Pharmacokinetics of selective serotonin reuptake inhibitors: clinical relevance

Long-term exposure to sediment-associated antidepressants impacts life-history traits in an estuarine deposit-feeding worm

Hydrophobic pollutants, such as the antidepressant sertraline (SER), tend to sorb to particles in the water column and subsequently accumulate in the sediment. Long-term exposure to these pollutants may significantly affect sediment-dwelling organisms´ fitness and behavior. To address this knowledge gap, we investigated the impact of chronic exposure to a range of environmentally relevant and higher concentrations of sediment-associated SER on the deposit-feeding polychaete Capitella teleta. Since certain antidepressants can function as neurotoxic chemicals and endocrine disruptors on non-target species, we examined feeding rate and burrowing behavior in adult worms after 23 days of exposure (Experiment 1), and key life-history traits in juvenile worms during 35 days of exposure (Experiment 2) to sediment-associated SER (0.33 - 100 µg/g dw sediment). SER did not affect survival but reduced maturation and time to first reproduction: 37%, 50%, and 29% of the worms exposed respectively to SER 0.33, 3.3 and 33 µg/g reached maturation on day 21, whereas worms in the other treatments did not mature (0%; control) or reached a lower maturation degree (6%; 100 µg/g). Although not statistically significant, growth, feeding, and burrowing manifested non-monotonic trends: at environmentally relevant SER concentrations adults increased feeding and extended time to fully burrow into the sediment, and juveniles increased growth, whereas high concentrations had an inhibitory or no effect. Reproductive endpoints appeared most sensitive to chronic SER exposure. Even at low environmental concentrations, antidepressants can cause sublethal effects in non-target species, potentially affecting population dynamics and ecosystem functioning. Further research is key to fully understanding the ecological impact of hydrophobic chemicals in natural environments.

Effects of selective serotonin reuptake inhibitors on endocrine system (Review)

Selective serotonin reuptake inhibitors (SSRIs) are typically prescribed for treating major depressive disorder (MDD) due to their high efficacy. These drugs function by inhibiting the reuptake of serotonin [also termed 5-hydroxytryptamine (5-HT)], which raises the levels of 5-HT in the synaptic cleft, leading to prolonged activation of postsynaptic 5-HT receptors. Despite the therapeutic benefits of SSRIs, this mechanism of action also disturbs the neuroendocrine response. Hypothalamic-pituitary-adrenal (HPA) axis activity is strongly linked to both MDD and the response to antidepressants, owing to the intricate interplay within the serotonergic system, which regulates feeding, water intake, sexual drive, reproduction and circadian rhythms. The aim of the present review was to provide up-to-date evidence for the proposed effects of SSRIs, such as fluoxetine, citalopram, escitalopram, paroxetine, sertraline and fluvoxamine, on the endocrine system. For this purpose, the literature related to the effects of SSRIs on the endocrine system was searched using the PubMed database. According to the available literature, SSRIs may have an adverse effect on glucose metabolism, sexual function and fertility by dysregulating the function of the HPA axis, pancreas and gonads. Therefore, considering that SSRIs are often prescribed for extended periods, it is crucial to monitor the patient closely with particular attention to the function of the endocrine system.

Case Report: Life-Threatening Fluoxetine-Linked Postoperative Bleeding Informed by Pharmacogenetic Evaluation

BACKGROUND

Selective serotonin reuptake inhibitors (SSRI) are commonly used for the treatment of depression and anxiety. Inhibition of serotonin reuptake in platelets increases bleeding risk in patients taking SSRIs.

CASE

Here, we present the case of a 52-year-old patient who developed severe postsurgical bleeding requiring blood transfusion following panniculectomy.

CONCLUSION

SSRI-induced bleeding is dose-related and strongly influenced by individual variations in drug metabolizing enzymes and transporters. Supplementary file1 (MP4 8441 KB).

Antidepressant Effects of Essential Oils: A Review of the Past Decade (2012-2022) and Molecular Docking Study of Their Major Chemical Components

Depression is a mental disorder that affects more than 300 million people worldwide. The medications available for treatment take a long time to exhibit therapeutic results and present several side effects. Furthermore, there is a decrease in the quality of life of people suffering from this affliction. Essential oils are traditionally used to relieve the symptoms of depression due to the properties of the constituents of these oils to cross the blood-brain barrier acting on depression-related biological receptors associated with reduced toxicity and side effects. In addition, compared to traditional drugs, they have several administration forms. This review provides a comprehensive assessment of studies on plants whose essential oil has exhibit antidepressant activity in the past decade and the mechanism of action of the major components and models tested. An additional in silico study was conducted with the frequent compounds in the composition of these essential oils, providing a molecular approach to the mechanism of action that has been reported in the past decade. This review is valuable for the development of potential antidepressant medications in addition to providing a molecular approach to the antidepressant mechanism of action of the major volatile compounds that have been reported in the past decade.

The selective serotonin reuptake inhibitor fluoxetine has direct effects on beta cells, promoting insulin secretion and increasing beta-cell mass

AIM

This study investigated whether therapeutically relevant concentrations of fluoxetine, which have been shown to reduce plasma glucose and glycated haemoglobin independent of changes in food intake and body weight, regulate beta-cell function and improve glucose homeostasis.

METHODS

Cell viability, insulin secretion, beta-cell proliferation and apoptosis were assessed after exposure of MIN6 beta cells or isolated mouse and human islets to 0.1, 1 or 10 μmol/L fluoxetine. The effect of fluoxetine (10 mg/kg body weight) administration on glucose homeostasis and islet function was also examined in ob/ob mice.

RESULTS

Exposure of MIN6 cells and mouse islets to 0.1 and 1 μmol/L fluoxetine for 72 hours did not compromise cell viability but 10 μmol/L fluoxetine significantly increased Trypan blue uptake. The dose of 1 μmol/L fluoxetine significantly increased beta-cell proliferation and protected islet cells from cytokine-induced apoptosis. In addition, 1 μmol/L fluoxetine induced rapid and reversible potentiation of glucose-stimulated insulin secretion from islets isolated from mice, and from lean and obese human donors. Finally, intraperitoneal administration of fluoxetine to ob/ob mice over 14 days improved glucose tolerance and resulted in significant increases in beta-cell proliferation and enhanced insulin secretory capacity.

CONCLUSIONS

These data are consistent with a role for fluoxetine in regulating glucose homeostasis through direct effects on beta cells. Fluoxetine thus demonstrates promise as a preferential antidepressant for patients with concomitant occurrence of depression and diabetes.

Fluoksetinin sıçan torasik aort düz kasındaki vazoaktif etkileri

Amaç: Literatürdeki çalışmaların çoğu fluoksetinin kardiyo/serebrovasküler sistemler üzerindeki etkilerine odaklanmış olsa da, vazomotor etkisi hakkında bilinenler hala sınırlıdır. Bu çalışma, fluoksetinin sıçan torasik aort halkalarında düz kas üzerindeki vazoaktif etkilerini deneysel bir düzende araştırmak için planlanmıştır. Gereç ve Yöntem: 24 adet yetişkin Wistar albino rat iki gruba ayrıldı. Grup1-Endotel sağlam grup, Grup2-Endotel hasarlı grup. Servikal dislokasyon sonrası torasik aort izole edildi. Aort halkaları hemen Krebs solüsyonu içeren organ banyosu haznelerine yerleştirildi. Aort halkalarının izometrik gerimindeki değişiklikler kaydedildi. Fenilefrin 10-6M uygulandı ve kasılmalar kaydedildi. Daha sonra Grup 1'e kümülatif dozlarda (0.01, 0.1, 1, 2 mM) fluoksetin uygulandı. Grup 2'de endotel hasarı oluşturuldu. Asetilkolin 10-6M ile endotel hasarı kontrol edildikten sonra, halkalar bir saat yıkanarak ikinci doz fenilefrin hazneye eklendi. Ardından Grup 2'ye kümülatif olarak fluoksetin uygulanıp kasılmalar kaydedildi. Bulgular: Fluoksetinin doza bağımlı ana vazodilatör etkisi anlamlı olarak farklıyken [F (5.110) =72.740, p

Simultaneous determination of four serotonin selective reuptake inhibitors by an UPLC MS-MS method with clinical application in therapeutic drug monitoring

An analytical method of ultra-high performance liquid chromatography coupled to tandem mass spectrometry detection was developed and validated for the simultaneous quantification in plasma of four selective serotonin reuptake inhibitor antidepressants: sertraline, escitalopram, paroxetine, fluoxetine, and its metabolite norfluoxetine. A simple protein precipitation was performed with acetonitrile containing 100 ng/mL of indomethacin, which was used as internal standard. Chromatographic separation was carried out on an Acquity BEH C18 column with isocratic elution of the mobile phase consisting of 5 mmol/L ammonium acetate with 0.1% formic acid (A) and acetonitrile (B) at a 60:40 proportion, respectively. The flow rate was 0.4 mL/min with a run time of 5 min. A positive electrospray ionization source was used for detection. The method was linear in a range of 5-800 ng/mL, with determination coefficients greater than 0.991. The accuracy ranged from 91% to 112% for intra-assay and from 89% to 112% for inter-assay. The variation coefficients ranged from 3.1% to 14.88% for intra-assay and from 3.60% to 14.74% for inter-assay precision. The method was successfully applied for the analysis of 73 samples from patients under treatment with these antidepressants; 36.9% of the samples had concentrations outside therapeutic ranges. This method can be applied for routine analysis in clinical practice, simplifying sample processing, reducing analysis time and consequently the costs associated with it.

Selective Serotonin Reuptake Inhibitors and Adverse Effects: A Narrative Review

Depression is the most prevalent psychiatric disorder in the world, affecting 4.4% of the global population. Despite an array of treatment modalities, depressive disorders remain difficult to manage due to many factors. Beginning with the introduction of fluoxetine to the United States in 1988, selective serotonin reuptake inhibitors (SSRIs) quickly became a mainstay of treatment for a variety of psychiatric disorders. The primary mechanism of action of SSRIs is to inhibit presynaptic reuptake of serotonin at the serotonin transporter, subsequently increasing serotonin at the postsynaptic membrane in the serotonergic synapse. The six major SSRIs that are marketed in the USA today, fluoxetine, citalopram, escitalopram, paroxetine, sertraline, and fluvoxamine, are a group of structurally unrelated molecules that share a similar mechanism of action. While their primary mechanism of action is similar, each SSRI has unique pharmacokinetics, pharmacodynamics, and side effect profile. One of the more controversial adverse effects of SSRIs is the black box warning for increased risk of suicidality in children and young adults aged 18–24. There is a lack of understanding of the complexities and interactions between SSRIs in the developing brain of a young person with depression. Adults, who do not have certain risk factors, which could be confounding factors, do not seem to carry this increased risk of suicidality. Ultimately, when prescribing SSRIs to any patient, a risk–benefit analysis must factor in the potential treatment effects, adverse effects, and dangers of the illness to be treated. The aim of this review is to educate clinicians on potential adverse effects of SSRIs.

Sertraline and Citalopram Actions on Gut Barrier Function

INTRODUCTION

Disruption of intestinal barrier is a key component to various diseases. Whether barrier dysfunction is the cause or effect in these situations is still unknown, although it is believed that translocation of luminal content may initiate gastrointestinal or systemic inflammatory disorders. Since trauma- or infection-driven epithelial permeability depends on Toll-like receptor (TLR) activity, inhibition of TLR signaling has been proposed as a strategy to protect intestinal barrier integrity after infection or other pathological conditions. Recently, selective serotonin recapture inhibitors including sertraline and citalopram were shown to inhibit TLR-3 activity, but the direct effects of these antidepressant drugs on the gut mucosa barrier remain largely unexplored.

MATERIALS AND METHODS

To investigate this, two approaches were used: first, ex vivo studies were performed to evaluate sertraline and citalopram-driven changes in permeability in isolated intestinal tissue. Second, both compounds were tested for their preventive effects in a rat model of disrupted gut barrier, induced by a low protein (LP) diet.

RESULTS

Only sertraline was able to increase transepithelial electrical resistance in the rat colon both when used in an ex vivo (0.8 μg/mL, 180 min) or in vivo (30 mg/kg p.o., 20 days) fashion. However, citalopram (20 mg/kg p.o., 20 days), but not sertraline, prevented the increase in phospho-IRF3 protein, a marker of TLR-3 activation, in LP-rat ileum. Neither antidepressant affected locomotion, anxiety-like behaviours or stress-induced defecation.

CONCLUSION

Our data provides evidence to support the investigation of sertraline as therapeutic strategy to protect intestinal barrier function under life-threatening situations or chronic conditions associated with gut epithelial disruption.

Precision dosing-based optimisation of paroxetine during pregnancy for poor and ultrarapid CYP2D6 metabolisers: a virtual clinical trial pharmacokinetics study

Objective

Paroxetine has been demonstrated to undergo gestation-related reductions in plasma concentrations, to an extent which is dictated by the polymorphic state of CYP 2D6. However, knowledge of appropriate dose titrations is lacking.

Methods

A pharmacokinetic modelling approach was applied to examine gestational changes in trough plasma concentrations for CYP 2D6 phenotypes, followed by necessary dose adjustment strategies to maintain paroxetine levels within a therapeutic range of 20–60 ng/ml.

Key findings

A decrease in trough plasma concentrations was simulated throughout gestation for all phenotypes. A significant number of ultrarapid (UM) phenotype subjects possessed trough levels below 20 ng/ml (73–76%) compared to extensive metabolisers (EM) (51–53%).

Conclusions

For all phenotypes studied, there was a requirement for daily doses in excess of the standard 20 mg dose throughout gestation. For EM, a dose of 30 mg daily in trimester 1 followed by 40 mg daily in trimesters 2 and 3 is suggested to be optimal. For poor metabolisers (PM), a 20 mg daily dose in trimester 1 followed by 30 mg daily in trimesters 2 and 3 is suggested to be optimal. For UM, a 40 mg daily dose throughout gestation is suggested to be optimal.

A Thorough QT Study to Evaluate the Effects of a Supratherapeutic Dose of Sertraline on Cardiac Repolarization in Healthy Subjects

The effect of steady-state supratherapeutic sertraline (Zoloft) on QT interval was assessed in a single-center, randomized, 3-way crossover, double-blind, placebo- and moxifloxacin-controlled thorough QT study. Healthy adults received sertraline 400 mg/day, moxifloxacin 400 mg, and placebo, with a washout period (≥14 days) between treatments. A 12-lead electrocardiogram was recorded in triplicate before dosing and at selected time points up to 72 hours after dosing. Analysis of covariance using a mixed-effect model with sequence, period, treatment, time, and treatment-by-time interaction as fixed effects; subject within sequence as a random effect; and baseline QT corrected for heart rate using Fridericia formula (QTcF) as a covariate was conducted. A 90% confidence interval for the least squares (LS) mean difference in QTcF between active treatment and placebo was computed for each postdose time point. Exposure-response was assessed using linear mixed-effect modeling. Fifty-four subjects were enrolled. Over 24 hours after dosing, the LS mean difference in QTcF for sertraline versus placebo ranged from 5.597 milliseconds to 9.651 milliseconds. The upper bound of the 90% confidence interval for the LS mean difference exceeded a predefined 10-millisecond significance threshold at the 4-hour postdose time point only (LS mean, 9.651 milliseconds [90% confidence interval, 7.635-11.666]). In the exposure-response analysis, QTcF values increased significantly with increasing sertraline concentration (slope = 0.036 milliseconds/ng/mL; P < .0001). Predicted change from baseline in QTcF at therapeutic maximum plasma sertraline concentration was 3.57 milliseconds. This thorough QTc study demonstrated a positive signal for QTc prolongation for sertraline at the steady-state 400-mg/day dose.

Effects of Binary Mixtures and Transpiration on Accumulation of Pharmaceuticals by Spinach

Many pharmaceuticals are present in reclaimed wastewater and effluent-dominated water bodies used to irrigate edible crops. Previous research has shown that plants irrigated with reclaimed wastewater can accumulate pharmaceuticals. However, plant-driven processes that contribute to differences in accumulation among compounds are not well understood. Here, we tested the effects of exposure to mixtures on spinach accumulation and metabolism of four psychoactive pharmaceuticals found in reclaimed wastewater: carbamazepine, fluoxetine, amitriptyline, and lamotrigine. Coexposure of plants to carbamazepine and fluoxetine or amitriptyline decreased accumulation of the toxic carbamazepine metabolite 10,11-epoxycarbamazepine. Furthermore, we tested a simple transpiration-based accumulation model and found that transpiration is a strong predictor for accumulation of the studied compounds. Amitriptyline accumulated to a larger extent than predicted from transpiration alone, and we suggest the possibility that a transporter protein may be involved in its uptake. Our findings highlight the need to consider plant physiology and mixture effects in studying accumulation of polar and ionizable organic contaminants and their metabolites.

Therapeutic Drug Monitoring of Antidepressants

For a number of antidepressants in current clinical use, concentrations in serum or plasma are a more reliable index of target drug concentrations than is dosage. For such drugs, therapeutic drug monitoring (TDM) may be a useful clinical guide for the purpose of maximizing the likelihood of favorable therapeutic outcome while minimizing the probability of clinical ineffectiveness or adverse side effects. TDM is of greatest benefit when a therapeutic range of serum concentrations has been well established. Even if such a range is not definitively determined, TDM can be of help in situations in which patients are refractory to therapy despite adequate or high dosages, when adverse events supervene even with low doses, or when noncompliance with the intended dosage plan is suspected. Serum antidepressant concentrations from TDM should be interpreted in the full context of the patient's demographic characteristics and clinical status, along with an understanding of the pharmacokinetics of the medication being taken, the timing of the sample in relation to the dosage regimen, and the specific laboratory assay procedure. TDM measurements may be costly, and the potential benefits of the information need to be weighed against the cost to the patient or to the health care system.

High-throughput liquid chromatography tandem mass spectrometry method for simultaneous determination of fampridine, paroxetine, and quinidine in rat plasma: Application to in vivo perfusion study

A selective and high-throughput liquid chromatography–mass spectrometry method has been developed and validated for the simultaneous quantification of paroxetine, fampridine, and quinidine in rat plasma using imipramine as an internal standard. Following protein precipitation extraction, the analytes and internal standard were run on X Bridge C18 column (150 mm × 4.6 mm, 5 μm) using a gradient mobile phase consisting of 5mM ammonium formate in water (pH 9.0) and acetonitrile in a flow gradience program. The precursor and product ions of the drugs were monitored on a triple quadrupole instrument operated in the positive ionization mode. The method was validated over a concentration range of 0.1–100 ng/mL for all the three analytes, with relative recoveries ranging from 69% to 82%. The intra- and interbatch precision (percent coefficient of variation) across four validation runs were less than 13.4%. The accuracy determined at four quality control (QC) levels (lower limit of quantitation, low QC, medium QC, and high QC) was within ±6.5% of coefficient of variation values. The method proved highly reproducible and sensitive, and was successfully applied in a pharmacokinetic study after single-dose oral administration to rats and also in perfusion study sample analysis.

Sub-chronic exposure to fluoxetine in juvenile oysters (Crassostrea gigas): uptake and biological effects

The bioconcentration potential of fluoxetine (FLX) and its biological effects were investigated in juvenile Pacific oyster exposed for 28 days to environmentally relevant concentrations of FLX (1 ng L(-1), 100 ng L(-1) and up to 10 μg L(-1)). FLX bioaccumulated in oyster flesh resulting in 28-day bioconcentration factors greater than 2,000 and 10,000 by referring to wet and dry weights, respectively. Nevertheless, FLX did not induce oyster mortality, delayed gametogenesis, or lead to adverse histopathological alterations. At the two highest concentrations, despite non-optimal trophic conditions, FLX stimulated shell growth but only in a transient manner, suggesting a role of serotonin in the regulation of feeding and metabolism in bivalves. Those high concentrations seemed to drive bell-shaped responses of catalase and glutathione S-transferase activities throughout the exposure period, which may indicate the activation of antioxidant enzyme synthesis and then an enhanced catabolic rate or direct inhibition of those enzymes. However, no clear oxidative stress was detected because no strong differences in thiobarbituric acid-reactive substance (TBARS) content (i.e. lipid peroxidation) were observed between oyster groups, suggesting that cellular defence mechanisms were effective. These results demonstrate the importance of considering additional biomarkers of oxidative stress to obtain a comprehensive overview of the FLX-induced changes in marine bivalves exposed under realistic conditions. Considering the battery of biomarkers used, FLX appears to induce little or no effects on oyster physiology even at a concentration of 10 μg L(-1). These results do not confirm the lowest observed effect concentration (LOEC) values reported by some authors in other mollusc species.

Dapoxetine and the treatment of premature ejaculation

Background

Premature ejaculation (PE) is the most common male sexual complaint. Off-label oral selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for the treatment of PE. Dapoxetine is a short-acting SSRI specifically designed for on-demand use. The objective of this communication is to summarize the clinical and physiological evidence regarding the role of the serotonergic pathway and specifically dapoxetine in the treatment of PE.

Methods

A PubMed search was conducted on articles reporting data on dapoxetine for the treatment of PE. Articles describing the pathophysiology and treatment options for PE were additionally included for review.

Results

The etiology of PE is multi-factorial in nature. There are many treatment options for PE such as psychological/behavioral therapy, topical anesthetic agents, phosphodiesterase type 5 (PDE-5) inhibitors, and tramadol hydrochloride. SSRIs play a major role in PE treatment. Animal and clinical studies in addition to its pharmacokinetic document dapoxetine’s clinical efficacy and safety for on-demand treatment of PE.

Conclusions

Dapoxetine demonstrates clinical efficacy and a favorable side effect profile. Dapoxetine is currently the oral drug of choice for on-demand treatment of PE.

Pharmacokinetics of antidepressants in patients with hepatic impairment

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

Long-term outcomes of developmental exposure to fluoxetine: a review of the animal literature

During and following pregnancy, women are at high risk of experiencing depression, for which fluoxetine (FLX; brand names Prozac, Sarafem, Rapiflux) is the most commonly prescribed treatment. An estimated 1.4-2.1% of pregnant women use this medication, which inhibits the reuptake of serotonin and thereby increases serotonergic activity at the synapse. Serotonin acts as a cue guiding numerous neurodevelopmental processes, and changes in the concentration of serotonin can disrupt normal in utero brain development and organization in humans and other animals, thus providing a mechanism by which maternal intake of FLX might alter neural development and ultimately behaviour. Despite this possibility, long-term alterations of behaviour and the brain have not been well studied in individuals exposed to FLX during pregnancy or soon after birth, perhaps because conducting such studies beyond infancy presents significant challenges. To remedy this problem, many researchers have turned to modelling the effects of developmental FLX exposure in non-human animals, primarily rodents. The body of literature on this topic has expanded considerably over the past several years, yet a comprehensive review is lacking. In order to fill this gap, we have summarized the findings of those studies describing the long-term behavioural and neurophysiological effects of FLX exposure in non-human animals in early development. We also discuss methodological considerations and common shortcomings of research in this area. The precise nature of the long-term effects of developmental FLX exposure remains difficult to specify, as these effects appear to be highly variable and dependent on numerous factors. Overall, however, it is clear that early FLX exposure in non-human animals can alter the development of the brain in ways that are relevant to behaviour in adulthood, decreasing exploration and social interaction, and in some cases altering anxiety- and depression-like behaviours..

An exploratory investigation of various modes of action and potential adverse outcomes of fluoxetine in marine mussels

The present study investigated possible adverse outcome pathways (AOPs) of the antidepressant fluoxetine (FX) in the marine mussel Mytilus galloprovincialis. An evaluation of molecular endpoints involved in modes of action (MOAs) of FX and biomarkers for sub-lethal toxicity were explored in mussels after a 7-day administration of nominal FX concentrations encompassing a range of environmentally relevant values (0.03-300ng/L). FX bioaccumulated in mussel tissues after treatment with 30 and 300ng/L FX, resulting in bioconcentration factor (BCF) values ranging from 200 to 800, which were higher than expected based solely on hydrophobic partitioning models. Because FX acts as a selective serotonin (5-HT) re-uptake inhibitor increasing serotonergic neurotransmission at mammalian synapses, cell signaling alterations triggered by 5-HT receptor occupations were assessed. cAMP levels and PKA activities were decreased in digestive gland and mantle/gonads of FX-treated mussels, consistent with an increased occupation of 5-HT1 receptors negatively coupled to the cAMP/PKA pathway. mRNA levels of a ABCB gene encoding the P-glycoprotein were also significantly down-regulated. This membrane transporter acts in detoxification towards xenobiotics and in altering pharmacokinetics of antidepressants; moreover, it is under a cAMP/PKA transcriptional regulation in mussels. Potential stress effects of FX were investigated using a battery of biomarkers for mussel health status that included lysosomal parameters, antioxidant enzyme activities, lipid peroxidation, and acetylcholinesterase activity. FX reduced the health status of mussels and induced lysosomal alterations, as suggested by reduction of lysosomal membrane stability in haemocytes and by lysosomal accumulation of neutral lipids in digestive gland. No clear antioxidant responses to FX were detected in digestive gland, while gills displayed significant increases of catalase and glutathione-s-transferase activities and a significant decrease of acetylcholinesterase activity. Though AOPs associated with mammalian therapeutic MOAs remain important during assessments of pharmaceutical hazards in the environment, this study highlights the importance of considering additional MOAs and AOPs for FX, particularly in marine mussels.

Ethnic differences in antidepressant response: a prospective multi-site clinical trial

BACKGROUND

Although depression is a highly prevalent condition that occurs in all ethnic groups, the influence of ethnicity on treatment response still remains unclear.

METHODS

A prospective 8-week, open-label clinical trial comparing the efficacy and side effects of citalopram (CIT) with dose escalation (20-60 mg/day) was performed in African-Americans and Caucasians with nonpsychotic major depression. The intent-to-treat sample consisted of 301 participants (169 African-Americans and 132 Caucasians).

RESULTS

Although African-Americans were more socially disadvantaged and had a more severe depression, outcomes between the groups were similar. Remission rates were approximately 50% in both groups and about 2/3 of participants met response criteria. Retention was greater than 75% in both groups, with no differences in dropout rate. There were no differences in the number of completers, number of visits made, final dose of CIT, or in side effect profiles.

CONCLUSIONS

These results confirm the growing body of evidence, including recent studies using measurement-based care, that patients from minority groups have outcomes that are similar to those of Caucasians. The provision of measurement-based care and encouragement of patient participation can reduce ethnic differences in response to treatment for depression.

Photosensitivity associated with selective serotonin reuptake inhibitors

Selective serotonin reuptake inhibitors (SSRIs) are a widely prescribed group of antidepressants. We report three cases of photosensitivity induced by fluvoxamine and paroxetine. These photoallergic reactions suggest cross-reactivity between different molecules. Methylation metabolism could explain common photosensitization. Although these drugs are widely prescribed, such photosensitization is rare. Nevertheless, we consider that clinicians and patients should be aware of the risk of photosensitization and these drugs should be stopped before phototherapy or prolonged sun exposure.

Uptake and depuration of the anti-depressant fluoxetine by the Japanese medaka (Oryzias latipes)

The selective serotonin reuptake inhibitor (SSRI) class of anti-depressants is among the most widely prescribed groups of pharmaceuticals. Consequently, aquatic ecosystems impacted by municipal wastewater discharges are predicted to receive substantial annual loadings of these compounds. Although SSRIs have been detected in fish tissues, little is known of their uptake and depuration in freshwater fish species. In this study, Japanese medaka (Oryzias latipes) were exposed to fluoxetine at a nominal concentration of 0.64 microg L(-1) for 7d and subsequently allowed to depurate in clean water over a 21d period. Fluoxetine uptake by medaka was observed within the first 5h of exposure and the biologically active metabolite, norfluoxetine, was also detected in medaka tissues during this timeframe. A maximum fluoxetine concentration was measured in medaka by the third day of the uptake phase, yielding an uptake rate constant (k(1)) of 5.9+/-0.5 (d(-1)). During the depuration phase of the experiment, a half life of 9.4+/-1.1d was determined for fluoxetine. Using these data, bioconcentration factor (BCF) values of 74 and 80 were estimated for fluoxetine and a pseudo-BCF (the ratio of the concentration of norfluoxetine in medaka and the aqueous fluoxetine concentration) of 117 was calculated for norfluoxetine. These results indicate longer persistence and greater potential for the bioaccumulation of fluoxetine and norfluoxetine in fish tissues than would be predicted from prior half life estimates derived using mammalian species.

Citalopram Improves Dexterity in Chronic Stroke Patients

Background. A majority of stroke patients have persisting motor deficits despite ongoing physiotherapy. Therefore, additional treatment options are desirable. Objective. We investigated if the serotonin reuptake inhibitor, citalopram, would improve motor functions in chronic stroke patients. Methods. In all, 8 patients >6 months after their stroke participated in a double-blind, placebo-controlled, single-dose crossover experiment. The order (first drug then placebo or vice versa) was randomized. Sessions were separated by at least 2 weeks. Motor function was assessed by nine-hole peg test, and measurements of hand grip-strength before drug intake, 2 hours after drug intake, and after 1 hour of training aimed at improving the function of the paretic hand. Results. Compared with placebo, citalopram intake significantly improved performance of the nine-hole peg test for the paretic hand but not for the unaffected hand. Hand grip-strength remained unchanged. Conclusions. A single dose of citalopram can enhance dexterity in chronic stroke patients. This pilot study justifies a test of efficacy of citalopram in a larger group of stroke patients.

Pharmacokinetics of Fluoxetine in Elderly Men and Women

Fluoxetine is widely prescribed as an antidepressant for geriatric patients. Despite a large scientific literature describing its efficacy and safety, there are few published data describing the pharmacokinetics of fluoxetine in the elderly. Given the common practice of polypharmacy in this population, additional pharmacokinetic information in elderly men and women is needed so that physicians can better assess potential drug-drug interactions. Twenty-five subjects, men and women between ages 65 and 83, received 20 mg of fluoxetine for 1 week followed by 40 mg for 5 weeks. Serum fluoxetine levels were measured during the period of drug administration and for 8 weeks after. The plasma concentration of fluoxetine and norfluoxetine in our subjects was higher than previously reported in the literature. Elderly women had a significantly higher serum level of norfluoxetine than men. The terminal half-life of norfluoxetine was longer in patients over age 75; elderly women had a significantly slower rate of norfluoxetine elimination than similarly aged men.

Time course of the effects of the serotonin-selective reuptake inhibitor sertraline on central and peripheral serotonin neurochemistry in the rhesus monkey

RATIONALE

Fundamental questions remain regarding the actions of the selective serotonin reuptake inhibitors (SSRIs).

OBJECTIVES

To examine the time course of central and peripheral neurochemical effects of sertraline (SER) in non-human primates.

METHODS

SER (20 mg/kg, p.o.) or placebo were administered daily for 4 weeks to two groups of six young adult male rhesus monkeys. Both groups received placebo during a 3-week baseline lead-in period and for 6 weeks after discontinuation. Blood and cisternal cerebrospinal fluid (cCSF) samples were obtained on days -21, -14, -7, 0, +3, +7, +14, +21, +28, +35 and +70.

RESULTS

In animals receiving SER, mean (+/-SD) levels of cCSF serotonin (5-HT) increased from 38.6+/-9.0 pg/ml at baseline to 128+/-46.4 pg/ml during treatment (paired t=4.17, P=0.014). Concentrations of cCSF 5-HT were 290% of baseline on day 0 (+3 h), ranged from 260% to 436% of baseline during treatment, and returned to baseline 7 days after discontinuation. Levels of cCSF 5-hydroxyindoleacetic acid declined to 51+/-2.0% of baseline by day +3 and remained at similarly reduced levels during treatment. Plasma drug levels and decrements in platelet 5-HT were similar to those seen in patients.

CONCLUSIONS

SER rapidly and substantially increases cCSF levels of 5-HT in primates, the extent of elevation is relatively constant during prolonged administration, and values return to baseline shortly after discontinuation. The results suggest that response latency for SSRIs in depression is not due to gradually increasing brain extracellular fluid 5-HT levels and tend not to support theories that posit SSRI response latency as being due to autoreceptor desensitization, transporter downregulation, or drug accumulation.

Paroxetine: a review of its pharmacology, pharmacokinetics and utility in the treatment of a variety of psychiatric disorders

Paroxetine is a selective serotonin re-uptake inhibitor (SSRI). In vitro studies show that it is able to produce a concentration-dependent competitive inhibition of serotonin uptake into brain synaptosomes. This effect can also be demonstrated following in vivo administration of the compound to animals. Paroxetine is almost completely absorbed following oral administration. However, the drug undergoes extensive first pass metabolism. As a result, less than 50% of a single dose of paroxetine reaches the general circulation. Paroxetine is primarily metabolised by the cytochrome P4502D6 isoenzyme. The compound has also been shown to inhibit the activity of this enzyme. As a result, plasma levels of compounds metabolised by the cytochrome P4502D6 isoenzyme can be increased in patients given paroxetine. Paroxetine has been extensively evaluated in clinical studies in depressed patients. The compound shows efficacy superior to placebo, and similar to that obtained with standard tricyclic or tetracyclic agents. Paroxetine also appears to be as efficacious as other SSRIs. The efficacy seen in short-term studies with paroxetine in the treatment of depression is maintained when the drug is given chronically. More recently, paroxetine has been shown to be efficacious in the treatment of panic disorder, obsessive-compulsive disorder, and social anxiety disorder. Nausea, headache and somnolence are the most common adverse events reported by patients given paroxetine. As with other selective serotonin re-uptake inhibitors, a significant percentage of men under therapy with paroxetine report abnormal ejaculation. Paroxetine is well-tolerated by elderly patients, and appears to be associated with few serious adverse events.

Fluoxetine during pregnancy: impact on fetal development

Women are at greatest risk of suffering from depression during the childbearing years and thus may either become pregnant while taking an antidepressant or may require a prescription for one during pregnancy. The antidepressant fluoxetine (FX) is a selective serotonin reuptake inhibitor (SSRI), which increases serotonin neurotransmission. Serotonin is involved in the regulation of a variety of physiological systems, including the sleep–wake cycle, circadian rhythms and the hypothalamic–pituitary–adrenal axis. Each of these systems also plays an important role in fetal development. Compared with other antidepressant drugs, the SSRIs, such as FX, have fewer side effects. Because of this, they are now frequently prescribed, especially during pregnancy. Clinical studies suggest poor neonatal outcome after exposure to FX in utero. Recent studies in the sheep fetus describe the physiological effects of in utero exposure to FX with an 8 day infusion during late gestation in the sheep. This is a useful model for determining the effects of FX on fetal physiology. The fetus can be studied for weeks in its normal intrauterine environment with serial sampling of blood, thus permitting detailed studies of drug disposition in both mother and fetus combined with monitoring of fetal behavioural state and cardiovascular function. Fluoxetine causes an acute increase in plasma serotonin levels, leading to a transient reduction in uterine blood flow. This, in turn, reduces the delivery of oxygen and nutrients to the fetus, thereby presenting a mechanism for reducing growth and/or eliciting preterm delivery. Moreover, because FX crosses the placenta, the fetus is exposed directly to FX, as well as to the effects of the drug on the mother. Fluoxetine increases high-voltage/non-rapid eye movement behavioural state in the fetus after both acute and chronic exposure and, thus, may interfere with normal fetal neurodevelopment. Fluoxetine also alters hypothalamic function in the adult and increases the magnitude of the prepartum rise in fetal cortisol concentrations in sheep. Fetal FX exposure does not alter fetal circadian rhythms in melatonin or prolactin. Studies of the effects of FX exposure on fetal development in the sheep are important in defining possible physiological mechanisms that explain human clinical studies of birth outcomes after FX exposure. To date, there have been insufficient longer-term follow-up studies in any precocial species of offspring exposed to SSRIs in utero. Thus, further investigation of the long-term consequences of in utero exposure to FX and other SSRIs, as well as the mechanisms involved, are required for a complete understanding of the impact of these agents on development. This should involve studies in both humans and appropriate animal models.

Lack of a Fluoxetine Effect on Prednisolone Disposition and Cortisol Suppression

STUDY OBJECTIVE

To evaluate the potential effect of fluoxetine, a cytochrome P450 isoenzyme inhibitor, on prednisolone disposition and cortisol suppression.

DESIGN

Sequential, two-phase, crossover, open-label pharmacokinetic study.

SETTING

General clinical research center.

SUBJECTS

Fourteen healthy volunteers.

INTERVENTION

A single intravenous dose of prednisolone 40 mg before and after 14 days of treatment with fluoxetine 20 mg/day for 5 days followed by 60 mg/day for 9 days to achieve steady-state concentrations.

MEASUREMENTS AND MAIN RESULTS

Pharmacokinetic parameters of the prednisolone and resulting pharmacodynamic effects on the time course of plasma cortisol suppression before and after fluoxetine administration were evaluated. No significant differences were observed for the mean +/- SD area under the prednisolone concentration-time curve (3739 +/- 992 vs 3498 +/- 797 microg x hr/L, respectively), clearance (8.58 +/- 2.62 vs 8.92 +/- 2.05 L/hr, respectively), volume of distribution (39.5 +/- 12.4 vs 38.2 +/- 9.9 L, respectively), elimination half-life (3.32 +/- 0.83 vs 3.05 +/- 0.80 hrs, respectively), or duration of plasma cortisol suppression (23.5 +/- 3.1 vs 22.0 +/- 4.2 hrs, respectively).

CONCLUSION

Fluoxetine administration did not significantly affect prednisolone disposition or prolong cortisol suppression. This finding suggests that coadministration of these agents is unlikely to result in clinically important pharmacokinetic or pharmacodynamic drug interactions. Prednisolone may be a useful alternative for patients who require both glucocorticoid and fluoxetine therapy.

STEREOSELECTIVE PHARMACOKINETICS OF FLUOXETINE AND NORFLUOXETINE ENANTIOMERS IN PREGNANT SHEEP

We examined the stereoselective disposition of fluoxetine (FX) and its metabolite norfluoxetine (NFX) in five pregnant sheep. Racemic FX was administered i.v. to the ewe (50 mg) and the fetus (10 mg) on separate occasions. Maternal and fetal blood, maternal urine, and fetal amniotic and tracheal fluid samples were collected for 72 h. FX and NFX isomers were quantified by gas chromatography-mass spectrometry. They rapidly crossed the placenta [maternal to fetal area under the plasma concentration versus time curve (AUC) ratios 0.59 and 0.65, respectively]. There was significant FX stereoselectivity with S/R FX AUC ratios averaging 1.65 +/- 0.33 and 1.73 +/- 0.29 in ewe and fetus, respectively, after maternal dosing. The maternal clearance and volume of distribution were also higher for (R)-fluoxetine than for (S)-fluoxetine. FX, NFX, and their glucuronides were present in maternal urine but accounted for only 3.4% of maternal drug elimination. In contrast, NFX was not detected in the fetus after fetal FX administration, which is consistent with the absence of measurable fetal nonplacental clearance of the drug and the lack of NFX formation in fetal hepatic microsomal incubations. There was also no fetal production of FX and NFX glucuronides in vivo. Both FX and NFX were extensively and stereoselectively bound in maternal and fetal plasma, with the free fraction S/R FX ratio averaging 0.46 +/- 0.06 and 0.58 +/- 0.10 in ewe and fetus, respectively. Thus, FX exhibits extensive stereoselective disposition, which is likely due to differential plasma protein binding of the FX isomers, and there is no detectable fetal formation of NFX, FX, and NFX glucuronides.

Citalopram-induced severe hyponatraemia with coma and seizure. Case report with literature and spontaneous reports review

Numerous case reports of hyponatraemia followed increasing use of selective serotonin re-uptake inhibitors (SSRIs) but this adverse effect was only rarely observed in relation to citalopram. We report a case of severe hyponatraemia associated with deep coma, seizure, atrial fibrillation and muscle damage in a 92-year-old woman after only two doses of citalopram, and review 14 cases previously published in the literature and 28 cases spontaneously reported to Australian Drug Reaction Advisory Committee (ADRAC). The data presented suggest that citalopram, as well as SSRIs may cause hyponatraemia secondary to syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The majority of symptomatic cases occurred in elderly patients (79% were older than 70 years) and in women (74%). Polymedication and concomitant use of another psychotropic drug or thiazide diuretic may precipitate and/or augment the development of hyponatraemia/SIADH. In 84% of cases, the hyponatraemia associated with citalopram was detected during the first month of treatment. High level of suspicion, close and careful monitoring of serum sodium concentration particularly in elderly patients and especially in the first month of therapy with citalopram may reduce the incidence of this serious and likely not rare adverse effect.

Safety of fluoxetine treatment in a case of acute intermittent porphyria

Acute intermittent porphyria (AIP) is a metabolic disease characterized by recurrent attacks of neurological and psychiatric dysfunction. It is a rare disorder of heme metabolism that usually presents with abdominal pain, gastrointestinal symptoms and autonomic nervous system disturbances. Exposure to certain drugs, dieting, starvation and infection during pregnancy may precipitate AIP attacks. Psychiatric manifestations of AIP include mood changes, organic brain syndrome and psychosis. Here, we present a 21-year-old female patient with AIP and major depression. She had a caesarean section under general anesthesia with pentothal and her recovery time from anesthesia took longer than usual. She had a blood transfusion because of severe anemia following the operation. Three days after her discharge she was readmitted to the hospital with confusion and seizure. It was her first AIP attack and it started 6 days after caesarean section. Two months after her first attack, we saw her for anxiety and depressive symptoms. She was in severe anxiety and depression and she was put on fluoxetine (20 mg/day liquid form). Following the treatment she did not develop any other porphyria attack. Her symptoms vanished and she improved functionally. She stayed on fluoxetine for 6 months without any new AIP attack. Despite limited data regarding fluoxetine therapy in porphyria patients, it seems to be safe for the treatment of depressive and anxiety symptoms in these patients.

Sertraline: a review of its use in the management of major depressive disorder in elderly patients

Sertraline is a selective serotonin reuptake inhibitor (SSRI) with well established antidepressant and anxiolytic activity. Results from several well designed trials show that sertraline (50 to 200 mg/day) is effective in the treatment of major depressive disorder in elderly patients (> or =60 years of age). Primary endpoints in most studies included the Hamilton Depression Rating Scale (HDRS), Clinical Global Impression (CGI) score and the Montgomery-Asberg Depression Rating Scale (MADRS). Sertraline was significantly more effective than placebo, and was as effective as fluoxetine, nortriptyline and imipramine in elderly patients. During one trial, amitriptyline was significantly more effective than sertraline [mean reduction from baseline on one of six primary outcomes (HDRS)], although no quantitative data were provided. Subgroup analysis of data from a randomised, double-blind trial in elderly patients with major depressive disorder suggests that vascular morbidity, diabetes mellitus or arthritis does not affect the antidepressant effect of sertraline. Secondary endpoints from these clinical trials suggest that sertraline has significant benefits over nortriptyline in terms of quality of life. In addition, significant differences favouring sertraline in comparison with nortriptyline and fluoxetine have been recorded for a number of cognitive functioning parameters. Sertraline is generally well tolerated in elderly patients with major depressive disorder, and lacks the marked anticholinergic effects that characterise the adverse event profiles of tricyclic antidepressants (TCAs). The most frequently reported adverse events in patients aged > or =60 years with major depressive disorder receiving sertraline 50 to 150 mg/day were dry mouth, headache, diarrhoea, nausea, insomnia, somnolence, constipation, dizziness, sweating and taste abnormalities. The tolerability profile of sertraline is generally similar in younger and elderly patients. Sertraline has a low potential for drug interactions at the level of the cytochrome P450 enzyme system. In addition, no dosage adjustments are warranted for elderly patients solely based on age.

CONCLUSION

Sertraline is an effective and well tolerated antidepressant for the treatment of major depressive disorder in patients aged > or =60 years. Since elderly patients are particularly prone to the anticholinergic effects of TCAs as a class, SSRIs such as sertraline are likely to be a better choice for the treatment of major depressive disorder in this age group. In addition, sertraline may have advantages over the SSRIs paroxetine, fluoxetine and fluvoxamine in elderly patients because of the drug's comparatively low potential for drug interactions, which is of importance in patient groups such as the elderly who are likely to receive more than one drug regimen.

Drug interactions with patient-controlled analgesia

Patient-controlled analgesia (PCA) has become standard procedure in the clinical treatment of pain. Its widespread use in patients with all kinds of diseases opens a variety of possible interactions between analgesics used for PCA and other drugs that might be administered concomitantly to the patient. Many of these drug interactions are of little clinical importance. However, some drug interactions have been reported to result in serious clinical problems. Drug interactions can either predominantly affect the pharmacokinetics or pharmacodynamics of the drug. Most important pharmacokinetic drug interactions occur at the level of drug metabolism or protein binding. Acceleration of methadone metabolism caused by cytochrome P450 (CYP) 3A4 induction by antiretroviral drugs or rifampicin (rifampin) has caused methadone withdrawal symptoms. Lack of morphine formation from codeine as a result of CYP2D6 inhibition by quinidine results in an almost complete loss of the analgesic effects of codeine. Alterations of methadone protein binding caused by an inhibition of alpha1-acid glycoprotein synthesis by alkylating substances are another possibility for predominantly pharmacokinetically based drug interactions during PCA. Furthermore, inhibition of P-glycoprotein by anticancer drugs could result in altered transmembrane transport of morphine, methadone or fentanyl, although this has not been shown to be of clinical relevance. Synergistic effects of systemically administered opioids with spinally or topically delivered opioids or anaesthetics have been reported frequently. The same is true for the opioid-sparing effects of coadministered non-opioid analgesics. Antidepressants, anticonvulsants or alpha2-adrenoreceptor agonists have also been shown to exert additive analgesic effects when administered together with an opioid. Inconsistent findings, however, are reported regarding the treatment of patients with opioid-induced nausea and sedation, since coadministration of antiemetics either increased or decreased the respective adverse effects or revealed additional unwanted drug effects.

Fluvoxamine: a review of its therapeutic potential in the management of anxiety disorders in children and adolescents

Fluvoxamine is a selective serotonin reuptake inhibitor (SSRI) which may be used for the management of anxiety disorders in children and adolescents. Absorption of fluvoxamine was similar in adolescents to that in adults, which suggests that the maximum dosage of the drug for patients aged between 12 and 17 years can be as high as 300 mg/day. However, steady-state plasma fluvoxamine [corrected] concentrations were 2 to 3 times higher in children (aged between 6 and 11 years) than in adolescents; thus, the maximum fluvoxamine dosage recommended for children is 200 mg/day. Fluvoxamine (50 to 300 mg/day) for 8 to 16 weeks significantly reduced symptoms of obsessive-compulsive disorder (OCD) [measured across multiple assessment scales] compared with placebo in a well controlled trial in paediatric patients (n = 120) or from baseline in noncomparative trials in adolescent (n = 20) or paediatric (n = 16) patients. Improvements with fluvoxamine (up to 200 mg/day) were observed for up to 1 year in 98 patients with OCD in a noncomparative trial. The drug (up to 250 or 300 mg/day) also improved symptoms of anxiety compared with placebo in an 8-week well controlled trial in 128 paediatric patients with social phobia, separation anxiety disorder or generalised anxiety disorder (GAD). Fluvoxamine (50 to 300 mg/day) appears to be well tolerated in paediatric patients, with most adverse events with the drug (except abdominal discomfort, which occurred more often in patients receiving fluvoxamine) occurring with a similar incidence to those with placebo. The most common adverse events involved the central nervous system or gastrointestinal system. Most adverse events reported by paediatric patients with OCD were similar to those reported by adults. In conclusion, fluvoxamine is generally well tolerated and has demonstrated short-term efficacy compared with placebo in the treatment of OCD, and social phobia, separation anxiety disorder or GAD in well controlled trials in paediatric patients. Reductions in symptoms of anxiety with fluvoxamine have been observed for up to 1 year in children and adolescents with OCD. However, there are currently no comparative trials of fluvoxamine with other pharmacological agents. In the absence of such trials, current consensus opinion recommends that when pharmacotherapy is indicated, fluvoxamine, like other SSRIs, can be used as first-line treatment for anxiety disorders, particularly OCD, in paediatric patients. However, direct comparisons are required to assess the relative efficacy and tolerability of pharmacological agents in order to make firm recommendations for the treatment of anxiety disorders in this patient group.

Prevalence and patterns of concomitant use of selective serotonin reuptake inhibitors and other antidepressants in a high-cost polypharmacy cohort

BACKGROUND

Concomitant antidepressant therapy for patients who do not respond to selective serotonin reuptake inhibitors (SSRIs) may be appropriate under close medical supervision. However, little is known about the prevalence or patterns of concurrent antidepressant therapy in a typical large health maintenance organization.

OBJECTIVE

The purpose of this study was to determine the prevalence of concomitant SSRI-antidepressant therapy and to assess the relationship between concomitant SSRI therapy, patient demographic characteristics, and the use of multiple prescribers and pharmacies.

METHODS

This was a retrospective analysis of administrative prescription and medical claims data from January 1998 through September 1999. Data were obtained on beneficiaries who had >15 prescriptions dispensed in either of the first 2 quarters of 1999 and/or patients who accrued >$1,000 in prescription costs in either or both of the quarters. Patients were defined as undergoing concomitant SSRI therapy if they had received > or = 14 days of concomitant treatment with 2 SSRIs, an SSRI and tricyclic antidepressant, an SSRI and benzodiazepine, or an SSRI and miscellaneous antidepressant. Contingency analysis and logistic regression were used to identify factors associated with concomitant SSRI therapy.

RESULTS

The relative risk for concomitant SSRI-SSRI therapy for patients with multiple prescribers versus a single prescriber was 2.32; the relative risk for patients receiving prescriptions from multiple pharmacies versus a single pharmacy was 2.97. Female patients were 19.8% more likely than male patients to receive concomitant SSRI therapy. Use of multiple prescribers increased the odds for concomitant SSRI therapy by >3.0 across the 4 therapeutic combinations. Use of multiple pharmacies increased the odds for concomitant SSRI-SSRI therapy by 5.42.

CONCLUSIONS

Prescription of concomitant SSRI therapy was strongly associated with changes in strength of dosage and products and with use of multiple prescribers and pharmacies.

Influence of coadministration of fluoxetine on cisapride pharmacokinetics and QTc intervals in healthy volunteers

STUDY OBJECTIVE

To evaluate the effect of fluoxetine on the pharmacokinetics and cardiovascular safety of cisapride at steady state in healthy men.

DESIGN

Open-label, three-phase, sequential study.

SETTING

Clinical research center.

SUBJECTS

Twelve healthy male volunteers.

INTERVENTIONS

Each subject was treated according to the following sequence: baseline; phase 1 (days 1-6): cisapride 10 mg 4 times/day; washout (days 7-13); phase 2 (days 14-44): fluoxetine 20 mg/day; and phase 3 (days 45-52): cisapride 10 mg 4 times/day (days 45-51) plus fluoxetine 20 mg/day (days 45-52).

MEASUREMENTS AND MAIN RESULTS

Blood samples were drawn and 12-lead electrocardiograms performed at specified time points after the last morning dose of cisapride in phases 1 and 3. Blood samples also were taken before morning doses on the 3rd, 4th, and 5th days of phases 1 and 3. Electrocardiograms were done at baseline and on the last day of the washout period and phase 2. Coadministration of fluoxetine significantly decreased cisapride plasma concentrations. There were no clinically significant changes in corrected QT intervals during administration of cisapride alone or with fluoxetine. Cisapride was well tolerated when administered alone or with fluoxetine.

CONCLUSION

Cisapride can be administered safely to patients receiving low therapeutic dosages of fluoxetine.

Selecting a Selective Serotonin Reuptake Inhibitor: Clinically Important Distinguishing Features

Selective serotonin reuptake inhibitors (SSRIs) are widely prescribed to treat depression. Although these drugs presumably have the same mechanism of action, they vary in several clinically important ways, including how long they remain in the body and the extent to which they interfere with the metabolism of other medications. This article reviews the pharmacologic differences among SSRIs and how these differences may affect various aspects of treatment, such as dosing, administration, and discontinuation. Understanding the distinct properties of SSRIs may help primary care physicians to design the most appropriate therapeutic plan for individual patients.

Is therapeutic drug monitoring a case for optimizing clinical outcome and avoiding interactions of the selective serotonin reuptake inhibitors?

The selective serotonin reuptake inhibitors (SSRIs) comprise citalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline and they differ from each other in chemical structure, by pharmacokinetic properties and, most importantly, with respect to enzyme-specific metabolism and interactions. Citalopram is administered as a racemic mixture. The drug is oxidated to desmethylcitalopram in the liver, partially by CYP2C19 and partially by CYP3A4. Fluoxetine is administered as a racemate of R- and S-fluoxetine. Both R- and S-fluoxetine are metabolized by CYP2D6 to the active metabolites R- and S-norfluoxetine. Fluvoxamine is metabolized to inactive metabolites by CYP1A2 and CYP2D6. Paroxetine is metabolized to inactive metabolites partially by CYP2D6, and accordingly the metabolism of paroxetine is dependent on the genetic polymorphism of CYP2D6. Sertraline is metabolized to desmethylsertraline, probably by CYP3A4. Several analytical methods have been described for all SSRIs. Most assays are based on separation by high-performance liquid chromatography or gas chromatography. Stereoselective methods for the analysis of racemic citalopram and fluoxetine have been published. The SSRIs are generally well tolerated and their therapeutic indices are large. In several studies there has not been found a clear relationship between clinical efficacy and plasma concentration, nor any threshold that defines toxic concentrations. The available data do not suggest that any benefit be obtained from routine monitoring of SSRI plasma levels. Therefore therapeutic drug monitoring (TDM) of the SSRIs may be useful mainly in situations where poor compliance is suspected and when therapeutic failure or toxic events are experienced at clinically relevant dosages. Further, in special populations, such as in elderly patients, poor metabolizers of sparteine (CYP2D6) or mephenytoin (CYP2C19), and patients with liver impairment, the measurement of plasma concentrations may be useful.

Clonazepam and sertraline: absence of drug interaction in a multiple-dose study

Thirteen subjects (seven men, six women) completed a placebo-controlled, randomized, double-blind, crossover study to determine whether an interaction occurs between clonazepam and sertraline. Ten days of once-daily doses of either clonazepam 1 mg and placebo (CZ + PL) or clonazepam 1 mg and sertraline 100 mg (CZ + SR) were administered; there was an 11-day washout period. Sertraline did not significantly affect the pharmacokinetics of clonazepam (p > 0.13). Clonazepam apparent oral clearance, volume of distribution, and half-life were 3.9 +/- 0.2 L/hr, 233 +/-11 L, and 40.5 +/- 0.3 hours, respectively. The kinetics of the inactive metabolite 7-aminoclonazepam were marginally affected by sertraline, with a 21% decrease in the elimination half-life (p = 0.03) relative to CZ + PL and no significant difference between treatments in area under the curve or metabolite ratio. Card sorting (CS), digit-symbol substitution test (DSST), nurse-rated sedation scale (NRSS), and self-rated sedation scores were assessed four times daily on days -1 (PL + PL), 1, 4, 7, and 10. There were no differences between treatments in area under the effect curve or maximum observed effect for CS, DSST, or NRSS. Maximum impairment on all assessment days was low, with a less than 10% change from the drug-free values for CS and DSST. Despite higher clonazepam concentrations, predose (time 0) psychomotor and sedation scores did not differ among days -1, 1, 4, 7, and 10 or between treatments. These results in healthy volunteers indicate that sertraline does not affect the pharmacokinetics or pharmacodynamics of clonazepam.

Pharmacokinetics of selective serotonin reuptake inhibitors

The five selective serotonin reuptake inhibitors (SSRIs), fluoxetine, fluvoxamine, paroxetine, sertraline, and citalopram, have similar antidepressant efficacy and a similar side effect profile. They differ, however, in their pharmacokinetic properties. Under steady-state concentrations, their half-lives range between 1 and 4 days for fluoxetine (7 and 15 days for norfluoxetine) and between 21 (paroxetine) and 36 (citalopram) hr for the other SSRIs. Sertraline and citalopram show linear and fluoxetine, fluvoxamine, and paroxetine nonlinear pharmacokinetics. SSRIs underlie an extensive metabolism with high interindividual variability, whereby cytochrome P450 (CYP) isoenzymes play a major role. Therefore, resulting blood concentrations are highly variable between individuals. Except for N-demethylated fluoxetine, metabolites of SSRIs do not contribute to clinical actions. Therapeutically effective blood concentrations are unclear so far, although there is evidence for minimal effective and upper-threshold concentrations that should not be exceeded. Paroxetine and, to a lesser degree, fluoxetine and norfluoxetine are potent inhibitors of CYP2D6 and fluvoxamine of CYP1A2 and CYP2C19. This can give rise to drug-drug interactions that may have no effect, lead to intoxication, or improve the therapeutic response. These different pharmacokinetic properties of the five SSRIs, especially their drug-drug interaction potential, should be considered when selecting a distinct SSRI for treatment of depression or other disorders with a suggested dysfunction of the serotonergic system in the brain.

Antidepressants noncompetitively inhibit nicotinic acetylcholine receptor function

Nicotinic acetylcholine receptors (nAChRs) are diverse members of the neurotransmitter-gated ion channel superfamily and play critical roles in chemical signaling throughout the nervous system. The present study establishes for the first time the acute functional effects of sertraline (Zoloft), paroxetine (Paxil), nefazodone (Serzone), and venlafaxine (Effexor) on two human and one chick nAChR subtype. This study also confirms previous findings of nAChR functional block by fluoxetine (Prozac). Function of human muscle-type nAChR (alpha1/beta gammadelta) in TE671/RD cells, human autonomic nAChR (alpha3/beta4alpha5 +/- beta2) in SH-SY5Y neuroblastoma cells, or chick V274T mutant alpha7-nAChR heterologously expressed in native nAChR-null SH-EP1 epithelial cells was measured using 86Rb+ efflux assays. Functional blockade of human muscle-type and autonomic nAChRs is produced by each of the drugs in the low to intermediate micromolar range, and functional blockade of chick V274T-alpha7-nAChR is produced in the intermediate to high micromolar range. Functional blockade is insurmountable by increasing agonist concentrations at each nAChR subtype tested for each of these drugs, suggesting noncompetitive inhibition of nAChR function. These studies open the possibilities that nAChR subtypes in the brain could be targets for therapeutic antidepressants and could play roles in clinical depression.

Paroxetine. An update of its pharmacology and therapeutic use in depression and a review of its use in other disorders

Paroxetine is a potent and selective inhibitor of the neuronal reuptake of serotonin (5-hydroxytryptamine; 5-HT), which was previously reviewed as an antidepressant in Drugs in 1991. Since then, more comparative trials with other antidepressants have become available, and its use in the elderly and as long term maintenance therapy has been investigated. Paroxetine has also been studied in several other disorders with a presumed serotonergic component, primarily obsessive compulsive disorder (OCD) and panic disorder. In short term clinical trials in patients with depression, paroxetine produced clinical improvements that were significantly greater than those with placebo and similar to those achieved with other agents including tricyclic antidepressants (TCAs), maprotiline, nefazodone and the selective serotonin reuptake inhibitors (SSRIs) fluoxetine, fluvoxamine and sertraline. Long term data suggest that paroxetine is effective in preventing relapse or recurrence of depression in patients treated for up to 1 year. In the elderly, the overall efficacy of paroxetine was at least as good as that of comparator agents. In short term clinical trials involving patients with OCD or panic disorder, paroxetine was significantly more effective than placebo and of similar efficacy to clomipramine. Limited long term data show that paroxetine is effective in maintaining a therapeutic response over periods of 1 year (OCD) and up to 6 months (panic disorder). Preliminary data suggest that paroxetine has potential in the treatment of social phobia, premenstrual dysphoric disorder and chronic headache. Like the other SSRIs, paroxetine is better tolerated than the TCAs, causing few anticholinergic adverse effects. The most commonly reported adverse event associated with paroxetine treatment is nausea, although this is generally mild and subsides with continued use. Fewer withdrawals from treatment due to adverse effects occurred with paroxetine treatment than with TCAs. The adverse events profile of paroxetine appears to be broadly similar to that of other SSRIs, although data from comparative trials are limited. Serious adverse effects associated with paroxetine are very rare. In conclusion, paroxetine is effective and well tolerated, and suitable as first-line therapy for depression. It also appears to be a useful alternative to other available agents for the treatment of patients with OCD or panic disorder.

Fluoxetine tenth anniversary update: the progress continues

This tenth anniversary review/update of fluoxetine concentrates on the past 5 years of its clinical application. The mechanism of action of fluoxetine; its metabolism; its efficacy in patients with various diagnostic subgroups of depression, patients with coincident medical disease, children and adolescents with depression, patients with eating disorders, and patients with obsessive-compulsive disorder (OCD); its long-term (maintenance) efficacy; its side effects and toxicity; and pharmacoeconomic considerations are reviewed. Pharmacotherapy is currently the only proven method for treating major depressive disorder that is applicable to all levels of severity of major depressive illness. Since its introduction 10 years ago, fluoxetine has been available to psychiatrists, primary care physicians, and other nonpsychiatric physicians as full-dose effective pharmacotherapy for patients with depression. Fluoxetine has been widely prescribed by physicians knowledgeable in pharmacology and in the treatment of depression because of its proven efficacy (ie, equal to that of tricyclic antidepressants [TCAs]), its ease of administration (with full therapeutic dosing usually starting from day 1), its generally benign side-effect profile, its remarkable safety in over-dose, and its proven effectiveness in the most common depressed patient population--anxious, agitated, depressed patients--as well as in patients with various subtypes and severities of depression. In more recent years it has also proved effective in the treatment of bulimia, an entity for which only limited or inadequate treatment options had been previously available. In OCD, fluoxetine, with its more acceptable side-effect profile and greater ease of dosing, presents a favorable alternative to previous drug therapy and is useful in treating both obsessions and compulsions. Fluoxetine is currently recognized among clinicians as efficacious in treating anxiety disorders and is being used successfully in special depressed populations such as patients with medical comorbidity, elderly patients, adolescents, and children. Rapid discontinuation or missed doses of short-half-life selective serotonin reuptake inhibitors, TCAs, and heterocyclic antidepressants are associated with withdrawal symptoms of a somatic and psychological nature, which cannot only be disruptive, but can also be suggestive of relapse or recurrence of depression. In striking contrast to these short-half-life antidepressants, fluoxetine is rarely associated with such sequelae on sudden discontinuation or missed doses. This preventive effect against withdrawal symptoms on discontinuation of fluoxetine is attributed to the unique extended half-life of this antidepressant. Current studies show that the overall increased effectiveness of fluoxetine in treating depression compensates for its higher cost, compared with older drugs, by reducing the need for physician contact because of increased compliance and less need of titration, and by reducing premature patient discontinuation, thereby yielding fewer relapses, less recurrence, and less reutilization of mental health services.