Pharmacokinetics of selective serotonin reuptake inhibitors

Plasma fluoxetine concentrations and clinical improvement in an adolescent sample diagnosed with major depressive disorder, obsessive-compulsive disorder, or generalized anxiety disorder

Fluoxetine (FLX) has been one of the most widely studied selective serotonin reuptake inhibitors in adolescents. Despite its efficacy, however, 30% to 40% of patients do not respond to treatment.

AIMS

The aim of this study was to evaluate whether clinical improvement or adverse events are related to the corrected dose of FLX at 8 and 12 weeks after starting treatment in a sample of adolescents diagnosed with major depressive disorder, obsessive-compulsive disorder, or generalized anxiety disorder.

METHODS

Seventy-four subjects aged between 10 and 17 years participated in the study. Clinical improvement was measured with the Clinical Global Impression-Improvement Scale, whereas the UKU (Udvalg for Klinske Undersogelser) scale was administered to assess adverse effects of treatment.

RESULTS

Fluoxetine per kilograms of body weight was related to serum concentration of FLX, NORFLX (norfluoxetine), FLX + NORFLX, and FLX/NORFLX. No relationship was found between dose-corrected FLX levels and therapeutic or adverse effects. No differences in serum concentrations were found between responders and nonresponders to treatment. Sex differences were observed in relation to dose and FLX serum concentration. The analysis by diagnosis revealed differences in FLX dose between obsessive-compulsive disorder patients and both generalized anxiety disorder and major depressive disorder patients.

CONCLUSIONS

Fluoxetine response seems to be influenced by factors such as sex, diagnosis, or certain genes that might be involved in the drug's pharmacokinetics and pharmacodynamics. Clinical and pharmacogenetic studies are needed to elucidate further the differences between treatment responders and nonresponders.

Combined effects of pharmaceuticals, personal care products, biocides and organic contaminants on the growth of Skeletonema pseudocostatum

Organisms in the environment are exposed to a number of pollutants from different compound groups. In addition to the classic pollutants like the polychlorinated biphenyls, polyaromatic hydrocarbons (PAHs), alkylphenols, biocides, etc. other compound groups of concern are constantly emerging. Pharmaceuticals and personal care products (PPCPs) can be expected to co-occur with other organic contaminants like biocides, PAHs and alkylphenols in areas affected by wastewater, industrial effluents and intensive recreational activity. In this study, representatives from these four different compound groups were tested individually and in mixtures in a growth inhibition assay with the marine algae Skeletonema pseudocostatum (formerly Skeletonema costatum) to determine whether the combined effects could be predicted by models for additive effects; the concentration addition (CA) and independent action (IA) prediction model. The eleven tested compounds reduced the growth of S. pseudocostatum in the microplate test in a concentration-dependent manner. The order of toxicity of these chemicals were irgarol>fluoxetine>diuron>benzo(a)pyrene>thioguanine>triclosan>propranolol>benzophenone 3>cetrimonium bromide>4-tert-octylphenol>endosulfan. Several binary mixtures and a mixture of eight compounds from the four different compound groups were tested. All tested mixtures were additive as model deviation ratios, the deviation between experimental and predicted effect concentrations, were within a factor of 2 from one or both prediction models (e.g. CA and IA). Interestingly, a concentration dependent shift from IA to CA, potentially due to activation of similar toxicity pathways at higher concentrations, was observed for the mixture of eight compounds. The combined effects of the multi-compound mixture were clearly additive and it should therefore be expected that PPCPs, biocides, PAHs and alkylphenols will collectively contribute to the risk in areas contaminated by such complex mixtures.

Chronic administration of fluoxetine or clozapine induces oxidative stress in rat liver: a histopathological study

Chronic exposure to stress contributes to the etiology of mood disorders, and the liver as a target organ of antidepressant and antipsychotic drug metabolism is vulnerable to drug-induced toxicity. We investigated the effects of chronic administration of fluoxetine (15mg/kg/day) or clozapine (20mg/kg/day) on liver injury via the measurement of liver enzymes, oxidative stress and histopathology in rats exposed to chronic social isolation (21days), an animal model of depression, and controls. The activity of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the liver content of carbonyl groups, malonyldialdehyde (MDA), reduced glutathione (GSH), cytosolic glutathione S-transferase (GST) and nitric oxide (NO) metabolites were determined. We also characterized nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2) and CuZn-superoxide dismutase (CuZnSOD) protein expression as well as histopathological changes. Increased serum ALT activity in chronically-isolated and control animals treated with both drugs was found while increased AST activity was observed only in fluoxetine-treated rats (chronically-isolated and controls). Increased carbonyl content, MDA, GST activity and decreased GSH levels in drug-treated controls/chronically-isolated animals suggest a link between drugs and hepatic oxidative stress. Increased NO levels associated with NF-κB activation and the concomitant increased COX-2 expression together with compromised CuZnSOD expression in clozapine-treated chronically-isolated rats likely reinforce oxidative stress, observed by increased lipid peroxidation and GSH depletion. In contrast, fluoxetine reduced NO levels in chronically-isolated rats. Isolation induced oxidative stress but histological changes were similar to those observed in vehicle-treated controls. Chronic administration of fluoxetine in both chronically-isolated and control animals resulted in more or less normal hepatic architecture, while clozapine in both groups resulted in liver injury. These data suggest that clozapine appears to have a higher potential to induce liver toxicity than fluoxetine.

ABCB1 C3435T polymorphism is associated with susceptibility to major depression, but not with a clinical response to citalopram in a Turkish population

BACKGROUND

The ATP-binding cassette sub-family B member 1 (ABCB1) gene, which encodes the p-glycoprotein at the blood-brain barrier, is investigated for patients' susceptibility to major depressive disorder (MDD) and their therapeutic response to antidepressants. However, there is an inconsistency between the studies of different ethnic groups. The current study aimed to determine the potential correlations of the ABCB1 gene C3435T polymorphism with the susceptibility to MDD and the therapeutic response to citalopram in a Turkish population.

METHODS

Fifty-four patients with MDD who received citalopram and 70 controls from the Turkish population were genotyped for ABCB1 C3435T polymorphism. To assess the therapeutic response to citalopram, all patients were rated baseline, first, second, fourth and sixth weeks according to the 17-item Hamilton Rating Scale for Depression (HAMD-17).

RESULTS

There was a significant correlation between the patient and control groups for ABCB1 C3435T polymorphism. Distribution of CC genotype and C allele frequency were higher in the patients than in the control group (p = 0.006, p = 0.020, respectively). However, no correlation between ABCB1 C3435T polymorphism and a therapeutic response to citalopram was observed.

CONCLUSION

Our results suggested that C3435T polymorphism in the ABCB1 gene may be an indicator of the susceptibility to major depression, without a likely treatment response to citalopram in a Turkish population. These findings should be replicated in studies on larger patient groups with different ethnicities.

Effects of the SSRI citalopram on behaviours connected to stress and reproduction in Endler guppy, Poecilia wingei

Psychoactive drugs, such as selective serotonin reuptake inhibitors (SSRI) have been identified in high levels in effluents from Swedish sewage treatment plants (STP) at concentrations high enough to give pharmacological effects in fish. In humans SSRIs are used in the treatment of depression and they have anxiolytic effects. In the present study we exposed Endler guppy (Poecilia wingei) of both sexes to citalopram that showed the highest concentrations of SSRIs in STP effluents and studied reproductive and non-reproductive behaviour. Male courting behaviours were not affected compared to control fish after 14-28 days exposure to 1 μg L(-1). In two experiments exposing both sexes to 0.2, 2.3 or 15 μg L(-1) for 21 days, fish exposed to the two highest doses showed anxiolytic effects when placed in a novel environment (novel tank diving test, NT). Males were only affected by exposure to 15 μg L(-1). They had significantly longer latency to explore the upper half of the aquarium, more visits and longer time spent in the upper half, and showed less bottom freezing behaviour, all markers of anxiolytic behaviour. In females exposure to 2.3 or 15 μg L(-1) significantly increased freezing behaviour, while no effects on other behaviour variables were observed. No effects on shoaling behaviour could be discerned. These results show that citalopram have anxiolytic effects on guppy fish and thus affect ecologically relevant behaviours of importance to survival of fish.

Exposures to a selective serotonin reuptake inhibitor (SSRI), sertraline hydrochloride, over multiple generations: changes in life history traits in Ceriodaphnia dubia

Selective serotonin reuptake inhibitors (SSRIs) have been reported to range from low parts per trillion to parts per billion levels in surface waters, wastewater effluents, and sediments. These low levels have led to concern for their potential long-term risks to the survival, growth, and reproduction of aquatic organisms. We investigated the acute and chronic effects of sertraline on the life history traits of Ceriodaphnia dubia over the course of three generations under environmentally realistic concentrations. Acute toxicity of sertraline in C. dubia offspring resulted in a 48h median effective concentration of 126µgL(-1). Under chronic exposure, the lowest concentration to affect fecundity and growth was at 53.4µgL(-1) in the first two generations. These parameters become more sensitive during the third generation where the LOEC was 4.8µgL(-1). The median effective concentrations (EC50) for the number of offspring per female, offspring body size, and dry weight were 17.2, 21.2, and 26.2µgL(-1), respectively. Endpoints measured in this study demonstrate that chronic exposure of C. dubia to sertraline leads to effects that occur at concentrations only an order of magnitude higher than predicted environmental concentrations. However, this study also demonstrates that multigenerational effects should be considered in chronic exposure studies because standard toxicity tests do not account for increases in sensitivity in successive generations to toxicants.

ParoXetine: A First for Selective Serotonin Reuptake Inhibitors – a New Use: Approved for Vasomotor Symptoms in Postmenopausal Women

In the USA, over 30 million women are In or near menopause. Menopause Is associated with a cluster of Issues. Vasomotor symptoms (VMS) are the number one complaint of most menopausal women. VMS are disruptive to women during the day and at night, which leads to poor sleep, anxiety, depression and poor concentration. Up until now, the only US FDA-approved medication for moderate-to-severe VMS was hormone therapy. Hormone therapy may not be appropriate for all women. Many drugs are used off-label to treat VMS. The most often used agents are agents that are FDA-approved medications, such as selective serotonin reuptake Inhibitors and serotonin–norepinephrine reuptake Inhibitors. The pharmaceutical company, Noven Pharmaceuticals (FL, USA), has studied paroxetine mesylate 7.5 mg, previously known as low-dose mesylate salt of paroxetine, specifically to treat moderate-to-severe VMS In postmenopausal women. Paroxetine is a selective serotonin reuptake Inhibitor, and Is thought to help decrease VMS by regulating body temperature via neurotransmitters. Paroxetine Is approved to treat various psychiatric disorders, but Is used at much higher doses (20–60 mg/day).

Genetic differences in cytochrome P450 enzymes and antidepressant treatment response

AIMS

Antidepressant response varies between patients, possibly due to differences in the rate cytochrome P450 enzymes metabolise antidepressants into inactive compounds. Drug metabolism rates are influenced by common variants in the genes encoding these enzymes. However, it remains unclear whether treatment outcomes can be predicted by either CYP450 genotype or antidepressant serum concentration.

METHODS

In GENDEP (a pharmacogenetic study of depressed individuals treated with either escitalopram or nortriptyline), serum concentrations of antidepressants and their primary metabolite were measured after eight weeks treatment and variants in CYP2D6 and CYP2C19 were genotyped.

RESULTS

Amongst patients taking escitalopram (n=223), the genotype CYP2C19 was significantly associated with escitalopram serum concentrations and desmethylescitalopram:escitalopram ratio. For those taking nortriptyline (n=161), the CYP2D6 genotype was significantly associated with nortriptyline and 10-hydroxynortriptyline serum concentrations and 10-hydroxynortriptyline:nortrip-tyline ratio. CYP450 genotypes conferring greater enzyme activity were linked to lower drug serum concentrations and higher metabolite:drug ratios. Nonetheless, no significant association was found between either CYP450 genotype or antidepressant serum concentration and treatment response.

CONCLUSIONS

While there is a significant relationship between the CYP450 genotype and serum concentrations of escitalopram and nortriptyline, the genotypes are not predictive of differences in treatment response for either drug. Furthermore, differences in antidepressant serum concentrations are not associated with variability in treatment response.

Advances in the development of genetic markers for the diagnosis of disease and drug response

Genetic diversity, including single nucleotide polymorphisms, contributes to both disease susceptibility and variability in drug response. Since most genes contain multiple single nucleotide polymorphisms, identifying those that are most relevant with respect to disease or drug response is important and may uncover variants that are predictive of either disease susceptibility or therapeutic response to drugs, both with respect to efficacy and toxic side effects. The candidate gene approach has been widely used to search for the genetic basis of pharmacogenomic traits. Although a few successful examples have emerged from this approach, notably trastuzumab (Herceptin; Genentech), imatinib mesylate (Gleevec (USA), Glivec; Novartis) and certain drugs that demonstrate variable efficacy or adverse effects that are attributed to metabolizing enzymes, for most drugs, the genetic variations that determine their clinical response remain uncovered. Genome-wide linkage approach presents an alternative to the candidate gene approach. The powerful combination of linkage when coupled to ultra-high-throughput genotyping, gene array and proteomics technology, together with innovative bioinformatic resources, provides a focused integrative strategy for pinpointing disease-causing genes that may generate validated drug targets and genes that are responsible for differential drug response. Thus, it is anticipated that genetic research will soon generate new information that can be used to develop novel therapeutic strategies and diagnostic tests that will ultimately lead to safer and more efficacious drugs for all patients. This review addresses recent advances in the development of genetic markers that can be used to diagnose disease or drug response.

Serotonin at the nexus of impulsivity and cue reactivity in cocaine addiction

Cocaine abuse and addiction remain great challenges on the public health agendas in the U.S. and the world. Increasingly sophisticated perspectives on addiction to cocaine and other drugs of abuse have evolved with concerted research efforts over the last 30 years. Relapse remains a particularly powerful clinical problem as, even upon termination of drug use and initiation of abstinence, the recidivism rates can be very high. The cycling course of cocaine intake, abstinence and relapse is tied to a multitude of behavioral and cognitive processes including impulsivity (a predisposition toward rapid unplanned reactions to stimuli without regard to the negative consequences), and cocaine cue reactivity (responsivity to cocaine-associated stimuli) cited as two key phenotypes that contribute to relapse vulnerability even years into recovery. Preclinical studies suggest that serotonin (5-hydroxytryptamine; 5-HT) neurotransmission in key neural circuits may contribute to these interlocked phenotypes well as the altered neurobiological states evoked by cocaine that precipitate relapse events. As such, 5-HT is an important target in the quest to understand the neurobiology of relapse-predictive phenotypes, to successfully treat this complex disorder and improve diagnostic and prognostic capabilities. This review emphasizes the role of 5-HT and its receptor proteins in key addiction phenotypes and the implications of current findings to the future of therapeutics in addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Selective inhibition of cytochrome P450 2D6 by Sarpogrelate and its active metabolite, M-1, in human liver microsomes

The present study was performed to evaluate the in vitro inhibitory potential of sarpogrelate and its active metabolite, M-1, on the activities of nine human cytochrome (CYP) isoforms. Using a cocktail assay, the effects of sarpogrelate on nine CYP isoforms and M-1 were measured by specific marker reactions in human liver microsomes. Sarpogrelate potently and selectively inhibited CYP2D6-mediated dextromethorphan O-demethylation with an IC50 (Ki) value of 3.05 μM (1.24 μM), in a competitive manner. M-1 also markedly inhibited CYP2D6 activity; its inhibitory effect with an IC50 (Ki) value of 0.201 μM (0.120 μM) was more potent than that of sarpogrelate, and was similarly potent as quinidine (Ki, 0.129 μM), a well-known typical CYP2D6 inhibitor. In addition, sarpogrelate and M-1 strongly inhibited both CYP2D6-catalyzed bufuralol 1'-hydroxylation and metoprolol α-hydroxylation activities. However, sarpogrelate and M-1 showed no apparent inhibition of the other following eight CYPs: CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2E1, or CYP3A4/5. Upon 30-minute preincubation of human liver microsomes with sarpogrelate or M-1 in the presence of NADPH, no obvious shift in IC50 was observed in terms of inhibition of the nine CYP activities, suggesting that sarpogrelate and M-1 are not time-dependent inactivators. Sarpogrelate strongly inhibited the activity of CYP2D6 at clinically relevant concentrations in human liver microsomes. These observations suggest that sarpogrelate could have an effect on the metabolic clearance of drugs possessing CYP2D6-catalyzed metabolism as a major clearance pathway, thereby eliciting pharmacokinetic drug-drug interactions.

Flexible and biomimetic analogs of triple uptake inhibitor 4-((((3S,6S)-6-benzhydryltetrahydro-2H-pyran-3-yl)amino)methyl)phenol: Synthesis, biological characterization, and development of a pharmacophore model

In this study we have generated a pharmacophore model of triple uptake inhibitor compounds based on novel asymmetric pyran derivatives and the newly developed asymmetric furan derivatives. The model revealed features important for inhibitors to exhibit a balanced activity against dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET). In particular, a 'folded' conformation was found common to the active pyran compounds in the training set and was crucial to triple uptake inhibitory activity. Furthermore, the distances between the benzhydryl moiety and the N-benzyl group as well as the orientation of the secondary nitrogen were also important for TUI activity. We have validated our findings by synthesizing and testing novel asymmetric pyran analogs. The present work has also resulted in the discovery of a new series of asymmetric tetrahydrofuran derivatives as novel TUIs. Lead compounds 41 and 42 exhibited moderate TUI activity. Interestingly, the highest TUI activity by lead tetrahydrofuran compounds for example, 41 and 42, was exhibited in a stereochemical preference similar to pyran TUI for example, D-161.

Rebound effect of modern drugs: serious adverse event unknown by health professionals

OBJECTIVE

Supported in the Hippocratic aphorism primum non nocere, the bioethical principle of non-maleficence pray that the medical act cause the least damage or injury to the health of the patient, leaving it to the doctor to assess the risks of a particular therapy through knowledge of possible adverse events of drugs. Among these, the rebound effect represents a common side effect to numerous classes of modern drugs, may cause serious and fatal disorders in patients. This review aims to clarify the health professionals on clinical and epidemiological aspects of rebound phenomenon.

METHODS

A qualitative, exploratory and bibliographic review was held in the PubMed database using the keywords 'rebound', 'withdrawal', 'paradoxical', 'acetylsalicylic acid', 'anti-inflammatory', 'bronchodilator', 'antidepressant', 'statin', 'proton pump inhibitor' and 'bisphosphonate'.

RESULTS

The rebound effect occurs after discontinuation of numerous classes of drugs that act contrary to the disease disorders, exacerbating them at levels above those prior to treatment. Regardless of the disease, the drug and duration of treatment, the phenomenon manifests itself in a small proportion of susceptible individuals. However, it may cause serious and fatal adverse events should be considered a public health problem in view of the enormous consumption of drugs by population.

CONCLUSION

Bringing together a growing and unquestionable body of evidence, the physician needs to have knowledge of the consequences of the rebound effect and how to minimize it, increasing safety in the management of modern drugs. On the other hand, this rebound can be used in a curative way, broadening the spectrum of the modern therapeutics.

The value of drug and metabolite concentration in blood as a biomarker of psychopharmacological therapy

Desirable and undesirable effects of a drug are related to its concentration at various sites of actions. For many psychotropic drugs, it has been shown that drug concentration in brain correlates with concentration in blood. The latter is also an available estimate of clearance and bioavailability. Its monitoring enables identification of multiple factors that have an impact on clinical outcomes, especially uncertain compliance and pharmacokinetic peculiarities. For this review we analysed for antidepressants if drug concentration in blood can be used as biomarker for psychopharmacological treatment. Systematic review of the literature revealed for new and old antidepressant drugs that drug and metabolite concentrations in blood are measures of the pharmacokinetic phenotype and related differentially to occupancy of primary target structures, therapeutic effects and unwanted anticholinergic, cardiac and other side effects. Drug concentration in blood can therefore be used as biomarker in clinical practice to guide psychopharmacological treatment with established antidepressant drugs. Monitoring of drug concentration is suitable to improve efficacy and safety of the pharmacotherapy, especially in elderly patients who require complex pharmacological therapies.

The relation between dosage, serum concentrations, and clinical outcome in children and adolescents treated with sertraline: a naturalistic study

OBJECTIVE

This naturalistic therapeutic drug monitoring (TDM) study aimed to evaluate the relationship between dosage, serum concentration, and clinical outcome in children and adolescents treated with the serotonin reuptake inhibitor sertraline for different indications.

METHODS

Steady-state trough serum concentrations were analyzed in 90 subjects, treated with 25-200 mg sertraline per day. Therapeutic efficacy was assessed by the Clinical Global Impression Improvement subscale and side effects by the Udvalg for Kliniske Undersogelser-Side Effect Rating Scale.

RESULTS

In the study population, children were administered higher body weight normalized daily doses than adolescents. The relationships between sertraline daily dosage and serum concentrations (rs = 0.67, P < 0.0001) as well as between body weight normalized daily doses and serum concentrations (r = 0.62, P < 0.0001) were linear. In the whole patient group, no correlation between serum concentrations and either the therapeutic effect or side effects could be observed, neither significant effects of gender, age, concomitant medications, or smoking habits. When analyzing just the patients with depression, those with side effects had significantly higher sertraline serum concentrations than those without (44.8 ng/mL versus 22.3 ng/mL, P = 0.01). In general, occurrence of side effects was significantly more frequent in patients with psychiatric comedication (37.9%) than those without (11.5%, P = 0.002).

DISCUSSION

As this study has the typical limitations of naturalistic studies, the results should be interpreted cautiously. From the data, it is not possible to suggest an age-specific therapeutic window for children and adolescents. However, as the intraindividual variability of sertraline serum concentrations is known to be low, TDM may certainly help to predict serum concentrations after dose adjustment, to assess pharmacokinetic drug-drug interactions influencing serum concentrations and the patient's compliance, finally allowing for personalizing dose through TDM.

The mode of action (MOA) approach reveals interactive effects of environmental pharmaceuticals on Mytilus galloprovincialis

Aquatic organisms are unintentionally exposed to a large number of pharmaceutical residues in their natural habitats. Ecotoxicological studies have agreed that these compounds are not harmful to aquatic organisms, as their environmental concentrations are typically too low. However, recent reports have shown biological effects at such low concentrations when biological endpoints related to the therapeutic effects are assessed. Therefore, conservation of molecular targets is now addressed as a key aspect for the development of more efficient test strategies for pharmaceutical environmental risk assessment, providing the rationale for the mode of action (MOA) approach. In the present study the MOA approach was used to investigate the interactive effects of fluoxetine (FX) and propranolol (PROP) on the Mediterranean mussels (Mytilus galloprovincialis). Indeed, organisms in the environment are exposed to pharmaceutical mixtures throughout their lifetime, and particular combinations may be of concern. The antidepressant FX increases serotonin (5-HT) levels in the synaptic cleft by inhibiting 5-HT reuptake. PROP, a prototypical β-adrenoceptor antagonist, also blocks 5-HT1 receptors, which are negatively coupled to cAMP-mediated signaling. Cell signaling alterations potentially triggered by 5-HT1 receptor occupation were therefore assessed after a 7-day mussel exposure to FX or PROP, alone or in combination, each at 0.3 ng/L concentration. FX decreased cAMP levels and PKA activities in digestive gland and mantle/gonads, in agreement with an increased occupation of 5-HT1 receptors. PROP caused a decrease in cAMP levels and PKA activities in digestive gland and an increase in cAMP levels in mantle/gonads, consistent with a differential expression of adrenergic and 5-HT receptors in the two tissues. Co-exposure to FX and PROP provides significant indications for antagonistic effects of the pharmaceuticals, consistent with a direct (PROP) and indirect (FX) action on the same molecular target. Interestingly, FX induced over-expression of a 5-HT1 gene product, and PROP counteracted such increase when the mixture was administered, while having per se no effect. Finally, mRNA expression of the ABCB gene encoding the MXR-related transporter P-glycoprotein was reduced by both pharmaceuticals in the digestive gland, while decreased by FX, increased by PROP, and not affected by the mixture in mantle/gonads. Since transcription of this gene product is under cAMP/PKA modulation, the impairment of regulatory pathways triggered by low concentrations of pharmaceuticals have the potential to affect the ability of animals to elaborate strategies of defense or adaptation toward further stress factors. In this specific case, the pharmaceutical mixture limits the detrimental effects of the single compounds.

In-stream attenuation of neuro-active pharmaceuticals and their metabolites

In-stream attenuation was determined for 14 neuro-active pharmaceuticals and associated metabolites. Lagrangian sampling, which follows a parcel of water as it moves downstream, was used to link hydrological and chemical transformation processes. Wastewater loading of neuro-active compounds varied considerably over a span of several hours, and thus a sampling regime was used to verify that the Lagrangian parcel was being sampled and a mechanism was developed to correct measured concentrations if it was not. In-stream attenuation over the 5.4-km evaluated reach could be modeled as pseudo-first-order decay for 11 of the 14 evaluated neuro-active pharmaceutical compounds, illustrating the capacity of streams to reduce conveyance of neuro-active compounds downstream. Fluoxetine and N-desmethyl citalopram were the most rapidly attenuated compounds (t1/2 = 3.6 ± 0.3 h, 4.0 ± 0.2 h, respectively). Lamotrigine, 10,11,-dihydro-10,11,-dihydroxy-carbamazepine, and carbamazepine were the most persistent (t1/2 = 12 ± 2.0 h, 12 ± 2.6 h, 21 ± 4.5 h, respectively). Parent compounds (e.g., buproprion, carbamazepine, lamotrigine) generally were more persistent relative to their metabolites. Several compounds (citalopram, venlafaxine, O-desmethyl-venlafaxine) were not attenuated. It was postulated that the primary mechanism of removal for these compounds was interaction with bed sediments and stream biofilms, based on measured concentrations in stream biofilms and a column experiment using stream sediments.

Slow delayed rectifier potassium current blockade contributes importantly to drug-induced long QT syndrome

BACKGROUND

Drug-induced long QT syndrome is generally ascribed to inhibition of the cardiac rapid delayed rectifier potassium current (IKr). Effects on the slow delayed rectifier potassium current (IKs) are less recognized. Triggered by a patient who carried the K422T mutation in KCNQ1 (encoding the α-subunit of the IKs channel), who presented with excessive QT prolongation and high serum levels of norfluoxetine, we investigated the effects of fluoxetine and its metabolite norfluoxetine on IKs.

METHODS AND RESULTS

ECG data from mutation carriers and noncarriers revealed that the K422T mutation per se had mild clinical effects. Patch clamp studies, performed on HEK293 cells, showed that heterozygously expressed K422T KCNQ1/KCNE1 channels had a positive shift in voltage dependence of activation and an increase in deactivation rate. Fluoxetine and its metabolite norfluoxetine both inhibited KCNQ1/KCNE1 current, with norfluoxetine being the most potent. Moreover, norfluoxetine increased activation and deactivation rates. Computer simulations of the effects of norfluoxetine on IKs and IKr demonstrated significant action potential prolongation, to which IKs block contributed importantly. Although the effects of the mutation per se were small, additional IKs blockade by norfluoxetine resulted in more prominent QTc prolongation in mutation carriers than in noncarriers, demonstrating synergistic effects of innate and drug-induced IKs blockade on QTc prolongation.

CONCLUSIONS

IKs blockade contributes importantly to drug-induced long QT syndrome, especially when repolarization reserve is reduced. Drug safety tests might have to include screening for IKs blockade.

Effects of the pharmaceutical fluoxetine in spiked-sediments on feeding activity and growth of the polychaete Capitella teleta

The marine-estuarine polychaete Capitella is an indicator of organic pollution and plays important roles in sewage waste cycling. The antidepressant fluoxetine can be accumulated in streams and sewage effluents and it could pose a hazard to infauna. Effects of fluoxetine on feeding and growth of Capitella teleta were investigated through the exposure to 0, 0.001, 0.03, 0.3 and 3.3 μg/g dry weight sediment-spiked fluoxetine during 18 days. No effects of fluoxetine concentrations were observed on egestion rates, body weight and size-specific egestion rates. Fluoxetine favoured the occurrence of males with abnormal genital spines. This suggests that fluoxetine can have important reproductive implications. Further studies are recommended to assess potential detrimental effects on benthic infauna inhabiting close to sewage treatment plants.

In vivo genotoxicity assessment of sertraline by using alkaline comet assay and the cytokinesis-block micronucleus assay

Sertraline, a leading antidepressant in the selective serotonin reuptake inhibitor (SSRI) group of medicine, is the most frequently prescribed drug. In this study, the alkaline comet assay and the cytokinesis-block micronucleus (CBMN) assay were used to investigate genotoxicity potential of sertraline in the peripheral blood lymphocytes (PBLs) of acute and chronic sertraline-treated Wistar albino rats. Male Wistar albino rats (n = 48) were administered low, medium and high doses of sertraline (10, 40, 80 mg/kg) for acute and chronic treatment by employing the gavage method to investigate genotoxicity of the administered drug. The data (tail length, tail intensity and tail moment) were analysed and indicated that there was no statistically significant difference between sertraline-treated groups and the negative control group with respect to DNA damage (p > 0.05). However, it was observed that acute sertraline administration had caused much more DNA damage in comparison with chronic treatment (p < 0.05). According to the data obtained from the CBMN test, an increase in the micronucleus (MN) frequency was detected at chronic and high-dose acute sertraline treatment. Based on the outcome of comet assay, detection of statistically insignificant DNA damage may be due to the fact that sertraline did not cause damage on DNA. Also, increase in frequency of MN in chronic sertraline treatment suggests that chronic sertraline administration might influence some mechanisms of cell division. Therefore, dose adjustment in depressed patients seems significant as it may help prevent further prognosis of the diseases.

World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for biological treatment of unipolar depressive disorders, part 1: update 2013 on the acute and continuation treatment of unipolar depressive disorders

OBJECTIVES

This 2013 update of the practice guidelines for the biological treatment of unipolar depressive disorders was developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBP). The goal has been to systematically review all available evidence pertaining to the treatment of unipolar depressive disorders, and to produce a series of practice recommendations that are clinically and scientifically meaningful based on the available evidence. The guidelines are intended for use by all physicians seeing and treating patients with these conditions.

METHODS

The 2013 update was conducted by a systematic update literature search and appraisal. All recommendations were approved by the Guidelines Task Force.

RESULTS

This first part of the guidelines (Part 1) covers disease definition, classification, epidemiology, and course of unipolar depressive disorders, as well as the management of the acute and continuation phase treatment. It is primarily concerned with the biological treatment (including antidepressants, other psychopharmacological medications, electroconvulsive therapy, light therapy, adjunctive and novel therapeutic strategies) of adults.

CONCLUSIONS

To date, there is a variety of evidence-based antidepressant treatment options available. Nevertheless there is still a substantial proportion of patients not achieving full remission. In addition, somatic and psychiatric comorbidities and other special circumstances need to be more thoroughly investigated. Therefore, further high-quality informative randomized controlled trials are urgently needed.

Pharmacokinetic properties of once-daily oral low-dose mesylate salt of paroxetine (LDMP 7.5 mg) following single and multiple doses in healthy postmenopausal women

BACKGROUND

Low-dose mesylate salt of paroxetine (LDMP 7.5 mg) is being investigated for the treatment of vasomotor symptoms associated with menopause.

OBJECTIVE

This Phase I, open-label, single- and multiple-dose study evaluated the pharmacokinetic properties, safety and tolerability of LDMP in postmenopausal, nonsmoking women aged ≥40 years.

METHODS

After a 3-week screening period, subjects received LDMP 7.5-mg capsules as a single dose on day 1 and then as multiple doses (once daily for 14 days) on Days 6-19. Blood samples were collected predose and up to 120 hours postdose on day 1 (single-dose pharmacokinetic profile), at predose (after 12 doses) on day 18, and at predose and up to 24 hours postdose on day 19 (multiple-dose pharmacokinetic profile). Capsules were taken with 240 mL of water while subjects were fasted. Safety was evaluated throughout the study.

RESULTS

Twenty-four women (mean age, 56 years) completed the study. On day 1, median Tmax was ~6 hours, and mean t1/2 was 17.30 hours. Mean plasma concentrations attained predose on days 18 and 19 (days 13 and 14 of multiple dosing) and at 24 hours postdose (day 20) were similar, suggesting that steady state was achieved by day 13 of multiple dosing after 12 daily doses. Mean AUC0-24 h at steady state (day 14 of multiple dosing) was ~3-fold greater than AUC0-∞ on day 1, indicating nonlinear pharmacokinetics. Mean Cmax on day 14 of multiple dosing was ~5-fold greater than that attained on day 1, and the accumulation index (AUCday 19/AUCday 1) at steady state was 9.71. Fluctuation index (calculated as [(Cmax - Cmin)/Cavg ss] × 100) was 75.8%. Most subjects (23/24 [95.8%]) experienced at least 1 treatment-emergent adverse event (AE); however, most AEs (67 events in 22/24 subjects [91.7%]) were mild, and the remainder were moderate. Seventeen subjects experienced 33 AEs that were deemed possibly or probably related to LDMP. No serious AEs were reported, and no clinically meaningful changes in laboratory values, vital signs, or ECGs were observed.

CONCLUSIONS

On multiple dosing, LDMP exhibited nonlinear pharmacokinetics and was well tolerated in these healthy postmenopausal women; the extent of accumulation was consistent with data from the published literature.

Behavioral and neurobiological effects of deep brain stimulation in a mouse model of high anxiety- and depression-like behavior

Increasing evidence suggests that high-frequency deep brain stimulation of the nucleus accumbens (NAcb-DBS) may represent a novel therapeutic strategy for individuals suffering from treatment-resistant depression, although the underlying mechanisms of action remain largely unknown. In this study, using a unique mouse model of enhanced depression- and anxiety-like behavior (HAB), we investigated behavioral and neurobiological effects of NAcb-DBS. HAB mice either underwent chronic treatment with one of three different selective serotonin reuptake inhibitors (SSRIs) or received NAcb-DBS for 1 h per day for 7 consecutive days. Animals were tested in established paradigms revealing depression- and anxiety-related behaviors. The enhanced depression-like behavior of HAB mice was not influenced by chronic SSRI treatment. In contrast, repeated, but not single, NAcb-DBS induced robust antidepressant and anxiolytic responses in HAB animals, while these behaviors remained unaffected in normal depression/anxiety animals (NAB), suggesting a preferential effect of NAcb-DBS on pathophysiologically deranged systems. NAcb-DBS caused a modulation of challenge-induced activity in various stress- and depression-related brain regions, including an increase in c-Fos expression in the dentate gyrus of the hippocampus and enhanced hippocampal neurogenesis in HABs. Taken together, these findings show that the normalization of the pathophysiologically enhanced, SSRI-insensitive depression-like behavior by repeated NAcb-DBS was associated with the reversal of reported aberrant brain activity and impaired adult neurogenesis in HAB mice, indicating that NAcb-DBS affects neuronal activity as well as plasticity in a defined, mood-associated network. Thus, HAB mice may represent a clinically relevant model for elucidating the neurobiological correlates of NAcb-DBS.

Selective serotonin reuptake inhibitor antidepressant treatment discontinuation syndrome: a review of the clinical evidence and the possible mechanisms involved

Besides demonstrated efficacy, selective serotonin reuptake inhibitors (SSRIs) hold other advantages over earlier antidepressants such as greater tolerability and a wider range of clinical applications. However, there is a growing body of clinical evidence which suggests that SSRIs could, in some cases, be associated with a withdrawal reaction upon cessation of regular use. In addition to sensory and gastrointestinal-related symptoms, the somatic symptoms of the SSRI discontinuation syndrome include dizziness, lethargy, and sleep disturbances. Psychological symptoms have also been documented, usually developing within 1–7 days following SSRI discontinuation. The characteristics of the discontinuation syndrome have been linked to the half-life of a given SSRI, with a greater number of reports emerging from paroxetine compared to other SSRIs. However, many aspects of the neurobiology of the SSRI discontinuation syndrome (or SSRI withdrawal syndrome) remain unresolved. Following a comprehensive overview of the clinical evidence, we will discuss the underlying pathophysiology of the SSRI discontinuation syndrome and comment on the use of animal models to better understand this condition.

Psychiatric morbidity and other factors affecting treatment adherence in pulmonary tuberculosis patients

As the overall prevalence of TB remains high among certain population groups, there is growing awareness of psychiatric comorbidity, especially depression and its role in the outcome of the disease. The paper attempts a holistic approach to the effects of psychiatric comorbidity to the natural history of tuberculosis. In order to investigate factors associated with medication nonadherence among patients suffering from tuberculosis, with emphasis on psychopathology as a major barrier to treatment adherence, we performed a systematic review of the literature on epidemiological data and past medical reviews from an historical perspective, followed by theoretical considerations upon the relationship between psychiatric disorders and tuberculosis. Studies reporting high prevalence rates of psychiatric comorbidity, especially depression, as well as specific psychological reactions and disease perceptions and reviews indicating psychiatric complications as adverse effects of anti-TB medication were included. In sum, data concerning factors affecting medication nonadherence among TB patients suggested that better management of comorbid conditions, especially depression, could improve the adherence rates, serving as a framework for the effective control of tuberculosis, but further studies are necessary to identify the optimal way to address such issues among these patients.

Cyclic-AMP mediated regulation of ABCB mRNA expression in mussel haemocytes

Background

The multixenobiotic resistance system (MXR) allows aquatic organisms to cope with their habitat despite high pollution levels by over-expressing membrane and intracellular transporters, including the P-glycoprotein (Pgp). In mammals transcription of the ABCB1 gene encoding Pgp is under cAMP/PKA-mediated regulation; whether this is true in mollusks is not fully clarified.

Methodology/Principal Findings

cAMP/PKA regulation and ABCB mRNA expression were assessed in haemocytes from Mediterranean mussels (Mytilus galloprovincialis) exposed in vivo for 1 week to 0.3 ng/L fluoxetine (FX) alone or in combination with 0.3 ng/L propranolol (PROP). FX significantly decreased cAMP levels and PKA activity, and induced ABCB mRNA down-regulation. FX effects were abolished in the presence of PROP. In vitro experiments using haemocytes treated with physiological agonists (noradrenaline and serotonin) and pharmacological modulators (PROP, forskolin, dbcAMP, and H89) of the cAMP/PKA system were performed to obtain clear evidence about the involvement of the signaling pathway in the transcriptional regulation of ABCB. Serotonin (5-HT) decreased cAMP levels, PKA activity and ABCB mRNA expression but increased the mRNA levels for a putative 5-HT₁ receptor. Interestingly, 5-HT₁ was also over-expressed after in vivo exposures to FX. 5-HT effects were counteracted by PROP. Forskolin and dbcAMP increased PKA activity as well as ABCB mRNA expression; the latter effect was abolished in the presence of the PKA inhibitor H89.

Conclusions

This study provides the first direct evidence for the cAMP/PKA-mediated regulation of ABCB transcription in mussels.

Metabolic and toxicological considerations for obsessive-compulsive disorder drug therapy

INTRODUCTION

Obsessive-compulsive disorder (OCD) affects the daily life of the patients. Chronic nature of this disease and the need for long-term high-dose drug therapy for its maintenance increase the risk of metabolic and toxicological complications.

AREAS COVERED

In this concise article, the metabolic and toxicological aspects of major medication categories prescribed in OCD, such as serotonin-specific reuptake inhibitors, tricyclic antidepressant (clomipramine), serotonin-norepinephrine reuptake inhibitors, and atypical antipsychotics indicated in OCD (both Food and Drug Administration-approved and off-label) are discussed.

EXPERT OPINION

The most critical point in pharmacotherapy of OCD is the need for the high-dose and long-term use of drugs. In OCD, generally the higher doses of applicable drugs than those used in depression are required, often exceeding the recommended maximum dose. Moreover, such high doses should be given for at least 10 - 12 weeks to ensure the adequate treatment duration for the clinical effects to emerge. This long-term high-dose maintenance therapy increases the risk of drug toxicity and adverse effects. Physicians should take extra care in periodical assessment of signs and symptoms of metabolic and toxicological complications in patients. Subjective symptoms reported by patients should be carefully assessed and not attributed to obsessive nature of the patients.

[Compliance to therapy with Dapoxetine in patients affected by Premature Ejaculation]

INTRODUCTION

Premature ejaculation (PE) is a sexual dysfunction with high prevalence. According to some reports, it is present in about 20-30% of the male population. Since 2009 PE has been treated with a novel inhibitor of serotonin re-uptake, Dapoxetine, which has been reported to be specifically active for PE.

MATERIALS AND METHODS

59 patients have been selected among the patients affected by PE observed at the outpatient department of Urology and Andrology of the "Paolo Giaccone" University Policlinic Hospital of Palermo. Diagnosis was confirmed unequivocally in all patients, who were suitable for drug treatment and accepted to participate in the study. They were divided in 2 groups: one receiving Dapoxetine (41 patients), another (18 patients) receiving Citalopram. Patients were followed up by telephone at monthly intervals, in order to compare compliance, efficacy and side effects:

RESULTS

Compliance to treatment was obtained in 56% of patients treated with Dapoxetine and in 61% of those treated with Citalopram. In the Dapoxetine group side effects were reported in 14.6% versus 38.4% in the Citalopram group. Benefit from the treatment was reported in 82% and 69.2%, respectively.

Dapoxetine Has No Pharmacokinetic or Cognitive Interactions With Ethanol in Healthy Male Volunteers

Dapoxetine is being investigated for the treatment of premature ejaculation. This study evaluated the potential pharmacokinetic and cognitive interactions of dapoxetine 60 mg with ethanol 0.5 g/kg in a single-center, double-blind, randomized, placebo-controlled crossover study in healthy adult male participants (n = 24). Dapoxetine was rapidly absorbed and eliminated; peak concentrations were noted 1.47 hours after administration and decreased with an alpha half-life of 1.33 hours and a terminal half-life of 15.6 hours. Pharmacokinetic parameters (C(max), AUC(infinity), t((1/2)), and t(max)) of dapoxetine were not altered with concurrent ethanol consumption. Furthermore, coadministration of dapoxetine did not affect the pharmacokinetics of ethanol or potentiate the cognitive and subjective effects of ethanol.

Dynamics and persistence of CYP2D6 inhibition by paroxetine

WHAT IS KNOWN AND OBJECTIVE

Paroxetine is both a substrate and an inhibitor of CYP2D6. The objective of the presented study was to determine the persistence of CYP2D6 inhibition after short term (6 weeks) and long term (18·7 ± 10·6 weeks) paroxetine treatment.

METHODS

Two the studies consisted of 30 depressive/anxiety patients each. In the first study, patients were subdivided into three groups treated with paroxetine (A1), alprazolam (A2) and paroxetine + alprazolam (A3). After 6 weeks, all the patients (A1+A2+A3) were switched to alprazolam treatment; metabolic activity was evaluated at the beginning, after 6 weeks of paroxetine/alprazolam/alprazolam + paroxetine treatment (A1/A2/A3) and 4 weeks after the switch to alprazolam treatment (Week 0, 6, 10). In the second study patients on previous long term paroxetine treatment were subdivided into two groups treated with mirtazapine (B1) or paroxetine (B2); metabolic activity of CYP2D6 was evaluated at the beginning and after 6 weeks of therapy.

RESULTS AND DISCUSSION

Metabolic ratio of dextromethorphan to dextrorphan has normalized in all subjects after 4 weeks of paroxetine wash out in the first study. In the second study, 6 weeks after paroxetine discontinuation, restoration of metabolic activity of CYP2D6 was observed in only five of eight originally poor metabolizers.

WHAT IS NEW AND CONCLUSION

We conclude that a wash-out period of 4 weeks seems to be sufficient for CYP2D6 disinhibition after short-term paroxetine treatment (6 weeks). On the other hand, treatment with a CYP2D6 substrate less than 6 weeks after long-term paroxetine treatment (18·7 weeks on average) could result in elevated drug plasma levels and occasionally also in drug toxicity.

Serotonin syndrome: pills, thrills and shoulder aches

This case demonstrates an acute presentation of unwitnessed seizure causing typical injuries. Progress in hospital was complicated by worsening autonomic disturbance and agitation, typical for serotonin syndrome, suspected in light of recent selective serotonin reuptake inhibitor antidepressant initiation. Supportive care required treatment in the intensive care unit setting but full recovery ensued. This case not only reminds clinicians of the potential pitfalls in assessing postictal injured patients, but also that serotonin syndrome requires a high-index of diagnostic suspicion given the range of presenting features. Management ranges from simple withdrawal of the offending agent to specific therapies such as a cyproheptadine.

The effects of perinatal fluoxetine treatment on the circadian system of the adult mouse

RATIONAL

Depression is prevalent among women of childbearing age and is frequently treated with selective serotonin reuptake inhibitors (SSRIs). As some SSRIs, such as fluoxetine (Flx), can cross the placenta, it is possible that the neurodevelopment of the fetus may be affected, leading to altered behavior in adulthood.

OBJECTIVES

In this study, we examined the effects of perinatal Flx exposure on the subsequent expression of circadian rhythms in adult mice.

METHODS

Dams were treated with 25 mg/kg/day Flx in their drinking water from embryonic day 15 to postnatal day 12. Circadian organization of wheel running rhythms and phase shifts to photic and non-photic stimuli were assessed in the offspring starting at 6 weeks of age.

RESULTS

We found that perinatal Flx exposure led to larger light-induced phase advances (1.19 ± 0.51 vs. 0.55 ± 0.25 h), smaller phase advances to the serotonin agonist 8-OH-DPAT during the mid-subjective day (0.44 ± 0.15 vs. 0.70 ± 0.17 h), and a shorter free-running period in constant darkness (23.47 ± 0.13 vs. 23.64 ± 0.13 h).

CONCLUSIONS

These results suggest that perinatal exposure to SSRIs may have consequences for the functioning of the circadian system later in life.

Consumption and occurrence of pharmaceutical and personal care products in the aquatic environment in Spain

The occurrence of sixty pharmaceutically active compounds (PhACs), twenty metabolites and eight personal care products (PCPs) in the aquatic environment in Spain and their predicted environmental concentrations (PECs) were calculated and compared with measured environmental concentrations (MECs) obtained from relevant published research. The occurrence in the aquatic environment was calculated through a mass balance approach considering the following: the number of pharmaceutical prescriptions issued, the amount of pharmaceutical discharged without consumption, consumption, self-medication, pharmacokinetics, treatment in wastewater facilities and discharged to aquatic environment. The estimation of consumption of active compounds of pharmaceuticals was conducted by at least one of the following methodologies: number of commercial packages sold, data for the number of defined daily dose per 1000 inhabitants per day (DHD), and pattern of treatment. Comparison of these methodologies for some compounds showed similar estimated consumption ranges. The highest pharmaceutical occurrence in the aquatic environment was for acetaminophen glucuronide, Galaxolide®, Iso-E-super®, acetaminophen, valsartan, amoxicillin, 2-hydroxy-ibuprofen, iopromide, omeprazole, carbamazepine 10, 11-epoxide, iopamidol, salicylic β-d-O-glucuronide acid, Tonalide®, acetylsalicylic acid (ASA), clarithromycin and iohexol, with releases between 5 and 600 ty(-1). The relation of PEC/MEC was calculated for 58% of the compounds under study, and 64.7% of them had PEC/MEC ratios between 0.5 and 2. PEC values were mostly overestimated (57.4%). The predicted concentrations for pharmaceutical and personal care products (PPCPs) that had a high occurrence in the aquatic environment were very close to the measured concentrations. This research provides information that had not been calculated and analyzed previously, at least for Spain. Estimation of the PECs for pharmaceutical, personal care products and metabolites is a useful tool for identifying compounds that should be considered for environmental concern, and such estimations could be used to improve environmental risk assessment studies.