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Clinical Chemistry and Laboratory... Jun 2024Primidone is an anticonvulsive drug used in the treatment of epilepsy and essential tremor. It offers beneficial effects in controlling seizures, but its usage is...
An isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS)-based candidate reference measurement procedure (RMP) for the quantification of primidone in human serum and plasma.
OBJECTIVES
Primidone is an anticonvulsive drug used in the treatment of epilepsy and essential tremor. It offers beneficial effects in controlling seizures, but its usage is also associated with possible side effects. To ensure optimal therapy, it is crucial to measure its concentration through accurate quantification methods. Therefore, our main goal was to develop and validate a new reference measurement procedure (RMP) for accurately measuring primidone levels in human serum and plasma.
METHODS
In our study, we focused on the separation of primidone from both known and unknown interferences using a C18 column. To achieve accurate sample preparation, we developed a protocol involving protein precipitation followed by a high dilution step. The validation of the assay and determination of measurement uncertainty were carried out following guidelines from organizations such as the Clinical and Laboratory Standards Institute, the International Conference on Harmonization, and the Guide to the Expression of Uncertainty in Measurement. These rigorous validation processes ensure the reliability and accuracy of our method for quantifying primidone levels in human serum and plasma samples.
RESULTS
The RMP was shown to be highly selective and specific, with no evidence of matrix interference. It can be used to quantify primidone in the range of 0.150-30.0 μg/mL. Intermediate precision was less than 4.0 %, and repeatability CV ranged from 1.0 to 3.3 % across all concentration levels. The relative mean bias ranged from 0.1 to 3.9 % for native serum levels, and from -2.6 to 2.8 % for lithium-heparin plasma levels. The measurement uncertainties for single measurements and target value assignment were 1.5-4.1 % and 0.9-1.0 %, respectively.
CONCLUSIONS
In this study, we introduce an innovative LC-MS/MS-based candidate RMP specifically designed for primidone in human serum and plasma. Our RMP offers a traceable platform, facilitating the standardization of routine assays and enabling the evaluation of clinically relevant samples. With this novel approach, we aim to enhance the accuracy and reliability of primidone measurements, ultimately benefiting the field of clinical research and patient care.
Topics: Humans; Tandem Mass Spectrometry; Primidone; Chromatography, Liquid; Reference Standards; Reproducibility of Results; Indicator Dilution Techniques; Limit of Detection; Anticonvulsants; Liquid Chromatography-Mass Spectrometry
PubMed: 38549258
DOI: 10.1515/cclm-2023-1032 -
CNS Drugs May 2024Post-stroke epilepsy represents an important clinical challenge as it often requires both treatment with direct oral anticoagulants (DOACs) and antiseizure medications... (Comparative Study)
Comparative Study Observational Study
BACKGROUND AND OBJECTIVE
Post-stroke epilepsy represents an important clinical challenge as it often requires both treatment with direct oral anticoagulants (DOACs) and antiseizure medications (ASMs). Levetiracetam (LEV), an ASM not known to induce metabolizing enzymes, has been suggested as a safer alternative to enzyme-inducing (EI)-ASMs in patients treated with DOACs; however, current clinical guidelines suggest caution when LEV is used with DOACs because of possible P-glycoprotein induction and competition (based on preclinical studies). We investigated whether LEV affects apixaban and rivaroxaban concentrations compared with two control groups: (a) patients treated with EI-ASMs and (b) patients not treated with any ASM.
METHODS
In this retrospective observational study, we monitored apixaban and rivaroxaban peak plasma concentrations (C) in 203 patients treated with LEV (n = 28) and with EI-ASM (n = 33), and in patients not treated with any ASM (n = 142). Enzyme-inducing ASMs included carbamazepine, phenytoin, phenobarbital, primidone, and oxcarbazepine. We collected clinical and laboratory data for analysis, and DOAC C of patients taking LEV were compared with the other two groups.
RESULTS
In 203 patients, 55% were female and the mean age was 78 ± 0.8 years. One hundred and eighty-six patients received apixaban and 17 patients received rivaroxaban. The proportion of patients with DOAC C below their therapeutic range was 7.1% in the LEV group, 10.6% in the non-ASM group, and 36.4% in the EI-ASM group (p < 0.001). The odds of having DOAC C below the therapeutic range (compared with control groups) was not significantly different in patients taking LEV (adjusted odds ratio 0.70, 95% confidence interval 0.19-2.67, p = 0.61), but it was 12.7-fold higher in patients taking EI-ASM (p < 0.001). In an analysis in patients treated with apixaban, there was no difference in apixaban C between patients treated with LEV and non-ASM controls, and LEV clinical use was not associated with variability in apixaban C in a multivariate linear regression.
CONCLUSIONS
In this study, we show that unlike EI-ASMs, LEV clinical use was not significantly associated with lower apixaban C and was similar to that in patients not treated with any ASM. Our findings suggest that the combination of LEV with apixaban and rivaroxaban may not be associated with decreased apixaban and rivaroxaban C. Therefore, prospective controlled studies are required to examine the possible non-pharmacokinetic mechanism of the effect of the LEV-apixaban or LEV-rivaroxaban combination on patients' outcomes.
Topics: Aged; Female; Humans; Male; Anticoagulants; Atrial Fibrillation; Dabigatran; Levetiracetam; Prospective Studies; Pyrazoles; Pyridones; Retrospective Studies; Rivaroxaban
PubMed: 38520503
DOI: 10.1007/s40263-024-01077-0 -
The International Journal of... Jan 2024To examine the link between tremor and sex chromosome abnormalities, emphasizing the necessity of comprehensive physical examination.
PURPOSE
To examine the link between tremor and sex chromosome abnormalities, emphasizing the necessity of comprehensive physical examination.
CASE DESCRIPTION
An 18-year-old man exhibited an isolated action tremor in both hands. Despite having no familial history of tremors and no identifiable secondary causes, his tall stature and learning difficulties suggested a genetic origin. His karyotype confirmed the diagnosis of Jacob's syndrome (XYY syndrome). Therapies with primidone and propranolol were ineffective for his tremor.
CONCLUSIONS
Tremor can be caused by various conditions, and aneuploidies might often be overlooked as a cause. They should be considered in young patients with concrete phenotypes and negative familiar history of tremors. Karyotyping is a cost-effective diagnostic tool crucial for genetic counselling. Common treatments for tremors often yield unsatisfactory results in these cases.
PubMed: 38294709
DOI: 10.1080/00207454.2024.2313009 -
Hospital Pharmacy Aug 2023The management of the drug-drug interaction (DDI) between primidone, a moderate to strong cytochrome P-450 (CYP) 3A4 inducer, and apixaban, a direct oral anticoagulant...
The management of the drug-drug interaction (DDI) between primidone, a moderate to strong cytochrome P-450 (CYP) 3A4 inducer, and apixaban, a direct oral anticoagulant (DOAC) and CYP3A4 substrate is complex and limited evidence exists to guide management. This case report describes a 65-year-old male, receiving primidone for essential tremor who developed an acute venous thromboembolism (VTE) requiring oral anticoagulation. DOACs are preferred over vitamin K antagonists for acute VTE treatment. Based on patient-specific variables, provider preference, and the avoidance of other DDIs, apixaban was selected. Apixaban's package insert recommends avoiding use with concomitant strong P-gp and CYP3A4 inducers due to the decreased exposure to apixaban; however, no recommendations are available for drugs that are moderate to strong CYP3A4 inducers and lack P-gp effects. Given that phenobarbital is an active metabolite of primidone, extrapolation of evidence from such literature is theoretical but provides insight into the management of this multi-faceted DDI. In the absence of the ability to monitor plasma apixaban levels, a management strategy of avoidance with a washout period of primidone based on pharmacokinetic parameters was used in this case. Additional evidence is needed to clearly understand the degree of impact and clinical significance of the DDI between apixaban and primidone.
PubMed: 37360203
DOI: 10.1177/00185787221150928 -
Molecules (Basel, Switzerland) Nov 2023The objective of the present report was to develop and validate a simple, selective, and reproducible high-performance liquid chromatography method with UV detection...
The objective of the present report was to develop and validate a simple, selective, and reproducible high-performance liquid chromatography method with UV detection suitable for routine therapeutic drug monitoring of the most commonly used antiepileptic drugs and some of their metabolites. Simple precipitation of plasma proteins with acetonitrile was used for sample preparation. 10,11-dihydrocarbamazepine was used as an internal standard. Chromatographic separation of the analytes was achieved by gradient elution on a Phenyl-Hexyl column at 40 °C, using methanol and potassium phosphate buffer (25 mM; pH 5.1) as a mobile phase. The method was validated according to the FDA guidelines for bioanalytical method validation. It showed to be selective, accurate, precise, and linear over the concentration ranges of 1-50 mg/L for phenobarbital, phenytoin, levetiracetam, rufinamide, zonisamide, and lacosamide; 0.5-50 mg/L for lamotrigine, primidone, carbamazepine and 10-monohydroxycarbazepine; 0.2-10 mg/L for carbamazepine metabolites: 10,11-trans-dihydroxy-10,11-dihydrocarbamazepine and carbamazepine-10,11-epoxide; 0.1-10 mg/L for oxcarbazepine; 2-100 mg/L for felbamate and 3-150 mg/L for ethosuximide. The suitability of the validated method for routine therapeutic drug monitoring was confirmed by quantification of the analytes in plasma samples from patients with epilepsy on combination antiepileptic therapy.
Topics: Humans; Anticonvulsants; Chromatography, High Pressure Liquid; Drug Monitoring; Carbamazepine; Oxcarbazepine
PubMed: 38067559
DOI: 10.3390/molecules28237830 -
Cureus Apr 2024Leber hereditary optic neuropathy (LHON) is a mitochondrial disorder that presents with acute to subacute onset of unilateral progressive optic neuropathy, with...
Leber hereditary optic neuropathy (LHON) is a mitochondrial disorder that presents with acute to subacute onset of unilateral progressive optic neuropathy, with sequential involvement of the fellow eye months to years later. The condition may be accompanied by neurological symptoms, including tremors, dystonia, seizures, or psychosis, in which case, it is termed LHON-plus. Here, we present the case of a 53-year-old man who was initially diagnosed with essential tremor but was later found to have LHON-plus after the onset of bilateral visual loss and a genetic panel. His essential tremor was refractory to standard pharmacological therapies, including propranolol, primidone, and topiramate. As a result, he elected to undergo bilateral deep brain stimulation (DBS) of the bilateral ventral intermediate nucleus of the thalamus with a dramatic improvement in symptoms. To our knowledge, this is the first case of essential tremor presenting in the context of LHON-plus to be treated successfully with DBS. While DBS has been applied in LHON-plus presenting with dystonia with limited success, our outcome suggests that there is promise in this approach and that more research is needed to evaluate it.
PubMed: 38756271
DOI: 10.7759/cureus.58255 -
Transplantation Proceedings Oct 2023Calcineurin inhibitor-related tremors occur in up to 50% of solid organ transplant recipients and are disabling in severe cases. We describe a bilateral lung transplant...
Calcineurin inhibitor-related tremors occur in up to 50% of solid organ transplant recipients and are disabling in severe cases. We describe a bilateral lung transplant recipient with essential tremors that significantly worsened after tacrolimus initiation. She did not have improvement with the change to extended-release tacrolimus, the use of everolimus as a calcineurin inhibitor-sparing agent, or the addition of primidone, clonazepam, or propranolol. She underwent magnetic resonance-guided focused ultrasound thalamotomy with significant improvement in her tremor and activities of daily living.
PubMed: 37495484
DOI: 10.1016/j.transproceed.2023.06.012