A versatile ratiometric fluorescence nanoprobe for the determination of clonazepam in patients' plasma samples.

Despite the necessity of the study of therapeutic drug monitoring of clonazepam (CLZ), there are only a few fast detection methods available for determining CLZ in biological media. This study aims to develop a cost-effective and ratiometric probe for the quantification of CLZ in plasma samples. Fluorescent polydopamine nanoparticles were produced through a self-polymerization process at a pH of 8.5. Rhodamine B molecules were employed as a fluorescent reference material, emitting stable fluorescence in the visible range. The fabricated probe exhibited a specific detection capability for CLZ. The fluorescence emission of the probe was enhanced in two concentration ranges: from 50 ng/mL to 1.0 µg/mL and from 1.0 to 15.0 µg/mL with a lower limit of quantification of 50 ng/mL, indicating the sensitivity of the probe for detecting CLZ plasma levels. The accuracy of the probe is favorable which could be recommended for CLZ monitoring in the biological media. Furthermore, this probe is highly specific towards CLZ in the presence of various interfering agents which is mainly caused by its ratiometric nature. The developed platform showed high reliability in quantifying CLZ concentrations in patients' plasma samples. Hence, the fabricated probe could be recommended as a reliable method for the routine detection of CLZ in clinical settings.

Seizure control and complications in patients switching from clobazam to clonazepam due to drug shortage.

BACKGROUND: Antiseizure medication (ASM) shortages are a global problem that have a negative impact on outcomes such as seizure control in patients with epilepsy (PWE). In the case of clobazam (CLB) shortage, there is no study regarding the management strategy. This study aims to investigate the alteration in seizure frequency and the occurrence of side effects in PWE undergoing an abrupt switch from clobazam (CLB) to clonazepam (CLZ), during CLB shortage. MATERIAL AND METHODS: A retrospective study was conducted from electronic health records at our neurology outpatient clinic from January to July 2022. Change in seizure frequency and percentage of CLZ-associated side effects were determined as primary and secondary outcomes, respectively. Potential drug-drug interactions (Level C and above) were evaluated by using Lexicomp Drug Interaction Checker. RESULTS: The analysis included a total of 29 adult patients (15F, median age: 29). The switching ratio was 10 mg CLB for every 1 mg CLZ (10:1). Seizure frequency was higher during the CLZ period compared to the CLB period (p < 0.05), but no status epilepticus cases were observed. All patients exhibited potential drug-drug interactions, leading to reduced CLZ levels in 12 cases. A total of 36 CLZ-associated side effects were identified, with fatigue (19.4 %), drowsiness (16.6 %), and somnolence (13.8 %) being the most prevalent. A positive and strong correlation was found between CLZ dose and the number of side effects (r: 0.556; p: 0.002). CONCLUSION: The abrupt switch from CLB to CLZ was observed to increase seizure frequency without leading to status epilepticus in PWE. CLZ-associated side effects were found to be tolerable despite the abrupt switch. Future studies may explore the effect of alternative switching ratios.

Pharmacokinetics of oral clonazepam in growing commercial pigs (Sus scrofa domestica).

Clonazepam causes sedation and psychomotor impairment in people. Due to similarities between people and swine in response to benzodiazepines, clonazepam may represent a viable option to produce mild-to-moderate tranquillization in pigs. The objective of this study was to determine the pharmacokinetic profile of a single oral dose (0.5 mg/kg) of clonazepam in eight healthy, growing commercial cross pigs. Serial plasma samples were collected at baseline and up to 96 h after administration. Plasma concentrations were quantified using reverse-phase high-performance liquid chromatography, and compartment models were fit to time-concentration data. A one-compartment first-order model best fits the data. Maximum plasma concentration was 99.5 ng/mL, and time to maximum concentration was 3.4 h. Elimination half-life was 7.3 h, mean residence time 7.4 h, and apparent volume of distribution 5.7 L/kg. Achieved plasma concentrations exceeded those associated with psychomotor impairment in people although pharmacodynamic effects have not been investigated in pigs. A simulated oral regimen consisting of 0.35 mg/kg administered every 8 h to pigs would achieve plasma concentrations above 32 ng/mL which are shown to produce psychomotor impairment in people. Further studies to test the clinical efficacy of these dosages in commercial and miniature pigs are warranted.

Clonazepam for the management of sleep disorders.

BACKGROUND: The objectives of this review and meta-analysis of polysomnographic data are those to focus on the clinical use of clonazepam for the management of sleep disorders by re-analyzing clinical trials and randomized clinical trials which have been published in peer-reviewed journals. METHODS: A review of the literature including clinical trials and randomized controlled trials was performed in PubMed®, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement protocol. A random effects model meta-analysis was then carried out for the four more frequently reported polysomnographic measures: total sleep time, sleep latency, sleep efficiency, and periodic leg movement during sleep (PLMS) index. RESULTS: A total of 33 articles were retrieved and screened in full text, of which 18 met the criteria for review; among the latter, nine met the criteria for meta-analysis. The studies included in the review involved patients with insomnia, REM sleep behavior disorder, sleep bruxism, and restless leg syndrome or PLMS which reported, most often, an increase in total sleep time with clonazepam. A clear sleep-promoting effect of clonazepam was found also by meta-analysis. DISCUSSION AND CONCLUSIONS: Our results indicate that the pharmacological treatment of sleep disorders with clonazepam must always be personalized according to the type of patient, the risk of addiction and the concomitant presence of respiratory disorders are key factors to take into account. However, in light of the clinical evidence of the few studies in the literature on the different types of disorders, more studies on the use of clonazepam (also in association with first choice treatments) are definitely needed.

Comparative efficacy of prolonged-release melatonin versus clonazepam for isolated rapid eye movement sleep behavior disorder.

PURPOSE: Clonazepam and melatonin are recommended as first-line treatments for isolated rapid eye movement (REM) sleep behavior disorder (iRBD). This study aimed to compare their efficacy and safety in REM sleep without atonia (RWA) and RBD-related symptoms. METHODS: This prospective, open-label, randomized trial included patients with video-polysomnography-confirmed iRBD. The patients were randomly assigned to receive either clonazepam 0.5 mg or prolonged-release (PR) melatonin 2 mg 30 min before bedtime for 4 weeks. The primary outcome was changes in RWA on follow-up polysomnography (PSG). Secondary endpoints were changes in other PSG parameters, clinical global improvement-impression scale (CGI-I) scores, and sleep questionnaire scores. The safety endpoint was adverse events. RESULTS: Of 40 patients with probable RBD considered, 34 were enrolled in the study and randomized. Visual scoring parameters of RWA indices were reduced, and automatic scoring parameters tended to be improved after clonazepam treatment but not after PR melatonin treatment. The proportion of N2 sleep was increased, and N3 and REM sleep were decreased only in the clonazepam group. The clonazepam group tended to answer "much or very much improvement" on the CGI-I more frequently than the PR melatonin group (p = 0.068). Daytime sleepiness and insomnia symptoms were reduced after PR melatonin but not after clonazepam. Depressive symptoms increased after clonazepam. Four of the patients (13.3%) reported mild to moderate adverse events, which were similar between the two groups. CONCLUSION: Four weeks of clonazepam, but not PR melatonin, improved RWA. RBD symptom improvement tended to be better after clonazepam than PR melatonin in exchange for increased depressive symptoms and daytime sleepiness. CLINICALTRIALS: gov identifier: NCT03255642 (first submitted August 21, 2017).

Population pharmacokinetics of clonazepam in saliva and plasma: Steps towards noninvasive pharmacokinetic studies in vulnerable populations.

AIM: Traditional studies focusing on the relationship between pharmacokinetics (PK) and pharmacodynamics necessitate blood draws, which are too invasive for children or other vulnerable populations. A potential solution is to use noninvasive sampling matrices, such as saliva. The aim of this study was to develop a population PK model describing the relationship between plasma and saliva clonazepam kinetics and assess whether the model can be used to determine trough plasma concentrations based on saliva samples. METHODS: Twenty healthy subjects, aged 18-30, were recruited and administered 0.5 or 1 mg of clonazepam solution. Paired plasma and saliva samples were obtained until 48 hours post-dose. A population pharmacokinetic model was developed describing the PK of clonazepam in plasma and the relationship between plasma and saliva concentrations. Bayesian maximum a posteriori optimization was applied to estimate the predictive accuracy of the model. RESULTS: A two-compartment distribution model best characterized clonazepam plasma kinetics with a mixture component on the absorption rate constants. Oral administration of the clonazepam solution caused contamination of the saliva compartment during the first 4 hours post-dose, after which the concentrations were driven by the plasma concentrations. Simulations demonstrated that the lower and upper limits of agreements between true and predicted plasma concentrations were -28% to 36% with one saliva sample. Increasing the number of saliva samples improved these limits to -18% to 17%. CONCLUSION: The developed model described the salivary and plasma kinetics of clonazepam, and could predict steady-state trough plasma concentrations based on saliva concentrations with acceptable accuracy.

Modulatory effect of long-term treatment with escitalopram and clonazepam on the expression of anxiety-related neuropeptides: neuromedin U, neuropeptide S and their receptors in the rat brain.

BACKGROUND: Newly identified multifunctional peptidergic modulators of stress responses: neuromedin U (NMU) and neuropeptide S (NPS) are involved in the wide spectrum of brain functions. However, there are no reports dealing with potential molecular relationships between the action of diverse anxiolytic or antidepressant drugs and NMU and NPS signaling in the brain. The present work was therefore focused on local expression of the aforementioned stress-related neuropeptides in the rat brain after long-term treatment with escitalopram and clonazepam. METHODS: Studies were carried out on adult, male Sprague-Dawley rats that were divided into 3 groups: animals injected with saline (control) and experimental individuals treated with escitalopram (at single dose 5 mg/kg daily), and clonazepam (at single dose 0.5 mg/kg). All individuals were sacrificed under anaesthesia and the whole brain excised. Total mRNA was isolated from homogenized samples of amygdala, hippocampus, hypothalamus, thalamus, cerebellum and brainstem. Real time-PCR method was used for estimation of related NPS, NPS receptor (NPSR), NMU, NMU and receptor 2 (NMUR2) mRNA expression. The whole brains were also sliced for general immunohistochemical assessment of the neuropeptides expression. RESULTS: Chronic administration of clonazepam resulted in an increase of NMU mRNA expression and formation of NMU-expressing fibers in the amygdala, while escitalopram produced a significant decrease in NPSR mRNA level in hypothalamus. Long-term escitalopram administration affects the local expression of examined neuropeptides mRNA in a varied manner depending on the brain structure. CONCLUSIONS: Pharmacological effects of escitalopram may be connected with local at least partially NPSR-related alterations in the NPS/NMU/NMUR2 gene expression at the level selected rat brain regions. A novel alternative mode of SSRI action can be therefore cautiously proposed.

Safety and efficacy of melatonin, clonazepam, and trazodone in patients with Parkinson's disease and sleep disorders: a randomized, double-blind trial.

BACKGROUND: Sleep disturbances are common non-motor symptoms of Parkinson's disease (PD). We aimed to compare the safety and efficacy of trazodone with melatonin and clonazepam in patients with PD and sleep complaints. METHODS: This single-center, double-blind, randomized clinical trial was conducted on PD patients with subjective sleep complaints. Eligible patients were randomized 1:1:1 to receive melatonin 3 mg/day, clonazepam 1 mg/day, or trazodone 50 mg/day for 4 weeks. The primary outcome measure was the changes in Pittsburgh Sleep Quality Index (PSQI) scores. The mean change in Epworth Sleepiness Scale (ESS) and RBD screening questionnaire (RBDSQ) was considered as the secondary outcome measures. RESULTS: A total of 112 eligible patients were randomized and 93 participants, melatonin (n = 31), trazodone (n = 31), and clonazepam (n = 31), completed the study. There was a significant decrease in PSQI scores after 4 weeks of treatment in all groups. The mean changes of PSQI from baseline were similar among the treatment arms (P = 0.325). Mean changes of RBDSQ and ESS from baseline were significantly different between study arms (P < 0.05). Melatonin intake was associated with a higher decrease in RBDSQ score compared to trazodone (P = 0.011) and clonazepam (P = 0.004). Trazodone intake was associated with a higher decrease in ESS score compared to clonazepam (P = 0.010). Mild adverse events were reported in three patients in the clonazepam, two patients in the trazodone group, and none in the melatonin group. CONCLUSIONS: Trazodone 50 mg/day, clonazepam 1 mg/day, and melatonin 3 mg/day were all tolerable and effective in improving sleep quality in patients with PD. TRIAL REGISTRATION: Iranian Registry of Clinical Trials (registration number; IRCT20170821035819N2).

Topical clonazepam for burning mouth syndrome: Is it efficacious in patients with anxiety or depression?

BACKGROUND: Burning mouth syndrome (BMS) is a chronic disorder characterised by pain in the oral cavity without clinically evident causative lesions. The aetiology of this condition is poorly understood, and treatment can be challenging. METHOD: A retrospective review of the medical records of 82 patients with BMS was performed. Data on demographics, BMS associated symptoms, symptoms' intensity score (NRS: 0-10) and response to treatment with topical clonazepam were extracted from clinical notes based on a standardised clinical questionnaire. Differences in the symptoms' intensity score between patients with or without concomitant anxiety/depression or systemic psychogenic medication use were analysed using the Wilcoxon signed rank test. RESULTS: Among the entire cohort, the median symptoms' intensity score at baseline was 4.5 and 3.0 at first follow-up, a statistically significant improvement (p < .001; 95% CI). Among the subjects with anxiety/depression and those who were prescribed systemic psychogenic medications, the median symptoms' intensity score at baseline was 5.0 and 3.0 at first follow-up, a statistically significant improvement (p < .001; 95% CI). Among those without anxiety/depression, the symptoms' intensity score at baseline was 4.0 and 2.0 at first follow-up, a statistically significant improvement (p < .05; 95% CI). The median symptoms' intensity score for those who were not on any psychogenic medications at baseline was 4.0 and 2.0 at first follow-up, a statistically significant improvement (p < .001; 95% CI). CONCLUSIONS: Clinicians are encouraged to prescribe topical clonazepam for BMS regardless of concomitant use of systemic psychogenic medications or comorbid mood disorders as it is an efficacious management approach in the presence or absence of these potentially complicating factors.

Age of Diagnosis and Comorbid PLMD Predict Poor Response of REM Behavior Disorder to Clonazepam.

Previous studies have shown the therapeutic effects of clonazepam for rapid eye movement sleep behavior disorder (RBD), but they had several limitations such as the lack of clear definition of treatment outcomes and little information about adjuvant therapy. The aims of this study were to evaluate the treatment outcomes with clonazepam and to explore possible determinants of treatment response. We performed a retrospective medical chart review of 171 patients with RBD. All the participants underwent overnight polysomnography and completed questionnaires. The positive treatment response was defined as the absence of disruptive behaviors causing sleep-related injuries during the last year of follow-up. Among the 171 patients presented with disruptive behaviors, 155 (90.6%) experienced positive treatment responses. Of the responders, 18 (11.6%) received adjunctive medication due to insufficient therapeutic effect of clonazepam monotherapy. After adjusted analysis, an earlier age of diagnosis (odds ratio [OR] = 0.74, 95% confidence interval [CI] = 0.64-0.86, P < .001) and comorbid periodic limb movement during sleep (OR = 4.96, 95% CI = 1.05-23.33, P = .043) were related to poor treatment response. Clinicians should recognize the predictors of poor treatment response and consider combination therapy for better prevention of sleep-related injuries in those who show unsatisfactory responses to clonazepam monotherapy.

Clonazepam-induced lichenoid drug eruption: a case report.

BACKGROUND: Lichenoid drug eruption is rare and can mimic idiopathic lichen planus and other dermatoses. Clonazepam, a commonly used drug for the treatment of anxiety-related disorders and seizures, is known to be an unlikely cause of cutaneous adverse effects. Only one case report of LDE due to clonazepam has been reported. CASE PRESENTATION: A 81-year-old male patient with Alzheimer's disease developed a lichenoid eruption after taking clonazepam. He developed a violaceous scaly patch on his lower extremities, from both buttocks to the feet. The cutaneous eruption resolved 2 months after cessation of clonazepam and with initiation of corticosteroid therapy. CONCLUSION: A skin eruption that develops after clonazepam administration can be a lichenoid drug eruption, which is less likely to resolve spontaneously and requires discontinuation of clonazepam administration.

Advances in hyperekplexia and other startle syndromes.

Startle, a basic alerting reaction common to all mammals, is described as a sudden involuntary movement of the body evoked by all kinds of sudden and unexpected stimulus. Startle syndromes are heterogeneous groups of disorders with abnormal and exaggerated responses to startling events, including hyperekplexia, stimulus-induced disorders, and neuropsychiatric startle syndromes. Hyperekplexia can be attributed to a genetic, idiopathic, or symptomatic cause. Excluding secondary factors, hereditary hyperekplexia, a rare neurogenetic disorder with highly genetic heterogeneity, is characterized by neonatal hypertonia, exaggerated startle response provoked by the sudden external stimuli, and followed by a short period of general stiffness. It mainly arises from defects of inhibitory glycinergic neurotransmission. GLRA1 is the major pathogenic gene of hereditary hyperekplexia, along with many other genes involved in the function of glycinergic inhibitory synapses. While about 40% of patients remain negative genetic findings. Clonazepam, which can specifically upgrade the GABARA1 chloride channels, is the main and most effective administration for hereditary hyperekplexia patients. In this review, with the aim at enhancing the recognition and prompting potential treatment for hyperekplexia, we focused on discussing the advances in hereditary hyperekplexia genetics and the expound progress in pathogenic mechanisms of the glycinergic-synapse-related pathway and then followed by a brief overview of other common startle syndromes.

Oral clonazepam versus lorazepam in the treatment of methamphetamine-poisoned children: a pilot clinical trial.

OBJECTIVES: To evaluate the efficacy of oral clonazepam versus oral lorazepam following initial parenteral benzodiazepine administration to control methamphetamine-induced agitation in children. METHODS: In a single-center clinical trial, intravenous diazepam (0.2 mg/Kg) was initially administered to all methamphetamine-poisoned pediatric patients to control their agitation, followed by a single dose of oral clonazepam (0.05 mg/Kg; n = 15) or oral lorazepam (0.05 mg/Kg; n = 15) to prevent relapse of toxicity. RESULTS: The median age [IQR] (range) was 15 [10, 36] (6-144) months. The source of poisoning was methamphetamine exposure from oral ingestion in 23 (76.7%) and passive inhalation in 7 (23.3%) patients. The most common symptoms/signs were agitation (29; 96.7%), mydriatic pupils (26; 86.7%), and tachycardia (20; 66.6%). Two in each group (13.3%) needed re-administration of intravenous diazepam due to persistent agitation. There was no report of benzodiazepine complications in either group. CONCLUSIONS: Clonazepam and lorazepam treatment was equally effective at similar doses. However, considering the higher potency of clonazepam, it seems that lorazepam is the safer benzodiazepine for oral maintenance treatment of methamphetamine-induced agitation in children and can be used with minimal complications. TRIAL REGISTRATION: IRCT20180610040036N2, April 18th, 2020. Retrospectively registered.

Factors associated with depression in people with epilepsy: a retrospective case-control analysis.

PURPOSE: This study investigated factors associated with depression in people with epilepsy. METHODS: All adult patients attending our epilepsy clinic in 2018 were screened for inclusion in this study. Eligible patients were divided into case and control groups, depending on the presence of co-morbid depression. Depressive disorders were diagnosed by a psychiatrist. Demographics and clinical characteristics, including epilepsy features and antiepileptic drug use, were compared between groups. The factors contributing to onset of depression after diagnosis of epilepsy were further analysed by binomial logistic regression. Statistical significance was set at P<0.05. RESULTS: Forty four patients with epilepsy who had depression and 514 patients with epilepsy who did not have depression were included in this study (occurrence rate=7.9%). Female sex (P=0.005), older age (P<0.001), temporal lobe epilepsy (P=0.01), and higher number of antiepileptic drugs used (P=0.003) were associated with depression in patients with epilepsy. No differences were observed in other epilepsy-related factors including aetiology, seizure type, and laterality of epileptic focus. Binomial logistic regression showed that female sex (P=0.01; odds ratio [OR]=3.56), drug-resistant epilepsy (P<0.001; OR=4.79), and clonazepam use (P<0.001; OR=14.41) were significantly positively associated with risk of depression after epilepsy diagnosis, whereas valproate use (P=0.03; OR=0.37) was significantly negatively associated with risk of depression. CONCLUSION: Female sex, refractoriness, and clonazepam use may be risk factors for depression after epilepsy diagnosis. Valproate may protect against depression in people with epilepsy. Better understanding of clinical features may aid in medical management or research studies regarding co-morbid depression in people with epilepsy.

Neonatal Clonazepam Administration Induced Long-Lasting Changes in GABAA and GABAB Receptors.

Benzodiazepines (BZDs) are widely used in patients of all ages. Unlike adults, neonatal animals treated with BZDs exhibit a variety of behavioral deficits later in life; however, the mechanisms underlying these deficits are poorly understood. This study aims to examine whether administration of clonazepam (CZP; 1 mg/kg/day) in 7-11-day-old rats affects Gama aminobutyric acid (GABA)ergic receptors in both the short and long terms. Using RT-PCR and quantitative autoradiography, we examined the expression of the selected GABAA receptor subunits (α1, α2, α4, γ2, and δ) and the GABAB B2 subunit, and GABAA, benzodiazepine, and GABAB receptor binding 48 h, 1 week, and 2 months after treatment discontinuation. Within one week after CZP cessation, the expression of the α2 subunit was upregulated, whereas that of the δ subunit was downregulated in both the hippocampus and cortex. In the hippocampus, the α4 subunit was downregulated after the 2-month interval. Changes in receptor binding were highly dependent on the receptor type, the interval after treatment cessation, and the brain structure. GABAA receptor binding was increased in almost all of the brain structures after the 48-h interval. BZD-binding was decreased in many brain structures involved in the neuronal networks associated with emotional behavior, anxiety, and cognitive functions after the 2-month interval. Binding of the GABAB receptors changed depending on the interval and brain structure. Overall, the described changes may affect both synaptic development and functioning and may potentially cause behavioral impairment.

Efficacy of yokukansan compared with clonazepam for rapid eye movement sleep behaviour disorder: a preliminary retrospective study.

AIM: Rapid eye movement sleep behaviour disorder (RBD) is characterized by abnormal behaviours accordant with nightmares during rapid eye movement sleep and is considered a prodromal marker of dementia with Lewy body. Most common in the elderly population, RBD is generally treated with clonazepam (CZP), a long-term acting benzodiazepine antiepileptic. As such, alternative drugs for RBD are urgently needed to minimize the adverse effects peculiar to benzodiazepines. The efficacy of yokukansan (YKS), a traditional Japanese herbal medicine, on RBD was initially reported by Shinno et al. in 2008. However, no study has compared YKS with CZP. Therefore, this study aimed to clarify the possibility of using YKS as an alternative to CZP. METHODS: This was a retrospective cohort study conducted at Jikei University Affiliated Hospital. The subjects were selected from 36 outpatients who had been diagnosed with RBD based on the International Classification of Sleep Disorders, third edition. Of the 23 who met the inclusion criteria but not the exclusion criteria, 11 were treated with YKS monotherapy, and 12 were treated with CZP monotherapy. The primary outcome was the total score on the Japanese version of the Rapid Eye Movement Sleep Behaviour Disorder Questionnaire (RBDQ-JP), and the secondary outcomes were the scores from the eight-item Short-Form Health Survey and factors 1 and 2 of the RBDQ-JP. RESULTS: The mean total RBDQ-JP score significantly improved from 52.5 to 21.7 (P = 0.002) after treatment with YKS (mean dosage: 3.0 g/day), which was similar to the change after CZP treatment (from 43.8 to 21.3). On RBDQ-JP factor 1 (dream content), the mean score on five of six items significantly improved after treatment with YKS. There was no significant change in Short-Form Health Survey scores after treatment with either drug. Potassium concentrations were within the normal range in patients treated with YKS. CONCLUSIONS: The present results suggest that a small amount of YKS may be an alternative to CZP for RBD, without remarkable adverse events. Further study is needed to prospectively clarify the efficacy and safety of YKS in more detail.

Retention Time and Ion Abundance Ratio of 8 Common Drugs （Poisons） by LC-MS/MS Qualitative Analysis.

ABSTRACT: Objective To investigate the maximum allowable deviations of retention time and ion abundance ratio of the 8 common drugs （poisons） from 3 categories, poisons （methamphetamine, morphine, ketamine）, benzodiazepines （estazolam, midazolam, diazepam, clonazepam） and barbiturates （phenobarbital） in blood, by liquid chromatography-tandem mass spectrometry （LC-MS/MS） in forensic toxicology analysis. Methods The deviations of retention time and ion abundance ratio at 7 low mass concentrations, limit of detection （LOD）, 2LOD, limit of quantitation （LOQ）, 1.5LOQ, 2LOQ, 4LOQ and 6LOQ, were tested by LC-MS/MS after liquid-liquid extraction under the conditions of two chromatographic columns and three chromatographs. Results The deviation of absolute retention time of 98.11% of 8 drugs （poisons） in the blood samples was within the range of ±0.05 min, and that of the relative retention time of 96.21% was within the range of ±0.4%. The maximum deviation of the ion abundance ratio was highly correlated with the mass concentration. When the mass concentration of drugs （poisons） was LOQ or above, more than 95% of the absolute deviation and relative deviation of the ion abundance ratio were in the range of ±25% and ±40%, respectively; when the mass concentration was below LOQ, the range could be expanded to ±35% and ±50%, respectively. Conclusion It is recommended for the determination range of the absolute retention time deviation of 8 common drugs （poisons） to be ±0.1 min and that of the relative retention time deviation to be ±1.0%. The determination range of absolute deviation of the ion abundance ratio should be ±25% when the mass concentration is LOQ or above, and the relative deviation should be ±40%. When the mass concentration is below LOQ, the deviation determination range can be expanded to ±35% and ±50%, respectively.

A randomized, single-dose, two-sequence, two-period, crossover study to assess the bioequivalence between two formulations of clonazepam tablet in healthy subjects.

Clonazepam is a benzodiazepine commonly prescribed to treat panic disorder, epilepsy, anxiety, depression and certain types of seizures. This study aimed to evaluate the bioequivalence between two formulations of clonazepam tablets in order to meet regulatory requirements for marketing in Colombia and other countries in Latin America. An open-label, randomized, single-dose, two-period, two-sequence, two-treatment crossover study was conducted in 36 healthy subjects of both genders. Subjects received a single dose of clonazepam 2 mg test tablet (Sanofi-Aventis de Colombia S.A.) and reference product (Rivotril®, Produtos Roche Químicos e Farmacêuticos S.A.) under fasting conditions according to a randomly assigned order with a 21-day washout period. Serial blood samples were collected up to 96 h post-dose. Plasma concentrations of clonazepam were obtained by a validated liquid chromatography-tandem mass spectrometry method. Pharmacokinetic parameters were calculated using non-compartmental methods. A total of 36 healthy subjects were enrolled and 31 of them completed the study. Twenty-nine adverse events were reported (11 events with test product versus 18 events with reference product). There were no serious adverse events during the study. Geometric mean ratios (90% confidence intervals) for Cmax and AUC0-96h were 103.28% (98.10-108.64) and 102.50% (99.87-105.19), respectively. The test formulation of clonazepam 2 mg tablet manufactured by Sanofi-Aventis de Colombia S.A. was considered bioequivalent to reference product Rivotril® (Produtos Roche Químicos e Farmacêuticos S.A.) according to regulatory requirements. Both formulations were safe and well-tolerated during the study.

Investigations on clonazepam-loaded polymeric micelle-like nanoparticles for safe drug administration during pregnancy.

Medication during pregnancy is often a necessity for women to treat their acute or chronic diseases. The goal of this study is to evaluate the potential of micelle-like nanoparticles (MNP) for providing safe drug usage in pregnancy and protect both foetus and mother from medication side effects. Clonazepam-loaded MNP were prepared from copolymers [polystyrene-poly(acrylic acid) (PS-PAA), poly(ethylene glycol)-b-poly(lactic acid) (PEG-PLA) and distearyl-sn-glycero-3-phosphoethanolamine-N-[methoxy-poly(ethylene glycol) (PEG-DSPE)] with varying monomer ratios and their drug-loading efficiency, drug release ratio, particle size, surface charge and morphology were characterised. The cellular transport and cytotoxicity experiments were conducted on clonazepam and MNP formulations using placenta-choriocarcinoma-BeWo and brain-endothelial-bEnd3 cells. Clonazepam-loaded PEG5000-PLA4500 MNP reduced the drug transport through BeWo cells demonstrating that MNP may lower foetal drug exposure, thus reduce the drug side effects. However, lipofectamine modified MNP improved the transport of clonazepam and found to be promising for brain and in-utero-specific drug treatment.

Nanostructured liquid crystalline formulation as a remarkable new drug delivery system of anti-epileptic drugs for treating children patients.

PURPOSE: Development of a new dosage-form of antiepileptic-drugs appropriated for children. METHODS: Clonazepam (Cl) was formulated as cubosomal-gel (cub-gel) to be used as a patch reservoir through transdermal-route. Cubosomes prepared using glycerol-mono-oleate(GMO)/Pluronic-F127(PF127) mixture. An actual-statistical design was used to investigate the effect of different stabilizing agents (Ethanol and PVA) and surfactant concentration on cubosomes' particle size and entrapping-efficiency. The selected formulae were evaluated by testing particle-morphology, in vitro drug release and stability. Cub-gel was prepared using selected cubosome formulae. The optimal cub-gel subjected to in vitro dissolution, ex-vivo permeation and skin deposition studies followed by studying its pharmacological effect. RESULTS: Using PVA or Et as stabilizers with PF127 significantly decreases the average cubosomes'PS (352 ±â€¯ 2.8 and 264 ±â€¯2.16 nm) and increases EE (58.97 ±â€¯4.57% and 54.21 ±â€¯3.89%). Cubosomes increase the initial release rate of Cl to ensure rapid therapeutic effect (37.39% and 46.04% in the first hour) followed by a prolonged release till 4 h. Cub-gel containing PVA showed significantly higher Cl-transdermal permeation when compared to Cl-suspension. Moreover, increases the retention-time (89.57% at 48 h) and skin-deposition up to 6-times. It also reduces the epileptic seizures and alters the behavioral parameters induced by pilocarpine. CONCLUSIONS: Cubosomal-gel could be considered an innovative dosage-form for Cl through the transdermal route.