Toxicological evaluation of oral exposure to isoniazid: behavioral, biochemical, and histopathological assessments in rats.

Isoniazid (INH), being the first-line drug used as an anti-tuberculosis drug, is known to be associated with physiological deteriorations including hepatic and neurologic disturbances. This study was aimed at biochemical and behavioral characterization of toxic manifestations of isoniazid treatment in Wistar rats. Experimental animals were divided into four groups. Each group consists of six animals including the control group (saline solution), I25 group (25 mg/kg of INH), I50 group (50 mg/kg of INH), and I100 group (100 mg/kg of INH). Animals received daily INH for 30 days. Isoniazid is known to be associated with hepatotoxicity; it's among the most common causes of drug-induced toxicities. For this reason assays for aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were performed to assess liver toxicity. Moreover, behavioral study, renal, and lipid parameters were also assessed in addition to histological features of the liver and brain. Significant differences in all studied parameters were seen especially in the I100 group and a marked increase in liver enzymes activities, such as AST and ALT was observed. In another hand, there were no major clinical signs in treated animals, except fatigue and anxiety in the I100 group. On the other hand, the histological findings showed potential liver and brain injury which was evidenced by degenerative changes, infiltration, and hepatocyte necrosis, in addition to the appearance of many pyramidales cells in the gyrus. The current study findings suggest that INH interacts with multiple biochemical pathways in the body what comes up by behavioral changes and liver disturbances in animals caused by INH toxicity.

Hypericum Humifusum Leaves Attenuates Hepatic Ischemia-Reperfusion Injury in a Rat Model.

INTRODUCTION: Effective prevention strategies require specific actions during the different phases of ischemia-reperfusion (I-R) injury. The objective of our study is to evaluate the effect of aqueous extract of Hypericum humifusum leaves (HHL) on liver I-R model in Rat. MATERIAL AND METHODS: Animals were subjected to 90 min of hepatic ischemia followed by reperfusion (120 min). HHL extract (25 mg/mL/kg) was injected 15 min before reperfusion. To evaluate the effect of HHL extract on I-R, we have monitored transaminases levels, Malondialdehyde (MDA) concentration, histological lesions (apoptosis and necrosis) and compared the results to a reference oxidant vitamin E. RESULTS: The determination of total phenol extracts of HHL was 59.91 ± 0.35 mg of Gallic Acid/g dry plant material with higher antioxidant activity (91.73% ± 1.67) compared to vitamin E (87.42%). Using aqueous extract of HHL, we noted a significant decrease of AST and ALT [1129 UI (585/1995) and 768 UI (335/1375)] compared to no-treated group [5,585.5 UI (5,035/12,070) and 8,099.5 UI (5,040/12,326)] as a decrease in MDA content [85.7% protection (50.9/91.5)]. HHL extract reduce the damage induced by I-R of 48.7% (27/48.7) and 96.1% (95.7/96.5) for necrosis and apoptosis lesions respectively. CONCLUSION: HHL aqueous extract have potential to protect liver from the damage effect induced by I-R better than vitamin E solution.

[Antiepileptic drugs administration by nasogastric tube in comatose patients]. / Modalités d'administration des antiépileptiques par sonde nasogastrique chez des patients comateux : étude des connaissances, attitudes et pratiques.

AIM: To evaluate the modalities of administration of antiepileptic drugs (AED) with nasogastric tube (NGT) by nurses and to draw up recommendations. METHODS: Our study consisted on investigating the modalities of administration of AED's with NGT by nurses during four months. We prepared 10 questions including demographic information. Participation was voluntary and anonymous. The questionnaire was distributed in seven intensive care departments after authorization of each head of the department. Thus, 45 nurses were included. RESULTS: Nurses sex ratio was 1.5 and mean age was 31 years (25 to 37 years). Among the nurses, 60% mentioned that the NGT were silicone made and 4% that they were PVC made. The mean duration before replacing the NGT was thought to be 5±3 days. Among the nurses, 91% affirmed to clear the NGT after each use. All the nurses had agreed that the solid form is the most commonly used pharmaceutical form in the NGT. AED were associated with the enteral feeding solution in 56%. The AED should be crushed before administration for 98% of the nurses even in case of polymedication. Among them, 62% recommended to crush all of the associated drugs together. Before introducing the AED into the NGT, 93% of the nurses reported mixing with tap water. We have noticed that 62% of nurses felt the need to improve their knowledge AED administration with NGT. CONCLUSION: To optimize AED therapy, modalities of administration by NGT in epileptic comatose patients should be enhanced.

Therapeutic monitoring of antiepileptic drugs in comatose patients.

OBJECTIVE: In this study, we aimed to analyze the trough plasmatic levels (C0) of the antiepileptic drugs (AED) administered by nasogastric tubes (NGT) in comatose patients and to draw up recommendations for therapeutic drug monitoring (TDM) and for the modalities of AED administration by NGT. METHODS: We conducted a retrospective study on comatose patients addressed over six years and 10 months in Clinical Pharmacology for C0 measurement of AED administered by NGT. RESULTS: In this study, the sex-ratio was 2.38 (44 patients). The patients' median age was 24 years. There was 14.5% of children (≤16 years). Among the 103 samples, C0 measurement concerned valproic acid in 57%, phenobarbital in 28 % and carbamazepine in 15%. Two AED or more were associated in 42% of patients. AED were associated to other drugs in 85% of cases. The AED C0 were subtherapeutic in 71% of cases. C0/Dp lower than recommanded in 65 %. In these samples, 55% presented at least one drug association with the concerned AED. In 45% of the cases, there was no drug association but a non-respect of modalities of AED administration by NGT in patients. CONCLUSION:   The drug monitoring is a useful tool to assess drug-drug interactions and to control modalities of AED administration in comatose patients.

Protective effect of Ulva lactuca extract during hepatic cold preservation in rats.

Introduction In recent years, many marine resources have drew attention in the research for bio-active compounds to develop new drugs and health foods. (1) Marine algae are now considered as a rich source of antioxidants (2). It is known that seaweeds contain numerous bioactive substances that have the ability to lower cholesterol, reduce blood pressure, promote healthy digestion; and antioxidant activity (3). Natural antioxidants are interesting compounds due to their properties which help prevent oxidative stress (4), among other potentially beneficial actions. For instance, several biological effects have been attributed to flavonoids, such as anti-tumoral, anti-inflammatory, anti-ischemic and anti-aggregate plaquetary activities. These activities are believed to be in part related to the antioxidant properties of the compounds, namely in scavenging radical oxygen species (ROS). (5, 6) The cold ischemia constitute a situation of oxidative stress in touch with liberation of oxygenated radicals, these situations incited the researchers to find means for the improvement of the conservation of organs allowing to prolong the durations of the cold ischemia of certain organs (in particular the liver) with conservation of the maximum functional value. However, the constant efforts led by the teams of transplantation to develop transplants, the conservation of organs remains a problem to be resolved. (7) Conservation solution of organ appears as being a stemming to remedy the fatal effects of the ischemia-reperfusion. For our part, we think that seaweeds have not delivered their secrets and yet especially that the marine environment of the Tunisian coast still remains little exploited in spite of the big variety of the fauna and the flora of the coast. We envisage in this work, to study a sort of seaweed collected on the Tunisian quotation in the region of "Chott Meriem" (North West of Tunisia). The purpose of our work is to estimate the capacity of extracts stemming from the green seaweed Ulva lactuca to improve the conservation solution of organs against the hepatic effects of ischemia.

Animal model of liver ischemia reperfusion: biochemical and histological evaluation.

INTRODUCTION: During last years, significant progress was made in the comprehension of the hepatic lesions after Ischemia-Reperfusion episode in order to improve the Results in practice clinical. AIM: To avoid or reduce the damage induced by Ischemia-Reperfusion, we developed a model of hepatic Ischemia-Reperfusion with variable periods of reperfusion from 0 to 24 hours.  METHODS: Our study related to rats Wistar males.  Six various groups were studied: the first reference group (without neither ischemia and reperfusion), the second group with ischemia of 90 min and without reperfusion and the 3end , 4end, 5end and 6end groups in addition to ischemia, underwent a reperfusion of 30 min, 2h, 6h and 24h respectively.  The damage of hepatic Ischemia-Reperfusion was evaluated by a biochemical test based on the proportioning of transaminases and an anatomopathologic study by optical microscopy for the determination of the degree of hepatic attack.  RESULTS: The RESULTS obtained seem to show an aggravation of the liver lesions and an increase in the plasmatic rates of AST and ALT in relation with the duration of the reperfusion.  Indeed, the maximum of damage was observed after 2 hours of reperfusion. We observed a reduction in the lesions after 6h and 24h of reperfusion.  CONCLUSION: Our work enabled us to describe a simple model of hepatic Ischemia-Reperfusion with functional, biochemical and anatomopathologic tests.

Contribution of Therapeutic Monitoring in the Assessment of Toxic Adverse Effects of Mitotane: a Case Report.

Mitotane provided serious side effects and low doses seemed to be tolerated. Determination of mitotane concentration in plasma is recommended. We report the case of toxic plasma levels with low doses of mitotane in a 47-year-old man with adrenocortical cancer.

Pharmacokinetik population of methotrexate in tunisian population with acute lymphoblastic leukemia.

BACKGROUND: The use of high dose of MTX in the treatment of the leukemia is actually better controlled by renal preparation, control of plasma concentrations and administration of folinic acid. However, High dose MTX has been proven to cause substantial toxicity and have high intra-and inter-patient variability. Population pharmacokinetic analysis is a useful tool for identification of sources of pharmacokinetic variability during anticancer drug development and can aid the design of alternative dosing regimens to enhance their efficacy and safety. AIM: The aim of our study is to developed and validate a population pharmacokinetics model of our population. We hereby describe the clinical covariates (age, sex and clearance of the creatinine) that influence MTX pharmacokinetic for predicting optimal dose to reduce MTX toxicity. METHOD: It is a prospective study achieved between January 2005 to January 2012 in the Service of Clinical Pharmacology. Including 273 patients treated for acute lymphocytic leukaemia 2582 plasma concentration was achieved. The data have been analyzed with Nonmem© software (non linear regression to mixed effect). RESULTS: The age of our patients varied from 2 to 23 years with an average of 13 years. The patients received high dose MTX therapy (1 to 8 g/m2) in 24 hours infusion every 15 days. Three compartiment models describe the pharmacokinetic of MTX. The most important covariables affecting the model were clearance of the creatinine, age and weight. We obtained a good correlation between the predicted and the observed concentrations. CONCLUSION: The development of population pharmacokinetics model of MTX allows us to propose a therapeutic diagram adapted to every patient according to its morphological and pharmacological features while taking in consideration the therapeutic objective.

[Development and validation of a new HPLC method for determination of Lamotrigine and clinical application]. / Mise au point validation d'une method de dosage de la lamotrigine par chromatographie liquid à haute performance et application clinique.

BACKGROUND: Lamotrigine is an effective anticonvulsant drug used in the treatment of epilepsy. It has a narrow therapeutic range, a large inter and intra-individual pharmacokinetic variability and some concentration-dependent side effects. AIM: The aim of this study was to develop and validate a new method for lamotrigine quantitation in plasma using HPLC with UV/visible detection. METHODS: A rapid HPLC-UV method was developed for the determination of lamotrigine in plasma. All solvents used were HPLC grade. RESULTS: After liquid-liquid extraction, chromatographic separation was achieved using an RP 18 (250 mm) column. The mobile phase was composed of acetonitrile and 0.1 M potassium dihyrogenophosphate (25/75) (v/v). Barbital sodium was used as internal standard. This technique was linear over the 2 µg/mL to 50 µg/mL range (r= 0.99). Detection and quantification limits were 0.07 µg/mL and 0.21 µg/mL, respectively. Within-day coefficient of variation (13.37 to 16 %) and day-to-day coefficients of variation (15.68 to 16.63 %) at three different concentrations. Under these conditions, each analysis required no longer than 10 min. We finally evaluated the plasma concentrations of lamotrigine in Tunisian patients treated with this drug. CONCLUSION: The results found are similar to those previously described and the developed method is repeatable and reproducible. It can be used for clinical applications.

Facial hyperpigmentation during imatinib therapy for gastrointestinal stromal tumor.

We report a rare case of facial hyperpigmentation during imatinib therapy for a gastrointestinal stromal tumor.

Vancomycin therapeutic drug monitoring in cerebrospinal fluid.

Vancomycin penetrates poorly through the blood-brain barrier. Determination of vancomycin concentration in plasma is recommended. In contrast, its determination in cerebrospinal fluid (CSF) is rarely performed. We report the case of a 74-year-old man with post traumatic meningitis with vancomycin concentration measured in CSF.

Drug-Drug Interaction between Tacrolimus and Fluconazole in a Kidney Transplant Recipient.

We report a case of tacrolimus and fluconazole drug-drug interaction in a 20-year-old female kidney transplant recipient with stable kidney function. The patient's tacrolimus blood concentrations were in the therapeutic range until fluconazole was administrated for Candida albicans infection, on day 58 posttransplant. Tacrolimus blood concentration increased by 125% (18.4 ng/mL) on day 79 and by 212% (25.4 ng/mL) on day 84 posttransplant. On day 92, tacrolimus trough blood concentration returned to the therapeutic range (5.6 ng/mL), with decrease of tacrolimus daily dose by 50% (to 4 mg). After fluconazole withdrawal, the patient was returned to the initial tacrolimus daily dose (8 mg) to maintain a tacrolimus trough blood concentration in the therapeutic range. Fluconazole coadministration with tacrolimus shows a significant clinical effect on tacrolimus trough blood concentration in kidney transplant patients. Maintaining a tacrolimus trough blood concentration in the therapeutic range is crucial for these patients; therefore, physicians should be aware of fluconazole prescriptions.

Interaction Between Tacrolimus and Proton Pump Inhibitor in a Kidney Transplant Recipient.

We aimed to present a drug monitoring profile of tacrolimus and proton pump inhibitor coadministration in a 23-year-old male patient with a history of high blood pressure who underwent kidney transplant. The patient's serum trough levels of tacrolimus were in the therapeutic range until omeprazole 20 mg daily was prescribed. Tacrolimus trough serum level increased to 29.5 ng/mL under the same daily dose and to 13.9 ng/mL after tacrolimus daily dose was decreased to 6 mg/day. This increase in tacrolimus serum level was behind a renal function alteration. After withdrawal of omeprazole, tacrolimus trough serum level returned to the therapeutic range. Because interactions between tacrolimus and omeprazole could result in toxicities, careful monitoring of tacrolimus serum levels should be considered to adjust the dosage.

Therapeutic Drug Monitoring of Tacrolimus in Tunisian Renal Transplant Patients during the Tuberculosis Infection: A Retrospective, Observational, Single-centre Analysis.

Tuberculosis is a challenge in organ transplantation due to the interaction between Anti- Tuberculosis Treatment (ATT) and immunosuppressive drugs, such as Tacrolimus (TAC). This study aimed to assess this interaction and discuss the guidelines used in this specific case. METHODS: A retrospective, observational, single-center analysis was performed at the Department of Clinical Pharmacology (National Centre of Pharmacovigilance, Tunisia). We analyzed the database of patients who received TAC from 2009 until 2018. We included samples provided from renal transplant patients infected by Mycobacterium tuberculosis after transplantation. Trough blood levels (C0) were determined using an immunoassay analyzer. The Therapeutic Range (TR) of TAC was considered between 5 and 10 ng/mL. Pharmacokinetic parameters were compared between the period of co-administration of TAC/ATT (period A) and the period during which patients received only TAC (period B). RESULTS: Seven renal transplant patients treated by TAC were included. 41 samples were analyzed (16; period A, 25; period B). Only 6 % of C0 values were found within TR during period A, while this rate was 44% during period B. During period A, 88% of TAC C0 was under the lower limit of TR, indicating a high risk of transplant rejection. The mean C0 and C0/D were significantly lower during period A (3.11±1.53 ng/mL vs 7.11 ± 3.37 ng/mL; p = 0.001 and 33.06 ± 24.89 vs 83.14 ± 44.46; p = 0.0006, respectively), without difference in doses between periods. CONCLUSION: Considering the results of this study, clinicians are suggested to monitor TAC closely in this particular circumstance.

The effects of the CYP3A5*3 variant on tacrolimus pharmacokinetics and outcomes in Tunisian kidney transplant recipients.

INTRODUCTION: Tacrolimus, exhibits interindividual pharmacokinetic variability and a narrow therapeutic index. The influence of the CYP3A5 6986A>G single nucleotide polymorphism (SNP) on this variability remains a topic of debate. AIM: To assess the impact of the aforementioned SNP on tacrolimus area under curve (AUC0-12h), adverse drug reactions (ADRs), and kidney graft outcomes. METHODS: Blood samples were collected from Tunisian kidney transplants over a five-year period during either the early (<3 months) or late (>3 months) post-transplant phases. Through blood concentration (C0) and AUC0-12h of tacrolimus were measured. Patients were prospectively followed to assess graft outcomes. Polymerase chain reaction of restriction fragment length polymorphism was used for CYP3A5 6986A>G genotyping. RESULTS: Fifty Tunisian kidney recipients receiving tacrolimus were enrolled in the study. Acute and chronic graft rejections were observed in eight and three patients, respectively. Twenty-one patients (42%) reported ADRs. C0 and AUC0-12h, showed a significant difference between CYP3A5*1 carriers (mean C0=4 ng.mL-1 and AUC0-12h=94.37 ng.h.mL-1) and CYP3A5*3/3 or poor metabolizers carriers (mean C0=7.45 ng.mL-1; AUC0-12h=151.27 ng.h.mL-1) (p=0.0001; p=0.003, respectively). Supratherapeutic tacrolimus levels were significantly more common in poor metabolizers (p=0.046; Odds-ratio =1.3; confidence interval 95% [1.12-1.66]). The impact of SNP was significant on C0, AUC0-12h, C0/Dose and AUC0-12h/Dose, only in the late phase (p=0.01, 0.002, 0.012, 0.003 respectively). CONCLUSION: CYP3A5*3 variant was significantly associated with tacrolimus pharmacokinetics but had no impact on graft outcomes.

Population pharmacokinetics and Bayesian estimation of cyclosporine in a Tunisian population of hematopoietic stem cell transplant recipient.

PURPOSE: Therapeutic drug monitoring of cyclosporine minimizes the risk of toxicity and acute rejection after transplantation. Areas under the curve (AUCs) rather than trough concentration-based monitoring are recommended. Population pharmacokinetics (PopPK) modeling and Bayesian estimation seem to be the best way to predict cyclosporine disposition and dose requirements to achieve the therapeutic target in an individual patient because of the possibility of predicting cyclosporine AUC using only a few blood samples. Our objectives were to build a PopPk model for cyclosporine in a Tunisian population of HSCT patients and to develop a Bayesian method for the estimation of individual cyclosporine AUC. PATIENTS AND METHODS: The PopPk of cyclosporine was studied using nonlinear mixed effects modeling (NONMEM) in 30 patients (index group) receiving cyclosporine on a twice-daily basis. Ten blood samples were collected after steady-state morning cyclosporine dose. Bayesian estimation of individual AUC was made on the basis of three blood concentration measurements in an independent group of 30 patients (test group). RESULTS: A two-compartment model with first-order absorption and a lag time provided the best fitting. The population mean estimate and interindividual variability from the final model for CL, Ka, Tlag, V1, V2, and Q were 25.4 L/h (CV = 38.72 %), 0.214 h(-1)(CV = 28.5 %), 0.382 h, 10.9 L (85.73 %), 496 L, and 5 L/h, respectively. Covariates had no discernible effects on cyclosporine pharmacokinetics in our population. Bayesian estimation provided an accurate estimation of AUC, although a bias was observed leading to slight underprediction of AUC (bias -1.03 %). A very satisfactory precision was observed (RMSE 12.07 %). CONCLUSION: We report a PopPK model for cyclosporine in Tunisian HSCT patients. Bayesian estimation using only three concentrations provides good prediction of cyclosporine exposure. These tools allow us to routinely estimate cyclosporine AUC in a clinical setting.

[Munchhausen syndrome by proxy revealed by falsely toxic methotrexate levels]. / Syndrome de Münchausen par procuration révélé par des méthotrexatémies toxiques artificielles.

Methotrexate is an antifolate drug used intravenously at high-dose in acute lymphocytic leukemia (ALL). Therapeutic drug monitoring is required to identify patients at risk of developing toxicity and to control folinic acid rescue. We report a case of Münchausen syndrome by proxy revealed by high and persistent falsely toxic methotrexate plasmatic levels. A 12 year-old child was treated with chemotherapy including methotrexate every 70 days for an ALL. The last methotrexate plasmatic level was 0.15 µmol/L at the 72th hour of the infusion. Then, he was treated by oral rout low-dose methotrexate. Ten days after methotrexate infusion, the patient consulted for asthenia, vomiting and presented a mucositis. Methotrexate plasmatic level was 2323 µmol/L. Renal function was normal. All drugs' intake was stopped. Folinic acid rescue was instituted. Even though there was no clinical sign of toxicity, therapeutic drug monitoring showed persistent high methotrexate plasmatic levels. Investigations eliminated measurement errors and pharmacokinetic problems. A deliberate methotrexate addition in each child blood sample brought by the mother was highly suspected. We confirmed this hypothesis by measuring methotrexate plasmatic levels in three samples: one brought by the mother, the second brought by the child's doctor and the last collected in our laboratory. Methotrexate plasmatic levels were respectively over 10,000 µmol/L (first sample) and lower than 0.02 µmol/L (the two others). The diagnosis of Munchausen's syndrome by proxy revealed by falsely toxic methotrexate plasmatic levels was made and the mother was addressed to the psychiatric department.

Comparing real-life carbamazepine exposure between innovator and generic formulation.

BACKGROUND: Carbamazepine is an anticonvulsant largely used in the treatment of epilepsy. The use of generic antiepileptic drugs (AEDs) is controversial because of the eventual possibility to loss seizures control. The aim of our study was to compare the concentration over dose ratio of two products containing carbamazepine, the innovator (Tégrétol®-NOVARTIS) and the generic (Taver®-MEDOCHEMIE). METHODS: It is a retrospective study (2009-2016) including 32 patients treated with carbamazepine. Patients were treated initially by innovator then switched to generic or vice versa. All patients have at least one level of carbamazepine plasma concentration (C0) with the innovator or the generic formulation. Monitoring of carabamazepine was made using immunoassay method (ARCHITECT-ABOTT®). RESULTS: The mean age of our patients was 28.4 years and ranged from 2 to 55 years. The sex ratio M/F was 1.46. The mean ratio C0/dose for the innovator group was 0.723 (min/max: 0.017/1.73), and the mean ratio C0/dose for the generic group was also 0.607 (min/max: 0.064/1.68). There was no statistically significant difference between both groups (P=0.16). CONCLUSION: Our results confirm the difference between the innovator and the generic formulation of carbamazepine. So, switching from innovator to generic seems to be safe and exposure to carbamazepine remains the same.

Is there a ceiling lamotrigine serum level in epileptic children in remission?

INTRODUCTION: Seizure control, in patients with epilepsy, is proportionally associated with health-related quality of life. Antiepileptic therapy leads to seizure remission in most cases. However, some patients are resistant to treatment despite achieving high doses which can be explained by interindividual variability of antiepileptic drugs' metabolism. A ceiling exposure, in epilepsy, helps to adapt the therapeutic strategy in a faster way and to prevent unnecessary exposure to adverse drug reactions. Due to the increasing use of new generations of antiepileptic drugs, we aimed to explore the distribution of lamotrigine (LMT) trough serum levels in epileptic children, stratified between remission and ongoing seizures, in order to determine whether there is a ceiling effect associated with remission. METHODS: We conducted a retrospective study (2012-2021) including children, with generalized epilepsy (2-18 years), addressed for a therapeutic drug monitoring of LMT trough serum levels. Patients in remission, should have as lasting three times the longest pre-treatment seizure-free interval and more than one year. RESULTS: The population of 114 children with generalized epilepsy was divided in to groups: epileptic children in remission (36) and epileptic children with ongoing seizures (78). There was no significant difference in age and sex in the two groups. Median LMT daily dose and trough serum levels were significantly higher in group 2. The highest LMT serum trough level was 11µg/mL in group 1 and 23.1µg/mL in group 2. Valproate was associated in 29%. There was no significant difference of the distribution of valproate in the two groups (P=0.08). CONCLUSIONS: Children in remission had a LMT trough serum levels under 11µg/mL and a daily dose of 3.36mg/kg/day or less. These results suggest that this LMT serum level and daily dose might be associated with a ceiling effect in epileptic children.