Effects of fluoxetine treatment of platelet 3H-imipramine binding, 5-HT uptake and 5-HT content in major depressive disorder

Using machine learning to develop a clinical prediction model for SSRI-associated bleeding: a feasibility study

INTRODUCTION

Adverse drug events (ADEs) are associated with poor outcomes and increased costs but may be prevented with prediction tools. With the National Institute of Health All of Us (AoU) database, we employed machine learning (ML) to predict selective serotonin reuptake inhibitor (SSRI)-associated bleeding.

METHODS

The AoU program, beginning in 05/2018, continues to recruit ≥ 18 years old individuals across the United States. Participants completed surveys and consented to contribute electronic health record (EHR) for research. Using the EHR, we determined participants who were exposed to SSRIs (citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, vortioxetine). Features (n = 88) were selected with clinicians' input and comprised sociodemographic, lifestyle, comorbidities, and medication use information. We identified bleeding events with validated EHR algorithms and applied logistic regression, decision tree, random forest, and extreme gradient boost to predict bleeding during SSRI exposure. We assessed model performance with area under the receiver operating characteristic curve statistic (AUC) and defined clinically significant features as resulting in > 0.01 decline in AUC after removal from the model, in three of four ML models.

RESULTS

There were 10,362 participants exposed to SSRIs, with 9.6% experiencing a bleeding event during SSRI exposure. For each SSRI, performance across all four ML models was relatively consistent. AUCs from the best models ranged 0.632-0.698. Clinically significant features included health literacy for escitalopram, and bleeding history and socioeconomic status for all SSRIs.

CONCLUSIONS

We demonstrated feasibility of predicting ADEs using ML. Incorporating genomic features and drug interactions with deep learning models may improve ADE prediction.

Systematic review of studies using platelet serotonin content to assess bioeffect of serotonin reuptake inhibitors at the serotonin transporter

RATIONALE

Assessment of the bioeffect of serotonin reuptake inhibitors (SRIs, including both selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs)) at the serotonin transporter (SERT) in patients and healthy controls can have important theoretical and clinical implications.

OBJECTIVES

Bioeffect at SERT has been assessed by neuroimaging of brain SERT occupancy, through in vitro measurements of platelet serotonin (5-HT) uptake, and by measuring platelet 5-HT content pre- and post-initiation of SRI administration. Studies of platelet 5-HT content were reviewed in order to (1) determine the overall apparent bioeffect of SRIs; (2) compare bioeffect across types of SRIs; (3) compare the three approaches to assessing SRI bioeffect; and (4) determine how the findings might inform clinical practice.

METHODS

We performed a systematic review of the published studies that measured platelet 5-HT content to assess SRI bioeffect at the platelet SERT. Studies using neuroimaging and in vitro platelet 5-HT uptake to assess SRI bioeffect were reviewed for comparison purposes.

RESULTS

Clinical doses of SRIs typically resulted in 70-90% reductions in platelet 5-HT content. The observed bioeffect at the platelet SERT appeared similar among different SSRIs and SNRIs. The bioeffect estimations based on platelet 5-HT content were consistent with those obtained using neuroimaging to assess brain SERT occupancy and those based on the in vitro measurement of platelet 5-HT uptake.

CONCLUSIONS

In general, excellent agreement was seen in the apparent SRI bioeffect (70-90% inhibition) among the platelet 5-HT content studies and across the three bioeffect approaches. Theoretical and practical clinical implications are discussed.

A different approach to ecchymosis due to paroxetine

Seçici serotonin gerialım inhibitörleri (SSGİ) sıklıkla reçete edilen ve başlıca depresyon ve anksiyete bozukluklarının tedavisinde kullanılan ilaçlardır. SSGİ ilaçlar serotonin taşıyıcısını inhibe ederek trombositlerdeki serotinin düzeylerinde azalmaya yol açarlar. SSGİ ilaçlar başta paroksetin olmak üzere anormal kanamalarla ilişkilendirilmiştir. Yazıda genç, sağlıklı olup, paroksetin 20 mg/gün kullanımı sonrası spontan ekimoz gelişen, tedavisine paroksetinle devam edilen ve takiplerinde ekimotik lezyonların azalarak geçtiği gözlenen bir olgu sunulmuştur. SSGİ ilaçlarla ilişkili kanama gelişmesi durumunda; belirtiler hafif ve koagülasyon testleri normalse, tedaviye aynı ilaçla devam etmenin de bir seçenek olabileceği akılda tutulmalıdır. Bu konuda geniş ölçekli izlem çalışmalarına ihtiyaç vardır.

Differential effects of antidepressant subgroups on risk of acute myocardial infarction: A nested case-control study

The primary objective of this study was to investigate the association between antidepressants use and the risk of acute myocardial infarction (AMI).

METHODS

We conducted a nested case-control study using a primary care database over the period 2002-2015. From a cohort of patients aged 40-99 years, we identified incident AMI cases and randomly selected 5 controls per case, matched to cases for exact age, sex and index date. Exposure to antidepressants were categorised as current, recent, past and nonusers. Adjusted odds ratio (AOR) and 95% confidence interval (CI) were computed using conditional logistic regression to assess the association between the current use of different antidepressants subgroups and AMI as compared to nonuse. Dose and duration effects were explored.

RESULTS

Totals of 24 155 incident AMI cases and 120 775 controls were included. The current use of antidepressants as a group was associated with a reduced risk (AOR = 0.86; 95% CI: 0.81-0.91), but mainly driven by selective serotonin reuptake inhibitors (AOR = 0.86; 95% CI:0.81-0.93). A reduced risk was also observed with trazodone (AOR = 0.76;95% CI: 0.64-0.91), and clomipramine (AOR = 0.62; 95% CI: 0.40-0.96), whereas no significant effect was observed with other antidepressants. A duration-dependent effect was suggested for selective serotonin reuptake inhibitors, trazodone and clomipramine, while there was no clear dose-dependency.

CONCLUSION

This study suggests that current use of antidepressants interfering selectively with the reuptake of serotonin, and those antagonizing the 5-HT_2A receptor, are associated with a decrease in AMI risk and should be the antidepressants of choice in patients at cardiovascular risk.

SSRI/SNRI Therapy is Associated With a Higher Risk of Gastrointestinal Bleeding in LVAD Patients

BACKGROUND

Gastrointestinal bleeding (GIB) is common in left ventricular assist device (LVAD) patients. Serotonin release from platelets promotes platelet aggregation, and selective serotonin reuptake inhibitor/serotonin-norepinephrine reuptake inhibitor (SSRI/SNRI) therapy inhibits the transporter responsible for re-uptake.

METHODS

We reviewed the records of LVAD (HeartMateII™, Abbott Medical, Lake Bluff, IL, USA and Heartware™, Medtronic, Minneapolis, MN, USA) patients at the Medical University of South Carolina and Johns Hopkins Hospital between January 2009 and January 2016. After exclusions, 248 patients were included for analysis. After univariate analysis, logistic regression multivariate analysis was performed to adjust for any demographic, cardiovascular, and laboratory data variables found to be associated with GI bleeding post-LVAD.

RESULTS

Gastrointestinal bleeding occurred in 85 patients (35%) with 55% of GIBs due to arteriovenous malformations (AVMs). Of the total cohort, 105 patients received an SSRI or SNRI during LVAD support. Forty-four (44) SSRI/SNRI (41.9%) and 41 non-SSRI/SNRI (28.7%) patients had a GIB (RR 1.46, p = 0.03). Twenty-six (26) (24.8%) of the SSRI/SNRI patients had a GIB due to AVMs versus 21 (14.7%) of the non-SSRI/SNRI patients (RR 1.69, p = 0.05). In fully-adjusted multivariate regression analysis, SSRI/SNRI therapy was independently associated with GIB (OR 1.78, p = 0.045). For GIB, the number needed to harm (NNH) was 7.6.

CONCLUSION

In conclusion, SSRI/SNRI therapy is independently associated with an increased risk of GIB in LVAD patients.

An East Meets West Approach to the Understanding of Emotion Dysregulation in Depression: From Perspective to Scientific Evidence

Depression, an emotion regulation disorder, is a prevalent mental illness in the world. Meanwhile, traditional Chinese medicine (TCM) has been increasingly regarded as a promising and effective alternative therapy approach for patients with depression. Despite many years of research on depression, the current understanding of the pathological mechanism of depression based on TCM theories is still in its infancy. Due to the lack of scientific evidence in the past, TCM is not fully recognized by researchers around the world. This review firstly summarizes the pathogenesis and etiology of depression in terms of both Eastern and Western medical systems. Secondly, it adopts an integrated Eastern and Western approach to propose some plausible neurophysiological pathways linking the liver, spleen, and heart functions explicated in TCM theory. The aim of this theoretical review is to bridge the knowledge gap between Eastern and Western medicine, which may better explain the pathology of depression.

Potential Role of Selective Serotonin Reuptake Inhibitors in Improving Functional Outcome after Stroke

The great advances in acute stroke treatment during the last decades have changed life after stroke considerably. However, the use of intravenous thrombolysis and endovascular thrombectomy is limited by a relatively narrow time window or contraindications for treatment. Further, patients receiving acute reperfusion therapies may still have cognitive and emotional complications due to underlying brain infarcts even though physical problems may almost disappear. Consequently, stroke is still a frequent cause of adult disability and death worldwide, and an effort to identify additional treatments to enhance recovery, preferably also feasible in the time after the acute phase, is warranted. Albeit several drugs and treatment modalities have been studied for their potential to enhance recovery after stroke, no treatment has unambiguously proven to potentiate the rehabilitation process. A promising candidate for pharmacological treatment is selective serotonin reuptake inhibitors (SSRIs), a group of commonly used antidepressants that may also possess neuro-regenerative properties. The current paper reviews the evidence for SSRIs as potential enhancers of stroke recovery and discusses the potential mechanisms behind the effects reported and the implications for the management of patients post-stoke, including potential adverse events and drug-drug interactions.

Use of Selective Serotonin Reuptake Inhibitors and Risks of Stroke in Patients with Obsessive Compulsive Disorder: A Population-Based Study

Background

Previous research has suggested a link between antidepressants use and the development of cerebrovascular events, but there has never been any study investigating the risk of stroke in obsessive-compulsive disorder (OCD) patients treated with a selective serotonin reuptake inhibitor (SSRI).

Methods

A retrospective observational cohort study was conducted using data from the National Health Insurance Database of Taiwan between the year of 2001 and 2009. A total of 527 OCD patients with 412 subjects in the SSRI use group and 115 in the non SSRI use group were included. Multivariable Cox proportional-hazards models were used to explore the associations between SSRI use and the occurrence of stroke, controlling for age, gender, concomitant medications, and comorbid medical illnesses.

Results

A total of nineteen OCD patients were diagnosed with new onset of stroke during the follow-up period including six cases in the SSRI group and thirteen in the non SSRI use group. SSRI use was demonstrated to be associated with a decreased risk of stroke (hazard ratio [HR] = 0.30; 95% confidence interval [CI] = 0.10–0.86, P = 0.02). The increase in age-related risk of strokes was 2.55 per decade (HR = 2.55; 95% CI = 1.74–3.75, P<0.001). Alternatively, sex, concomitant use of aspirin and non-steroidal anti-inflammatory drugs, and comorbidities with angina pectoris, diabetes mellitus, hypertension, and hyperlipidemia were not found to be associated with an increased risk for stroke in OCD patients.

Conclusions

Our study showed that SSRI use was associated with decreased risk of stroke in OCD patients. Further investigation into the possible biological mechanisms underlying the relationship between stroke and SSRI use in OCD patients is warranted.

Effects of selective serotonin reuptake inhibitors on platelet function: mechanisms, clinical outcomes and implications for use in elderly patients

Among the antidepressants, the selective serotonin reuptake inhibitors (SSRIs) are often preferred to other classes of antidepressants in the treatment of depression in the elderly because of their better safety profile. Most of the known effects of SSRIs, either beneficial or adverse, are linked to their inhibitory action on the serotonin reuptake transporter (5-HTT). This reuptake mechanism is present not only in neurons but also in other cells such as platelets. Serotoninergic mechanisms seem to play an important role in haemostasis, and their importance in this regard has long been underestimated. Abnormal activation may lead to a pro-thrombotic state, as may occur in patients with major depressive disorder, whilst downregulation, as occurs in patients treated with SSRIs, may have two clinical consequences, both of particular interest in the elderly. On the one hand, there may be an increased risk of bleeding; on the other hand, a reduction in thrombotic risk may be possible. Polymorphism in the promoter region of the gene that transcribes the 5-HTT has been shown to have a relevant impact on its function and, in turn, on the beneficial and adverse effects of SSRIs. Bleeding has been a concern since the introduction of SSRIs, with multiple case reports published and communicated to the pharmacovigilance systems. The first epidemiological study was published in 1999 and since then, 34 epidemiological studies from different areas, most of them including elderly patients in their study populations, have been published with a variety of results. Broadly, the epidemiological evidence supports a moderately increased risk of bleeding associated with the use of SSRIs, which may be critically dependent on patient susceptibility and the presence of risk factors. The impairment of primary haemostasis induced by SSRIs may result, as a beneficial counterpart, in a reduction in the thrombotic risk. A small number of clinical trials and an increasing number of epidemiological studies that include elderly patients have been conducted to clarify whether SSRIs reduce the risk of primary and secondary ischaemic disorders. However, the results have been inconclusive with some studies suggesting a preventive effect and others no effect or even an increased risk. Behind such contradictory results may be the role of depression itself as a cardiovascular risk factor and, therefore, a major confounding factor. How to disentangle its effect from that of the antidepressants is the methodological challenge to be overcome in future studies. In this complex scenario, the elderly seem to be at a crossroads, because they are the group in which both the risks and the benefits can be the greatest. Studies performed to date have provided us with some clues that can help orient clinicians in taking the most appropriate course of action. For instance, as the gastrointestinal bleeding risk appears to increase with age, prudent advice in patients with a previous history of upper-gastrointestinal bleeding or peptic ulcer, and in those who take NSAIDs, oral anticoagulants, antiplatelet drugs or corticosteroids, would be to suggest addition of an acid-suppressing agent to the drug regimen in those elderly patients in whom SSRIs are indicated.

Monoamine depletion by reuptake inhibitors

BACKGROUND

Disagreement exists regarding the etiology of cessation of the observed clinical results with administration of reuptake inhibitors. Traditionally, when drug effects wane, it is known as tachyphylaxis. With reuptake inhibitors, the placebo effect is significantly greater than the drug effect in the treatment of depression and attention deficit hyperactivity disorder, leading some to assert that waning of drug effects is placebo relapse, not tachyphylaxis.

METHODS

Two groups were retrospectively evaluated. Group 1 was composed of subjects with depression and Group 2 was composed of bariatric subjects treated with reuptake inhibitors for appetite suppression.

RESULTS

In Group 1, 200 subjects with depression were treated with citalopram 20 mg per day. A total of 46.5% (n = 93) achieved relief of symptoms (Hamilton-D rating score ≤ 7), 37 (39.8%) of whom experienced recurrence of depression symptoms, at which point an amino acid precursor formula was started. Within 1-5 days, 97.3% (n = 36) experienced relief of depression symptoms. In Group 2, 220 subjects were treated with phentermine 30 mg in the morning and citalopram 20 mg at 4 pm. In this group, 90.0% (n = 198) achieved adequate appetite suppression. The appetite suppression ceased in all 198 subjects within 4-48 days. Administration of an amino acid precursor formula restored appetite suppression in 98.5% (n = 195) of subjects within 1-5 days.

CONCLUSION

Reuptake inhibitors do not increase the total number of monoamine molecules in the central nervous system. Their mechanism of action facilitates redistribution of monoamines from one place to another. In the process, conditions are induced that facilitate depletion of monoamines. The "reuptake inhibitor monoamine depletion theory" of this paper offers a novel and unified explanation for the waning of response seen after a reuptake inhibitor is started, independent of a drug or placebo etiology.

Association between selective serotonin reuptake inhibitors and gastrointestinal damage: advances and prospects

Selective serotonin reuptake inhibitors (SSRIs) are among the most commonly prescribed drugs in the world and have widely been used in the treatment of depression, because they have similar efficacy to tricyclic antidepressants and demonstrate a favorable safety and tolerability profile. However, with the increase in the number of patients receiving SSRIs, low-frequency adverse effects associated with use of SSRIs have become more prevalent. Since 1990, a number of case reports and epidemiological studies have described the risk of gastrointestinal bleeding in patients after the initiation of SSRI therapy. This article reviews the recent advances and future prospects for understanding the association between SSRIs and upper gastrointestinal bleeding.

There is an association between selective serotonin reuptake inhibitor use and uncomplicated peptic ulcers: a population-based case-control study

BACKGROUND

Persons who use serotonin reuptake inhibitors (SSRIs) seem to be at increased risk of having serious upper gastrointestinal bleeding. In vitro studies have shown that SSRIs inhibit platelet aggregation. It remains unknown if SSRIs have a direct ulcerogenic effect.

AIM

To investigate if there is a possible association between use of SSRIs and uncomplicated peptic ulcers.

METHODS

A population-based case-control study was conducted in the county of Funen, Denmark, using local prescription database and patient register. The 4862 cases all had a first diagnosis of uncomplicated peptic ulcers from 1995 to 2009. Controls (n = 19 448), matched for age and gender, were selected by risk-set sampling.

RESULTS

The adjusted odds ratios (OR) of uncomplicated peptic ulcers among current, recent and past users of SSRIs were 1.50 (95% CI 1.18-1.90), 1.56 (95% CI 0.98-2.49) and 1.32 (95% CI 1.08-1.61). There was no association with tricyclic antidepressants [OR 0.94 (95% CI 0.65-1.35)]. The adjusted OR for the SSRI-uncomplicated peptic ulcers association was 0.76 (95% CI 0.46-1.25) among users of proton pump inhibitors.

CONCLUSIONS

Use of SSRI is associated with uncomplicated peptic ulcers, possibly by some effect on the healing process. We cannot exclude some effects of residual confounding or bias by frequent physician contact.

An association between selective serotonin reuptake inhibitor use and serious upper gastrointestinal bleeding

BACKGROUND & AIMS

In vitro studies have shown that selective serotonin reuptake inhibitors (SSRIs) inhibit platelet aggregation. It is controversial whether use of SSRIs is a cause of clinically important bleeding; results from observational studies have been equivocal.

METHODS

A population-based case-control study was conducted in Denmark. The 3652 cases all had a first discharge diagnosis of serious upper gastrointestinal bleeding (UGB) from 1995 to 2006. Controls (n = 36,502), matched for age and sex, were selected by risk-set sampling. Data on drug exposure and medical history were retrieved from a prescription database and the county's patient register. Confounders were controlled for by conditional logistic regression and the case-crossover design.

RESULTS

The adjusted odds ratio (OR) of UGB among current, recent, and past users of SSRIs was 1.67 (95% confidence interval [CI], 1.46-1.92), 1.88 (95% CI, 1.42-2.5), and 1.22 (95% CI, 1.07-1.39). The adjusted OR for concurrent use of SSRI and nonsteroidal anti-inflammatory drugs (NSAIDs) was 8.0 (95% CI, 4.8-13). The adjusted OR for the concurrent use of NSAID, aspirin, and SSRI was 28 (95% CI, 7.6-103). Of the UGB cases, 377 were current users of SSRI; the adjusted OR for UGB in the case crossover analysis was 2.8 (95% CI, 2.2-3.6). The adjusted OR among users of proton pump inhibitors was 0.96 (95% CI, 0.50-1.82).

CONCLUSIONS

Use of SSRI was associated with UGB, consistent with its antiplatelet effects. SSRIs should be prescribed with caution for patients at high risk for UGB.

Serotonin stimulates platelet receptor shedding by tumor necrosis factor-alpha-converting enzyme (ADAM17)

BACKGROUND

Peripheral serotonin (5-hydroxytryptamine, 5-HT) is transported by platelets and released upon stimulation. In the platelet cytoplasm, 5-HT is transamidated to small GTPases, promoting alpha-granule release and primary hemostasis.

OBJECTIVE

We hypothesized that 5-HT could also stimulate platelet receptor shedding after binding to the membrane 5-HT receptor (5-HT2AR).

METHODS

Western blot and flow cytometry were used to determine levels of the adhesion receptor glycoprotein (GP)Ibalpha on platelets or its shed fragment glycocalicin in plasma and serum from wild-type mice, Tph1(-/-) mice lacking peripheral 5-HT, and mice lacking functional tumor necrosis factor-alpha-converting enzyme (TACE, ADAM17). Flow chamber experiments and intravital microscopy were used to examine the adhesive properties of platelets after stimulation of 5-HT2AR.

RESULTS

Glycocalicin was significantly reduced in Tph1(-/-) plasma and serum. In isolated platelets, 5-HT induced shedding of GPIbalpha, which was increased to 60% when 5-HT uptake was inhibited by the selective serotonin reuptake inhibitor fluoxetine. Specific 5-HT2AR agonism and antagonism suggested activation of this receptor. The shedding could not be induced in TACE(DeltaZn/DeltaZn) platelets, suggesting that activated TACE mediated the shedding of GPIbalpha. Intracellular signaling involved phosphorylation of p38 mitogen-activated protein kinase rather than G-protein signaling. 5-HT2AR stimulation decreased platelet adhesion to collagen-bound von Willebrand factor under arterial shear (1500 s(-1)) and incorporation into FeCl3-induced thrombi in mesenteric arterioles.

CONCLUSIONS

Stimulation of 5-HT2AR on platelets induces TACE-mediated shedding of GPIbalpha, the key adhesion molecule under high shear conditions. Our observations demonstrate a new pathway through which 5-HT could modulate cardiovascular disease.

Serotonin (5-HT) transporter ligands affect plasma 5-HT in rats

Dual dopamine (DA)/serotonin (5-HT)-releasing agents are promising candidate medications for stimulant addiction and other disorders. However, certain 5-HT transporter (SERT) substrates are associated with development of idiopathic pulmonary arterial hypertension (IPAH) and valvular heart disease (VHD). According to the "5-HT hypothesis," SERT substrates increase the risk for developing IPAH and VHD by increasing plasma 5-HT. To test this hypothesis directly, we determined the effects of acute and chronic fenfluramine, and other SERT ligands, on plasma 5-HT in male rats. For acute treatments, rats received i.v. vehicle or test drug (0.3 and 1.0 mg/kg), and serial blood samples were withdrawn. For chronic treatments, vehicle or test drug was infused via osmotic minipump (3 and 10 mg/kg/d) for 2 weeks. On the last day of infusion, rats received i.v. fenfluramine challenge (1 mg/kg), and serial blood samples were withdrawn. Plasma 5-HT was measured using ex vivo microdialysis in whole-blood samples. Baseline plasma 5-HT was <1.0 nM. Acute injection of fenfluramine or other SERT substrates caused large (up to 24-fold) dose-dependent increases in plasma 5-HT. Chronic fenfluramine at 3 and 10 mg/kg/d produced 1.7- and 3.5-fold increases in baseline plasma 5-HT, while chronic fluoxetine had no effect. Chronic infusions of fenfluramine or fluoxetine diminished the ability of acute fenfluramine to elevate dialysate 5-HT, and both drugs markedly reduced whole-blood 5-HT. Acute fenfluramine increases plasma 5-HT to concentrations that are below the micromolar levels necessary to produce adverse cardiovascular effects. Chronic fenfluramine and fluoxetine have minimal effects on plasma 5-HT, suggesting that the increased risk for IPAH associated with fenfluramine does not depend upon elevations in plasma 5-HT.

Antidepressants and risk of upper gastrointestinal bleeding

Selective serotonin reuptake inhibitors (SSRIs) are nowadays the most widely used antidepressants in the world, mainly because they have a better adverse reaction profile and a higher safety margin in overdoses, when compared to other antidepressants. These drugs recently have been the target of important debates concerning safety issues, among them the possibility that they may increase the risk of bleeding. Over the 1990s, an increasing number of individual cases of bleeding disorders were reported in the literature and to the pharmacovigilance programmes which prompted several epidemiological and pharmacological studies. In this review we have examined all available data. The whole evidence supports the hypothesis that antidepressants with a relevant blockade action on serotonin reuptake mechanism increase the risk of bleeding. Such disorders may have different degrees of severity and may be located anywhere in the body. The epidemiological evidence is, however, more robust for upper gastrointestinal bleeding. It has been estimated that upper gastrointestinal bleeding may occur at a frequency ranging from 1 in 100 to 1 in 1,000 patient-years of exposure to high-affinity drugs (the SSRIs), with the very old patients being in the highest part of the range. The increased risk may be of particular relevance when the SSRIs are associated with NSAIDs as well as low-dose aspirin.

SSRIs and upper gastrointestinal bleeding: what is known and how should it influence prescribing?

SSRIs have achieved a high usage rate in the treatment of depression because of a similar efficacy to TCAs and a favourable safety and tolerability profile. However, SSRI use has been associated with bleeding. We reviewed the epidemiological evidence on the association between SSRI use alone and the risk of upper gastrointestinal bleeding, and on synergistic effects reported with other commonly used drugs that can also cause bleeding.A literature search identified four studies of SSRI use and risk for upper gastrointestinal bleeding and a further two studies of SSRI use and bleeding in general, including upper gastrointestinal bleeding. The available evidence indicates quite convincingly that SSRI use may play a causal role in upper gastrointestinal bleeding and that these drugs may act synergistically with other bleeding risk-increasing medications such as NSAIDs or low-dose aspirin. Assuming a causal role of SSRIs, reported excess gastrointestinal bleedings attributable to SSRI use was reported to be 3.1 per 1000 treatment years, 4.1 per 1000 treatment years among octogenarians and 11.7 per 1000 treatment years among persons with prior upper gastrointestinal bleeding. These non-negligible risks warrant that prescribing doctors consider strategies on the individual level to reduce the likelihood of an upper gastrointestinal adverse event. Patients at particular risk include those with previous ulcers or gastrointestinal bleeding, the elderly and those with certain concurrent illnesses and/or high-risk comedications. Suggested strategies include alternatives to SSRI use, prescribing of less gastrotoxic NSAIDs or co-prescribing of gastroprotective drugs. Patients should be informed about the likelihood of possible upper gastrointestinal bleeding and high-risk patients should be followed closely.

Platelets and anti-platelet therapy

Platelets play a central role in the hemostatic process and consequently are similarly involved in the pathological counterpart, thrombosis. They adhere to various subendothelial proteins, exposed either by injury or disease, and subsequently become activated by the thrombogenic surface or locally produced agonists. These activated platelets aggregate to form a platelet plug, release agonists which recruit more platelets to the growing thrombus, and provide a catalytic surface for thrombin generation and fibrin formation. These platelet-rich thrombi are responsible for the acute occlusion of stenotic vessels and ischemic injury to heart and brain. A range of anti-platelet drugs are currently used, both prophylactically and therapeutically, in regimens to manage thrombo-embolic disorders. These include inhibitors of the generation, or effects, of locally produced agonists; several large clinical trials have supported roles for cyclooxygenase inhibitors, which prevent thromboxane generation, and thienopyridine derivatives, which antagonize ADP receptors. Similarly intravenous alpha IIb beta 3 antagonists have been shown to be effective anti-thrombotics, albeit in highly selective situations; in contrast, to date studies with their oral counterparts have been disappointing. Recent advances in understanding of platelet physiology have suggested several novel, if yet untested, targets for anti-platelet therapy. These include the thrombin receptor, the serotonin handling system, and the leptin receptor.

Maternal fluoxetine treatment in the postpartum period: effects on platelet serotonin and plasma drug levels in breastfeeding mother-infant pairs

OBJECTIVE

Postpartum major depression, a frequently (10%) occurring complication of childbirth, adversely affects the mother's functioning, the mother-infant relationship, and the child's subsequent development and propensity for later psychopathology. Although selective serotonin reuptake inhibitors (SSRIs) are effective in treating postpartum depression, concerns have been raised regarding their use in lactating women. Although plasma drug levels of infants who are exposed to SSRIs through breast milk are low compared with those typically seen in patients, infant levels in some reports do seem to be at or near the drugs' reported affinities (K(D)s) and IC(50)s for inhibition at the serotonin (5-hydroxytryptamine [5-HT]) transporter. The impact of central serotonin 5-HT modulation by SSRIs during critical periods of brain development is unknown. These concerns have led our group to examine whether exposure through breast milk has a discernible effect on platelet 5-HT uptake. Taking advantage of the similarities between platelet and neuronal serotonin transporters, we previously used measurements of platelet 5-HT before and during maternal sertraline treatment to determine the degree of 5-HT transporter blockade in breastfed infants. We found that infants who were exposed to sertraline through their mothers' breast milk experienced little to no change in platelet 5-HT levels, suggestive of minimal effects on peripheral and central 5-HT transporter blockade. Compared with sertraline and most other SSRIs, fluoxetine and its active metabolite, norfluoxetine, have substantially longer plasma half-lives, and both compounds have been found in measurable quantities in plasma of nursing infants. Thus, to extend our previous work in this area, we measured platelet 5-HT levels and plasma drug levels in breastfeeding mother-infant pairs before and during maternal treatment with fluoxetine.

METHODS

Maternal and infant transporter blockade was assessed by measurement of platelet 5-HT in 11 breastfeeding mother-infant pairs before and after 4 to 12 weeks of maternal fluoxetine (20-40 mg/d) treatment for postpartum depression. The study was approved by the Human Investigation Committee of Yale University School of Medicine, and each mother (mean age: 34.5 years; standard deviation [SD]: 5.3) gave written informed consent. Whole-blood 5-HT levels and plasma fluoxetine and norfluoxetine levels were determined by high-performance liquid chromatography.

RESULTS

Five mothers were taking 20 mg of fluoxetine daily, 4 were taking 30 mg daily, and 2 were taking 40 mg daily. Mean infant age at the start of the study was 16.8 (SD: 8.8) weeks. All infants except 1 were <6 months of age and 4 were <3 months of age when their mothers began treatment. Six infants were breastfed exclusively; the remaining were breastfed between 3 and 8 times daily and were given supplemental feedings. Mean maternal postexposure 5-HT levels of 22.9 ng/mL (SD: 12.5) were markedly lower than mean preexposure (baseline) levels of 156.6 ng/mL (SD: 71.4; paired t = 6.9, df = 10). In contrast, the mean infant pre- and postexposure 5-HT concentrations of 217.1 (SD: 66.5) and 229.9 (SD: 83.5) ng/mL, respectively, were similar (paired t = -0.24, df = 10). However, the 1 infant with measurable plasma fluoxetine had a substantial decline in 5-HT to 40% of baseline. In samples obtained from the same infant 4 months later, plasma drug levels were undetectable (<1 ng/mL) and the platelet serotonin levels were no longer reduced (12% increase from baseline).

CONCLUSIONS

The marked declines (to 9%-28% of baseline) in platelet 5-HT concentrations seen in mothers who were treated with the SSRI fluoxetine were similar to those observed in our study of sertraline in breastfeeding and other previous studies. In contrast, all but 1 infant experienced little or no decline in whole-blood (platelet) 5-HT concentrations after exposure to fluoxetine through breast milk. The substantial drop in platelet 5-HT seen in 1 infant and the coupling of this drop with measurable plasma fluoxetine leves drop with measurable plasma fluoxetine level raises some concern. Possible reasons for the infant's measurable plasma fluoxetine level include his mother's high plasma drug level and his being breastfed exclusively. However, the observations may be coincidental, and the infant experienced no discernible adverse effects. These data suggest that most infants may continue to breastfeed without experiencing meaningful changes in platelet 5-HT transport while their mothers are treated with 20 to 40 mg of fluoxetine daily. Given the limited data regarding occurrence and extent of SSRI exposure and the uncertainties concerning the possible effects of exposure, it is premature to propose treatment guidelines. Our own advice to women who are thinking of combining breastfeeding and SSRI treatment will weigh a range of factors, including severity of postpartum depression, any demonstrated preferential response to a specific SSRI, and the mother's commitment to breastfeeding. Additional research is needed to establish more definitively the frequency of physiologically meaningful infant SSRI exposure during breastfeeding and to determine the behavioral consequences of such exposure.

The effects of paroxetine and tianeptine on peripheral biochemical markers in major depression

Depression is related to the alterations of the central serotonergic system and some antidepressants achieve their therapeutic effects through alteration of serotonin (5-HT) (re)uptake. Peripheral biochemical markers, platelet and serum 5-HT concentrations, platelet monoamine oxidase (MAO) activity, plasma levels of cortisol and prolactin (PRL), were investigated in patients with major depression before and after 4 weeks of treatment with paroxetine (an inhibitor of 5-HT uptake) or tianeptine (a stimulator of 5-HT uptake). Study was open, single center and included female depressed patients, 21 treated with tianeptine (37.5 mg/day) and 15 treated with paroxetine (20 mg/day), and 11 drug-free healthy women (controls). Before treatment, depressed patients as a group had significantly higher serum 5-HT and cortisol concentrations than healthy controls. There were no differences in the other biochemical markers. Response to antidepressant treatment was estimated according to the 50% fall in the initial scores of Hamilton Depression Rating Scale (HAMD) after 4 weeks of treatment. Good therapeutic response was observed in 47% and 45% patients treated with paroxetine and tianeptine, respectively. Paroxetine treatment induced significant decrease in platelet 5-HT concentrations in both responders and nonresponders, while no alterations in platelet 5-HT values were found in tianeptine-treated patients. There was a subgroup of depressed patients in paroxetine-treated group with high pretreatment platelet 5-HT concentration and later poor therapeutic response to paroxetine treatment. Serum 5-HT values, platelet MAO activity or plasma cortisol or PRL levels were unchanged after both treatments. The results suggest that pretreatment platelet 5-HT levels, but not other peripheral biochemical markers, might predict therapeutic outcome at least in paroxetine-treated patients.

Stimulated platelets use serotonin to enhance their retention of procoagulant proteins on the cell surface

Activated platelets bind numerous adhesive and procoagulant proteins by receptor-mediated processes. Although there is little evidence to suggest that these processes are heterogeneous in platelets, we previously found that platelets co-stimulated with collagen and thrombin express functional alpha-granule factor V only on a subpopulation of cells. Here we show that these cells, referred to as 'COAT-platelets', bind additional alpha-granule proteins, including fibrinogen, von Willebrand factor, thrombospondin, fibronectin and alpha2-antiplasmin. These proteins are all transglutaminase substrates, and inhibitors of transglutaminase prevent the production of COAT-platelets. A synthetic transglutaminase substrate (CP15) also binds to COAT-platelets, and analysis by high performance liquid chromatography/mass spectrometry shows that a product is formed with a relative molecular mass (Mr) equal to CP15 plus 176. Serotonin, an abundant component of platelet-dense granules, has an Mr of 176, and fibrinogen isolated from COAT-platelets contains covalently linked serotonin. Synthetic bovine serum albumin-(serotonin)6 binds selectively to COAT-platelets and also inhibits the retention of procoagulant proteins on COAT-platelets. These data indicate that COAT-platelets use serotonin conjugation to augment the retention of procoagulant proteins on their cell surface through an as yet unidentified serotonin receptor.

Evidence that serotonin affects female sexual functioning via peripheral mechanisms

A review of the literature indicates that serotonin is active in several peripheral mechanisms that are likely to affect female sexual functioning. Serotonin has been found in several regions of the female genital tract in both animals and humans. In the central nervous system (CNS), serotonin acts primarily as a neurotransmitter, but in the periphery, serotonin acts primarily as a vasoconstrictor and vasodilator. Since, in the periphery, the principal component of sexual arousal is vasocongestion of the genital tissue, it is likely that serotonin participates in producing normal sexual arousal. In addition, serotonin administration produces contraction of the smooth muscles of the genito-urinary system and is found in nerves innervating the sexual organs. Taken together, this evidence suggests that peripheral serotonergic activity may be involved in the normal sexual response cycle. In addition, exogenous substances that alter serotonin activity, such as selective serotonin uptake inhibitors (SSRIs) and the atypical antipsychotics, can produce sexual dysfunction. It is possible that sexual side effects seen with these drugs may result, at least in part, from their action on peripheral mechanisms.

Intracranial haemorrhage and use of selective serotonin reuptake inhibitors

AIMS

In the past few years an increasing number of bleeding disorders have been reported in association with the use of selective serotonin reuptake inhibitors (SSRIs), including serious cases of intracranial haemorrhage, raising concerns about the safety of this class of drugs. The present study was performed to test the hypothesis of an increased risk of intracranial haemorrhage associated with the use of SSRIs.

METHODS

We carried out a case-control study nested in a cohort of antidepressants users with the UK-based General Practice Research Database (GPRD) as the primary source of information. The study cohort encompassed subjects aged between 18 and 79 years who received a first-time prescription for any antidepressant from January, 1990 to October, 1997. Patients with presenting conditions or treatments that could be associated with an increased risk of intracranial haemorrhage were excluded from the cohort. Patients were followed-up until the occurrence of an idiopathic intracranial haemorrhage. Up to four controls per case, matched on age, sex, calendar time and practice were randomly selected from the study cohort. We estimated adjusted odds ratios and 95% confidence intervals of intracranial haemorrhage with current use of SSRIs and other antidepressants as compared with nonuse using conditional logistic regression.

RESULTS

We identified 65 cases of idiopathic intracranial haemorrhage and 254 matched controls. Current exposure to SSRIs was ascertained in 7 cases (10. 8%) and 24 controls (9.7%) resulting in an adjusted OR (95%CI) of 0. 8 (0.3,2.3). The estimate for 'other antidepressants' was 0.7 (0.3,1. 6). The effect measures were not modified by gender or age. No effect related to dose or treatment duration was detected. The risk estimates did not change according to the location of bleeding (intracerebral or subarachnoid).

CONCLUSIONS

Our results are not compatible with a major increased risk of intracranial haemorrhage among users of SSRIs or other antidepressants at large. However, smaller but still relevant increased risks cannot be ruled out.

Association between selective serotonin reuptake inhibitors and upper gastrointestinal bleeding: population based case-control study

OBJECTIVE

To examine the association between selective serotonin reuptake inhibitors and risk of upper gastrointestinal bleeding.

DESIGN

Population based case-control study.

SETTING

General practices included in the UK general practice research database.

SUBJECTS

1651 incident cases of upper gastrointestinal bleeding and 248 cases of ulcer perforation among patients aged 40 to 79 years between April 1993 and September 1997, and 10 000 controls matched for age, sex, and year that the case was identified.

INTERVENTIONS

Review of computer profiles for all potential cases, and an internal validation study to confirm the accuracy of the diagnosis on the basis of the computerised information.

MAIN OUTCOME MEASURES

Current use of selective serotonin reuptake inhibitors or other antidepressants within 30 days before the index date.

RESULTS

Current exposure to selective serotonin reuptake inhibitors was identified in 3.1% (52 of 1651) of patients with upper gastrointestinal bleeding but only 1.0% (95 of 10 000) of controls, giving an adjusted rate ratio of 3.0 (95% confidence interval 2.1 to 4.4). This effect measure was not modified by sex, age, dose, or treatment duration. A crude incidence of 1 case per 8000 prescriptions was estimated. A small association was found with non-selective serotonin reuptake inhibitors (relative risk 1.4, 1.1 to 1.9) but not with antidepressants lacking this inhibitory effect. None of the groups of antidepressants was associated with ulcer perforation. The concurrent use of selective serotonin reuptake inhibitors with non-steroidal anti-inflammatory drugs increased the risk of upper gastrointestinal bleeding beyond the sum of their independent effects (15.6, 6.6 to 36.6). A smaller interaction was also found between selective serotonin reuptake inhibitors and low dose aspirin (7.2, 3.1 to 17.1).

CONCLUSIONS

Selective serotonin reuptake inhibitors increase the risk of upper gastrointestinal bleeding. The absolute effect is, however, moderate and about equivalent to low dose ibuprofen. The concurrent use of non-steroidal anti-inflammatory drugs or aspirin with selective serotonin reuptake inhibitors greatly increases the risk of upper gastrointestinal bleeding.

The acute effects of dexfenfluramine on human and porcine pulmonary vascular tone and resistance

STUDY OBJECTIVES

Treatment with anorectics has become an important aspect of care for the severely obese. One such anorectic, the phenylethylamine dexfenfluramine (dFen), has been associated with the development of pulmonary hypertension. It works by reducing the neuronal uptake of 5-hydroxytryptamine (5-HT; serotonin) through inhibition of the 5-HT transporter. In this study we investigated whether dFen has a direct vasoconstrictor action on human and porcine pulmonary vasculature.

DESIGN

For the human study, tissue was obtained from patients who had undergone lung and heart-lung transplantation. The effect of dFen was studied in seven isolated colloid perfused human lungs and in rings of human pulmonary artery (PA) dissected from the lungs of a further 19 patients. For the porcine study, regional pulmonary vascular resistances (PVRs) were measured in isolated perfused porcine lungs. Vasoconstriction was assessed following dFen alone and in combination with hypoxia, cyclo-oxygenase blockade (indomethacin, 10(-5) mol/L), or nitric oxide synthase (NOS) blockade (N(G)-nitro-L-arginine, 10(-5) mol/L).

RESULTS

In the human study, 5-HT and dFen caused only limited increases in tension of isolated rings of PA. The concentration of dFen, 10(-4) mol/L, that was needed to increase tension was higher than that found normally in treated patients where peak levels are 3. 3 x 10(-7) mol/L. Other vasoconstrictors such as prostaglandin F(2)alpha, 10(-5) mol/L, and the thromboxane analog U46619, 10(-6) mol/L, produced far greater increases in tension. Ketanserin, 10(-4) mol/L, attenuated the constrictor response to 5-HT but had no effect on the constrictor response to dFen. Removal of the endothelium did not influence the response to dFen. In the isolated ventilated and perfused lungs, dFen caused an increase in PVR again only at a comparatively high concentration, 10(-4) mol/L. In the porcine study, dFen, 10(-4) mol/L, did not increase any PVR during normoxia or following NOS blockade. Small insignificant increases in PVR occurred during hypoxia and after cyclo-oxygenase blockade.

CONCLUSION

These results do not support the view that dFen would act as a direct vasoconstrictor when given in the usual doses. However, delayed elimination of dFen could raise tissue concentrations to high levels and give rise to vasoconstriction and pulmonary hypertension.

Platelet serotonin transporter in depressed children and adolescents: 3H-paroxetine platelet binding before and after sertraline

OBJECTIVE

To evaluate serotonin transporter protein (5HTPR) binding in platelets from children and adolescents with major depression (MDD) compared to normal controls using the selective ligand 3H-paroxetine.

METHOD

Children and adolescents with MDD (n = 24) defined by DSM-III-R criteria and normal controls (n = 22) were compared by platelet 5HTPR kinetic analysis with the hypothesis that 5HTPR is reduced in MDD. A subset of MDD subjects (n = 18) continued to participate in a fixed-dose, open-label sertraline trial for 6 weeks followed by drug-free washout and repeated 5HTPR analysis.

RESULTS

Sex, prepubertal status, and age had no effect on 5HTPR. Medication-free MDD subjects differed from controls in reduced binding capacity (Bmax) (p < .001). Sertraline therapy decreased binding affinity from baseline non-selectively (p < .05), and Bmax elevation from baseline was associated with nonresponse and suicide attempt history.

CONCLUSION

Earlier literature in this population is replicated with regard to reduced platelet 5HTPR Bmax in MDD. Findings support a continuum of 5HTPR involvement in MDD across the developmental spectrum.

Serotonin transporter-blocking properties of nefazodone assessed by measurement of platelet serotonin

This study aims to determine whether the newly introduced serotonin type 2 (5-HT2) antagonist nefazodone has serotonin (5-HT) transporter-blocking properties at clinical doses in depressed patients. Change in platelet 5-HT was used as an index of the cumulative peripheral 5-HT uptake blockade produced by nefazodone and selective serotonin reuptake inhibitors (SSRIs). Platelet 5-HT was measured before and during treatment with nefazodone (N = 6) or an SSRI (N = 10) in patients with major depression. Corresponding Hamilton Rating Scale for Depression (HAM-D) scores were also obtained over the course of the study. The results of the study demonstrated that the decrease from mean baseline platelet 5-HT after SSRI treatment was significantly greater than the change after nefazodone treatment (-88% vs. -3%; Mann-Whitney U-test, p = 0.0002). Pretreatment platelet 5-HT level, posttreatment platelet 5-HT level, nor the percent decrease in platelet 5-HT correlated with the percent change in HAM-D scores in either treatment group. In conclusion, therapeutic doses of nefazodone do not cause sustained 5-HT uptake inhibition at the platelet 5-HT transporter.

Demonstration of clomipramine and venlafaxine occupation at serotonin reuptake sites in man in vivo

We describe the use of 11CRTI-55 and the Multiple Objects Coincidences Counter (MOCC) to detect in-vivo binding to peripheral serotonin reuptake sites (left chest comprising platelet and lung serotonin reuptake sites) in man. Displacement and preloading experiments with clomipramine and venlafaxine in two healthy volunteers demonstrated that 11CRTI-55 binding is decreased in a dose-dependent fashion by both these drugs which bind to the serotonin transporter. In addition parallel data from the total head curve (representing 11CRTI-55 binding to central serotonin and dopamine (DA) reuptake sites) suggest that prior blockade of the serotonin transporter may be a useful strategy to maximize radioactive counts in the head when measuring the DA transporter. The MOCC is likely to be useful to determine sequential indices of relative serotonin reuptake blockade in patients on treatment.

Effects of selective serotonin reuptake inhibitors on platelet serotonin parameters in major depressive disorder

The effects of treatment with serotonin (5-HT) reuptake inhibitors on platelet 5-HT2 receptors, 5-HT reuptake sites an 5-HT uptake were studied in a double-blind trial comparing two selective serotonin reuptake inhibitors (SSRI), paroxetine, and fluoxetine, for the treatment of major depression. Hamilton Depression Rating Scale (HAM-D) scores and platelet 5-HT parameters were determined in 21 depressed patients at baseline, after 4 and 8 weeks of treatment, and were compared to 21 healthy controls. Antidepressant treatment did not significantly alter the density of 5-HT reuptake sites, labelled with [3H]paroxetine, or 5-HT2 receptors, labelled with [3H]LSD. However, a strong correlation was observed between the HAM-D suicidality item and 5-HT2 receptor density at baseline. A marked increase in platelet 5-HT2 receptors at baseline was observed in suicidal depressed patients compared to those with no suicidal ideation and healthy controls. Changes in [3H]paroxetine Bmax and in [3H]5-HT uptake significantly correlated with change in HAM-D score at 4 and 8 weeks respectively. These results confirm previous reports of an association between suicidality and platelet 5-HT2 receptor upregulation. Our data also lends support to the use of platelet 5-HT parameters as indicators of antidepressant efficacy, particularly in suicidal depressed patients.

Is platelet imipramine binding reduced in depression? A meta-analysis

Although it has been suggested that decreased platelet imipramine binding may be a putative biological marker of depressive illness, a number of studies have not confirmed this finding, including a recent multicenter investigation by the World Health Organization (Mellerup and Langer 1990). We performed a meta-analysis of published reports on imipramine binding in groups of depressed and healthy control subjects and found that there was a highly significant decrease in Bmax (maximal binding) values in the depressed subject groups, which was even greater among those who had been free of medication for 4 weeks at the time of investigation. This finding remained highly significant even when only high affinity binding studies (Kd < 1 nmol/L) were considered, although the absolute size of this decrease was smaller.

Plasma 5-hydroxyindoleacetic acid as an indicator of monoamine oxidase-A inhibition in rat brain and peripheral tissues

We have examined the changes induced by the monoamine oxidase (MAO; EC 1.4.3.4) inhibitors tranylcypromine, clorgyline, and deprenyl on MAO activity and 5-hydroxytryptamine (serotonin, 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content in rat brain and blood (plasma and whole blood). The decreases of MAO-A activity observed in the liver and lungs after different doses of clorgyline or tranylcypromine correlated significantly (r > 0.80 in all cases) with the decline of plasma 5-HIAA. This was unaffected by 0.25 and 5 mg kg-1 of deprenyl, indicating that 5-HT was deaminated exclusively in the periphery by MAO-A. It is interesting that very potent and significant correlations (r > 0.75) were found between plasma 5-HIAA and MAO-A activity, 5-HIAA and 5-HT content in brain tissue. These results suggest that plasma 5-HIAA can be used confidently as a peripheral indicator of the inhibition of MAO-A in brain. This may represent a favorable alternative to the analysis of 5-HIAA in CSF in psychiatric patients undergoing antidepressant treatment with nonspecific MAO inhibitors or with the new selective MAO-A inhibitors.

Effects of the antidepressant drug tianeptine on plasma and platelet serotonin of depressive patients and healthy controls

We have examined the effects of a single 12.5 mg dose and of 12 weeks treatment up to 37.5 mg daily with tianeptine, a new antidepressant drug that potentiates in vivo the uptake of serotonin (5-HT). On day 0, tianeptine reduced plasma 5-HT concentration. This acute effect occurred also on subsequent examination days. However, long-term treatment tended (P < 0.06) to increase basal plasma 5-HT concentrations, in covariation with decreases of MADRS (Montgomery-Asberg Depression Rating Scale) and HARS (Hamilton Anxiety Rating Scale). Platelet 5-HT increased only in elderly patients, probably due to the higher plasma concentration of the drug in this group than in younger patients. These results show that the acute effects of therapeutic doses of tianeptine are consistent with an enhancement of the 5-HT uptake. However, long-term treatment does not result in a decreased plasma 5-HT, as might be expected from the acute effects of the drug.

Effects of acute and chronic treatment with fluvoxamine on extracellular and platelet serotonin in the blood of major depressive patients. Relationship to clinical improvement

The effects of the treatment with fluvoxamine (FVX) on platelet and plasma serotonin (5-HT) have been examined in eleven drug-free major depressive patients. Acute FVX was without effect, whereas the repeated oral treatment (100-150 mg daily, 12 weeks) reduced platelet 5-HT (-89%, P less than 0.001) and plasma 5-HT (-60%, P less than 0.02). Patients who responded to the treatment at 6 weeks (Hamilton score less than or equal to 10) had significantly lower (-39%, P less than 0.02) pretreatment values of platelet 5-HT than the rest. This suggests that 'low 5-HT' patients may have a more rapid improvement after fluvoxamine. Platelet 5-HT and HDRS correlated significantly along the treatment (r = 0.679, P less than 0.01). These data demonstrate a marked action of fluvoxamine as 5-HT uptake inhibitor at therapeutic doses and confirm that this mechanism is relevant for its efficacy as antidepressant drug.

Platelet 3H-imipramine binding during recovery from depression

Decreased binding of tritiated imipramine to platelets has been considered to be a potential biological marker of depression. However, it has been unclear how binding values alter during treatment and recovery. This study investigated imipramine binding parameters and depressive symptoms in 25 patients suffering from major depression at entry to the study and 1, 3 and 6 months later. Although the initial Bmax values were significantly lower in the depressed patients than in healthy subjects, it was not possible to establish a clear relationship between recovery from depression and Bmax. The power of this study to detect an effect of at least 10% of the variance in Bmax due to factors related to recovery from depression was 0.78.

Effect of antidepressant treatment on platelet 5-HT content and relation to therapeutic outcome in unipolar depressive patients

Platelet 5-HT levels and scores on the 17-item Hamilton Rating Scale for Depression (HRS) were studied in patients with unipolar depression before and after antidepressant treatment. Before treatment there were no differences in platelet 5-HT values or in HRS scores between patients who showed a good and a poor therapeutic response. Repeated administration of 5-HT uptake inhibitors (amitriptyline, clovoxamine, fluvoxamine) for 28 days markedly decreased platelet 5-HT levels. Chronic treatment with trazodone or maprotiline (weak inhibitors of platelet 5-HT uptake) produced no changes in platelet 5-HT levels. No significant correlation was observed between platelet 5-HT concentrations and the HRS scores before or during treatment. The findings suggest that the changes in platelet 5-HT levels after antidepressant treatment are mainly due to the effects of antidepressants on the 5-HT uptake system.

Aggression, hyperactivity and platelet imipramine binding

We measured platelet 3H-imipramine binding parameters in 16 subjects affected by different types of mental deficiency, all characterized by hyperactive and/or aggressive behaviour, and in 16 healthy controls. The patients had a lower maximum binding capacity than the controls, with no difference in Kd, irrespectively of the type of mental disorder. These findings suggest a link between 5-HT disturbances, reflected by reduced imipramine binding sites, and behavioural dyscontrol, expressed as hyperactivity and aggression.