5-HTT基因多态性与SSRIs,SNRIs类抗抑郁药治疗抑郁症临床疗效的关系研究

目的研究中国人群中5-HTT基因多态性与抑郁症及SSRIs和SNRIs类药物临床疗效是否存在相关性。方法用聚合酶链式反应多态性分析(PCR)技术对148例抑郁症患者和100例健康者进行基因型分析;用HAMD量表评定抗抑郁药的疗效。结果抑郁症5-HTT基因型频率(LL 24.3％,LS 44.6％,SS 31.1％)、等位基因频率(L 46.6％,S 53.4％)与正常对照组基因型频率(LL29.0％,LS 47.0％,SS 24.0％)、等位基因频率(L 52.5％,S 47.5％)比较没有显著性差异(P>0.05);不同基因型抑郁症患者治疗前,HAMD总分有显著差异(P<0.01);经4周SSRIs和SNRIs类抗抑郁药治疗后,HAMD总分均显著下降,减分值有显著差异(P<0.05)。结论中国人群中5-HTT基因多态性与抑郁症的发病不存在相关性,但与抑郁症疾病严重程度和抗抑郁药治疗效存在显著的相关性,这一区域的基因型可能成为抑郁症患者实现个体化治疗的一个参考指标。     

Evidence of a role for the 5-HTTLPR genotype in the modulation of motor response to antidepressant treatment

Rationale Serotonergic mechanisms are thought to play an important role in the regulation of mood, motor activity and sleep patterns. Serotonin reuptake is controlled by the serotonin transporter (5-HTT) and by a common functional insertion/deletion polymorphism in the corresponding genes promoter region (5-HTTLPR). Homozygosity for the long variant may confer a favourable response to treatment with serotonin reuptake inhibitors (SSRIs), and to sleep deprivation.Objectives The study assessed the role of the 5-HTTLPR genotype in determining motor side effects of antidepressant medication.Methods Motor activity patterns of 62 patients with major depression who were being treated with either SSRIs or tricyclic antidepressants (TCAs) were monitored over a 24-h period using a wrist-actograph. Additionally, motor activity was rated in a semi-structured interview using the motor agitation and retardation scale (MARS).Results Night-time motor activity was significantly increased in homozygous carriers of the long 5-HTTLPR allele (LL-genotype) who were being treated with SSRIs in comparison to short allele carriers (LS-genotype and SS-genotype), regardless of the type of antidepressant treatment (P<0.001). It was also significantly increased in comparison to patients with the LL-genotype who were being treated with TCAs (P<0.01). Differences in actographic motor activity were most prominent between 11 p.m. and 4 a.m. Clinical ratings of motor activity also showed a trend toward higher agitation scores in patients with the LL-genotype who received SSRI treatment.Conclusions Homozygosity for the long variant of the 5-HTTLPR may cause a predisposition to increased night-time motor activity in conjunction with SSRI treatment.     

Longitudinal patterns of antidepressant prescribing in primary care in the UK: comparison with treatment guidelines.

The objective of this study was to determine whether patients beginning therapy on the most common tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) differed in their likelihood of having antidepressant treatment that was consistent with recommended treatment guidelines in the UK. An analytical file constructed from a large general practitioner medical records database (DIN-LINK) from the UK for the years 1992-97 was constructed. A total of 16,204 patients with a new episode of antidepressant therapy who initiated therapy on one of the most often prescribed TCAs (amitriptyline, dothiepin, imipramine and lofepramine) or SSRIs (fluoxetine, paroxetine and sertraline) were analysed. A dichotomous measure was defined to indicate whether subjects were prescribed at least 120 days of antidepressant therapy at an adequate average daily dose within the first 6 months after initiation of therapy. Only 6.0% of patients initiating therapy on aTCA and 32.9% of patients initiating therapy on a SSRI were prescribed antidepressant treatment that was consistent with treatment guidelines. After controlling for observable characteristics, patients who initiated therapy on a SSRI were much more likely (odds ratio=7.473, p<0.001) to have a prescribed average daily dose and duration consistent with recommended treatment guidelines within the first 6 months of initiating therapy than were patients who initiated therapy on a TCA. These findings suggest that initial antidepressant selection is an important determinant of whether the subsequent course of treatment is consistent with current national guidelines for the treatment of depression in the UK.     

5-羟色胺转运蛋白基因多态性与抗抑郁药临床疗效的关系

目的:研究南京地区人群中5-羟色胺转运蛋白(5-HTT)基因多态性与血浆5-羟色胺(5-HT)浓度及选择性5-羟色胺再摄取抑制剂(SSRIs)的抗抑郁临床疗效是否存在相关性。方法;采用聚合酶链式反应(PCR)多态性分析技术对132例抑郁症患者和100名健康者进行基因型分析;HPLC-ECD法分析血浆中5-HT浓度;用汉密尔顿抑郁量表(HAMD)评定抗抑郁药的疗效。结果:抑郁症5-HTT基因基因型频率(LL24.2％,LS44.7％,SS31.1％)、等位基因频率(L46.59％,S53.41％);与正常对照组基因型频率(LL29.0％,LS47.0％,SS24.0％)、等位基因频率(L52.5％,S47.5％)比较无显著性差异(P>0.05);不同基因型抑郁症患者治疗前HAMD总分有显著差异,F=6.48,P=0.0021:经4wk SSRIs类抗抑郁药治疗后,HAMD总分均显著下降,减分值有显著差异,F=3.38,P=0.037;治疗前不同基因型患者5-HT浓度有显著差异,F=5.38,P=0.005 7;4wk治疗后,血浆中5-HT浓度均升高,不同基因型的增高值有明显差异,F=23.55,P<0.01。结论:南京地区人群中5-HTT基因多态性与抑郁症的发病不存在相关性,但与抑郁症疾病严重程度和SSRIs治疗效应存在显著的相关性,这一区域的基因型可能成为抑郁症患者实现个体化治疗的一个参考指标。     

Serotonin transporter occupancy of high-dose selective serotonin reuptake inhibitors during major depressive disorder measured with [<Superscript>11</Superscript>C]DASB positron emission tomography

Rationale Previous work has shown 80% serotonin transporter (5-HTT) occupancy to be a consistent finding at the minimum therapeutic dose during selective serotonin reuptake inhibitor (SSRI) treatment. [¹¹C]N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine positron emission tomography ([¹¹C]DASB PET) is currently the best method available to quantify 5-HTT occupancy in humans. Objectives The purpose of the present study is to determine 5-HTT occupancy during high dose SSRI treatment using [¹¹C]DASB PET. Materials and methods Twelve healthy subjects and 12 subjects with major depressive disorder completed the protocol. Depressed subjects received one [¹¹C]DASB PET scan after a minimum of 4 weeks treatment at high doses of venlafaxine, sertraline, or citalopram. Baseline 5-HTT binding potential (BP) was taken as the average 5-HTT BP of the 12 healthy subjects. Results Mean striatal 5-HTT occupancy for each antidepressant group was approximately 85% at high therapeutic dose. This was significantly greater than 80% (one-sample t test; p < 0.04, venlafaxine group; p < 0.02, sertraline group; p < 0.01, citalopram group) for each high dose antidepressant group. Conclusions Significantly greater 5-HTT blockade at high dose provides a rationale for raising the dose from the minimum therapeutic dose in specific clinical circumstances. It is likely that 15% unoccupied 5-HTT remains, which should be addressed in future drug development.     

PET measurement of serotonin transporter occupancy: a comparison of escitalopram and citalopram

The selective serotonin reuptake inhibitor (SSRI) citalopram (R,S-citalopram) is a racemic compound of two enantiomers. On the basis of in-vitro studies, inhibition of the human serotonin transporter (5-HTT) is achieved by the S-enantiomer (S-citalopram or escitalopram). The aim of the present PET study was to compare 5-HTT occupancy after single equimolar doses (with respect to S-enantiomer) in humans in vivo using R,S-citalopram (20 mg) and S-citalopram (10 mg) using PET and the radioligand [(11)C]MADAM. The design was a single-dose, double-blind, two-way crossover study in eight healthy male subjects. The 5-HTT binding potential at baseline and after single doses of study drugs was used to calculate 5-HTT occupancy in seven brain regions. Serum concentrations of the study drugs were determined in order to calculate the apparent inhibition constant (K(i),(app)), a secondary parameter of interest for the comparison. In all brain regions examined, occupancy was numerically higher after treatment with R,S-citalopram [66+/-19% to 78+/-17% (mean+/-s.d.) depending on the region] than after S-citalopram (59+/-15% to 69+/-13%; overall comparison: F=14.8, d.f.=1, 90, p<0.001). In line with this the apparent inhibition constant was significantly lower for R,S-citalopram than for S-citalopram (overall comparison: F=6.7, d.f.=1, 90, p<0.05). The small but significant difference in occupancy and K(i),(app) found between R,S-citalopram and S-citalopram suggests that not only S-citalopram but also R-citalopram to some degree occupies the 5-HTT in the human brain in vivo.     

Serum levels and cardiovascular effects of tricyclic antidepressants and selective serotonin reuptake inhibitors in depressed patients

Tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs) are used to treat depression. Whereas cardiovascular effects have occasionally been reported during controlled studies with SSRIs, TCA treatment poses a well-known problem in this respect. To investigate the putative correlation between antidepressant dose or serum levels and adverse effects, the authors devised a naturalistic study to evaluate the tricyclic antidepressants' and SSRIs' effect on the cardiovascular system. The authors also compared antidepressant serum levels to adverse effects. Inpatients treated with TCAs or SSRIs were included; an electrocardiogram (ECG) and a Schellong test were carried out on the day patients entered the hospital and during steady-state treatment with antidepressant drugs when blood was drawn for therapeutic drug monitoring. The patient population consisted of 114 acutely depressed patients; 81 patients were treated with TCAs and 33 with SSRIs. The TCAs comprised amitriptyline (n = 43), clomipramine (n = 11), doxepin (n = 19) and imipramine (n = 8); the SSRIs comprised fluvoxamine (n = 14) and paroxetine (n = 19). In TCA-treated patients, the authors observed the same type of abnormalities in conduction and orthostatic hypotension as had been observed earlier. The authors also observed cases of first-degree atrioventricular block, prolonged QTc interval, and orthostatic hypotension in SSRI-treated patients. Thus SSRIs also appear to affect the cardiovascular system, which might pose a problem for patients with preexisting conduction disease. The authors observed a strong correlation between the decrease in systolic pressure and antidepressant serum concentration (except for clomipramine and paroxetine), suggesting that antidepressant serum level is a better correlate than dose.     

Monoamine transporter gene polymorphisms affect susceptibility to depression and predict antidepressant response

Rationale  Serotonin transporter (5-HTT) and norepinephrine transporter (NET) are the primary targets of many antidepressants. We aimed to determine the potential correlations of 5-HTT/NET gene polymorphisms with the susceptibility to depression and the antidepressant response to selective serotonin reuptake inhibitors (SSRIs) or dual selective serotonin/norepinephrine reuptake inhibitors (SNRIs). Methods  A total of 579 depressed patients and 437 healthy controls, all of Chinese Han region, were collected and genotyped by polymerase chain reactions (PCR). All patients were under treatment of SSRI or SNRI for 6 weeks, and were evaluated using a 17-item Hamilton Depression Rating Scale (HAMD). Results  Five hundred sixty-seven of 579 patients completed the total treatment, of which 362 were in SSRI and 205 in SNRI group. It was shown that the NET-T182C, interacting with 5-HTTLPR, was associated with the susceptibility to depression. Patients with both NET-T182C C/C and 5-HTTLPR S/S genotypes had lower baseline HAMD scores. Patients with 5-HTTLPR L/L or STin2 12/12 genotype experienced better clinical response to the SSRI treatment. Besides, the STin2 12/12 carriers showed a superior reduction to HAMD scores over treatment period. No correlation between NET T182C/G1287A polymorphisms and antidepressant response was observed. Conclusions  Our study revealed a positive association of the NET-T182C polymorphism with susceptibility to and severity of depression, and a positive association between the 5-HTT polymorphisms and the antidepressant response to SSRI. Combinations of these polymorphisms provided some potential gene–gene interaction effects. These findings might be of some clinical values in optimization of depression treatment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Serotonin transporter polymorphism and response to SSRIs in major depression and relevance to anxiety disorders and substance abuse

The selective serotonin re-uptake inhibitors (SSRIs) which modulate serotonergic activity are effective in the treatment of serotonin-related mental disorders, such as depression and anxiety. These agents bind to the serotonin transporter (5-HTT) and inhibit its capacity to transport serotonin (5-hydroxytryptamine; 5-HT). A functional polymorphism in the promoter region of 5-HTT (5-HTTLPR) has been described. The insertion variant of this polymorphism (long allele) is associated with higher expression of brain 5-HTT compared to the deletion variant (short allele). An association between the 5-HTTLPR polymorphism and mental disorders has been reported by some, but not all, investigators. In addition, the 5-HTT gene polymorphisms were found to be associated with a better and faster response to SSRIs with or without pindolol augmentation in depressed patients. Further studies are needed to clarify the relationship between the 5-HTT genotype, the susceptibility to mental disorders, the response to serotonergic agents and the side effect profile.     

Antidepressant use and resource utilization in the general practitioner setting in The Netherlands

OBJECTIVE: To assess antidepressant use and resource utilization in the general practitioner (GP) setting in the Netherlands following initiation of antidepressant therapy. DESIGN: Longitudinal study in a retrospective database. PARTICIPANTS: Sample of 869 patients from a new database in the Netherlands who initiated therapy on a selective serotonin re-uptake inhibitor (SSRI) or a tricyclic antidepressant (TCA). MAIN OUTCOME MEASURES: Mean length of antidepressant therapy within the first 90 days and resource utilization in the GP setting in the first 180 days following therapy initiation. RESULTS: (1) patients who initiated therapy on an SSRI were younger (48.6 years old versus 54.1 years old, p<0.01) and more likely to have a depression diagnosis (58% versus 30%, p<0.01) than patients who initiated therapy on a TCA; (2) patients who initiated therapy on an SSRI were more likely than patients who initiated therapy on a TCA (65% versus 52%, p<0.01) to have more than 30 days of therapy within the first 90 days and to receive antidepressant doses consistent with Dutch guidelines; (3) patients with greater than 30 days of antidepressant therapy within the first 90 days had more general practitioner visits than patients with 30 days of therapy or less (TCA patients: 9.6 versus 7.0; SSRI patients: 8.8 versus 6.9, p<0.01). CONCLUSIONS: Patients in the GP setting in the Netherlands who initiate therapy on SSRIs are more likely than patients who initiate therapy on TCAs to receive recommended doses and duration of therapy consistent with Dutch antidepressant treatment guidelines.     

The economics of selective serotonin reuptake inhibitors in depression: a critical review

The prevalence of depression and the high costs associated with its treatment have increased interest in pharmacoeconomic evaluations of drug treatment, particularly in the 1990s as the use of selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs) expanded substantially. This review presents results from specific studies representing the key study designs used to address the pharmacoeconomics of SSRI use: retrospective administrative database analyses, clinical decision analysis models, and randomised clinical trials. Methodological considerations in interpreting results are highlighted. In retrospective administrative database analyses, most comparisons have been made between SSRIs and tricyclic antidepressants (TCAs). A few studies have addressed differences between SSRIs. The studies focused on healthcare cost (to payer) and cost-related outcomes (e.g. treatment duration, drug switching). Although SSRIs are generally associated with higher drug acquisition costs than are TCAs, total healthcare costs are at least offset, if not decreased, by reductions in costs associated with use of SSRIs. Although studies from the early 1990s show some advantage for fluoxetine, the results are limited by use of data from shortly after the introduction of paroxetine and sertraline; studies from the mid- 1990s on that compare drugs within the SSRI class show general equivalence in terms of cost. Important methodological advances are occurring in retrospective studies, with selection bias and other design limitations being addressed statistically. Clinical decision analysis models permit flexibility in terms of ability to specify different alternative treatment scenarios and varying durations. Sensitivity analysis aids interpretability, although model inputs are limited by data availability. Results from short term (1 year duration or less) studies comparing SSRIs and TCAs suggest that SSRIs are more cost effective or that there is no difference. Longer term studies (lifetime Markov models) focus more on the impact of maintenance antidepressant therapy and show more mixed results, generally favouring SSRIs over TCAs. The results indicate that the effect of SSRIs is mainly through prevention of relapse. Important assumptions of these models include fewer serious adverse effects and lower treatment discontinuation rates with SSRIs. Naturalistic clinical trials provide greater generalisability than traditional randomised clinical trials. One naturalistic trial found that nearly half of TCA-treated patients switched to another antidepressant within 6 months; only 20% of SSRI-treated patients switched. Cost differences between groups were minimal. These studies indicate few differences in medical costs, depression outcomes and health-related quality of life between TCAs and fluoxetine, although fewer fluoxetine-treated patients switched treatment.     

Insensitivity of NMRI mice to selective serotonin reuptake inhibitors in the tail suspension test can be reversed by co-treatment with 5-hydroxytryptophan

RATIONALE: Exploring differences between mouse strains in drug effects in models of antidepressant-like activity may provide clues to the neurobiology of antidepressant responses. OBJECTIVES: The objective of this study was to explore whether insensitivity to selective serotonin reuptake inhibitors (SSRIs) in NMRI mice in the tail suspension test can be related to 5-hydroxytryptamine (5-HT) function. MATERIALS AND METHODS: We compared NMRI and C57Bl/6 mice, a SSRI-sensitive strain, in the tail suspension test following citalopram, paroxetine, or fluoxetine and determined 5-HT transporter (5-HTT) densities, 5-HT tissue and extracellular levels, 5-HT synthesis, tryptophan hydroxylase 2 (TPH2) genotypes and hypothermia induced by the 5-HT(1A) agonist 8-OH-DPAT. In NMRI mice, we tested if co-treatment with 5-HTP would increase 5-HT levels and confer SSRI sensitivity in the tail suspension test. RESULTS: C57Bl/6, but not NMRI, mice responded to SSRIs in the tail suspension test. 5-HTT densities in the frontal cortex and hippocampus were similar between the strains. NMRI mice had lower tissue 5-HT levels in these regions and decreased extracellular 5-HT in the frontal cortex at baseline and following citalopram. C57Bl/6 mice were more sensitive to 8-OH-DPAT-induced hypothermia. Both strains had the 1473C TPH2 genotype and similar 5-HT synthesis. In NMRI mice, 5-HTP co-treatment restored the tail suspension and extracellular 5-HT responses to SSRIs to levels equivalent to those seen in C57Bl/6 mice. CONCLUSION: Low 5-HT function in NMRI mice may account for their insensitivity to SSRIs in the tail suspension test. As the tail suspension test is a predictor of clinical efficacy, the current data suggest that 5-HTP adjunct treatment may benefit SSRI treatment refractory patients.     

Fluvoxamine treatment of mixed anxiety and depression: evidence for serotonergically mediated anxiolysis

Although increasing evidence suggests that selective serotonin reuptake inhibitor (SSRI) treatment may be effective for anxiety in addition to depression, SSRI anxiolysis has not been definitively related to the inhibition of serotonin (5-HT) transport. The gene that encodes for the human serotonin transporter (5-HTT) expresses its protein in neurons and in blood platelets, and both tissues respond to transport inhibition similarly in response to SSRI treatment. This study examined the relationship between the change in the 5-HTT's apparent affinity for 5-HT and the anxiolytic response in a group of 18 fluvoxamine-treated patients meeting Structured Clinical Interview for DSM-IV criteria for both generalized anxiety disorder and major depression. Significant decreases were found in both Hamilton anxiety and Hamilton depression scores over a 2-month treatment period. Robust increases were found in the apparent affinity constant (Km) for platelet 5-HT transport with treatment, and the increases covaried significantly with the decrease in anxiety (F = 4.97, p < 0.03). The pretreatment 5-HTT Km significantly correlated with the improvement in depression scores (r = 0.53, p < 0.03), consistent with the Hypothesis of Initial Conditions. These results suggest that the therapeutic effect of SSRI treatment can be linked to the magnitude and time-course of 5-HT transport inhibition effected with fluvoxamine, a drug that seems to have an antianxiety effect of the same magnitude as its effect on depression.     

Biochemical and pharmacological characterization of the serotonin transporter in human peripheral blood lymphocytes.

The serotonin transporter (5-HTT) plays a critical role in the termination of serotonin neurotransmission and represents the prime target for selective serotonin reuptake inhibitors (SSRIs). In the present study, the 5-HTT protein in human peripheral blood lymphocyte was characterized pharmacologically and biochemically. The tricyclic antidepressant drug [(3)H]imipramine, an established ligand for the neuronal and platelet 5-HTT, bound saturably and reversibly to a single population of non-interacting binding sites in fresh human peripheral blood lymphocytes. The affinity of [(3)H]imipramine (K(d)) to the transporter, calculated from association and dissociation kinetic experiments, was similar to that obtained from the equilibrium study. The function of the transporter was studied using high affinity [(3)H]5-HT uptake into fresh lymphocytes. [(3)H]Imipramine binding and [(3)H]5-HT uptake were inhibited by tricyclic antidepressants as well as by SSRIs. Western blot analysis as well as immunoprecipitation analysis revealed labeling of a single protein band of approximately 100 kDa. The presence of the 5-HTT in easily accessible nucleated cells such as peripheral blood lymphocytes might permit molecular genetic studies in mood and anxiety disorder patients, and might enhance the understanding of the different efficacies of antidepressants in depressed patients.     

Relative toxicity of selective serotonin reuptake inhibitors (SSRIs) in overdose

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) have increasingly replaced tricyclic antidepressants (TCAs) in the treatment of depression. They appear to be safer in overdose, but there is little information on their spectrum of toxicity in overdose, or relative toxicity of each agent. Objective: To determine the effect of SSRIs in overdose, as a group, and the relative toxicity of five different SSRIs. METHODS: A review of consecutive SSRI poisoning admissions to a single toxicology unit. Outcomes examined were length of stay [LOS], intensive care [ICU] admission rate, coma, seizures, electrocardiographic [ECG] abnormalities, and presence of serotonin syndrome [SS]. Logistic regression was used to model the outcome QTc >440 msec. RESULTS: There were 469 SSRI poisoning admissions analyzed after exclusions. The median LOS for all SSRI overdose admissions was 15.3 h (IQR: 10.5-21.3) and 30 of 469 (6.4%; 95% CI 4.3-9.0%) cases were admitted to ICU. The incidence of seizures was 1.9% and coma was 2.4%. Serotonin syndrome occurred in 14% of overdoses. Comparison of median QTc intervals of the five SSRIs was significantly different (p=0.0002); citalopram (450 IQR: 436-484) was individually different to fluoxetine (p=0.045), fluvoxamine (p=0.022), paroxetine (p=0.0002), and sertraline (p=0.001). The proportion of citalopram overdoses with a QTc >440 msec was 68%, differing significantly from sertraline (adjusted OR: 5.11 95% CI 2.32-11.27). Comparison of median QT intervals of the five SSRIs was statistically different (p=0.026); citalopram (400 IQR: 380-440) was individually different from sertraline (p=0.023). CONCLUSIONS: This study shows SSRIs are relatively safe in overdose despite serotonin syndrome being common. The exception was citalopram, which was significantly associated with QTc prolongation. We believe that cardiac monitoring should be considered in citalopram overdose, particularly with large ingestions and patients with associated cardiac disease.     

Tricyclic antidepressant pharmacology and therapeutic drug interactions updated

New data on the pharmacology of tricyclic antidepressants (TCAs), their affinities for human cloned CNS receptors and their cytochrome P450 enzyme inhibition profiles, allow improved deductions concerning their effects and interactions and indicate which of the TCAs are the most useful. The relative toxicity of TCAs continues to be more precisely defined, as do TCA interactions with selective serotonin reuptake inhibitors (SSRIs). TCA interactions with monoamine oxidase inhibitors (MAOIs) have been, historically, an uncertain and difficult question, but are now well understood, although this is not reflected in the literature. The data indicate that nortriptyline and desipramine have the most pharmacologically desirable characteristics as noradrenaline reuptake inhibitors (NRIs), and as drugs with few interactions that are also safe when coadministered with either MAOIs or SSRIs. Clomipramine is the only available antidepressant drug that has good evidence of clinically relevant serotonin and noradrenaline reuptake inhibition (SNRI). These data assist drug selection for monotherapy and combination therapy and predict reliably how and why pharmacodynamic and pharmacokinetic interactions occur. In comparison, two newer drugs proposed to have SNRI properties, duloxetine and venlafaxine, may have insufficient NRI potency to be effective SNRIs. Combinations such as sertraline and nortriptyline may therefore offer advantages over drugs like venlafaxine that have fixed ratios of SRI/NRI effects that are not ideal. However, no TCA/SSRI combination is sufficiently safe to be universally applicable without expert knowledge. Standard texts (e.g. the British National Formulary) and treatment guidelines would benefit by taking account of these new data and understandings.     

Disturbed development of the enteric nervous system after in utero exposure of selective serotonin re-uptake inhibitors and tricyclic antidepressants. Part 1: Literature review

The increase in selective serotonin re-uptake inhibitor (SSRI) use during pregnancy, questions concerning abnormal development of the enteric nervous system (ENS), increase in laxative use in children and the association of fluoxetine with infantile hypertrophic pyloric stenosis (IHPS) gave rise to this pharmacological literature review. The role of 5-HT and the NE uptake in ontogeny of the ENS and the effects SSRIs and TCAs might have on the development of the ENS were investigated. The literature study showed that SSRIs may influence the development of the ENS in two ways. Blockage of the serotonin re-uptake transporter (SERT) during foetal development could influence migration, differentiation and survival of cells. This could lead to abnormal development in the first trimester of pregnancy. The other way is that 5-HT seems to be a growth factor in the primitive ENS. This growth factor like action is mediated through the 5-HT(2B) receptor and stimulation of this receptor by SSRIs influences the fate of late-developing enteric neurons. This could lead to abnormal development in the second and third trimester. TCAs could influence the development of the ENS, besides through inhibition of the SERT, through inhibition of the norepinephrine transporter (NET). Expression of the NET seems to be essential for a full development of enteric neurons and especially for serotonergic neurons. In addition the NET was detected early in ontogeny and precedes neuronal differentiation, which suggests that TCAs might influence development of the ENS when exposed early in pregnancy. The insights of this study gave rise to hypotheses which will be tested in an epidemiological cohort study.