Serotonin syndrome resulting from drug interactions

We describe six patients diagnosed with serotonin syndrome after exposure to drugs with serotonergic activity. Drug interactions occurred as a result of a combination of tricyclic antidepressants, selective serotonin reuptake inhibitors, selective noradrenaline reuptake inhibitors or monoamine oxidase inhibitors. Management included supportive care and the use of non-specific serotonin antagonists (cyproheptadine, benzodiazepines and chlorpromazine). All patients made uneventful recoveries.     

General practitioners' perceptions of the tolerability of antidepressant drugs: a comparison of selective serotonin reuptake inhibitors and tricyclic antidepressants

OBJECTIVE: To examine inceptions and discontinuations of antidepressants in general practice. DESIGN: An observational study analysing data from an ongoing cross sectional postal survey. Every three months a representative sample of 250 doctors recorded prescribing activity for four weeks. This provided 4000 general practitioner weeks of recording per year. SETTING: A representative panel of general practitioners in England, Wales, and Scotland. SUBJECTS: Patients who began a new course of an antidepressant or had their treatment stopped or changed by the general practitioner between 1 July 1990 and 30 June 1995. MAIN OUTCOME MEASURES: Numbers of patients prescribed a new course of antidepressant; numbers discontinuing treatment; the ratio of antidepressant discontinuations to antidepressant inceptions; reasons for discontinuation; proportion of switches to another antidepressant. RESULTS: There were 13,619 inceptions and 3934 discontinuations of selective serotonin reuptake inhibitors and tricyclic antidepressants during the study. The number of newly prescribed courses of antidepressants increased by 116%, mostly due to an increase in prescribing of serotonin reuptake inhibitors. The ratio of total discontinuations to inceptions was significantly lower for serotonin reuptake inhibitors (22%) than for tricyclic antidepressants (33%). Differences persisted when controlled for age and sex of patients and severity of depression. However, there was more switching away from selective serotonin reuptake inhibitors when they failed (72%) than from tricyclic antidepressants (58%). CONCLUSIONS: Selective serotonin reuptake inhibitors are less likely than tricyclic antidepressants to be discontinued. A prospective study is needed in general practice to assess the implications of differences in discontinuation rates and switches on clinical and economic outcomes.     

Selenium and iodine deficiencies and selenoprotein function

The present study was designed to evaluate the roles of 5-HT2 and 5-HT3 receptors in the mouse forced swimming test, by using selective agonists and antagonists of 5-HT(2A/C) and 5-HT3 receptor sites. Agonists/antagonists and antidepressants were administered 45 min and 30 min, respectively, prior to testing. Pretreatment with (+/-)-2,5-dimethoxy-4-iodoamphetamine (DOI) (4 mg/kg, i.p.) or 2-methyl-5-HT (4 mg/kg, i.p.) had no effect on the anti-immobility effects of any antidepressant tested. Prior administration of ritanserin (4 mg/kg, i.p.) or ketanserin (8 mg/kg, i.p.), on the other hand, potentiated the effects of sub-active doses of imipramine (8 mg/kg, i.p.) and desipramine (16 mg/kg, i.p.) but not of maprotiline (8 mg/kg, i.p.), fluoxetine (16 mg/kg, i.p.), citalopram (16 mg/kg, i.p.) or fluvoxamine (8 mg/kg, i.p.). Pretreatment with ondansetron (1 X 10(-5) mg/kg, i.p.) enhanced the antidepressant-like effects of sub-active doses of the selective serotonin reuptake inhibitors. The results of the present study suggested that, in the forced swimming test, the selective serotonin reuptake inhibitors act partially through 5-HT3 receptor sites, whereas the tricyclic antidepressants exert effects at 5-HT(2A/C) receptor sites. Anti-immobility effects of the selective noradrenaline reuptake inhibitor, maprotiline, do not seem to be mediated by 5-HT(2A/C) or 5-HT3 receptor function.     

The combined effects of memantine and fluoxetine on an animal model of obsessive compulsive disorder.

Obsessive Compulsive Disorder (OCD) is currently treated with behavioral modification and psychotropic medications, with varying degrees of success. The most popular drugs for the treatment of OCD are the selective serotonin reuptake inhibitors (SSRIs). Another drug, the N-methyl-d-aspartate antagonist memantine, has recently been tested in the treatment of OCD. The present study investigates the effect of fluoxetine and memantine alone and in combination in a mouse model of compulsive behavior. In this model, compulsive scratching is induced by a subcutaneous injection of serotonin or a serotonin releasing agent, compound 48–80, in the back of the neck. The effects of the memantine and fluoxetine combination were found to synergistic, specifically as defined by an isobologram. The results of the present investigation suggest the potential of a more effective management of the symptoms of OCD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prediction of lung cancer mortality in four Central European countries, 1990-2009

In the present pilot study, our aim was to investigate whether associations could be demonstrated in psychiatric patients between the changes in plasma lipid and lipoprotein levels expected during treatment with psychoactive drugs and the changes in the patients' depressive and hostile behavior. One hundred and fourteen patients with various psychiatric disorders (depressive episode in bipolar affective disorder, depressive episode or recurrent depressive disorder, paranoid schizophrenia, and schizoaffective disorders) were included in the study. The following examinations were carried out in each patient on admission and at discharge: (1) the plasma lipid parameters total cholesterol (TC), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), high-density lipoprotein (HDL), and triglycerides (TRI) were determined, and (2) the psychopathological features were recorded employing the AMDP system and the AMDP Syndrome Scales. Within the context of a naturalistic clinical setting with a choice of psychoactive drugs available, patients were subdivided at the end of treatment into eight treatment groups, as follows: group 1, treatment with butyrophenones; group 2, treatment with tricyclics; group 3, treatment with butyrophenones and tricyclics; group 4, treatment with butyrophenones, tricyclics and selective serotonin reuptake inhibitors; group 5, treatment with butyrophenones and lithium; group 6, treatment with tricyclics and lithium; group 7, treatment with butyrophenones, tricyclics and lithium; and group 8, treatment with butyrophenones, tricyclics, selective serotonin reuptake inhibitors and lithium. To compare the changes in the eight treatment groups, mixed general linear models including diagnosis, gender, age, body mass index changes, and baseline values were applied using proc GLM of SAS. Butyrophenones induce an increase in TC, LDL, and TC/TRI ratio, whereas tricyclics lead to an increase in TC, LDL, VLDL, and TRI. In combined medication of butyrophenones and tricyclics the effects of tricyclics predominate. Comedication of lithium inhibits the increase in TC and LDL induced by butyrophenones and/or tricyclics. Treatment groups with lipid changes of the same type (decrease, no change, or increase) were combined in "lipid change groups". Analyses of variance or covariance (with psychopathological admission value as covariate where there were significant differences in psychopathological admission mean values between the groups) of these lipid change groups with regard to the changes in the Depressive Syndrome Scale and the Hostility Syndrome Scale gave results which are interpreted as follows: an increase in TC or LDL inhibits the remission of hostility, whereas an increase in TRI with concomitant decrease in TC, or else a relatively greater increase in TRI than in TC promotes the remission of hostility. A decrease in TRI or VLDL promotes the remission of depression. Our data and findings published in the literature may suggest that systemic changes in plasma lipid parameters, at the cellular level, induce changes in the fluidity of brain cell membranes. We hypothesize that an increase in plasma TC or LDL and/or a decrease in plasma TRI or VLDL may induce a relative decrease in brain cell membrane fluidity with decreased presynaptic serotonin reuptake and increased postsynaptic serotonin function. This proposed increase in brain serotonin function would finally result in an anti-depressive, aggression-promoting effect. Conversely, a decrease in plasma TC or LDL and/or an increase in plasma TRI or VLDL may induce a relative increase in brain cell membrane fluidity with increased presynaptic serotonin reuptake and decreased postsynaptic serotonin function. This proposed decrease in brain serotonin function would result in an anti-aggressive, depression-promoting effect.     

Adaptation of cortical NMDA receptors by chronic treatment with specific serotonin reuptake inhibitors

Glycine displaces [3H]CGP-39653 ([3H]D,L-(E)-2-amino-4-propyl-5-phosphono-3-pentenoic acid) binding to the glutamate recognition site with both high and low affinity. We reported previously that chronic treatment with antidepressants reduced the proportion of high to low affinity sites, or, even eliminated the high affinity sites in case of citalopram. Here, we compared the effects of citalopram with another serotonin specific reuptake inhibitor, fluoxetine on this measure. Chronic administration of citalopram or fluoxetine eliminated high affinity glycine-displaceable [3H]CGP-39653 binding to the mouse cortex in 78 and 56% of animals, respectively, indicating that selective serotonin reuptake inhibitors produce qualitatively similar adaptive changes at NMDA receptors, that differ from other antidepressants in this neurochemical measure.     

Alteration of central serotonin modifies onset and severity of adjuvant-induced arthritis in the rat

OBJECTIVE: Previous studies have determined that depletion of serotonin reduces the severity of hind-paw inflammation in adjuvant-induced arthritis (AA) in the rat. We wished to (i) test the hypothesis that this effect may be mediated, at least in part, through a central mechanism and (ii) to investigate further the pro-inflammatory role of serotonin we determined whether increasing serotonin using a selective serotonin reuptake inhibitor (SSRI), to increase serotonin availability at the active site of release, would increase inflammation. METHODS: (i) Serotonin was depleted in the brain of rats with the selective neurotoxin 5'7'-dihydroxytryptamine. (ii) Rats were treated with an SSRI on days 10, 11 and 12 following adjuvant injection. Hind-paw inflammation was determined with plethysmometry as an index of severity of inflammation, and brain, pituitaries and blood were collected for assessment of changes in the hypothalamo -pituitary adrenal (HPA) axis. RESULTS: (i) Serotonin depletion significantly reduced hind-paw inflammation. (ii) SSRI-treated animals developed hind-paw inflammation sooner, and the severity was increased compared to vehicle-treated AA rats. The changes in the HPA axis associated with inflammation were partly reversed by this treatment. CONCLUSION: These data suggest a pro-inflammatory role for central serotonin in this disease model and indicate that treatment with SSRIs may exacerbate the development of inflammation.     

Delirium during fluoxetine treatment. A case report

The correlation between high serum tricyclic antidepressant concentrations and central nervous system side effects has been well established. Only a few reports exist, however, on the relationship between the serum concentrations of selective serotonin reuptake inhibitors (SSRIs) and their toxic effects. In some cases, a high serum concentration of citalopram (> 600 nmol/L) in elderly patients has been associated with increased somnolence and movement difficulties. Widespread cognitive disorders, such as delirium, have not been previously linked with high blood levels of SSRIs. In this report, we describe a patient with acute hyperkinetic delirium connected with a high serum total fluoxetine (fluoxetine plus desmethylfluoxetine) concentration.     

Effects of the co-administration of 5-HT1A receptor antagonists with an SSRI in conditioned fear stress-induced freezing behavior

The effects of the co-administration of the serotonin (5-HT) 1A receptor antagonists NAN-190 or (+)-WAY100135 with a selective 5-HT reuptake inhibitor (SSRI) citalopram on conditioned fear stress (CFS)-induced freezing behavior, which is the animal model of anxiety, were examined. The inhibitory effects of co-administration of NAN-190 (0.1-10 mg/kg) with citalopram on CFS-induced freezing were potent; in particular, at 0.1 and 0.25 mg/kg, NAN-190 significantly enhanced the effect of citalopram alone. At 0.1 mg/kg, (+)-WAY100135 also markedly enhanced the inhibitory effect of citalopram on freezing behavior. These findings suggest that 5-HT1A receptor antagonist, particularly at low doses, enhances the antifreezing effect of citalopram by blocking the autoreceptor-mediated negative feedback mechanisms of the 5-HT neuron. These experimental results concur with clinical findings that 5-HT1A receptor antagonist pindolol potentiates the effect of 5-HT reuptake inhibitors.     

Renal nerve responses to somatic nerve activation in stroke-prone spontaneously hypertensive rats

Antidepressant-induced adverse sexual effects are becoming more frequently reported by patients who require pharmacotherapy. A MED-LINE search was conducted to generate articles reporting such events. We report here on the sexual side effects associated with tricyclics, monoamine oxidase inhibitors including moclobemide, selective serotonin reuptake inhibitors, bupropion, and on the newer antidepressants venlafaxine and nefazadone. We conclude that adverse sexual effects are an increasingly important side effect of antidepressant medications, and patients must be routinely asked about their occurrence.     

Sepsis and endotoxaemia in mice stimulate the expression of interleukin-I and interleukin-6 in the central nervous system

This retrospective chart review examines the impact of selective serotonin reuptake inhibitors on 20 patients with both depression and psychosis complicating dementia of the Alzheimer type (DAT) and other dementias. Fifteen of the 20 patients had moderate to marked improvement in depressive and psychotic symptoms. Eleven of 12 patients with DAT had moderate to marked improvement compared to only four of eight patients with dementia from other causes. The drugs were effective in diminishing or eliminating psychotic symptoms in six patients who had previously not responded to a trial of a neuroleptic. The selective serotonin reuptake inhibitors may have an important role to play in patients with DAT who have coexisting depression and psychosis. These drugs are very well tolerated and may have a place as first-line agents in non-emergent settings where a clinician might otherwise think of instituting a neuroleptic or as a second-line agent when a neuroleptic has proven ineffective.     

Reduction in suicidal ideation with SSRIs: a review of 459 depressed patients

This paper is a review of 459 outpatients treated in double-blind clinical drug trials using similar protocols which compared the clinical responses to specific serotonin reuptake inhibitors, norepinephrine reuptake inhibitors, mixed norepinephrine serotonin reuptake inhibitors, serotonin-2 antagonists and placebo. Although improvements in the total score on the Hamilton Rating Scale for Depression did not differ significantly among the groups, there were differences in the profile of response based on analysis of the items of the scale. The most striking difference was the significantly more rapid and effective improvement in depressed mood and the lessening of suicidal ideation among the patients treated with specific serotonin reuptake inhibitors.     

Venlafaxine and nefazodone, two pharmacologically distinct antidepressants

Venlafaxine, a phenylethylamine, and nefazodone, a phenylpiperazine compound, are the newest antidepressants to receive approval of the Food and Drug Administration and to be marketed in the United States. Both strongly inhibit serotonin (5-HT) reuptake; venlafaxine also inhibits norepinephrine reuptake, and nefazodone also exhibits 5-HT2-receptor antagonism. Venlafaxine inhibits the cytochrome P-450 2D6 isozyme to a lesser extent than the selective serotonin reuptake inhibitors (SSRIs) and is 27% protein bound. Structurally, the drugs are unrelated to SSRIs and have some clinically important differences in side effect profiles. Nausea, headache, somnolence, and dry mouth are the most frequently reported side effects with both. Sustained hypertension was reported by a limited number of venlafaxine-treated patients.     

ECG changes after paroxetine. 3 case reports

Selective serotonin reuptake inhibitors (SSRI) are known to exhibit far less cardiac side effects than tricyclic antidepressants. We report three cases in which the SSRI, paroxetine, induced clinically relevant ECG changes in patients with high risk profile. In two cases an increase in QTc time was observed, severe bradycardia was also observed twice.     

Treatment of antidepressant-induced sexual dysfunction

Sexual dysfunction is a common side effect seen in patients taking selective serotonin reuptake inhibitors. Spontaneous resolution may occur in some patients, but modifications to therapy can be employed to eliminate undesirable side effects. These include reducing drug dosages, altering timing of drug dosages, taking drug holidays, adding an adjunctive drug, and switching to alternative antidepressants.     

Serotonin reuptake inhibitor withdrawal

We studied reported withdrawal symptoms in a retrospective chart review of 352 patients treated in an outpatient clinic with the nonselective serotonin reuptake inhibitor clomipramine or with one of the selective serotonin reuptake inhibitors (SSRIs), fluoxetine, fluvoxamine, paroxetine, or sertraline. In 171 patients who were supervised during medication tapering and discontinuation, the most common symptoms were dizziness, lethargy, paresthesia, nausea, vivid dreams, irritability, and lowered mood. When patients with at least one qualitatively new symptom were defined as cases, these symptoms occurred significantly more frequently in patients who had been treated either with one of the shorter half-life SSRIs, fluvoxamine or paroxetine (17.2%), or with clomipramine (30.8%), than in patients taking one of the SSRIs with longer half-life metabolites, sertraline or fluoxetine (1.5%). The rate was not significantly different between the different shorter half-life treatments. Cases treated with fluvoxamine or paroxetine had received a significantly longer period of treatment (median 28 weeks) than noncases (16 weeks), but there were no significant associations with age or with diagnostic grouping. There was a trend toward an association with male sex. The majority of cases occurred despite slowly tapered withdrawal. Symptoms persisted for up to 21 days (mean = 11.8 days) after onset. These symptoms were relieved within 24 hours by restarting the medication, but were not relieved by benzodiazepines or by moclobemide. A role has been suggested for serotonin in coordinating sensory and autonomic function with motor activity. We suggest that this may lead to useful hypotheses about the pathophysiology of withdrawal symptoms from serotonin reuptake inhibitors.     

Living arrangement transitions among America''s older adults

Enhanced serotonergic transmission may underlie therapeutic effects of serotonin reuptake inhibitors in obsessive-compulsive disorder. However, such treatment may decrease serotonin receptor responsivity. We investigated whether the serotonin antagonist metergoline would exacerbate or further improve systems in fluoxetine-responsive patients. Pilot results suggested open metergoline produced delayed symptom worsening in fluoxetine-treated patients. Fourteen patients continuing fluoxetine received metergoline and placebo (double-blind, randomized). Symptom ratings continued for 1 week afterwards. Ten unmedicated patients underwent the same procedures. Symptoms improved 4 h after both metergoline and placebo. The day after metergoline but not placebo, fluoxetine-treated patients had significantly increased anxiety, obsessions and compulsions, abating over several days. Depression was unchanged. Metergoline had no similar delayed effects in unmedicated patients. Metergoline levels were higher in fluoxetine-treated patients. These results, consistent with less conclusive earlier findings, suggest that prolonged changes in brain serotonin function underlie symptom re-emergence following administration of metergoline to fluoxetine-treated patients with obsessive-compulsive disorder.     

Activation of c-Jun NH2-terminal kinase (JNK/SAPK) in LLC-PK1 cells by cadmium

A male rat put in an open-field arena in which it is free to spend time in the vicinity of--but not in contact with--an estrous female, or in the vicinity of a male, usually spends more time with the female than with the male or elsewhere. Tentatively, the percentage of time spent in the vicinity of the female in this paradigm may be regarded as a measure of sexual motivation. In humans, treatment with selective serotonin reuptake inhibitors (SSRIs) may cause reduced libido. To investigate to what extent serotonin reuptake inhibition influences sexual motivation also in rats, we have tested the effect of subchronic treatment with fluoxetine on the behavior in the sexual motivation test described above; in addition, the effect of fluoxetine on male copulatory behavior was studied. Fluoxetine significantly reduced sexual motivation at subchronic but not at acute administration; moreover, fluoxetine-treated rats displayed an increased ejaculation latency. It is concluded that humans and rats respond similarly to the SSRI fluoxetine with respect to various aspects of sexual behavior.     

Controversial association of left ventricular hypertrophy and the ACE I/D polymorphism--is the mist clearing up?

The calcium channel blocker nifedipine has analgesic properties that are enhanced by nicotine. Although it is not known how this analgesic state might affect the awareness of anginal pain and impending myocardial infraction, recent studies have shown an increased mortality associated with the use of large doses of nifedipine. Because both nifedipine- and nicotine-induced analgesia involve serotonergic mechanisms, we studied the effects of the serotonin biosynthesis inhibitor parachlorophenylalanine (pCPA) on nifedipine- and nicotine-induced analgesia. Nociception was assessed by tail-flick method. Rats pretreated with pCPA (300 mg/kg intraperitoneally [IP]) followed by either nifedipine (15 mg/kg IP) or nicotine (1 mg/kg subcutaneously) had a increase in tail-flick latency of 41% (P = 0.09) and 50% (P = 0.05), respectively, compared with animals that did not receive pCPA. Additionally, rats pretreated with pCPA followed by a combination of nicotine and nifedipine doubled their tail-flick latency (P = 0.0001) compared with animals that were not treated with pCPA. These data further support the involvement of the serotonergic system in both nifedipine- and nicotine-induced analgesia and suggest that drugs that affect serotonin levels, including tricyclic antidepressants and serotonin-specific reuptake inhibitors, may also affect the analgesia induced by nifedipine and nicotine. IMPLICATIONS: This study examines the effect of serotonin depletion on nicotine- and nifedipine-induced analgesia. Nifidipine is a calcium channel blocker used to treat high blood pressure. It also has pain-relieving properties that are enhanced by nicotine. Because both nifedipine- and nicotine-induced analgesia involve the neurotransmitter serotonin, it is important to know how changes in serotonin concentration might affect both nicotine- and nifedipine-induced analgesia. This study not only supports the involvement of the serotonergic system in both nifidipine- and nicotine-induced analgesia, but also suggests that drugs that affect serotonin levels may also affect analgesia induced by nifidipine and nicotine.     

Sexually transmitted infections in female sex workers: reduced by condom use but not by a limited periodic examination program

Mental depression and myocardial infarction (MI) are closely related. The current paper reviews pathophysiological mechanisms that could link depression to MI and discusses the pros and cons of different pharmacological and non-pharmacological treatment modalities that could be considered. The selective serotonin reuptake inhibitors lack arrhythmogenic effects, and have a beneficial effect in addition to depression on psychological factors, such as anxiety and mood disturbances, which are not uncommon in post-MI patients. Studies to further determine the impact of depression on the outcome of MI, and the place of different treatment modalities are in progress.