeted UGT genes were exceptionally high in the Khyber Pakhtunkhwa population compared to the ethnic groups of other countries. In UGT1A6-A552C and UGT1A6-A541G, AC and AG were the most prevalent genotypes with respective frequencies of 43.2% and 41.1% whereas, in UGT2B7-T161C and UGT2B7-G211T, TC and GG were the most prevalent genotypes with respective frequencies of 42.7% and 99.4%. In the VPA-treated group, the homozygous and heterozygous variants of UGT1A6-A552C and UGT1A6-A541G were significantly associated with lower drug plasma concentrations (p<0.05). However, none of the genotypes of UGT2B7-T161C revealed any significant association with VPA plasma concentration (p>0.05). In the CBZ-treated group, UGT gene polymorphisms were not recognized to cause alteration in the drug plasma concentrations (p>0.05). The genetic polymorphisms of UGT1A6, but not UGT2B7 significantly affected the plasma levels of valproic acid. The chosen SNPs did not reveal a role in determining the plasma levels of carbamazepine.

Evaluation of the clinical and quantitative performance of a practical HPLC-UV platform for in-hospital routine therapeutic drug monitoring of multiple drugs

BackgroundIn-hospital therapeutic drug monitoring (TDM) requires a suitable quantification method for target drugs from the viewpoint of precision, throughput, and testing costs. We previously developed a practical HPLC-UV platform for quantification of serum levels of various drugs. In this report, the platform was effectively applied to the quantification of patient serum levels of five different drugs by clinical professionals in our hospital during their daily work.MethodsThe residual sera of patients receiving carbamazepine (CBZ), phenytoin (PHT), lamotrigine (LTG), vancomycin (VCM), or voriconazole (VRCZ) were used in the present clinical study. The quantification method for each drug consisted of rapid solid-phase extraction (SPE) of each drug in the patient serum, followed by optimized HPLC-UV analysis of the drug in the SPE eluate. Furthermore, patient serum levels of PHT, CBZ, and VCM were also measured by ligand-binding assay using a cobas® analyzer in our hospital, and those of LTG and VRCZ were measured by HPLC-MS/MS at an outsourced provider. Passing–Bablok regression analysis and Bland–Altman analysis were employed to analyze the agreement of drug levels in patient sera, which was separately quantified using two different methods—our HPLC-UV platform and the cobas analyzer, or HPLC-UV and HPLC-MS/MS.ResultsAll analytical conditions of the present method using our HPLC-UV platform were well optimized for each target drug quantification in the patient’s serum, and the quantification method for each drug was fully validated for accuracy, precision and reproducibility. Furthermore, Passing–Bablok regression analysis and Bland–Altman analysis revealed that patient serum levels of PHT, CBZ, and VCM quantified by our HPLC-UV platform were closely correlated with those quantified by the cobas® analyzer, and the levels of LTG and VRCZ quantified by our HPLC-UV platform were also correlated with those quantified by HPLC-MS/MS.ConclusionsOur HPLC-UV platform can be performed without requiring special analytical techniques. This platform is expected to be used for the measurement of blood levels of multiple drugs for in-hospital routine TDM.

Pharmacogenetic variants of CYP2C9 and CYP2C19 associated with adverse reactions induced by antiepileptic drugs used in Peru

Epilepsy is the most common neurological disorder with a worldwide incidence of 20% and a treatment failure rate of 25–30%. The fluctuation in serum levels, efficacy and safety of antiepileptic drugs can be attributed to single nucleotide polymorphisms of genes encoding their respective proteins involved in drug metabolism. The present study attempted to evaluate the pharmacogenetic variants of CYP2C9 and CYP2C19 associated with adverse reactions induced by antiepileptic drugs used in Peru. Few studies were found to significantly associate the CYP2C9*2, CYP2C9*3, CYP2C19*2, and CYP2C19*3 single nucleotide polymorphisms with elevated serum levels of valproic acid and carbamazepine, and valproic acid induction of hyperammonemia, and adverse reactions cutaneous for carbamazepine. There is further evidence of a significant association of CYP2C9*2/CYP2C9*3 with severe cutaneous adverse reactions (SCARs) such as Stevens-Johnson syndrome (SJS) and epidermal necrolysis (TEN) phenytoin-induced. CYP2C9*3 may be a pharmacogenetic biomarker for such a drug. It is proposed to reduce the dose of drugs for intermediate and poor metabolizers. No pharmacogenetic studies were found in patients with epilepsy in Peruvian populations. It is concluded that this review could help physicians in the prediction and prevention of adverse reactions induced by antiepileptic drugs, as well as to improve their pharmacotherapeutic results. It could also be used as scientific evidence to carry out pharmacogenetic and precision medicine studies in Peruvian patients with epilepsy, due to their tricontinental and Latin American ancestry.

A simple approach for determination of plasmatic levels of carbamazepine and phenobarbital in poisoning cases using DLLME and liquid chromatography

Carbamazepine (CBZ) and phenobarbital (PHB) are commonly used antiepileptic medications. Due to their accessibility and narrow therapeutic range, many cases of poisoning cases involving these substances have been reported, whether intentional or unintentional. In managing cases of CBZ and PHB poisoning, monitoring plasma levels are important to choose the best treatment for the patient and staging intoxication cases. The use of dispersive liquid-liquid microextraction (DLLME) has proven to be a good approach for toxicological analysis in biological samples and is increasingly used in the clinical-forensic scenario. This study aims to develop a simple method using DLLME and HPLC-UV for the quantification of CBZ and PHB in plasma samples from poisoning cases. The main variables involved in the DLLME were optimized using multivariate experiments. The procedure is based on plasma deproteinization using a dispersive solvent with subsequent extraction with the extractor solvent. The bioanalytical method was fully validated. The lower limits of quantification were 2 μg/mL for CBZ and 10 μg/mL for PHB and the calibration curve was linear (r2 > 0.99) for both analytes. The RSD% in within-run precision varied from 3.2% to 8.7% and between-run precision varied from 3.4% to 8.4%. Accuracy ranged from 85.4% to 105.0%. Normalized matrix factor (NMF%) ranged from 96.1% to 101.2% and the obtained recovery extraction was from 33.9% to 41.5%. The method was successfully applied to 42 plasma samples from suspected poisoning cases. All samples were positive for at least CBZ and/or PHB. The developed and validated method proved to be efficient, easy to execute, and implement, helping in the diagnosis of poisoning.

Cytotoxicity Activity of Graviola Fruit Extract with Carbamazepine and Valproic Acid Show Antagonistic and Indifferent Effects.

Graviola is a tropical fruit with medicinal properties, used for treating various diseases such as inflammation, diabetes, and cancer. Histone deacetylase inhibitors (HDACIs), including carbamazepine (CBZ) and valproic acid (VPA), have been proven strong inhibitors against cancer cell growth. This study investigated the effect of Graviola fruit extract (GFE) on CBZ in healthy rat plasma using high-performance liquid chromatography (HPLC). In addition, the effect of GFE in combination with CBZ and VPA on two human cancer cell lines (PC3 and MCF-7) was explored. The CBZ levels were analyzed using a simple validated HPLC method. The linearity was achieved at a 0.9998 coefficient of determination over a range of 75-5000 ng/mL CBZ. The MTT assay was used to quantify the percentage of viable cells. The maximum plasma concentration (Cmax) and area under the curve (AUC) for CBZ alone were 4,631 ng/mL and 49,225 ng. h/mL, respectively. However, in the presence of GFE, the values reduced significantly to 2,994 ng/mL and 26,587 ng. h/mL, while the p-value was <0.05. The 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay results for VPA showed a weak cytotoxicity activity on PC3 and MCF-7 cell lines. A simple and validated HPLC method was used to determine CBZ levels in rats' plasma. The plasma CBZ levels (Cmax) were significantly reduced in the presence of GFE, indicating the importance of drug-herb interactions. For in vitro studies, two human cancer cell lines, MCF-7 (breast cancer cells) and PC3 (prostate cancer cells), were used to screen the cytotoxicity activity of GFE, CBZ, and VPA. We observed an antagonism effect for GFE and CBZ combination in both cell lines with FIC values > 4. On the contrary, the combination of GFE and VPA showed an additive or indifferent effect.

Genetic polymorphisms of microsomal epoxide hydrolase and UDP-glucuronosyltransferase (UGT) and its effects on plasma carbamazepine levels and metabolic ratio in persons with epilepsy of South India: A cross-sectional genetic association study.

Carbamazepine (CBZ), an anti-seizure drug, is widely prescribed for the management of focal seizures. At a given therapeutic dose, CBZ exhibits marked interindividual variation in the plasma CBZ levels. The aim wasto study the influence of EPHX1 c.337 T>C and UGT2B7*2 genetic polymorphisms on plasma carbamazepine (CBZ) levels in persons with epilepsy (PWE) from South India. 115 PWE belong to South India origin who are on carbamazepine monotherapy were recruited. Genotyping of the two variants weredone using RT-PCR method. PWE who had seizure freedom for one year and their last dose which was not changed for one year duration were included and their plasma levels of CBZ and its active metabolite CBZ 10,11 epoxide were analysed by reverse phase HPLC. In EPHX1 c. 337 (T>C) polymorphism, the PWE carrying CC had lower plasma CBZ levels when compared to CT genotype (2.45 μg/ml vs 3.15 μg/ml. In UGT2B7*2, PWE carrying homozygous mutant TT had higher levels when compared with CT (3.09 μg/ml vs 2.74 μg/ml) genotype but found no statistical significance. Mutant genotype of EPHX1 (CC) had higher metabolic ratio compared to TT genotype (1.33 vs 1.17) but not found to be statistically significant. Mutant genotype of UGT2B7*2 (TT) was found to be having lower metabolic ratio when compared with CC genotype (1.18 vs 1.35; p value =0.08). PWE carrying EPHX1 c.337 T>C (rs1051740) and UGT2B7*2 (rs7439366) genetic polymorphisms did not affect the plasma CBZ levels and metabolic ratio of PWE of South Indian origin. However, this finding should be confirmed in a larger sample size which may help in optimization and personalized CBZ therapy in South Indians.

Influence of EPHX1 c.337T>C and UGT2B7*2 genetic polymorphisms on the requirement of carbamazepine maintenance dose in persons with epilepsy (PWE) of Southern part of India: a cross-sectional genetic association study.

Carbamazepine (CBZ) is a first-line antiseizure drug used for focal onset seizures. It exhibits inter-individual variability in plasma carbamazepine levels and there are both genetic and non-genetic factors having arole in the requirement of CBZ maintenance dose. The aim was to study the influence of EPHX1 c.337T>C and UGT2B7*2 genetic polymorphisms on CBZ maintenance dose requirement in persons with epilepsy. Persons with epilepsy (PWE) of both gender of age 15-65 years on carbamazepine monotherapy who had been taking same maintenance dose for one year were eligible. Five milliliter of venous blood was collected in 10%EDTA under aseptic precautions. After centrifugation, the cellular component was used for DNA extraction and genotyping. For three genotypes of EPHX1 c.337T>C and UGT2B7*2, the differences in mean carbamazepine dose were analyzed using Analysis of Variance (ANOVA). An unpaired t-test was used to draw a comparison between thegenotypes and CBZ maintenance dose requirement fordominant and recessive models of EPHX1 c.337T>C andUGT2B7*2. A value of p<0.05 was considered to be statistically significant. For UGT2B7*2 (rs 7439366), CT required a higher dose (CT 626mg/day and TT 523mg/day) but not found tobesignificant (p-value 0.167). PWE carrying CT genotypeofEPHX1 c.337T>C had 62mg higher dose when compared to homozygous mutant CC (590mg/day for CT and 528mg/day for CC) but p-value was not found to be significant (p-value 0.835). The results of our study done in 115 PWE showed there was a lack of association between SNPs of EPHX1 c.337T>C, UGT2B7*2 and CBZ maintenance dose requirement in Southern part of India and this finding has tobe confirmed in a larger sample size.

A Case of Downbeat Nystagmus Induced by Carbamazepine Intoxication

We report the case of a 33-year-old man who presented with disequilibrium and downbeat nystagmus. Balance testing showed failure of visual suppression of caloric nystagmus with insufficient optokinetic nystagmus responses, suggesting central vestibular dysfunction. However, MRI showed no lesions in the brain, including in the cerebellum. The patient had been diagnosed previously as having epilepsy, and the convulsions had remained under control for more than 10 years with a maintenance dose of carbamazepine (900mg/day). Blood tests revealed a serum level of carbamazepine of 10.7mEq/l, which was over the therapeutic range (4.0-10.0mEq/l). Therefore, his carbamazepine dose was reduced, and with a reduction of the dose to 600mg/day, his disequilibrium and downbeat nystagmus gradually disappeared, along with a decrease in return of the serum level of carbamazepine to the therapeutic range. Therefore, we diagnosed the disequilibrium with downbeat nystagmus in this patient as having been caused by carbamazepine intoxication. Although carbamazepine is metabolized by CYP3A4 in the liver, elevated levels of the drug have been reported in cases of renal failure. As he also suffered from polycystic kidneys, we consider that the progressive renal dysfunction in our patient could have precipitated the carbamazepine intoxication.

Effects of carbamazepine on gut microbiota, ARGs and intestinal health in zebrafish

Carbamazepine (CBZ) in the aquatic environment is recognized as a potential threat to aquatic organisms and public health. However, the response of organism intestinal health, resistome, microbiota, and their relationship after CBZ exposure has been rarely reported. This study aimed to explore the impacts of CBZ on gut microbiota, antibiotic resistance genes (ARGs) and the expression of intestinal health related genes as well as their interaction using the zebrafish model. 16S ribosomal RNA sequencing indicated CBZ altered the composition of gut microbiota. Using high-throughput quantitative polymerase chain reaction (HT-qPCR), we found the number and abundance of ARGs were impacted by CBZ levels and exposure duration. We also observed the upregulated expression of the pro-inflammatory gene IL6 and downregulated expression of toll-like receptor gene TLR2 and intestinal barrier gene TJP2a at different exposure times. Correlation analyses revealed that Geobacillus, Rhodococcus, Ralstonia, Delftia, Luteolibacter and Escherichia-Shigella might be the main bacterial genera carrying ARGs. Meanwhile, Cetobacterium and Aeromonas could be the dominant bacteria affecting intestinal health related genes. Our results could contribute to understanding the health risks of CBZ to the intestinal microecology of aquatic animals.

Mixtures of environmental pharmaceuticals in marine organisms: Mechanistic evidence of carbamazepine and valsartan effects on Mytilus galloprovincialis

Unravelling the adverse outcomes of pharmaceuticals mixture represents a research priority to characterize the risk for marine ecosystems. The present study investigated, for the first time, the interactions between two of the most largely detected pharmaceuticals in marine species: carbamazepine (CBZ) and valsartan (VAL), elucidating mechanisms that can modulate bioaccumulation, excretion and the onset of toxicity. Mytilus galloprovincialis were exposed to environmental levels of CBZ and VAL dosed alone or in combination: measurement of drug bioaccumulation was integrated with changes in the whole transcriptome and responsiveness of various biochemical and cellular biomarkers. Interactive and competing mechanisms between tested drugs were revealed by the much higher CBZ accumulation in mussels exposed to this compound alone, while an opposite trend was observed for VAL. A complex network of responses was observed as variations of gene expression, functional effects on neurotransmission, cell cycle, immune responses and redox homeostasis. The elaboration of results through a quantitative Weight of Evidence model summarized a greater biological reactivity of CBZ compared to VAL and antagonistic interactions between these compounds, resulting in a reduced effect of the antiepileptic when combined with valsartan. Overall, new perspectives are highlighted for a more comprehensive risk assessment of environmental mixtures of pharmaceuticals.