Citalopram: a comprehensive review

Citalopram exposure of hESCs during neuronal differentiation identifies dysregulated genes involved in neurodevelopment and depression

Selective serotonin reuptake inhibitors (SSRIs), including citalopram, are widely used antidepressants during pregnancy. However, the effects of prenatal exposure to citalopram on neurodevelopment remain poorly understood. We aimed to investigate the impact of citalopram exposure on early neuronal differentiation of human embryonic stem cells using a multi-omics approach. Citalopram induced time- and dose-dependent effects on gene expression and DNA methylation of genes involved in neurodevelopmental processes or linked to depression, such as BDNF, GDF11, CCL2, STC1, DDIT4 and GAD2. Single-cell RNA-sequencing analysis revealed distinct clusters of stem cells, neuronal progenitors and neuroblasts, where exposure to citalopram subtly influenced progenitor subtypes. Pseudotemporal analysis showed enhanced neuronal differentiation. Our findings suggest that citalopram exposure during early neuronal differentiation influences gene expression patterns associated with neurodevelopment and depression, providing insights into its potential neurodevelopmental impact and highlighting the importance of further research to understand the long-term consequences of prenatal SSRI exposure.

Dysregulation of adipogenesis and disrupted lipid metabolism by the antidepressants citalopram and sertraline

Selective Serotonin Reuptake Inhibitors (SSRIs) are widely used medications for the treatment of major depressive disorder. However, long-term SSRI use has been associated with weight gain and altered lipid profiles. These findings suggest that SSRIs may have negative effects on metabolism. Exposure to certain chemicals called 'obesogens' is known to promote lipid accumulation and obesity by modulating adipogenesis. Here, we investigated whether citalopram (CIT) and sertraline (SER) interfere with the process of adipogenesis, using human mesenchymal stem cells (MSCs) in a 2D and a 3D model. Assessment of intracellular lipid accumulation by fluorescence staining was used as a measure for enhanced adipogenesis. To explore possible mechanisms behind SSRIs' effects, receptor mediated activity was studied using responsive cell lines for various nuclear receptors. Furthermore, RNA sequencing was performed in the 3D model, followed by differential gene expression and pathway analysis. A dose dependent increase in lipid accumulation was observed in both models with CIT and SER. For the 3D model, the effect was seen in a range close to reported steady-state plasma concentrations (0.065-0.65 μM for SER and 0.12-0.92 μM for CIT). Pathway analysis revealed unexpected results of downregulation in adipogenesis-related pathways and upregulation in phospholipids and lysosomal pathways. This was confirmed by an observed increase in lysosomes in the 2D model. Our findings suggest lysosomal dysfunction and disrupted lipid metabolism in mature adipocytes, leading to excessive phospholipid synthesis. Moreover, important adipogenic processes are inhibited, potentially leading to dysfunctional adipocytes, which might have implications in the maintenance of a healthy metabolic balance.

Current Understanding of Compulsive Sexual Behavior Disorder and Co-occurring Conditions: What Clinicians Should Know about Pharmacological Options

Compulsive sexual behavior disorder (CSBD) has recently been recognized as a psychiatric disorder. Pharmacological treatments for CSBD have received little study and thus have limited empirical support. The main objective of the present work is to review existing literature on the efficacy of different drugs on the symptomatology of CSBD, including the subtype of problematic pornography use (PPU). The main pharmacological approaches to treating CSBD have included opioid antagonists (naltrexone and nalmefene), selective serotonin reuptake inhibitors (paroxetine, citalopram, fluoxetine, and sertraline), mood stabilizers (topiramate), tricyclic antidepressants (clomipramine), serotonin antagonist and reuptake inhibitors (nefazodone), and N-acetylcysteine. Since people with CSBD may experience different co-occurring disorders, these should be considered when choosing the best pharmacological treatment. Pharmacological therapy for CSBD/PPU has been suggested as an adjunct to psychological therapies, which, for the moment, have the most empirical evidence. However, to evaluate the efficacy of most of the drugs presented in this narrative review, data to date have only been available from case studies. Thus, empirical support is scant and generalizability of results is limited, highlighting the need for more research in this area.

A Comprehensive Review of the Generalized Anxiety Disorder

Excessive, uncontrollable, and usually unjustified worry about certain things is a sign of the mental and behavioral disease known as generalized anxiety disorder (GAD). Genetic research suggests that numerous genes are likely implicated in the development of GAD, even if much is yet unclear about this. As a result, if someone in a family has GAD, there is a high likelihood that someone else will also suffer from the illness, as well as another anxiety disorder. Individuals with GAD are frequently overly bothered about workaday affairs like health, assets, demise, family, accord issues, or effort challenges. Worry frequently interferes with daily functioning. Excessive concern, restlessness, difficulty sleeping, tiredness, irritability, sweating, and trembling are a few symptoms that may be present. For a formal diagnosis of GAD, symptoms must be persistent for at least six months and consistent. Conversion in the amygdala's utilitarian congruence and how it processes fear and anxiety have been linked to generalized anxiety disorder. Neurotransmitters, and particularly the gamma-aminobutyric acid (GABA) variant, have long been known to cause GAD through dysregulating amygdala activity in the brain. Anxiety, concern, or physical symptoms must significantly hinder social, academic, or occupational functioning in order to qualify for a GAD diagnosis. The Diagnostic and Statistical Manual of Mental Disorders-V (DSM-V) provides explicit ethos to aid doctors in identifying this disorder. Psychological therapy based on cognitive behavioral therapy (CBT) principles is effective in reducing anxiety symptoms for short-term treatment of GAD. In this, the patient's thinking ability and methods are focused. The main principle behind CBT is that your thought patterns affect your feelings, which in turn can affect your behavior. Drugs like antidepressants, buspirone, benzodiazepines, and can all be worn to goody GAD. Outside of therapy, patients with anxiety can learn to manage it by practicing relaxation methods, reframing unfavorable ideas, and adopting stress-relieving adjustments. Being socially active and setting aside time for proper self-care are crucial components of managing generalized anxiety disorder.

Milnacipran Ameliorates Executive Function Impairments following Frontal Lobe Traumatic Brain Injury in Male Rats: A Multimodal Behavioral Assessment

Traumatic brain injuries (TBIs) affect more than 10 million patients annually worldwide, causing long-term cognitive and psychosocial impairments. Frontal lobe TBIs commonly impair executive function, but laboratory models typically focus primarily on spatial learning and declarative memory. We implemented a multi-modal approach for clinically relevant cognitive-behavioral assessments of frontal lobe function in rats with TBI and assessed treatment benefits of the serotonin-norepinephrine reuptake inhibitor, milnacipran (MLN). Two attentional set-shifting tasks (AST) evaluated cognitive flexibility via the rats' ability to locate food-based rewards by learning, unlearning, and relearning sequential rule sets with shifting salient cues. Adult male rats reached stable pre-injury operant AST (oAST) performance in 3-4 weeks, then were isoflurane-anesthetized, subjected to a unilateral frontal lobe controlled cortical impact (2.4 mm depth, 4 m/sec velocity) or Sham injury, and randomized to treatment conditions. Milnacipran (30 mg/kg/day) or vehicle (VEH; 10% ethanol in saline) was administered intraperitoneally via implanted osmotic minipumps (continuous infusions post-surgery, 60 μL/h). Rats had a 10-day recovery post-TBI/Sham before performing light/location-based oAST for 10 days and, subsequently, odor/media-based digging AST (dAST) on the last test day (26-27 days post-injury) before sacrifice. Both AST tests revealed significant deficits in TBI+VEH rats, seen as elevated total trials and errors (p < 0.05), which generally normalized in MLN-treated rats (p < 0.05). This first simultaneous dual AST assessment demonstrates oAST and dAST are sufficiently sensitive and robust to detect subtle attentional and cognitive flexibility executive impairments after frontal lobe TBI in rats. Chronic MLN administration shows promise for attenuation of post-TBI executive function deficits, thus meriting further investigation.

Impact of COVID- 19 pandemic on antidepressants consumptions by wastewater analysis in Turkey

The COVID-19 pandemic has been a major challenge worldwide, forcing countries to take restrictive measures beyond conventional methods in their fight against the spread of the disease. Followingly, many studies have been conducted on the effects of these measures on mental health. Wastewater-based epidemiology (WBE) was used in this study to monitor and estimate changes in antidepressant use under normal conditions (2019) and COVID-19 pandemic conditions (2020). Likewise, this study utilized wastewater-based epidemiology (WBE) to monitor and assess changing trends from the pre-pandemic period (2019) to COVID-19 pandemic conditions in antidepressant use (2020). Wastewater samples were collected from 11 cities in Turkey throughout six sampling periods covering the pre-pandemic and during-pandemic periods (June 2019-December 2020). Then, samples were analyzed via LC-MS/MS method. As a result, we observed that venlafaxine was the drug with the highest concentration (mean ± SD: 103.6 ± 112.1 mg/1000p/day). Moreover, city number 6 presented the highest venlafaxine use and the most dramatic increase during the pandemic period. Finally, this study revealed the potential of WBE to estimate the changing trends in mental health during the ongoing pandemic.

A Focus on Abuse/Misuse and Withdrawal Issues with Selective Serotonin Reuptake Inhibitors (SSRIs): Analysis of Both the European EMA and the US FAERS Pharmacovigilance Databases

Despite increasing reports, antidepressant (AD) misuse and dependence remain underestimated issues, possibly due to limited epidemiological and pharmacovigilance evidence. Thus, here we aimed to determine available pharmacovigilance misuse/abuse/dependence/withdrawal signals relating to the Selective Serotonin Reuptake Inhibitors (SSRI) citalopram, escitalopram, paroxetine, fluoxetine, and sertraline. Both EudraVigilance (EV) and Food and Drug Administration-FDA Adverse Events Reporting System (FAERS) datasets were analysed to identify AD misuse/abuse/dependence/withdrawal issues. A descriptive analysis was performed; moreover, pharmacovigilance measures, including the reporting odds ratio (ROR), the proportional reporting ratio (PRR), the information component (IC), and the empirical Bayesian geometric mean (EBGM) were calculated. Both datasets showed increasing trends of yearly reporting and similar signals regarding abuse and dependence. From the EV, a total of 5335 individual ADR reports were analysed, of which 30% corresponded to paroxetine (n = 1592), 27% citalopram (n = 1419), 22% sertraline (n = 1149), 14% fluoxetine (n = 771), and 8% escitalopram (n = 404). From FAERS, a total of 144,395 individual ADR reports were analysed, of which 27% were related to paroxetine, 27% sertraline, 18% citalopram, 16% fluoxetine, and 13% escitalopram. Comparing SSRIs, the EV misuse/abuse-related ADRs were mostly recorded for citalopram, fluoxetine, and sertraline; conversely, dependence was mostly associated with paroxetine, and withdrawal to escitalopram. Similarly, in the FAERS dataset, dependence/withdrawal-related signals were more frequently reported for paroxetine. Although SSRIs are considered non-addictive pharmacological agents, a range of proper withdrawal symptoms can occur well after discontinuation, especially with paroxetine. Prescribers should be aware of the potential for dependence and withdrawal associated with SSRIs.

Chirality of antidepressive drugs: an overview of stereoselectivity

Stereochemistry plays an important role in drug design because the enantiomers of a drug frequently vary in their biological action and pharmacokinetic profiles. Racemates of a drug with either an inactive or an unsafe enantiomer can lead to detrimental effects. The manufacturing industry may still produce racemates, but such decisions must pass through rigorous analyses of the pharmacological and pharmacokinetic characteristics of the particular enantiomer related to the racemates. The pharmacokinetics of antidepressants or antidepressive agents is stereoselective and predominantly favors one enantiomer. The use of pure enantiomers offers (i) better specificity than the racemates in terms of certain pharmacological actions, (ii) enhanced clinical indications, and (iii) optimized pharmacokinetics. Therefore, controlling the stereoselectivity in the pharmacokinetics of antidepressive drugs is of critical importance in dealing with depression and psychiatric conditions. The objective of this review is to highlight the importance of the stereochemistry of antidepressants in the context of the design and development of new chirally pure pharmaceuticals, the potential complications caused by using racemates, and the benefits of using pure enantiomers.

An update on the treatment of premature ejaculation: A systematic review

To analyse the current therapeutic options for patients with premature ejaculation (PE) and highlight their mechanism(s) of action, effectiveness, advantages and limitations. A literature search was conducted using the PubMed database searching for articles exploring different PE treatment modalities. A Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) approach was used to report the results of the literature search. A total of 149 articles were included in this review. The currently available treatment methods for PE include behavioural therapy, local anaesthetics, tricyclic antidepressants, selective serotonin reuptake inhibitors, and selective phosphodiesterase inhibitors. Most PE treatments are either experimental or used off-label. New treatments are certainly warranted to overcome this exasperating sexual dysfunction.

Abbreviations: AIPE: Arabic Index of Premature Ejaculation; CNS: central nervous system; CYP: cytochrome P450; ED: erectile dysfunction; FDA: United States Food and Drug Administration; H1: histamine receptors; 5-HT: 5-hydroxytryptamine; IELT: The intravaginal ejaculation latency time; IPE: Index of Premature Ejaculation; M1: muscarinic receptors; OCD: obsessive–compulsive disorder; PDE5: phosphodiesterase type 5; PE: premature ejaculation; PEP: Premature Ejaculation Profile; PRO: patient-reported outcome; RCT: randomised controlled trial; SS: Severance Secret (cream); SSRIs: selective serotonin reuptake inhibitors; TCAs: tricyclic antidepressants

Selective LC-MS/MS determination of citalopram enantiomers and application to a pharmacokinetic evaluation of generic and reference formulations

Two methods using LC-MS/MS were validated to quantify citalopram (CTP) racemate [(R/S)-CTP] and the enantiomers (R)-CTP and (S)-CTP in human plasma, respectively. Paroxetine hydrochloride was used as the internal standard, and samples were extracted by protein precipitation with acetonitrile. The non-enantioselective method was conducted using a C18 column, and the mobile phase consisted of water for solvent A and acetonitrile for solvent B, both with 0.1% formic acid. For the chiral method, an analytical column Lux Cellulose-1 was used. Mobile phase A was composed of water with 0.025% of formic acid and 0.05% of diethylamine, and mobile phase B consisted of acetonitrile:2-propanol (95:5, v/v). No significant matrix effects were observed at the retention times of analytes and internal standard. The mean recovery was 89%, and the assays were linear in the concentration range of 1-50 and 5-30 ng/mL for the non-enantioselective and enantioselective methods, respectively. The intra- and inter-day precisions of both methods were less than 12.30%, and the accuracies were less than 12.13%. The validated methods were successfully applied to a pharmacokinetic study in which 20-mg CTP tablets were administered to healthy volunteers, and their plasma levels were monitored over time in a bioequivalence study. HIGHLIGHTS: Simple and rapid LC-MS/MS method for the quantification of citalopram and its enantiomers in human plasma. Both methods were demonstrated to be selective, reliable, and sensitive. Both methods have sufficient sensitivity to quantify the steady state through concentrations already reported for citalopram and escitalopram. Validated method presented in this study can be suitably applied to pharmacokinetic studies involving citalopram and escitalopram. Bland-Altman analysis suggested that non-enantioselective and enantioselective methods can be applied in pharmacokinetic studies.

Differential effects of citalopram on the intake of high fat or high carbohydrates diets in female and male rats

Chronic administration of selective serotonin reuptake inhibitors (SSRI), usually prescribed as antidepressants, decreases total energy intake; however, at present the differential effect on the intake of distinct macronutrients and on female vs. male organisms is not clear. On this basis, female and male adult Wistar rats were exposed to two types of diets: (1) a standard balanced diet (BD); or (2) two types of diets simultaneously, (a) one high in carbohydrates (HC); the other (b) high in fat (HF). Both study groups were given a dose of 10 mg/kg/day i.p. of citalopram or a vehicle for 21 days. Food and water consumption and body weight were recorded daily at baseline (BL), during treatment (TX), and post-treatment (PTx1-PTx2). The male rats exposed to BD reduced total energy consumption during treatment with citalopram, but body weight gain decreased both females and males compared to BL. During exposure to the two types of diets, citalopram treatment reduced fat consumption with respect to BL and PTx1 only in the male group. This group also decreased its total energy consumption during TX compared to PTx1. Finally, the females gained less body weight in TX than PTx1, while weight gain in the males during TX decreased with respect to BL and PTx1. Results show a differential effect of citalopram on females vs. males that was dependent on the type of macronutrient administered.

Alkynoates as Versatile and Powerful Chemical Tools for the Rapid Assembly of Diverse Heterocycles under Transition-Metal Catalysis: Recent Developments and Challenges

Heterocycles, heteroaromatics and spirocyclic entities are ubiquitous components of a wide plethora of synthetic drugs, biologically active natural products, marketed pharmaceuticals and agrochemical targets. Recognizing their high proportion in drugs and rich pharmacological potential, these invaluable structural motifs have garnered significant interest, thus enabling the development of efficient catalytic methodologies providing access to architecturally complex and diverse molecules with high atom-economy and low cost. These chemical processes not only allow the formation of diverse heterocycles but also utilize a range of flexible and easily accessible building units in a single operation to discover diversity-oriented synthetic approaches. Alkynoates are significantly important, diverse and powerful building blocks in organic chemistry due to their unique and inherent properties such as the electronic bias on carbon-carbon triple bonds posed by electron-withdrawing groups or the metallic coordination site provided by carbonyl groups. The present review highlights the comprehensive picture of the utility of alkynoates (2007-2019) for the synthesis of various heterocycles (> 50 types) using transition-metal catalysts (Ru, Rh, Pd, Ir, Ag, Au, Pt, Cu, Mn, Fe) in various forms. The valuable function of versatile alkynoates (bearing multifunctional groups) as simple and useful starting materials is explored, thus cyclizing with an array of coupling partners to deliver a broad range of oxygen-, nitrogen-, sulfur-containing heterocycles alongside fused-, and spiro-heterocyclic compounds. In addition, these examples will also focus the scope and reaction limitations, as well as mechanistic investigations into the synthesis of these heterocycles. The biological significance will also be discussed, citing relevant examples of drug molecules highlighting each class of heterocycles. This review summarizes the recent developments in the synthetic methods for the synthesis of various heterocycles using alkynoates as readily available starting materials under transition-metal catalysis.

Toxicity Profile, Pharmacokinetic, and Drug-Drug Interaction Study of Citalopram and Sertraline Following Oral Delivery in Rat: An LC-MS/MS Method for the Simultaneous Determination in Plasma

The burden of depression and other mental disorders is on the rise globally, and successful treatment sometimes requires modifications of drugs and/or dose regimens. The development of novel analytical methods for the determination of antidepressant drugs in biological fluids is thus urgently required. Herein, a sensitive, robust, and rapid liquid chromatographic coupled tandem mass spectrometric method was developed and validated for the determination of citalopram (CIT) and sertraline (SER) in rat plasma after oral administration. The analytes of interest and internal standard (duloxetine (DUL)) were extracted from 100 μL of plasma with solid-phase extraction on an Oasis HLB cartridge followed by the separation with gradient elution with water containing 0.1% formic acid and acetonitrile on an Agilent Eclipse Plus ODS (4.6 × 100 mm, 3.5 μm) column at flow rate 0.2 mL min^-1. The triple quadrupole mass spectrometry was applied via electrospray ionization source for detection. The fragmentation pattern of the protonated CIT, SER, and DUL was elucidated using multiple reaction monitoring of the transitions of m/z 325.2 to 109, 306.1 to 158.9, and 298.1 to 154.1 as [M + H]⁺ for CIT, SER, and DUL, respectively. The proposed method has been validated as per US-FDA bioanalytical guidelines in terms of linearity, accuracy, precision, matrix effects, stability, selectivity, and recovery. The method was linear over the concentration range of 1-2000 and 1-1000 ng mL^-1 with the lower limit of detection of 0.12 and 0.19 ng mL^-1 for CIT and SER, respectively. The interday and intraday precisions and accuracy expressed by the relative standard deviation and the relative standard error were both lower than 11.1% and 2.1%, respectively. The proposed method was successfully applied for the pharmacokinetics and drug monitoring studies of CIT and SER in rat plasma after a single oral dose of 120 mg kg^-1 of CIT and SER. Coadministration of SER with CIT has affected the peak plasma concentrations, maximum plasma concentration time, area under the concentration-time curve, and oral clearance of CIT. Molecular modeling study showed that SER could competitively inhibit CYP2D6, the main enzyme involved in CIT metabolism. A possible drug-drug interaction in psychiatric patients undergoing chronic SER and CIT treatment is therefore worthy of more attention in an effort to avoid side effects and serotonin syndrome.

Analytical methodologies for the enantiodetermination of citalopram and its metabolites

Citalopram (CIT) is a highly selective serotonin reuptake inhibitor (SSRI) frequently used in the treatment of major depressive disorders. It has a chiral centre in its structure and is used in therapy both as a racemic mixture (R,S-CIT) and a pure enantiomer (S-CIT). The differences between the pharmacokinetic and pharmacological profiles of the two enantiomers are well established. Consequently, the development of new efficient chiral analysis methods for their enantiomeric separation is a topic of great actuality. CIT metabolism is stereoselective as it is metabolized in chiral active metabolites, which retain considerable SSRI activity and contribute to the pharmacological effect. Chiral analytical methods are employed for the determination of enantiomeric ratio in pharmaceutical preparations and for monitoring the enantiomer levels in biological samples for therapeutic and toxicologic purposes. The current study reviews the published literature for the chiral analysis of CIT and its metabolites based on chromatographic and electrophoretic methods coupled with UV, fluorescence and mass spectrometry detectors.

Selective Serotonin Reuptake Inhibitor Use and Risk of Arrhythmia: A Nationwide, Population-Based Cohort Study

PURPOSE

This study compares the risks of arrhythmia among patients with depression receiving selective serotonin reuptake inhibitors (SSRIs) and those receiving other classes of antidepressants and among patients with depression receiving citalopram-escitalopram and those receiving other SSRIs.

METHODS

This retrospective cohort study used data from the 2000-2011 National Health Insurance Research Database in Taiwan. Patients with depression who were new antidepressant users were included in the study sample. Propensity score matching was used to balance the covariates between the comparison groups. Crude incidence rates were generated by Poisson regressions, and Cox proportional hazards regression models were used to assess the rates of arrhythmia among SSRI users and nonusers of SSRI antidepressants as well as between citalopram-escitalopram users and users of other SSRIs.

FINDINGS

Neither SSRI (hazard ratio [HR] = 0.95; 95% CI, 0.83-1.08) nor citalopram-escitalopram (HR = 1.20; 95% CI, 0.95-1.51) exposure was associated with a risk of arrhythmia compared with other, newer non-SSRI antidepressants or noncitalopram SSRIs. An increase in mortality was, however, observed among citalopram-escitalopram users (HR = 1.21; 95% CI, 1.08-1.31).

IMPLICATIONS

Citalopram, escitalopram, and other SSRIs were not associated with an elevated risk of arrhythmia compared with each other or with non-SSRI antidepressants. Nevertheless, citalopram and escitalopram were associated with an increase in mortality risk compared with other SSRIs and deserve further investigation.

Benzene construction via Pd-catalyzed cyclization of 2,7-alkadiynylic carbonates in the presence of alkynes

A palladium-catalyzed highly regio- and chemo-selective cyclization of 2,7-alkadiynylic carbonates with functionalized alkynes to construct 1,3-dihydroisobenzofuran and isoindoline derivatives under mild conditions has been developed. Functional groups such as alcohol, sulfonamide, and indoles could be well tolerated. After careful mechanistic studies, a mechanism involving oxidative addition and regioselectivity-defined double alkyne insertions has been proposed.

A population pharmacokinetic model for R- and S-citalopram and desmethylcitalopram in Alzheimer's disease patients with agitation

The citalopram for Alzheimer’s disease trial evaluated citalopram for the management for agitation in Alzheimer’s disease patients. Sparse data was available from this elderly patient population. A nonlinear mixed effects population pharmacokinetic modeling approach was used to describe the pharmacokinetics of R- and S-citalopram and their primary metabolite (desmethylcitalopram). A structural model with 4 compartments (one compartment/compound) with linear oral absorption and elimination described the data adequately. Overall, the model showed that clearance of the R-enantiomer was slower than the clearance of the S-enantiomer. Without accounting for any patient-specific covariates, the population estimate of the metabolic clearance of citalopram was 8.6 (R-citalopram) and 14 L/h (S-citalopram). The population estimate of the clearance of desmethylcitalopram was 23.8 (R-Dcit) and 38.5 L/h (S-Dcit). Several patient-specific covariates were found to have a significant effect on the pharmacokinetics of R,S-citalopram and desmethylcitalopram. A significant difference in the metabolic clearance of R-citalopram between males and females (13 vs 9.05 L/h) was identified in this analysis. Both R- and S-citalopram metabolic clearance decreased with age. Additionally, consistent with literature reports S-citalopram metabolic clearance increased with increasing body weight and was significantly influenced by CYPC19 genotype, with a difference of 5.8 L/h between extensive/rapid and intermediate/poor metabolizers. R,S-desmethylcitalopram clearance increased with increasing body weight. This model may allow for the opportunity to delineate the effect of R- and S-citalopram on pharmacodynamics outcomes related to the management of agitation in Alzheimer’s disease.

A population PK model for citalopram and its major metabolite, N-desmethyl citalopram, in rats

A population PK model was developed in order to simultaneously describe citalopram and its major metabolite, n-desmethyl citalopram, plasma concentrations in two different strain of rats after intravenous (IV) and oral (PO) administration of citalopram. Citalopram was administered to Sprague-Dawley (SD) rats at doses: 0.3, 1, 3, and 10 mg/kg IV and 10 mg/kg PO. The compound was dosed orally to Wistar rats at doses: 0.3, 1, 3, 10, 30 and 60 mg/kg. Plasma samples were collected for citalopram and metabolite. Pharmacokinetic analyses were conducted using NONMEM 7.2. Values below the quantification limit (BLQ < 0.1 ng/mL) were included in the analyses and treated as censored information. The disposition of citalopram was best described by a 3-compartment model and its desmethyl metabolite by a 2-compartment model. Several models for the absorption rate were explored (e.g. first, zero order and combined first and zero order absorption, Michaelis-Menten, lag time) in combination with dose and/or time dependent covariate effects. Dose dependent oral bioavailability properties were also identified in this analysis. Citalopram IV clearance and metabolite formation rate were adequately described as linear processes. Metabolite clearance was adequately described using a Michaelis-Menten clearance with different parameters depending on the strain. This analysis demonstrates a very complex absorption/metabolism process explaining the highly non-linear pharmacokinetics observed across all the doses. This is the first combined parent/metabolite population PK analysis in both SD and Wistar rats over a wide range of IV and PO dosages for citalopram, a compound that exhibits highly nonlinear oral pharmacokinetics in rats.

Comet-FISH studies for evaluation of genetic damage of citalopram in somatic cells of the mouse

Damage to DNA can lead to many different acute and chronic pathophysiological conditions, ranging from cancer to endothelial damage. The present study was designed to evaluate the DNA damage of an antidepressant drug, citalopram, at the recommended human doses in somatic cells of mice in vivo. Mice exposed to citalopram at varying oral doses of 12 or 24 mg kg(-1) for 7 days exhibited a significant increase in the level of DNA-strand breaking and micronuclei formation as detected by a bone marrow comet assay and micronucleus test, respectively. Furthermore, using fluorescence in situ hybridization (FISH) analysis with the centromeric mouse-satellite DNA-probe for erythrocyte micronuclei it could be shown that citalopram is aneugen as well as clastogen in somatic cells in vivo. Colchicine (COL) and mitomycin C (MMC) were used as positive controls and these compounds produced the expected responses. Both the clastogenic and the aneugenic potential of citalopram can give rise to the development of secondary tumours and abnormal reproductive outcomes. Overall, the results suggest that citalopram at the recommended human doses induces some genetic alterations, which can adversely affect the normal cellular functioning in mice. The mechanism(s) by which citalopram cause this adverse effect appear related, in part, to primary DNA strand breakage as detected by the comet assay as well as clastogenic and aneugenic events as detected by the FISH assay. Therefore, the clinical use of citalopram must be weighed against the risks of genetic damages in citalopram users.

Differential sensitivity to SSRI and tricyclic antidepressants in juvenile and adult mice of three strains

Clinical studies have shown differential efficacy of several antidepressants in children and adolescents compared to adults, yet few animal studies have sought to characterize this phenomenon. We compared effects of fluoxetine and imipramine in two common behavioral assays that hold high predictive validity for antidepressant activity, tail suspension and forced swim test, using juvenile (5 weeks) and adult (12 weeks) mice from 3 strains. C57BL/6J-Tyr(c-Brd) (C57), hybrid C57BL/6J-Tyr(c-Brd)x129S5/SvEvBrd (F2), and Balb/cAnNTac (Balb/C) mice were tested in forced swim test and tail suspension after i.p. dosing with either fluoxetine or imipramine. Brain tissues were analyzed to evaluate levels of VMAT2, a possible modulator of age-dependent sensitivity to antidepressants. Imipramine had more consistent antidepressant effect across age groups and strains. Imipramine increased struggle in mice of both ages. Fluoxetine did not have an effect on immobility in Balb/C of both ages in tail suspension. Fluoxetine also did not increase forced swim struggle behavior in juvenile mice of all strains, but was effective in increasing struggle in adults. Juvenile mice had higher immobility and lower struggle than adults in forced swim, and juveniles also had higher immobility in tail suspension test for Balb/C and C57. In addition, VMAT2 levels were increased in juveniles. These results confirm that standard antidepressants produce effects in both juveniles and adults but age-related differences were evident in both tests. Further examination of these effects is needed to determine whether it may be related to age-dependent difference in the clinical response to antidepressants of these classes.

Strain differences in paroxetine-induced reduction of immobility time in the forced swimming test in mice: role of serotonin

We studied the antidepressant-like effect of paroxetine in strains of mice carrying different isoforms of tryptophan hydroxylase-2 (TPH-2), the enzyme responsible for the synthesis of brain serotonin (5-HT). The effect of paroxetine alone and in combination with pharmacological treatments enhancing or lowering 5-HT synthesis or melatonin was assessed in the forced swimming test in mice carrying allelic variants of TPH-2 (1473C in C57BL/6 and 1473G in DBA/2 and BALB/c). Changes in brain 5-hydroxytryptophan (5-HTP) accumulation and melatonin levels were measured by high-performance liquid chromatography. Paroxetine (2.5 and 5 mg/kg) reduced immobility time in C57BL/6J and C57BL/6N mice but had no such effect in DBA/2J, DBA/2N and BALB/c mice, even at 10 mg/kg. Enhancing 5-HT synthesis with tryptophan reinstated the antidepressant-like effect of paroxetine in DBA/2J, DBA/2N and BALB/c mice whereas inhibition of 5-HT synthesis prevented the effect of paroxetine in C57BL/6N mice. The response to paroxetine was not associated with changes in locomotor activity, brain melatonin or brain levels of the drug measured at the end of the behavioral test. These results support the importance of 5-HT synthesis in the response to SSRIs and suggest that melatonin does not contribute to the ability of tryptophan to rescue the antidepressant-like effect of paroxetine.

High dopamine transporter selectivity can be displayed by remarkably simple non-nitrogen containing inhibitors

A series of 2-(3,4-dichlorophenyl)-cyclopent-1-enyl carboxylic acid esters and amides were prepared and tested for binding to the DAT, SERT, and NET. The achiral compounds were easily attained and found to inhibit DAT binding with K(i)-values ranging from 0.095 to 0.00003 mM. Among the compounds tested 2-(3,4-dichlorophenyl)-cyclopent-1-enyl carboxylic acid 2-methylphenyl ester was found to be highly selective with SERT/DAT>7000; NET/DAT>1700, K(i)=60 nM.

Long-term administration of citalopram reduces basal and stress-induced extracellular noradrenaline levels in rat brain

RATIONALE

Panic disorders are commonly treated with selective serotonin reuptake inhibitors (SSRIs). However, the effect of SSRIs on noradrenaline systems in the brain has not been fully elucidated at the present time.

OBJECTIVES

The effects of long-term administration of citalopram, an SSRI, on basal as well as stress-induced extracellular noradrenaline levels in the basolateral nucleus of the amygdala (BLA) and the locus coeruleus (LC) were determined. In addition, the responsiveness of noradrenaline transporters and alpha2-adrenoceptors were determined after long-term administration of citalopram.

MATERIALS AND METHODS

Brain microdialysis was used to assess the extracellular levels of noradrenaline in conscious rats. Desipramine and clonidine were used to functionally evaluate the noradrenaline transporter and alpha2-adrenoreceptor, respectively.

RESULTS

In rats treated daily for 14 days with citalopram (10 mg kg(-1) day(-1) s.c.), dialysate noradrenaline levels showed remarkable decreases in both the BLA and the LC to about 25 and 45% of controls, respectively. The stress-induced increase of noradrenaline was almost completely abolished in the BLA, but was relatively stable in the LC. The effect of local application of desipramine tended to be suppressed only in the LC. The effect of local application of clonidine was enhanced only in the BLA.

CONCLUSION

The present results indicate that chronic administration of citalopram strongly decreases the extracellular levels of noradrenaline in the brain. The anti-panic effect of citalopram might be due to sensitization of the alpha2-adrenoceptors leading to suppression of the stress response through noradrenergic activity. This mechanism is specific for the BLA.

1H NMR spectroscopic study of complexation of citalopram with beta-cyclodextrin in aqueous solution

(1)H NMR spectroscopic study of citalopram (CT) in the absence as well as in the presence of beta-cyclodextrin (beta-CD) in aqueous solution revealed the formation of four 1:1 beta-CD-CT inclusion complexes. The stoichiometry of the complexes was determined by the continuous variation (Job) method, which was further confirmed by Scott's method. The binding constants (K(R) and K(R, S)) were calculated using Scott's method. The structures of all the complexes have been proposed as shown in the diagrams. All the CT proton resonances showed splitting in the presence of beta-CD, owing to chiral discrimination by the beta-CD, between the two enantiomers. The chiral discrimination appears to be due to different modes of binding of the R- and S-CT in the complexes involving a CN-containing aromatic ring.

A single dose of the selective serotonin reuptake inhibitor citalopram exacerbates anxiety in humans: a fear-potentiated startle study

Serotonin reuptake inhibitors may increase symptoms of anxiety immediately following treatment initiation. The present study examined whether acute citalopram increased fear-potentiated startle to predictable and/or unpredictable shocks in healthy subjects. Eighteen healthy subjects each received two treatments, placebo and 20 mg citalopram in a crossover design. Participants were exposed to three conditions including one in which predictable aversive shocks were signaled by a cue, a second in which unpredictable shocks were anticipated, and a third in which no shocks were administered. Changes in aversive states were investigated using acoustic startle stimuli. Citalopram did not affect baseline startle. However, the phasic startle potentiation to the threat cue in the predictable condition was robustly increased by acute citalopram. The sustained startle potentiation in the unpredictable conditions was also increased by citalopram, but only when the drug was given during the first session. These results indicate that a single dose of citalopram is not anxiogenic in itself, but can exacerbate the expression of fear and anxiety.

Serotonin-, protein kinase C-, and Hic-5-associated redistribution of the platelet serotonin transporter

Emerging data indicate the existence of multiple regulatory processes supporting serotonin (5HT) transporter (SERT) capacity including regulated trafficking and catalytic activation, influenced by post-translational modifications and transporter-associated proteins. In the present study, using differential extraction and sedimentation procedures optimized for the purification of cytoskeletal and membrane-skeletal associated proteins, we analyze SERT localization in platelets. We find that most of the plasma membrane SERT is associated with the membrane skeleton. This association can be enhanced by both transporter activation and 5HT2A receptor activation. Inactivation of transport activity by phorbol ester treatment of intact platelets relocates SERT to the cytoskeleton fraction, consequently leading to transporter internalization. The translocation of SERT between these compartments is correlated with changes in the interaction with the LIM domain adaptor protein Hic-5. Co-immunoprecipitation and uptake activity studies suggest that Hic-5 is a determinant of transporter inactivation and relocation to a compartment subserving endocytic regulation. Associations of SERT with Hic-5 are evident in brain synaptosomes, suggesting the existence of parallel mechanisms operating to regulate SERT at serotonergic synapses.

Genotype-dependent activity of tryptophan hydroxylase-2 determines the response to citalopram in a mouse model of depression

Polymorphism of tryptophan hydroxylase, the rate-limiting enzyme in the synthesis of brain serotonin (5-HT), is associated with less synthesis of brain 5-HT in DBA/2J and BALB/c than in C57BL/6J and 129/Sv mice. We selected the forced swimming test, a mouse model used to assess the antidepressant potential of drugs, and neurochemical techniques to study strain differences in the response to citalopram, a selective 5-HT reuptake inhibitor. Citalopram reduced immobility time in C57BL/6J and 129/Sv mice but had no such effect in DBA/2J and BALB/c mice. The drug reduced accumulation of 5-hydroxytryptophan (5-HTP), an indicator of 5-HT synthesis, in C57BL/6J and 129/Sv mice but much less in DBA/2J and BALB/c mice. Pretreatment with tryptophan raised 5-HTP accumulation and reinstated the antidepressant-like effect of citalopram in DBA/2J and BALB/c mice, whereas pharmacological inhibition of 5-HT synthesis prevented the effect of citalopram in C57BL/6J and 129/Sv mice. Because there were no strain differences in catecholamine synthesis, locomotor activity, and brain levels of citalopram at the end of the behavioral test, the results suggest that the failure of citalopram to reduce immobility time in DBA/2J and BALB/c mice is attributable to genotype-dependent impairment of 5-HT synthesis. Interstrain comparisons could probably be a useful strategy for understanding the mechanisms underlying the response to selective serotonin reuptake inhibitors.

Low dose citalopram reverses memory impairment and electroconvulsive shock-induced immobilization

Citalopram, a selective serotonin reuptake inhibitor (SSRI), is one of the most widely used antidepressants. Recently, citalopram has been reported to improve working memory in patients with depression, and psychotic symptoms and behavioral disturbances in patients with dementia. However, the possibility of using citalopram in the treatment of cognitive disorders has not received much attention. The present study investigated the effects of citalopram on scopolamine- and Delta9-tetrahydrocannabinol (THC)-induced impairment of spatial memory using an eight-arm radial maze and electroconvulsive shock (ECS)-induced immobilization (a behavioral model for the disturbance of consciousness). Low dose citalopram reversed both scopolamine- and THC-induced impairment of spatial memory, suppressed ECS-induced immobilization reversed the THC-induced decrease of acetylcholine (ACh) release in the dorsal hippocampus in vivo microdialysis, and enhanced tremors induced by oxotremorine, a muscarinic M1 receptor agonist. Taken together these findings suggest that low dose citalopram is useful for the treatment of memory deficits and consciousness disturbance.

Effect of age and gender on citalopram and desmethylcitalopram steady-state plasma concentrations in adults and elderly depressed patients

The effect of aging on steady-state plasma concentrations of citalopram (CIT) and desmethylcitalopram (DCIT) was investigated in 128 depressive patients treated with 10-80 mg/day CIT. They were separated into three groups, with age up to 64 years (mean age+/-S.D.: 47+/-12 years; n=48), between 65 and 79 years (72+/-1 years; n=57), and from 80 years or older (84+/-1 years; n=23). Body mass index (BMI), renal and hepatic functions were similar in the three groups. A large interindividual variability of plasma levels of CIT (16-fold) and DCIT (12-fold) was measured for a given dose. The mean plasma levels of CIT corrected for a 20 mg daily dose were 55% higher in the very elderly (>=80 years) patients (65+/-30 ng/ml; p<0.001) and 38% higher in the elderly (65-79 years) patients (58+/-24 ng/ml; p<0.001) when compared to the adult patients (42+/-17 ng/ml). DCIT mean plasma level was 38% higher (p<0.05) in the group of very elderly patients (22+/-10 ng/ml) when compared to the adult patients (16+/-9 ng/ml). As a consequence, the mean plasma concentration of CIT+DCIT was 48% higher in the very elderly patients (86+/-36 ng/ml; p<0.001) and 33% higher in the elderly patients (77+/-28 ng/ml; p<0.001) when compared to the adult patients (58+/-21 ng/ml). Age correlated significantly with CIT (r=0.43, p<0.001), DCIT (r=0.28, p<0.01), and CIT+DCIT plasma levels (r=0.44, p<0.001), and thus accounts for 18% of the variability of CIT plasma levels, with no influence of gender. The recommended dose reduction of CIT in elderly patients seems therefore justified.

The Flinders Sensitive Line rat: a selectively bred putative animal model of depression

The Flinders Sensitive Line (FSL) rats were originally selectively bred for increased responses to an anticholinesterase agent. The FSL rat partially resembles depressed individuals because it exhibits reduced appetite and psychomotor function but exhibits normal hedonic responses and cognitive function. The FSL rat also exhibits sleep and immune abnormalities that are observed in depressed individuals. Neurochemical and/or pharmacological evidence suggests that the FSL rat exhibits changes consistent with the cholinergic, serotonergic, dopaminergic, NPY, and circadian rhythm models but not the noradrenergic, HPA axis or GABAergic models of depression. However, evidence for the genetic basis of these changes is lacking and it remains to be determined which, if any, of the neurochemical changes are primary to the behavioral alterations. The FSL rat model has been very useful as a screen for antidepressants because known antidepressants reduced swim test immobility when given chronically and psychomotor stimulants did not. Furthermore, rolipram and a melatonin agonist were shown to have anti-immobility effects in the FSL rats and later to have antidepressant effects in humans. Thus, the FSL rat model of depression exhibits some behavioral, neurochemical, and pharmacological features that have been reported in depressed individuals and has been very effective in detecting antidepressants.

Utility of sparse concentration sampling for citalopram in elderly clinical trial subjects

The objective of this study was to evaluate whether the disposition of the selective serotonin reuptake inhibitor, citalopram, could be robustly captured using 1 to 2 concentration samples per subject in 106 patients participating in 2 clinical trials. Nonlinear mixed-effects modeling was used to evaluate the pharmacokinetic parameters describing citalopram's disposition. Both a prior established 2-compartment model and a de novo 1-compartment pharmacokinetic model were used. Covariates assessed were concomitant medications, race, sex, age (22-93 years), and weight. Covariates affecting disposition were assessed separately and then combined in a stepwise manner. Pharmacokinetic characteristics of citalopram were well captured using this sparse sampling design. Two covariates (age and weight) had a significant effect on the clearance and volume of distribution in both the 1- and 2-compartment pharmacokinetic models. Clearance decreased 0.23 L/h for every year of age and increased 0.14 L/h per kilogram body weight. It was concluded that hyper-sparse sampling designs are adequate to support population pharmacokinetic analysis in clinically treated populations. This is particularly valuable for populations such as the elderly, who are not typically available for pharmacokinetic studies.