An assessment of selective serotonin reuptake inhibitor discontinuation symptoms with citalopram

The selective serotonin reuptake inhibitors (SSRIs) have recently been associated with a variety of somatic and psychiatric symptoms upon abrupt drug discontinuation. These symptoms have been variously termed SSRI withdrawal, or SSRI discontinuation syndrome. Although all of the available SSRIs have been reported to cause discontinuation symptoms, some appear to have a greater propensity to cause these adverse events than others. Data from a previously completed placebo-controlled, double-blind study designed to assess citalopram in depression relapse prevention were analysed to assess patients for the emergence of discontinuation effects following randomization to placebo after 8 weeks of active drug treatment. Side-effects that occurred during the first 2 weeks following randomization to active drug (n = 150) or placebo (n = 72) were measured using the UKU unwanted side-effect list. The proportion of patients that experienced one or more events over the 2-week period following randomization was similar in the two groups, and there was no association between citalopram dose prior to randomization and the reporting of symptoms. Most of the events that did occur were mild in intensity and none resulted in discontinuation from the study. Events occurring at a higher frequency in the placebo group were most associated with the central nervous system (CNS). These events may reflect a re-emergence of depressive symptoms, since only 14.8% of patients randomized to placebo who did not relapse experienced CNS events, a low symptom incidence that was non-significant (P = 0.562) compared to patients continuing treatment (10.9%). Therefore, this assessment suggests that any symptoms associated with rapid discontinuation of citalopram are mild and transient, and emphasizes the significant role re-emerging depression and / or anxiety may play in the assessment and identification of SSRI discontinuation symptoms.     

Influence of citalopram, a selective serotonin reuptake inhibitor, on oesophageal hypersensitivity: a double-blind, placebo-controlled study

Background Tricyclic antidepressants, which have multiple pharmacological influences, have a therapeutic effect in non-cardiac chest pain, but selective serotonin reuptake inhibitors have a single pharmacological effect. Aim To evaluate the acute effect of citalopram on oesophageal hypersensitivity. Methods On two separate occasions, 10 healthy subjects (seven men, mean age 25 years) with established oesophageal hypersensitivity, underwent oesophageal manometry with evaluation of mechanical and chemical sensitivity. Subjects received placebo or citalopram 20 mg i.v. in a randomized, crossover, double-blind fashion. Results Citalopram did not alter oesophageal motility. Citalopram significantly increased the threshold inducing first perception (4.6+/-0.3 vs. 6.7+/-0.4 mL, P<0.005) and discomfort (8.6+/-0.4 vs. 9.9+/-0.6 mL, P<0.01) during balloon distention. It also significantly prolonged the acid perfusion time to induce perception of heartburn (6.0+/-0.9 vs. 10.7+/-0.6 min, P<0.005) and discomfort (12.2+/-0.8 vs. 16.7+/-0.7 mL, P<0.001). Seven subjects experienced a retrosternal sensation during edrophonium provocation with placebo, and this was reduced to two of 10 after citalopram (P=0.02). Conclusions Acute administration of citalopram significantly lowers chemical and mechanical oesophageal sensitivity in oesophageal hypersensitivity, without altering the motility.     

Escitalopram,the S-(+)-enantiomer of citalopram,is a selective serotonin reuptake inhibitor with potent effects in animal models predictive of antidepressant and anxiolytic activities

Objective. The pharmacological profile of escitalopram, the S-(+)-enantiomer of citalopram, was studied and compared with citalopram and the R-(−)-enantiomer, R-citalopram. Methods. Inhibition of the serotonin transporter (5-HTT) was studied in COS-1 cells expressing the human 5-HTT (h-5-HTT) and in rat brain synaptosomes. In vitro selectivity was studied relative to noradrenaline transporter (NAT) and dopamine transporter (DAT) function in rat brain synaptosomes, and affinities for other binding sites were determined. In vivo 5-HT activity was measured as inhibition of neuronal firing rate in rat dorsal raphe nucleus (DRN) and enhancement of 5-hydroxytryptophan (5-HTP)-induced behaviour (mouse and rat). Furthermore, studies were conducted in models of antidepressant (mouse forced-swim test), anxiolytic [foot-shock-induced ultrasonic vocalization (USV) in adult rats and mouse black and white box] and anti-aggressive activity (socially isolated mice). Results. Escitalopram inhibited 5-HTT functions approximately 2 times more potently than citalopram and at least 40 times more potently than R-citalopram. Escitalopram showed insignificant activity at other monoamine transporters and 144 other binding sites. Escitalopram inhibited 5-HT neuronal firing in DRN and potentiated 5-HTP-induced behaviours more potently than citalopram; R-citalopram was inactive. Escitalopram and citalopram, but not R-citalopram, reduced forced-swimming-induced immobility and facilitated exploratory behaviour in the black and white box. Escitalopram and citalopram inhibited USV potently; R-citalopram was several times less potent. Escitalopram, citalopram and R-citalopram inhibited aggressive behaviour weakly. Escitalopram and citalopram had very potent anti-aggressive effects when co-administered with l-5-HTP. Conclusion. Escitalopram is a very selective 5-HT reuptake inhibitor. It is more potent than its racemate citalopram and is effective in animal models predictive of antidepressant and anxiolytic activities. Electronic Publication     

Venlafaxine extended release versus citalopram in patients with depression unresponsive to a selective serotonin reuptake inhibitor

Findings from the National Institute of Mental Health's Sequenced Treatment Alternatives to Relieve Depression trial indicate that approximately 50% of patients with major depressive disorder do not experience a treatment response after adequate first-line treatment with a selective serotonin reuptake inhibitor (SSRI). This study was designed to test the hypothesis that, after treatment failure with an SSRI, switching to venlafaxine extended release (ER) would offer advantages over switching to another SSRI, citalopram. The objectives of this trial were to compare the efficacy and safety of venlafaxine ER and citalopram in the treatment of moderate-to-severe depression in patients who did not experience a treatment response to an SSRI other than citalopram and to investigate the effects of severity of depression by categorizing treatment groups according to baseline severity. This was a 12-week, double-blind, randomized, parallel-group, multicenter study. Participants were adult outpatients who, following 8 weeks of monotherapy with an adequate dosing regimen of an SSRI other than citalopram and had not responded, met the diagnostic criteria for depression as described in the Diagnostic and statistical manual of mental disorders, fourth edition, and had a score > or =20 on the 21-item Hamilton Rating Scale for Depression (HAM-D21). After a 7-day screening period, patients were randomly assigned to receive venlafaxine ER 75 mg/day or citalopram 20 mg/day for the first 2 weeks. Doses could be increased every 2 weeks through week 6. Treatment lasted 12 weeks and was followed by a 1-week tapering period. Maximum dosages were venlafaxine ER 300 mg/day or citalopram 60 mg/day. The primary end point was the final on-therapy total HAM-D21 score. To investigate the treatment effects of the severity of depression on efficacy, a subgroup analysis was performed for baseline HAM-D21 total score < or =31 and >31. The analyses for HAM-D21, Montgomery-Asberg Depression Rating Scale (MADRS), Clinical Global Impressions - Severity (CGI-S), and Clinical Global Impressions - Improvement scores were based on intent-to-treat (ITT) population, for both the primary analysis and subgroup analysis according to baseline HAM-D21 total scores < or =31 or >31. Safety assessments included the recording of adverse events (AEs). A total of 406 patients (200 venlafaxine ER, 206 citalopram) were randomly assigned and 396 patients were included in the ITT population (194 venlafaxine ER, 202 citalopram). Treatment groups were similar in terms of demographics and baseline psychiatric assessments. Two hundred and eighty-four patients (137 venlafaxine ER, 147 citalopram) were present in the ITT population with a baseline HAM-D21 total score < or =31 and 112 patients (57 venlafaxine ER, 55 citalopram) in the >31 group. In the primary analysis, there was no statistical difference between groups. The group with a baseline HAM-D21 total score of 20-31 did not differ significantly in any efficacy parameters. In the group with a baseline HAM-D21 total score >31, the venlafaxine ER group differed significantly from the citalopram group on the primary end point HAM-D21 total score (P=0.0121). The secondary end point CGI-S score was statistically significant (P=0.0359), although the MADRS total score (P=0.0930) was not. AEs were reported by 57.8 and 63.4% of venlafaxine ER and citalopram patients, respectively. Overall discontinuation rates were 24.5% for venlafaxine ER and 20.9% for citalopram. Discontinuation rates owing to an AE as a primary or secondary reason were 5.5% for venlafaxine ER and 5.3% for citalopram. Overall, venlafaxine ER and citalopram showed similar efficacy in patients who had an inadequate response to an SSRI. In the subset of more severely depressed patients, venlafaxine ER was significantly more effective on a number of efficacy measures. Patients who remain severely depressed following treatment with an SSRI may gain more benefit from the dual-action drug venlafaxine, rather than switching to another SSRI.     

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

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

N-methyl-citalopram: A quaternary selective serotonin reuptake inhibitor

We describe the synthesis and the pharmacological characterization of a new quaternary selective serotonin reuptake inhibitor (SSRI) N-methyl-citalopram (NMC) with periphery restricted action due to its inability to cross the blood brain barrier. NMC recognized and blocked the human platelet serotonin transporter (SERT) with similar affinity to that of citalopram as was evident from competition binding studies with [³H]citalopram and uptake studies with [³H]5-HT. In contrast, the affinity of NMC to rat brain SERT was 10-fold lower than its parent compound citalopram. Similarly to citalopram, NMC did not inhibit dopamine and noradrenaline uptake in rat brain synaptosomes at 10⁻⁷ M as well as [³H]ketanserin binding to rat brain membranes at 10⁻⁵ M, demonstrating its SSRI profile. A comparison of radioactivity retained in perfused mice brain following in vivo intraperitoneal injections of tritium-labeled NMC or citalopram showed that unlike citalopram, NMC did not penetrate the brain. Taken together, our observations suggest that N-methyl-citalopram is a selective serotonin reuptake inhibitor that does not penetrate the mouse brain. Epidemiological studies have suggested that chronic use of SSRI drugs may confer a protective effect against myocardial infarction (MI) apparently reflecting reduced platelet aggregation secondary to reduced platelet serotonin levels. N-methyl-citalopram may therefore have a potential as a new anti-platelet drug that does not cross the blood brain barrier and is thus devoid of the adverse CNS effects of SSRI drugs.     

Fluvoxamine, a selective serotonin reuptake inhibitor, suppresses tetrahydrobiopterin in the mouse hippocampus

In the present study, we investigated the effects of fluvoxamine, a selective serotonin reuptake inhibitor, on brain tetrahydrobiopterin (BH4) levels. We directly measured levels of BH4 by Tani and Ohno's direct method as well as the serotonin (5-HT) turnover ratio, i.e. 5-hydroxyindoleacetic acid (5-HIAA)/5-HT, after sub-acute s.c. injection of fluvoxamine in the hippocampus of mice. Our animal model incorporated two risk factors of depression, social isolation and acute environmental change. Male ddY mice (6W) were housed in isolation (1 per cage; 35 days), injected with fluvoxamine (20 or 40 mg/kg; days 29-35), and exposed to novelty stress (20 min; day 35). In the stress session, behavioral parameters, i.e. total distance and rearing behavior, were measured. Isolation housing increased both behaviors. Fluvoxamine attenuated rearing behavior, but did not influence total distance. Isolation housing increased BH4 levels. Novelty stress increased BH4 levels in group housing, although it did not change them in isolation housing. Fluvoxamine suppressed BH4 levels. In isolation housing, fluvoxamine increased 5-HT turnover ratios, while it decreased them in group housing. In conclusion, fluvoxamine, housing condition, and novelty stress regulated BH4 levels. Fluvoxamine may have changed behavior and 5-HT turnover by suppressing BH4 levels as well as by inhibiting 5-HT reuptake.     

Relationship between brain serotonin transporter binding, plasma concentration and behavioural effect of selective serotonin reuptake inhibitors

1. The present study was undertaken to characterise the relationship between in vivo brain serotonin transporter (SERT) binding, plasma concentration and pharmacological effect of selective serotonin reuptake inhibitors (SSRIs) in mice. Oral administration of fluvoxamine, fluoxetine, paroxetine and sertraline at pharmacologically relevant doses exerted dose- and time-dependent binding activity of brain SERT as revealed by significant increases in KD for specific [3H]paroxetine binding, and the in vivo SERT-binding potency was in the order of paroxetine>fluoxetine, sertraline>fluvoxamine. 2. The time courses of brain SERT binding by SSRIs in mice were mostly in parallel to those of their plasma concentrations. Also, norfluoxetine (active metabolite) has been suggested to contribute largely to the long-lasting binding activity of brain SERT after the fluoxetine administration. 3. Oral administration of each SSRI suppressed significantly the marble-burying behaviour with no change in locomotor activity in mice, and the extent and time course of suppression agreed well with those of brain SERT binding. Thus, the pharmacological potencies of SSRIs in the attenuation of marble-burying behaviour correlated significantly with their brain SERT binding activities. 4. In conclusion, the present study has provided the first in vivo evidences to support that fluvoxamine, fluoxetine, paroxetine and sertraline orally administered bind to the pharmacologically relevant brain SERT in mice and that their SERT-binding characteristics is closely associated with the pharmacokinetics and inhibition of marble-burying behaviour.     

哺乳期使用选择性5羟色胺再摄取抑制剂类抗抑郁药的安全性

抑郁症是哺乳期常见的疾病之一,目前关于哺乳期使用选择性5羟色胺再摄取抑制剂(SSRI)类抗抑郁药的安全性尚缺乏足够的证据。本文就哺乳期常用的SSRI类抗抑郁药安全性研究作一综述,并给出建议。     

Citalopram,a selective serotonin reuptake inhibitor: Clinical antidepressive and long-term effect — a phase II study

In a phase II study the antidepressive effect of citalopram, a selective and potent serotonin reuptake inhibitor, was examined in 20 endogenously and three nonendogenously depressed hospitalized patients. Four endogenously depressed patients dropped out due to deterioration early in the treatment period. The remaining 19 patients completed a 4–6 week treatment schedule. Of 16 endogenously depressed patients 11 responded, one was a partial responder and four did not respond. Of three patients with non-endogenous depressions, two responded and one did not respond.No correlation between plasma citalopram concentration and therapeutic outcome was found.Fourteen patients were given maintenance treatment for 8–113 weeks. One patient developed depression when the dose was reduced from 60 to 40 mg and one patient became manic. After discontinuation of treatment seven patients had a depressive relapse and six of these who again were treated with citalopram responded completely.Side effect rating scores of symptoms usually associated with depression or treatment with tricyclic antidepressants declined during treatment. Three patients complained of increased need of sleep for a period after several weeks of treatment. Apart from an unspecific, transient rise in liver enzymes in two patients, detailed biochemical laboratory tests were all normal. There were no effects on blood pressure, pulse rate, orthostatic reaction, or electrocardiogram. One patient took an overdose of citalopram resulting in plasma levels about six times higher than the average therapeutic level, but there were no signs of severe toxicity. In particular no change in consciousness, electrocardiogram or blood pressure occurred.Pharmacokinetic variables such as dose schedule, steady state kinetics, and metabolism are discussed.     

Sertraline, a selective serotonin reuptake inhibitor modulates extracellular noradrenaline in the rat frontal cortex

The selective action of selective serotonergic reuptake inhibitors (SSRIs) on 5-hydroxytryptamine (5-HT) neurotransmission underlies the therapeutic effectiveness of this class of drugs. Yet there is increasing evidence that changes in extracellular 5-HT content may result in changes in the regulation of other neurotransmitter systems. The present study examines the effects of acute and chronic administration of the SSRI sertraline on release of endogenous noradrenaline (NA) in the frontal cortex and hippocampus of the rat using in vivo microdialysis. Acute administration of sertraline did not significantly alter NA release in either the cortex or the hippocampus. However, 24 h after chronic (14 days) administration of the drug (10 mg/kg i.p. once daily), NA release in the cortex but not hippocampus was significantly enhanced. The lack of an effect on NA release following a challenge with the alpha2-antagonist idazoxan suggests that chronic drug treatment has reduced the sensitivity of cortical pre-synaptic alpha2-adrenoceptors, activation of which would normally inhibit further NA release. The possible mechanisms underlying the regional specificity of the effect of chronic and not acute sertraline administration and the implications of these results for our understanding of depression are discussed.     

Pharmacogenetics of selective serotonin reuptake inhibitor response: a 6-month follow-up

BACKGROUND: We previously reported the association between some genetic factors and short-term antidepressant outcome. In the present paper we investigated the same gene variants in a prospective 6-months naturalistic follow-up. METHODS: The sample included 185 inpatients affected by recurrent major depression consecutively admitted to the Psychiatric Inpatient Unit of San Raffaele Hospital from 1998 to 2003 and prospectively followed for 6 months after their recovery. All the patients were undertaking continuation therapy. The functional polymorphism in the upstream regulatory region of the serotonin transporter gene (SERTPR), the tryptophan hydroxylase A218C substitution, a VNTR polymorphism located 1.2 kb upstream of the monoamine oxidase-A coding sequences, the CLOCK gene T3111C and the PER3exon15 gene T1940G substitutions were analysed, using PCR-based techniques. RESULTS: No association was found between clinical variables and relapses; subjects showing TT genotype at CLOCK gene tended to relapse within 6 months after recovery more than TC and CC subjects taken together. A non-significant tendency of SERTPR*s/s subjects to a minor frequency of relapse was also observed. CONCLUSION: Some subjects showing remission after acute treatment relapsed within 6 months, despite undertaking a maintenance treatment; the causes could be heterogeneous, but CLOCK gene variants may influence the outcome.     

Fluoxetine, a selective serotonin reuptake inhibitor modulates inflammatory and neuropathic pain in the rat

The clinical usefulness of classical tricyclic antidepressants has been indicated in a variety of neuropathic pain. The role of selective serotonin reuptake inhibitors (SSRIs) is, however, controversial in pain control. The present study was aimed at evaluating the efficacy of an SSRI, fluoxetine, in neuropathic pain involving peripheral (carrageenan-induced inflammation) and central sensitization (spinal nerve ligation) in rats. Fluoxetine was also assessed for antinociceptive and antiphlogistic effect against acetic acid-induced chemonociception in mice and carrageenan-induced inflammation. Fluoxetine (100-400 g, intraplantar administration) failed to attenuate either hyperalgesia or cold allodynia in any of the tests employed. Fluoxetine dose dependently increased paw volume in the absence or presence of an inflammatory stimulus which was not reversed by indomethacin (10 mg/kg, p.o). Fluoxetine was ineffective in reducing hyperalgesia and allodynia associated with the rat models. However, fluoxetine dose dependently decreased acetic acid-induced writhings. The results indicated that 5-HT plays a differential role in pain modulation and may not be playing a major role in the maintenance of hyperalgesia and allodynia in the rat models.     

The discriminative stimulus properties of LY233708, a selective serotonin reuptake inhibitor, in the pigeon

Rationale: Understanding the contribution of the various serotonin (5-HT) receptor subtypes to the behavioral effects of selective serotonin reuptake inhibitors (SSRIs) may contribute to the discovery of increasingly effective drugs for the treatment of conditions such as depression, panic and obsessive-compulsive disorders. Objectives: A drug discrimination procedure was used to determine whether the administration of an SSRI was associated with a specific interoceptive stimulus cue and to what extent that cue was related to activation of the 5-HT_1A receptor. Method: Pigeons were trained to discriminate 20 mg/kg of the short acting, SSRI, LY233708 dihydrochloride dihydrate [(–)-cis-1-(6-chloro-1,2,3,4- tetrahydro-1-methyl-2-naphthalenyl)piperazine] from saline. Results: LY233708 induced a specific, dose-related stimulus cue. The SSRIs, fluoxetine and citalopram, induced dose-related responding on the LY233708-associated key. In contrast, nisoxetine, a selective norepinephrine uptake inhibitor, induced responding on the saline-associated key. The prototypical 5-HT_1A agonist, 8-OH-DPAT [8-hydroxy-(2-di-n-propylamino)tetralin] substituted for LY233708. This generalization was blocked by the selective 5-HT_1A antagonist, WAY-100635 [N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl) cyclohexanecarboxamide]. Conclusion: These data demonstrate that an SSRI can induce a specific, stable discriminative stimulus that appears to involve activation of the 5-HT_1A receptor in the pigeon. Received: 11 January 1999 / Final version: 7 May 1999     

A meta-analysis of clinical trials comparing milnacipran, a serotonin--norepinephrine reuptake inhibitor, with a selective serotonin reuptake inhibitor for the treatment of major depressive disorder.

CONTEXT: Over the past few years, a number of studies have emerged suggesting that the treatment of major depressive disorder (MDD) with antidepressants which enhance both noradrenergic as well as serotonergic neurotransmission may result in higher response or remission rates than treatment with antidepressants which selectively enhance serotonergic neurotransmission. OBJECTIVE: The objective of this paper was to compare response rates among patients with MDD treated with either milnacipran, an antidepressant thought to simultaneously enhance both noradrenergic and serotonergic neurotransmission, or a selective serotonin reuptake inhibitor (SSRI). DATA SOURCES: Medline/Pubmed were searched. No year of publication or language limits were used. STUDY SELECTION: Double-blind, randomized clinical trials comparing milnacipran with an SSRI for the treatment of MDD. DATA EXTRACTION: Data were extracted with the use of a pre-coded form. DATA SYNTHESIS: Analyses were performed comparing response rates between the two antidepressant agents. Data from 6 reports involving a total of 1082 outpatients with MDD were identified and combined using a random-effects model. Patients randomized to treatment with milnacipran were as likely to experience clinical response as patients randomized to treatment with an SSRI according to the MADRS (RR = 1.04, 95% CI: 0.88-1.23, p = 0.533) or the HDRS (RR = 1.06, 95% CI: 0.90-1.24, p = 0.456) for the random effects model. Simply pooling MADRS-based response rates between the two agents revealed a 58.9% response rate for milnacipran and a 58.3% response rate for the SSRIs. Similarly, HDRS-based response rates were 59.7% and 57.5%. There was also no difference in overall discontinuation rates (RR = 0.93; 95% CI: 0.76-1.14; p = 0.506), the rate of discontinuation due to adverse events (RR = 0.77; 95% CI: 0.55-1.1; p = 0.157), or the rate of discontinuation due to inefficacy (RR = 0.98; 95% CI: 0.7-1.38; p = 0.95) between the two groups. CONCLUSIONS: These results suggest that milnacipran and the SSRIs do not differ with respect to their overall efficacy in the treatment of MDD.