Clinical pharmacokinetics of clomipramine

Improved Pharmacokinetic and Pharmacodynamic Profile of Deuterium-Reinforced Tricyclic Antidepressants Doxepin, Dosulepin, and Clomipramine in Animal Models

BACKGROUND AND OBJECTIVES

Doxepin, dosulepin, and clomipramine are tricyclic antidepressants (TCAs) that act as serotonin and noradrenaline reuptake inhibitors. The metabolites formed by N-dealkylation of these tricyclic antidepressants contribute to overall poor pharmacokinetics and efficacy. Deuteration of the methyl groups at metabolically active sites has been reported to be a useful strategy for developing more selective and potent antidepressants. This isotopic deuteration can lead to better bioavailability and overall effectiveness. The objective is to study the effect of site-selective deuteration of TCAs on their pharmacokinetic and pharmacodynamic profile by comparison with their nondeuterated counterparts.

METHODS

In the current study, the pharmacokinetic profile and antidepressant behavior of deuterated TCAs were evaluated using the forced swim test (FST) and tail suspension test (TST), using male Wistar rats and male Swiss albino mice, respectively; additionally, a synaptosomal reuptake study was carried out.

RESULTS

Compared with the nondeuterated parent drugs, deuterated forms showed improved efficacy in the behavior paradigm, indicating improved pharmacological activity. The pharmacokinetic parameters indicated increased maximum concentration in the plasma (Cmax), elimination half-life (t1/2), and area under the concentration-time curve (AUC)  in deuterated compounds. This can have a positive clinical impact on antidepressant treatment. Synaptosomal reuptake studies indicated marked inhibition of the reuptake mechanism of serotonin (5-HT) and norepinephrine.

CONCLUSIONS

Deuterated TCAs can prove to be potentially better molecules in the treatment of neuropsychiatric disorders as compared with nondeuterated compounds. In addition, we have demonstrated a concept that metabolically active, site-selective deuteration can be beneficial for improving the pharmacokinetic and pharmacodynamic profiles of TCAs. A further toxicological study of these compounds is needed to validate their future clinical use.

Antidepressant pharmaceuticals in aquatic systems, individual-level ecotoxicological effects: growth, survival and behavior

The growing consumption of antidepressant pharmaceuticals has resulted in their widespread occurrence in the environment, particularly in waterways with a typical concentration range from ng L^-1 to μg L^-1. An increasing number of studies have confirmed the ecotoxic potency of antidepressants, not only at high concentrations but also at environmentally relevant levels. The present review covers literature from the last decade on the individual-level ecotoxicological effects of the most commonly used antidepressants, including their impact on behavior, growth, and survival. We focus on the relationship between antidepressants physico-chemical properties and dynamics in the environment. Furthermore, we discuss the advantages of considering behavioral changes as sensitive endpoints in ecotoxicology, as well as some current methodological shortcomings in the field, including low standardization, reproducibility and context-dependency.

The Pharmacological Treatment of Obsessive-Compulsive Disorder

Pharmacological treatment is a mainstay of the care of individuals with obsessive-compulsive disorder. Robust evidence supports the use of the selective serotonin reuptake inhibitors and the older tricyclic drug clomipramine. Other antidepressants are less effective (or have been insufficiently studied). When first-line treatment with these agents, and with appropriate psychotherapy, is ineffective, several augmentation strategies are available, though their evidentiary support is weaker. A substantial minority of patients have persistent symptoms despite optimal evidence-based treatment. Further work and more treatment options are needed.

The pharmacogenetics of CYP2D6 and CYP2C19 in a case series of antidepressant responses

Pharmacogenetics has potential for optimizing use of psychotropics. CYP2D6 and CYP2C19 are two clinically relevant pharmacogenes in the prescribing of antidepressants. Using cases recruited from the Understanding Drug Reactions Using Genomic Sequencing (UDRUGS) study, we aimed to evaluate the clinical utility of genotyping CYP2D6 and CYP2C19 in antidepressant response. Genomic and clinical data for patients who were prescribed antidepressants for mental health disorders, and experienced adverse reactions (ADRs) or ineffectiveness, were extracted for analysis. Genotype-inferred phenotyping of CYP2D6 and CYP2C19 was carried out as per Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines. A total of 52 patients, predominantly New Zealand Europeans (85%) with a median age (range) of 36 years (15-73), were eligible for analysis. Thirty-one (60%) reported ADRs, 11 (21%) ineffectiveness, and 10 (19%) reported both. There were 19 CYP2C19 NMs, 15 IMs, 16 RMs, one PM and one UM. For CYP2D6, there were 22 NMs, 22 IMs, four PMs, three UMs, and one indeterminate. CPIC assigned a level to each gene-drug pair based on curated genotype-to-phenotype evidence. We analyzed a subgroup of 45 cases, inclusive of response type (ADRs/ineffectiveness). Seventy-nine (N = 37 for CYP2D6, N = 42 for CYP2C19) gene-drug/antidepressant-response pairs with CPIC evidence levels of A, A/B, or B were identified. Pairs were assigned as 'actionable' if the CYP phenotypes potentially contributed to the observed response. We observed actionability in 41% (15/37) of CYP2D6-antidepressant-response pairs and 36% (15/42) of CYP2C19-antidepressant-response pairs. In this cohort, CYP2D6 and CYP2C19 genotypes were actionable for a total of 38% pairs, consisting of 48% in relation to ADRs and 21% in relation to drug ineffectiveness.

A Pan-Cancer Analysis of Transcriptome and Survival Reveals Prognostic Differentially Expressed LncRNAs and Predicts Novel Drugs for Glioblastoma Multiforme Therapy

Numerous studies have identified various prognostic long non-coding RNAs (LncRNAs) in a specific cancer type, but a comprehensive pan-cancer analysis for prediction of LncRNAs that may serve as prognostic biomarkers is of great significance to be performed. Glioblastoma multiforme (GBM) is the most common and aggressive malignant adult primary brain tumor. There is an urgent need to identify novel therapies for GBM due to its poor prognosis and universal recurrence. Using available LncRNA expression data of 12 cancer types and survival data of 30 cancer types from online databases, we identified 48 differentially expressed LncRNAs in cancers as potential pan-cancer prognostic biomarkers. Two candidate LncRNAs were selected for validation in GBM. By the expression detection in GBM cell lines and survival analysis in GBM patients, we demonstrated the reliability of the list of pan-cancer prognostic LncRNAs obtained above. By constructing LncRNA-mRNA-drug network in GBM, we predicted novel drug-target interactions for GBM correlated LncRNA. This analysis has revealed common prognostic LncRNAs among cancers, which may provide insights into cancer pathogenesis and novel drug target in GBM.

Tools for optimising pharmacotherapy in psychiatry (therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests): focus on antidepressants

Objectives: More than 40 drugs are available to treat affective disorders. Individual selection of the optimal drug and dose is required to attain the highest possible efficacy and acceptable tolerability for every patient.Methods: This review, which includes more than 500 articles selected by 30 experts, combines relevant knowledge on studies investigating the pharmacokinetics, pharmacodynamics and pharmacogenetics of 33 antidepressant drugs and of 4 drugs approved for augmentation in cases of insufficient response to antidepressant monotherapy. Such studies typically measure drug concentrations in blood (i.e. therapeutic drug monitoring) and genotype relevant genetic polymorphisms of enzymes, transporters or receptors involved in drug metabolism or mechanism of action. Imaging studies, primarily positron emission tomography that relates drug concentrations in blood and radioligand binding, are considered to quantify target structure occupancy by the antidepressant drugs in vivo. Results: Evidence is given that in vivo imaging, therapeutic drug monitoring and genotyping and/or phenotyping of drug metabolising enzymes should be an integral part in the development of any new antidepressant drug.Conclusions: To guide antidepressant drug therapy in everyday practice, there are multiple indications such as uncertain adherence, polypharmacy, nonresponse and/or adverse reactions under therapeutically recommended doses, where therapeutic drug monitoring and cytochrome P450 genotyping and/or phenotyping should be applied as valid tools of precision medicine.

The SARS-CoV-2 Cytopathic Effect Is Blocked by Lysosome Alkalizing Small Molecules

Understanding the SARS-CoV-2 virus’ pathways of infection, virus–host–protein interactions, and mechanisms of virus-induced cytopathic effects will greatly aid in the discovery and design of new therapeutics to treat COVID-19. Chloroquine and hydroxychloroquine, extensively explored as clinical agents for COVID-19, have multiple cellular effects including alkalizing lysosomes and blocking autophagy as well as exhibiting dose-limiting toxicities in patients. Therefore, we evaluated additional lysosomotropic compounds to identify an alternative lysosome-based drug repurposing opportunity. We found that six of these compounds blocked the cytopathic effect of SARS-CoV-2 in Vero E6 cells with half-maximal effective concentration (EC₅₀) values ranging from 2.0 to 13 μM and selectivity indices (SIs; SI = CC₅₀/EC₅₀) ranging from 1.5- to >10-fold. The compounds (1) blocked lysosome functioning and autophagy, (2) prevented pseudotyped particle entry, (3) increased lysosomal pH, and (4) reduced (ROC-325) viral titers in the EpiAirway 3D tissue model. Consistent with these findings, the siRNA knockdown of ATP6V0D1 blocked the HCoV-NL63 cytopathic effect in LLC-MK2 cells. Moreover, an analysis of SARS-CoV-2 infected Vero E6 cell lysate revealed significant dysregulation of autophagy and lysosomal function, suggesting a contribution of the lysosome to the life cycle of SARS-CoV-2. Our findings suggest the lysosome as a potential host cell target to combat SARS-CoV-2 infections and inhibitors of lysosomal function could become an important component of drug combination therapies aimed at improving treatment and outcomes for COVID-19.

The Anti-inflammatory Effect of the Tricyclic Antidepressant Clomipramine and Its High Penetration in the Brain Might Be Useful to Prevent the Psychiatric Consequences of SARS-CoV-2 Infection

At the time of writing (December 2020), coronavirus disease 2019 (COVID-19) has already caused more than one million deaths worldwide, and therefore, it is imperative to find effective treatments. The “cytokine storm” induced by Severe Acute Respiratory Syndrome-Coronavirus type 2 (SARS-CoV-2) is a good target to prevent disease worsening, as indicated by the results obtained with tocilizumab and dexamethasone. SARS-CoV-2 can also invade the brain and cause neuro-inflammation with dramatic neurological manifestations, such as viral encephalitis. This could lead to potentially incapacitating long-term consequences, such as the development of psychiatric disorders, as previously observed with SARS-CoV. Several pathways/mechanisms could explain the link between viral infection and development of psychiatric diseases, especially neuro-inflammation induced by SARS-CoV-2. Therefore, it is important to find molecules with anti-inflammatory properties that penetrate easily into the brain. For instance, some antidepressants have anti-inflammatory action and pass easily through the blood brain barrier. Among them, clomipramine has shown very strong anti-inflammatory properties in vitro, in vivo (animal models) and human studies, especially in the brain. The aim of this review is to discuss the potential application of clomipramine to prevent post-infectious mental complications. Repositioning and testing antidepressants for COVID-19 management could help to reduce peripheral and especially central inflammation and to prevent the acute and particularly the long-term consequences of SARS-CoV-2 infection.

Tolerability and Optimal Therapeutic Dosage of Clomipramine for Premature Ejaculation: A Systematic Review and Meta-Analysis

INTRODUCTION

Clomipramine is effective in treating premature ejaculation, a common form of male sexual dysfunction that affects individual's mental health and quality of life, but its optimal dosage remains controversial.

AIM

In this systematic review and meta-analysis, we aimed to evaluate the efficacy, safety, and optimal dose of clomipramine for treating premature ejaculation among men.

METHODS

Eligible studies of PubMed, Embase, and Web of Science were identified from the date of inception to June 21, 2020. We conducted the study according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data of the study characteristics, intravaginal latency ejaculatory time (IELT), adverse events, success rate, and satisfaction rate of clomipramine vs placebo were extracted and analyzed. The risk ratio and mean difference were used for quantitatively analyzing binary outcomes and continuous outcomes. The standardized mean difference was applied to the outcome of satisfaction rate. The Mantel-Haenszel method was used for meta-analysis under random-effects model. To assess dose effect of clomipramine, a meta-regression analysis was performed.

MAIN OUTCOME MEASURES

The primary outcomes were the IELT and adverse events, and the secondary outcomes were the success rate and satisfaction rate of clomipramine treatment relative to the placebo.

RESULTS

A total 14 randomized controlled trials with 710 patients were included for quantitative analysis. Clomipramine significantly increased the IELT compared with the placebo (mean difference: 1.47, 95% CI: 0.73-2.21). However, clomipramine was associated with higher risks of overall adverse events and adverse events in the nervous and respiratory systems. Significant dosage effects on the IELT (estimate: 0.0637, 95% CI: 0.0074-0.12) and a slightly increasing slope on adverse events were revealed.

CONCLUSION

Clomipramine increased the IELT and yielded greater satisfaction than the placebo, and the higher dose results in a superior IELT without leading to higher risk of adverse events under a dosage of 50-mg clomipramine. Wu P-C, Hung C-S, Kang Y-N, et al. Tolerability and Optimal Therapeutic Dosage of Clomipramine for Premature Ejaculation: A Systematic Review and Meta-Analysis. Sex Med 2021;9:100283.

The SARS-CoV-2 cytopathic effect is blocked with autophagy modulators

SARS-CoV-02 is a new type of coronavirus capable of rapid transmission and causing severe clinical symptoms; much of which has unknown biological etiology. It has prompted researchers to rapidly mobilize their efforts towards identifying and developing anti-viral therapeutics and vaccines. Discovering and understanding the virus' pathways of infection, host-protein interactions, and cytopathic effects will greatly aid in the design of new therapeutics to treat COVID-19. While it is known that chloroquine and hydroxychloroquine, extensively explored as clinical agents for COVID-19, have multiple cellular effects including inhibiting autophagy, there are also dose-limiting toxicities in patients that make clearly establishing their potential mechanisms-of-action problematic. Therefore, we evaluated a range of other autophagy modulators to identify an alternative autophagy-based drug repurposing opportunity. In this work, we found that 6 of these compounds blocked the cytopathic effect of SARS-CoV-2 in Vero-E6 cells with EC50 values ranging from 2.0 to 13 μM and selectivity indices ranging from 1.5 to >10-fold. Immunofluorescence staining for LC3B and LysoTracker dye staining assays in several cell lines indicated their potency and efficacy for inhibiting autophagy correlated with the measurements in the SARS-CoV-2 cytopathic effect assay. Our data suggest that autophagy pathways could be targeted to combat SARS-CoV-2 infections and become an important component of drug combination therapies to improve the treatment outcomes for COVID-19.

Genotypes of cytochrome P450 and clinical response to clomipramine in patients with major depression

The genetic cytochrome P450 polymorphism is reported in factors affecting the individual response to drugs. The interindividual variation at steady-state levels or also in elimination of drugs, finds an explanation in genetic differences in the metabolism. In particular, activities of the P450-IID6 isoenzyme are related to the sparteine/debrisoquine oxidation polymorphism. Phenotyping such a system has been proposed to analyse variability in the tricyclic antidepressant level. To analyse clinical relevance of a pharmacogenetic approach, we studied the cytochrome P450 CYP2D6 genotypes and the clinical responses to clomipramine in 21 hospitalised patients who met DSM-III-R criteria for major depression. Three patients were predicted as poor metabolizers. We suggested a limitation of clomipramine (CMI) hydroxylation in poor metaboliser (PM) patients which is balanced by a desmethylation. The clinical efficacy pattern does not differ in poor metaboliser and early metaboliser patients. Firstly, there is no significant differences in the evolution of scores on MADRS and specific retardation scale into the two groups. Secondly, outcome of side effects does not occur more frequently in PM patients. Clinical relevance of such an approach needs further study.

In Vitro and In Vivo Pipeline for Validation of Disease-Modifying Effects of Systems Biology-Derived Network Treatments for Traumatic Brain Injury-Lessons Learned

We developed a pipeline for the discovery of transcriptomics-derived disease-modifying therapies and used it to validate treatments in vitro and in vivo that could be repurposed for TBI treatment. Desmethylclomipramine, ionomycin, sirolimus and trimipramine, identified by in silico LINCS analysis as candidate treatments modulating the TBI-induced transcriptomics networks, were tested in neuron-BV2 microglial co-cultures, using tumour necrosis factor α as a monitoring biomarker for neuroinflammation, nitrite for nitric oxide-mediated neurotoxicity and microtubule associated protein 2-based immunostaining for neuronal survival. Based on (a) therapeutic time window in silico, (b) blood-brain barrier penetration and water solubility, (c) anti-inflammatory and neuroprotective effects in vitro (p < 0.05) and (d) target engagement of Nrf2 target genes (p < 0.05), desmethylclomipramine was validated in a lateral fluid-percussion model of TBI in rats. Despite the favourable in silico and in vitro outcomes, in vivo assessment of clomipramine, which metabolizes to desmethylclomipramine, failed to demonstrate favourable effects on motor and memory tests. In fact, clomipramine treatment worsened the composite neuroscore (p < 0.05). Weight loss (p < 0.05) and prolonged upregulation of plasma cytokines (p < 0.05) may have contributed to the worsened somatomotor outcome. Our pipeline provides a rational stepwise procedure for evaluating favourable and unfavourable effects of systems-biology discovered compounds that modulate post-TBI transcriptomics.

Pharmacokinetics of serotonergic drugs: focus on OCD

INTRODUCTION

Although the treatment of obsessive-compulsive disorder (OCD), a common, chronic, and disabling psychiatric condition, has significantly improved in the last decades, with the demonstration of the specific effectiveness of serotonin reuptake inhibitors (SRIs), a large proportion of patients still show high relapse rates. In addition, pharmacological treatments should be maintained for years, so that the clinicians should take into account the pharmacokinetic changes in the long-term, which may be responsible for dangerous side effects or interactions. Areas covered: The aim of this paper was to review the literature on the pharmacokinetics of SSRIs and clomipramine, and on their pharmacokinetic parameters in OCD patients. Expert opinion: Although the literature on the pharmacokinetics of both clomipramine and SSRIs is consistent, data on pharmacokinetic parameters in OCD patients are very few. Given the impact of OCD, its chronicity requiring long-term treatments, together with the need to increase the clinical response rate, more studies in this field are urgently required.

Relevance of Trypanothione Reductase Inhibitors on Trypanosoma cruzi Infection: A Systematic Review, Meta-Analysis, and In Silico Integrated Approach

Due to the rudimentary antioxidant defenses in Trypanosoma cruzi, disruptors of redox balance are promising candidates for new antitrypanosomal drugs. We developed an integrated model based on systematic review, meta-analyses, and molecular modeling to evaluate the effect of trypanothione reductase (TR) inhibitors in T. cruzi infections. Our findings indicated that the TR inhibitors analyzed were effective in reducing parasitemia and mortality due to Trypanosoma cruzi infection in animal models. The most investigated drugs (clomipramine and thioridazine) showed no beneficial effects on the occurrence of infection-related electrocardiographic abnormalities or the affinity and density of cardiac β-adrenergic receptors. The affinity between the tested ligands and the active site of TR was confirmed by molecular docking. However, the molecular affinity score was unable to explain TR inhibition and T. cruzi death in vitro or the antiparasitic potential of these drugs when tested in preclinical models of T. cruzi infection. The divergence of in silico, in vitro, and in vivo findings indicated that the anti-T. cruzi effects of the analyzed drugs were not restricted to TR inhibition. As in vivo studies on TR inhibitors are still scarce and exhibit methodological limitations, mechanistic and highly controlled studies are required to improve the quality of evidence.

Systematic screening of generic drugs for progressive multiple sclerosis identifies clomipramine as a promising therapeutic

The treatment of progressive multiple sclerosis (MS) is unsatisfactory. One reason is that the drivers of disease, which include iron-mediated neurotoxicity, lymphocyte activity, and oxidative stress, are not simultaneously targeted. Here we present a systematic screen to identify generic, orally available medications that target features of progressive MS. Of 249 medications that cross the blood–brain barrier, 35 prevent iron-mediated neurotoxicity in culture. Of these, several antipsychotics and antidepressants strongly reduce T-cell proliferation and oxidative stress. We focus on the antidepressant clomipramine and found that it additionally inhibits B-lymphocyte activity. In mice with experimental autoimmune encephalomyelitis, a model of MS, clomipramine ameliorates clinical signs of acute and chronic phases. Histologically, clomipramine reduces inflammation and microglial activation, and preserves axonal integrity. In summary, we present a systematic approach to identify generic medications for progressive multiple sclerosis with the potential to advance rapidly into clinical trials, and we highlight clomipramine for further development.

Progressive multiple sclerosis is an inflammatory and degenerative disease of the central nervous system, for which effective treatment is lacking. The authors carry out a screen to identify orally available generic medications, and show that the antidepressant clomipramine reduces pathology in mouse models.

Serum clomipramine and desmethylclomipramine levels in a CYP2C19 and CYP2D6 intermediate metabolizer

Pharmacogenetics within psychiatry has the potential to aid in the dose and selection of medications. A substantial number of psychiatric medications are metabolized through either of the highly polymorphic drug-metabolizing enzymes CYP2D6 and CYP2C19. Of these, clomipramine is subject to metabolism by both CYP2C19 and CYP2D6, leaving individuals with deficiencies of these drug-metabolizing enzymes at risk of higher concentrations of the parent molecule. Herein, we present the case of a 29-year-old male with diagnoses of depression and obsessive compulsive disorder who had trialed and failed a dozen psychiatric medications, many of which are subject to metabolism by CYP2D6 and/or CYP2C19, and had most recently been taking clomipramine for approximately 2.5 years. Pharmacogenetic testing revealed this patient to be an intermediate metabolizer for both CYP2C19 (*1/*2) and CYP2D6 (*4/*41), which resulted in considerably elevated serum trough concentrations of clomipramine and its active metabolite desmethylclomipramine. This case provides a retrospective view of how the knowledge of an individual's pharmacogenetic test results can aid in their clinical care.

Pharmacogenetics of Agents Acting on the Central Nervous System

This article will review the various agents affecting the central nervous system (CNS) such as the analgesics, antidepressants, anticonvulsants, antipsychotics, and benzodiazepines. Most of the research in pharmacogenetics with the CNS agents have been conducted in the antidepressants. The cytochrome 450 IID6 isozyme system has been shown to influence the disposition of the antidepressants and antipsychotics. Amitriptyline metabolism to nortriptyline and nortriptyline conversion to its 10-OH metabolite were shown to be influenced by the IID6 isozyme. Interestingly, imipramine metabolism to desipramine is only partially related to the IID6 isozyme. Biotransformation of imipramine to its 2-OH metabolite was shown to be affected by the IID6 isozyme, but its metabolism to the 10-OH remains to be investigated. Of the antipsychotic drugs, haloperidol and thioridazine are two agents most studied. Haloperidol is converted to a reduced metabolite via a ketone reductase enzyme. The reduced metabolite is oxidized back to Haloperidol. This oxidation pathway was reported to be affected by the IID6 isozyme. Thioridazine metabolism to mesoridazine and conversion of codeine to morphine appear to be also influenced by CP-450 IID6. Other 450 isozymes are reported to be involved with other CNS agents.

Pharmacokinetics of antidepressants in patients with hepatic impairment

Appropriate use of antidepressant in patients with hepatic impairment requires careful consideration of how the hepatic illness may affect pharmacokinetics. This review aims to analyze pharmacokinetic profile, plasma level variations so as the metabolism of several antidepressants relating to their use in patients with an hepatic impairment. Due to the lack of data regarding hepatic impairment itself, the review is focused mainly on studies investigating pharmacokinetics in hepatic cirrhosis or alcohol-related conditions. More data on reduced hepatic metabolism can be extrapolated by drug studies conducted in elderly populations. Dose adjustment of antidepressants in these patients is important as most of these drugs are predominantly metabolized by the liver and many of them are associated with dose-dependent adverse reactions. As no surrogate parameter is available to predict hepatic metabolism of drugs, dose adjustment according to pharmacokinetic properties of the drugs is proposed. There is a need for a more balanced assessment of the benefits and risks associated with antidepressants use in patients with hepatic impairment, particularly considering pharmacokinetic profile of the drugs to ensure that patients, who would truly benefit from these agents, are not denied appropriate treatment. In conclusion, kinetic studies for centrally acting drugs including antidepressants with predominant hepatic metabolism should be carried out in patients with liver disease to allow precise dose recommendations for enhanced patient safety.

The bio-distribution of the antidepressant clomipramine is modulated by chronic stress in mice: effects on behavior

Major depression (MD) is one of the most common psychiatric disorders, severely affecting the quality of life of millions of people worldwide. Despite the availability of several classes of antidepressants, treatment efficacy is still very variable and many patients do not respond to the treatment. Clomipramine (CMI), a classical and widely used antidepressant, shows widespread interindividual variability of efficacy, while the environmental factors contributing to such variability remain unclear. We investigated whether chronic stress modulates the bio-distribution of CMI, and as a result the behavioral response to CMI treatment in a mouse model of chronic social defeat stress (CSDS). Our results show that stress exposure increased anxiety-like and depressive-like behaviors and altered the stress response. Chronic defeat stress furthermore significantly altered CMI bio-distribution. Interestingly, CMI bio-distribution highly correlated with anxiety-like and depressive-like behaviors only under basal conditions. Taken together, we provide first evidence demonstrating that chronic stress exposure modulates CMI bio-distribution and behavioral responses. This may contribute to CMI’s broad interindividual variability, and is especially relevant in clinical practice.

Clomipramine concentration and withdrawal symptoms in 10 neonates

AIM

After in utero exposure to tricyclic antidepressants, neonatal withdrawal symptoms have been reported with an estimated incidence between 20 and 50%; however, few data are available for clomipramine. This could also be the case for neonatal pharmacokinetic clomipramine parameters and so this study was set up.

METHODS

Babies exposed to clomipramine in utero were included in an observational study, approved by the local ethics committee, after written informed consent. Withdrawal symptoms were scored at 12, 24 and 48 h after birth using the Finnegan score. Plasma concentrations were determined using an in-house-developed, validated liquid chromatography with mass detection (LC-MSMS) method at 0, 12, 24 and 48 h after birth.

RESULTS

We found that three of 11 pregnancies were complicated with pre-eclampsia. Ten neonates were observed for clomipramine withdrawal symptoms. The observed withdrawal symptoms were too short a period of sleep after feeding (6), poor feeding (3), mild to severe tremors (6), hyperactive Moro reflex (3) and respiratory rate >60 breaths min(-1). Serious withdrawal reactions, such as tachycardia and cyanosis, were seen. We calculated a half-life value of 42 ± 16 h for clomipramine in neonates. Only a weak correlation was found between withdrawal reactions and clomipramine plasma concentration or desmethylclomipramine plasma concentration.

CONCLUSIONS

In neonates, clomipramine is eliminated with a half-life value of 42 h, compared with 20 h in adults. In two of 10 neonates, tachycardia and cyanosis were seen as serious withdrawal symptoms after maternal use of clomipramine.

Therapeutic drug monitoring of clomipramine and amitriptyline in a depressed patient with upper digestive tract resection

We describe a 55-year-old woman with extensive digestive resection and recurrent depressive disorder resistant to oral clomipramine tablets but not to an oral solution of amitriptyline. In the light of this case report, the potential mechanisms of drug resistance after digestive resection are discussed, including the importance of drug monitoring.

Pharmacokinetics of clomipramine, an antidepressant, in poloxamer 407-induced hyperlipidaemic model rats

Objective

This study was undertaken to investigate the effects of hyperlipidaemia on the pharmacokinetics of clomipramine, an antidepressant, particularly addressing the change of clomipramine distribution to plasma components in poloxamer 407-induced hyperlipidaemia model rats.

Methods

Clomipramine pharmacokinetic studies in hyperlipidaemic rats were performed with clomipramine continuous infusion. Furthermore, clomipramine protein binding and distribution to the brain and plasma components such as lipoproteins were investigated.

Key findings

Mean plasma concentration of clomipramine at steady state during continuous infusion (17.5 µg/min/kg) in hyperlipidaemic rats (0.45 ± 0.01 µg/ml) was significantly higher than that in the control rats (0.30 ± 0.02 µg/ml). However, the amount of clomipramine in the brain in hyperlipidaemic rats (0.31 ± 0.06 µg/g) was dramatically lower than in the control rats (1.89 ± 0.13 µg/g). However, the plasma unbound fraction in hyperlipidaemic rats (0.98 ± 0.05%) was significantly lower than that of the control rats (6.51 ± 0.62%).

Conclusions

Lower distribution to the brain and lower plasma clearance of clomipramine in hyperlipidaemic rats resulted from lower plasma unbound fraction because of higher lipid-rich protein contents in blood. Results of this study provide useful information for dosage adjustment of clomipramine in hyperlipidaemia.

Bio-sample preparation and analytical methods for the determination of tricyclic antidepressants

An extended and comprehensive review is presented herein, focusing on sample preparation (pretreatment and extraction) and different analytical methods applied for the quantification of tricyclic antidepressants. These procedures are relevant tools in clinical and forensic toxicology. It is revealed that SPE, for sample preparation, and HPLC, using reversed-phase alkyl (C18) or cyanopropyl-bonded silica columns for the analytes separation, are effective and versatile methods for assay of tricyclic antidepressants. These methods enable achievable detection limits using UV/diode array detection, readily available in most laboratories, down to 1–8 ng ml-1, and using electron capture detection better than 1 ng ml-1, which is lower than that for nitrogen–phosphorus detector. MS interfaced with electrospray ionization offered similar sensitivity, whilst sonic spray ionization provided detection down to 0.03 ng ml-1. A brief discussion on chemical structures, metabolism and mechanism of action of this group of drugs is also presented.

Regional distribution of clomipramine and desmethylclomipramine in rat brain and peripheral organs on chronic clomipramine administration

The tricyclic antidepressant (TCA) clomipramine has been widely used in psychiatry for over 40 years. More recently, its therapeutic potential as an antineoplastic drug has been identified. However, there are no prior data on regional distribution in the brain of clomipramine and its primary metabolite (desmethylclomipramine) after chronic oral administration. The aim of this study was to determine the concentrations of clomipramine and desmethylclomipramine in different rat-brain regions and to compare those with levels in plasma and peripheral organs after chronic oral treatment of Sprague Dawley rats (15 mg/kg) for 14 days. The levels of both parent TCA and metabolite were analysed by high-performance liquid chromatography in six brain regions (cortex, hypothalamus, hippocampus, striatum, brainstem and cerebellum), five peripheral organs and in plasma. Our data show that the cerebral cortex had the highest concentration of clomipramine (2.9 microg/mg), with successively lower concentrations in the hypothalamus, striatum, cerebellum, hippocampus and brainstem. Of the peripheral organs, the lungs and liver, had the highest levels of clomipramine, while in the heart, only the metabolite was detected. The plasma concentration (0.17 microg/ml or 0.48 microM) was comparable to that in the hippocampus and cerebellum (approximately 0.20 microg/mg). The differential distribution of clomipramine in different brain regions and the regional variation in clomipramine to desmethylclomipramine ratios have implications for the use of clomipramine in psychiatry and neuro-oncology.

Drug screening to identify suppressors of GFAP expression

Glial fibrillary acidic protein (GFAP) is the major intermediate filament protein of astrocytes in the vertebrate central nervous system. Increased levels of GFAP are the hallmark feature of gliosis, a non-specific response of astrocytes to a wide variety of injuries and disorders of the CNS, and also occur in Alexander disease where the initial insult is a mutation within the coding region of GFAP itself. In both settings, excess GFAP may cause or exacerbate astrocyte dysfunction. With the goal of finding drugs that reduce the expression of GFAP, we have devised screens to detect changes in GFAP promoter activity or protein levels in primary cultures of mouse astrocytes in a 96-well format. We have applied these screens to libraries enriched in compounds that are already approved for human use by the FDA. We report that several compounds are active at micromolar levels in suppressing the expression of GFAP. Treatment of mice for 3 weeks with one of these drugs, clomipramine, causes nearly 50% reduction in the levels of GFAP protein in brain.

Intravenous anti-obsessive agents: a review

Oral antidepressants are currently the first-line pharmacotherapy for obsessive-compulsive disorder (OCD), but response rates can often be low and with delayed onset of therapeutic action. Some reports have suggested that intravenous (i.v.) anti-obsessive agents may have faster onset of action and greater efficacy. A Medline search was conducted for all reports pertaining to the use of i.v. antidepressants for OCD. Search terms included: 'intravenous', 'clomipramine', 'selective serotonin reuptake inhibitor', 'tricyclic', 'citalopram', 'sertraline', 'paroxetine', 'fluvoxamine', 'SSRIs' and 'intravenous antidepressants'. Relevant articles mainly investigated clomipramine (CMI) with one open trial examining citalopram. Intravenous agents appear to be well-tolerated, particularly in those who have failed oral agents, and may act more rapidly to produce initial clinical response, although this advantage is often lost over time. Preliminary evidence suggests subgroups of patients with severe treatment-refractory OCD may benefit from i.v. anti-obsessive agents, CMI and citalopram. Larger, controlled trials are needed for more definitive conclusions.

Inhibition of serotonin but not norepinephrine transport during development produces delayed, persistent perturbations of emotional behaviors in mice

Serotonin (5-HT) acts as a neurotransmitter, but also modulates brain maturation during early development. The demonstrated influence of genetic variants on brain function, personality traits, and susceptibility to neuropsychiatric disorders suggests a critical importance of developmental mechanisms. However, little is known about how and when developmentally perturbed 5-HT signaling affects circuitry and resulting behavior. The 5-HT transporter (5-HTT) is a key regulator of extracellular 5-HT levels and we used pharmacologic strategies to manipulate 5-HTT function during development and determine behavioral consequences. Transient exposure to the 5-HTT inhibitors fluoxetine, clomipramine, and citalopram from postnatal day 4 (P4) to P21 produced abnormal emotional behaviors in adult mice. Similar treatment with the norepinephrine transporter (NET) inhibitor, desipramine, did not adversely affect adult behavior, suggesting that 5-HT and norepinephrine (NE) do not share the same effects on brain development. Shifting our period of treatment/testing to P90/P185 failed to mimic the effect of earlier exposure, demonstrating that 5-HT effects on adult behavior are developmentally specific. We have hypothesized that early-life perturbations of 5-HT signaling affect corticolimbic circuits that do not reach maturity until the peri-adolescent period. In support of this idea, we found that abnormal behaviors resulting from postnatal fluoxetine exposure have a post-pubescent onset and persist long after reaching adult age. A better understanding of the underlying 5-HT sensitive circuits and how they are perturbed should lead to new insights into how various genetic polymorphisms confer their risk to carriers. Furthermore, these studies should help determine whether in utero exposure to 5-HTT blocking drugs poses a risk for behavioral abnormalities in later life.

Computational models to assign biopharmaceutics drug disposition classification from molecular structure

PURPOSE

We applied in silico methods to automatically classify drugs according to the Biopharmaceutics Drug Disposition Classification System (BDDCS).

MATERIALS AND METHODS

Models were developed using machine learning methods including recursive partitioning (RP), random forest (RF) and support vector machine (SVM) algorithms with ChemDraw, clogP, polar surface area, VolSurf and MolConnZ descriptors. The dataset consisted of 165 training and 56 test set molecules.

RESULTS

RF model 3, RP model 1, and SVM model 1 can correctly predict 73.1, 63.6 and 78.6% test compounds in classes 1, 2 and 3, respectively. Both RP and SVM models can be used for class 4 prediction. The inclusion of consensus analysis resulted in improved test set predictions for class 2 and 4 drugs.

CONCLUSIONS

The models can be used to predict BDDCS class for new compounds from molecular structure using readily available molecular descriptors and software, representing an area where in silico approaches could aid the pharmaceutical industry in speeding drugs to the patient and reducing costs. This could have significant applications in drug discovery to identify molecules that may have future developability issues.

A kinetic-pharmacodynamic model for clinical trial simulation of antidepressant action: Application to clomipramine–lithium interaction

A generic kinetic-pharmacodynamic (K-PD) model to describe the response to treatment assessed by a clinical score for depressed patients treated by antidepressants alone or combined with a drug that shortens the lag-time before effect was developed. The aims of this study were: (1) to verify model's ability to characterize clinical data, (2) to evaluate several statistics to summarize the clinical effect, (3) to compare the analysis based on these statistics to the conventional intent-to-treat analysis and (4) to determine the optimal dates of clinical assessment. The population K-PD model was fitted to the individual data from a randomized clinical trial assessing the efficacies of clomipramine and placebo or clomipramine and lithium to treat major depression in 141 patients. The K-PD model was able to fit the individual data even in the case of oscillating score profiles. The interindividual coefficient of variation of the model parameters ranged from 33 to 161%. The statistical analysis based on the secondary parameters yielded conclusions comparable to those of the conventional intent-to-treat analysis. The population model was then used for a clinical trial simulation. According to the simulation, the most sensitive summary statistics for detecting a difference between lithium and placebo were the fractional reduction of depression and the proportion of responders. The optimal dates to assess these parameters were day 9 and 11 respectively. The K-PD model might serve as a tool for clinical trial planning in the field of research on antidepressants and their facilitators.

Pharmacokinetics and interactions of headache medications, part II: prophylactic treatments

The present part II review highlights pharmacokinetic drug-drug interactions (excluding those of minor severity) of medications used in prophylactic treatment of the main primary headaches (migraine, tension-type and cluster headache). The principles of pharmacokinetics and metabolism, and the interactions of medications for acute treatment are examined in part I. The overall goal of this series of two reviews is to increase the awareness of physicians, primary care providers and specialists regarding pharmacokinetic drug-drug interactions (DDIs) of headache medications. The aim of prophylactic treatment is to reduce the frequency of headache attacks using beta-blockers, calcium-channel blockers, antidepressants, antiepileptics, lithium, serotonin antagonists, corticosteroids and muscle relaxants, which must be taken daily for long periods. During treatment the patient often continues to take symptomatic drugs for the attack, and may need other medications for associated or new-onset illnesses. DDIs can, therefore, occur. As a whole, DDIs of clinical relevance concerning prophylactic drugs are a limited number. Their effects can be prevented by starting the treatment with low dosages, which should be gradually increased depending on response and side effects, while frequently monitoring the patient and plasma levels of other possible coadministered drugs with a narrow therapeutic range. Most headache medications are substrates of CYP2D6 (e.g., beta-blockers, antidepressants) or CYP3A4 (e.g., calcium-channel blockers, selective serotonin re-uptake inhibitors, corticosteroids). The inducers and, especially, the inhibitors of these isoenzymes should be carefully coadministered.

Therapeutic Drug Monitoring and Pharmacogenetic Tests as Tools in Pharmacovigilance

Therapeutic drug monitoring (TDM) and pharmacogenetic tests play a major role in minimising adverse drug reactions and enhancing optimal therapeutic response. The response to medication varies greatly between individuals, according to genetic constitution, age, sex, co-morbidities, environmental factors including diet and lifestyle (e.g. smoking and alcohol intake), and drug-related factors such as pharmacokinetic or pharmacodynamic drug-drug interactions. Most adverse drug reactions are type A reactions, i.e. plasma-level dependent, and represent one of the major causes of hospitalisation, in some cases leading to death. However, they may be avoidable to some extent if pharmacokinetic and pharmacogenetic factors are taken into consideration. This article provides a review of the literature and describes how to apply and interpret TDM and certain pharmacogenetic tests and is illustrated by case reports. An algorithm on the use of TDM and pharmacogenetic tests to help characterise adverse drug reactions is also presented. Although, in the scientific community, differences in drug response are increasingly recognised, there is an urgent need to translate this knowledge into clinical recommendations. Databases on drug-drug interactions and the impact of pharmacogenetic polymorphisms and adverse drug reaction information systems will be helpful to guide clinicians in individualised treatment choices.

Classification of orally administered drugs on the World Health Organization Model list of Essential Medicines according to the biopharmaceutics classification system

Since its inception in 1995, the biopharmaceutical classification system (BCS) has become an increasingly important tool for regulation of drug products world-wide. Until now, application of the BCS has been partially hindered by the lack of a freely available and accurate database summarising solubility and permeability characteristics of drug substances. In this report, orally administered drugs on the Model list of Essential Medicines of the World Health Organization (WHO) are assigned BCS classifications on the basis of data available in the public domain. Of the 130 orally administered drugs on the WHO list, 61 could be classified with certainty. Twenty-one (84%) of these belong to class I (highly soluble, highly permeable), 10 (17%) to class II (poorly soluble, highly permeable), 24 (39%) to class III (highly soluble, poorly permeable) and 6 (10%) to class IV (poorly soluble, poorly permeable). A further 28 drugs could be provisionally assigned, while for 41 drugs insufficient or conflicting data precluded assignment to a specific BCS class. A total of 32 class I drugs (either certain or provisional classification) were identified. These drugs can be further considered for biowaiver status (drug product approval based on dissolution tests rather than bioequivalence studies in humans).

Comparison of the efficacy of a synthetic dog-appeasing pheromone with clomipramine for the treatment of separation-related disorders in dogs

Sixty-seven dogs that showed signs of distress when separated from their owners (destructiveness, excessive vocalisation and house soiling) and hyperattachment were used in a randomised, blind trial to assess the potential value of a dog-appeasing pheromone in reducing the unacceptable behaviours. For ethical reasons, there was no placebo group and the effects of the pheromone were compared with the effects of clomipramine which is regularly used to treat this type of problem. The undesirable behaviours decreased in both groups, but the overall assessment by the owners indicated that there was no significant difference between the two treatments, although there were fewer undesirable events in the dogs treated with the pheromone, and the administration of the pheromone appeared to be more convenient.

Polymorphic cytochrome P450 2D6: humanized mouse model and endogenous substrates

Cytochrome P450 2D6 (CYP2D6) is the first well-characterized polymorphic phase I drug-metabolizing enzyme, and more than 80 allelic variants have been identified for the CYP2D6 gene, located on human chromosome 22q13.1. Human debrisoquine and sparteine metabolism is subdivided into two principal phenotypes--extensive metabolizer and poor metabolizer--that arise from variant CYP2D6 genotypes. It has been estimated that CYP2D6 is involved in the metabolism and disposition of more than 20% of prescribed drugs, and most of them act in the central nervous system or on the heart. These drug substrates are characterized as organic bases containing one nitrogen atom with a distance about 5, 7, or 10 A from the oxidation site. Aspartic acid 301 and glutamic acid 216 were determined as the key acidic residues for substrate-enzyme binding through electrostatic interactions. CYP2D6 transgenic mice, generated using a lambda phage clone containing the complete wild-type CYP2D6 gene, exhibits enhanced metabolism and disposition of debrisoquine. This transgenic mouse line and its wild-type control are models for human extensive metabolizers and poor metabolizers, respectively, and would have broad application in the study of CYP2D6 polymorphism in drug discovery and development, and in clinical practice toward individualized drug therapy. Endogenous 5-methoxyindole- thylamines derived from 5-hydroxytryptamine were identified as high-affinity substrates of CYP2D6 that catalyzes their O-demethylations with high enzymatic capacity and specificity. Thus, polymorphic CYP2D6 may play an important role in the interconversions of these psychoactive tryptamines, including a crucial step in a serotonin-melatonin cycle.

Stir bar sorptive extraction-thermal desorption-capillary GC-MS for profiling and target component analysis of pharmaceutical drugs in urine

Stir bar sorptive extraction (SBSE) in combination with thermal desorption (TD) on-line coupled to capillary gas chromatography-mass spectrometry (CGC-MS) was applied to the analysis of pharmaceutical drug compounds and metabolites in urine. SBSE implies stirring of the aqueous sample (urine, blood, etc.) with a glass stir bar coated with a thick layer (24 microl) of polydimethylsiloxane (PDMS) for sorptive enrichment of the analytes of interest. In combination with quantitative TD, on-line coupled with CGC-MS, the technique showed to be very versatile and sensitive for the analysis of a wide range of drug substances. Moreover, the relative high enrichment efficiencies of SBSE allow to use mass spectrometric detection (MSD) in the full scan mode. In situ derivatization of polar compounds before SBSE is demonstrated for the analysis of paracetamol and this resulted in both improved chromatographic behavior and higher sensitivity. The quantitative performance of SBSE-TD-CGC-MS is illustrated with the analysis of some barbiturates in urine.

Differential neurochemical properties of central serotonergic transmission in Roman high- and low-avoidance rats

The selective breeding of Roman high- (RHA/Verh) and low-avoidance (RLA/Verh) rats for rapid versus poor acquisition of active avoidant behaviour has produced two behavioural phenotypes with different performances in a variety of animal models of anxiety, in which RLA/Verh rats are consistently more fearful than RHA/Verh rats. In addition, these two lines display different functional properties of brain neurotransmitters like serotonin (5-HT), known to be involved in the expression of anxiety- and depression-related behaviours. Therefore, we used brain microdialysis and [3H]-citalopram binding autoradiography to characterize further the neurochemical properties of 5-HTergic transmission in the two lines. No significant line-related differences were detected in the basal 5-HT output in the frontoparietal cortex (FPCx). In contrast, the increase in the cortical 5-HT output elicited by the systemic administration or the local application, via reverse dialysis, of chlorimipramine and fluoxetine was more robust in RHA/Verh than in RLA/Verh rats. Moreover, the binding signal of [3H]-citalopram to 5-HT re-uptake sites was more intense in the FPCx of RHA/Verh rats than in their RLA/Verh counterparts. These findings suggest that the functional tone of the 5-HTergic projection to the FPCx is stronger in the RHA/Verh line relative to the RLA/Verh line. It is proposed that RLA/Verh rats may be used as a model with heuristic value for studying the role of 5-HTergic transmission in anxiety and in the anxiolytic effects of monoamine re-uptake inhibitors.

Sympathetic nerve destruction in spleen in murine AIDS

In susceptible strains of mice, the LP-BM5 mixture of murine retroviruses induces the fatal immunodeficiency disease known as murine acquired immunodeficiency syndrome (murine AIDS or MAIDS). We have previously reported that murine AIDS produces a profound depletion of splenic norepinephrine (NE). Here, we demonstrate that NE depletion is limited to the spleen, a major site affected by LP-BM5 infection. NE depletion in the spleen is first observed at two weeks following LP-BM5 inoculation, concurrent with the onset of splenomegaly, and continues through 12 weeks post-infection. Neuroanatomical studies revealed that the reduction in NE is due to destruction of splenic sympathetic nerve fibers. Administration of the NE reuptake blocker desipramine did not prevent LP-BM5-induced NE depletion, suggesting that destruction is not caused by excess release and reuptake of NE. Elucidating the mechanism of MAIDS-induced sympathetic nerve destruction may provide insight into autonomic and peripheral neuropathies reported in people with AIDS.

Modeling panic attacks

The isomorphism of dorsal periaqueductal gray-evoked defensive behaviors and panic attacks was appraised in the present study. Thresholds of electrically induced immobility, trotting, galloping, jumping, exophthalmus, micturition and defecation were recorded before and after acute injections of anxiolytic, anxiogenic and antidepressant drugs. Antidepressant effects were further assessed 24h after injections of 7-14- and 21-day treatments. Chronic administration of clomipramine (CLM, 5-10mg/kg) a clinically effective antipanic drug increased the thresholds of immobility (24%), trotting (138%) galloping (75%), jumping (45%) and micturition (85%). The 21-day treatment with fluoxetine (FLX, 1mg/kg) virtually abolished galloping without changing the remaining responses. Galloping thresholds were also increased by 5mg/kg acute injections of CLM (19%) and FLX (25%). In contrast, chronically administered maprotiline (10mg/kg), a noradrenaline (NE) selective reuptake inhibitor, selectively increased the thresholds of immobility (118%). Diazepam (1.8mg/kg) and midazolam (MDZ, 2.5mg/kg) failed in attenuating the somatic defensive responses. Yet, the sedative dose of MDZ (5mg/kg) attenuated immobility. The panicogenic drug, pentylenetetrazole (50mg/kg), markedly decreased the thresholds of galloping (-51%) and micturition (-66%). These results suggest that whereas immobility is a NE-mediated attentional response, galloping is the panic-like behavior best candidate.