Fluoxetine in the treatment of obsessive compulsive disorder

The neuropharmacological profile of interval responding during operant tasks

Responses occurring during intervals of operant tasks have been subdivided as interim, facultative, and terminal, depending on the time between response onset and reward. Although interval responses, also known as adjunctive responses, have been described in pigeons, rats, mice, monkeys, and humans, most experiments have been conducted in rats. We review the neurochemical basis of interval responses and examine the hypothesis that these responses modulate operant performance. Preliminary experiments indicate the involvement of biogenic amines, acetylcholine, and GABA during interval responding associated with operant tasks. In particular, catecholaminergic deafferentation of the basal ganglia modulated interval responses as did the peripheral injection of catecholamine reuptake blockers. Under the influence of amphetamine, interval responding may either increase or decrease, so that a wide range of responses must be selected to gauge drug effects. In non-drugged pigeons and rats, the expression of interval responses facilitates operant training.

Mechanisms of action of current and potential pharmacotherapies of obsessive-compulsive disorder

A significant body of evidence documented that the orbitofrontal cortex (OFC) and the head of caudate nucleus are involved in the mediation of obsessive-compulsive disorder (OCD) symptoms. Potent serotonin (5-HT) reuptake inhibitors (SRIs) are the only antidepressant agents thus far shown to be effective in the treatment of OCD. The present review summarizes information on 5-HT release and the adaptive changes in pre- and postsynaptic 5-HT receptors sensitivity induced by SRI treatment in rat and guinea pig structures involved in OCD. It emphasizes that the time course for the occurrence of increased 5-HT release and terminal 5-HT1D desensitization is congruent with the delayed therapeutic response to SRI in OCD. In addition, a greater dose of SRI inducing a greater degree of reuptake inhibition may play an essential role in this phenomenon. This is consistent with the common clinical observation that high doses of SRIs are sometimes necessary to obtain an anti-OCD effect, and with the results of some fixed-dose double blind trials showing a dose-dependent therapeutic effect of SRIs. It is hypothesized that enhanced 5-HT release in the OFC is mediated by the activation of normosensitive postsynaptic 5-HT2-like receptors and underlies the therapeutic action of SRI in OCD. This is supported by the beneficial effect of some hallucinogens with 5-HT2 agonistic properties in obtaining a more rapid therapeutic response. Finally, based on this knowledge, new strategies aimed at producing more rapid, effective and safe anti-OCD drugs, such as a selective action on terminal 5-HT1D receptors, on 5-HT2 receptors as well as on the glutamate system, are discussed.

Long-term pharmacotherapy of obsessive-compulsive disorder: a double-blind controlled study

The aim of this study was to investigate whether obsessive-compulsive patients previously treated successfully with clomipramine or fluvoxamine could tolerate reduction of the daily dosage without worsening of the clinical condition. Thirty informed obsessive-compulsive patients, given a diagnosis according to DSM-III-R criteria, were recruited consecutively into the study. Patients were blindly assigned to one of the groups of treatment with different rates of reduction of the previously effective daily drug dosage: group 1 (control group, no reduction), group 2 (reduction of 33-40%), and group 3 (reduction of 60-66%). The entire study lasted 102 days. From baseline to the end of the study, the clinical condition was evaluated by the administration of standardized tests (Yale-Brown Obsessive-Compulsive Scale, Hamilton Rating Scale for Depression, Clinical Global Impression [CGI] scale), and blood samples were collected for plasma drug level determinations. The criterion for discontinuation of the study was the worsening of obsessive-compulsive symptoms, arbitrarily defined by an increase of > 5% from the baseline total Yale-Brown Obsessive-Compulsive Scale score, as measured in two successive assessments, and a worsening of global clinical condition as measured by the CGI scale. The main result of the study was borne out from the survival analysis. There were no significant differences in the cumulative proportion of patients from each group of treatment who did not worsen during the 102 days of observation. This preliminary result, which needs to be confirmed in larger samples, suggests that long-term maintenance therapy for obsessive-compulsive disorder might be provided with lower dosages of the antiobsessional drug, with clear advantages for tolerability and compliance.

Paroxetine versus clomipramine in the treatment of obsessive-compulsive disorder. OCD Paroxetine Study Investigators

BACKGROUND

The aim was to assess the effect of a flexible dose of paroxetine, compared with clomipramine and placebo, in obsessive-compulsive disorder (OCD).

METHOD

In a multinational randomised study, 406 subjects with OCD of at least six months duration received double-blind medication for up to 12 weeks. Doses were adjusted according to therapeutic effect and side-effects. Primary efficacy measures were the Yale-Brown Obsessive-Compulsive Scale and the National Institute of Mental Health Obsessive-Compulsive Scale. Secondary efficacy measures were the Montgomery-Asberg Depression Rating Scale, Symptom Check-List (90), Clinical Global Impression, and Patients Global Evaluation.

RESULTS

Paroxetine was significantly more effective than placebo, and of comparable efficacy to clomipramine. Paroxetine had significantly superior tolerability to clomipramine on three measures: CGI efficacy index, anticholinergic adverse events, and adverse events leading to withdrawal.

CONCLUSION

Paroxetine is as effective as clomipramine in the treatment of OCD. The comparable efficacy and better tolerability of paroxetine suggest that it would be an appropriate treatment for OCD.

Potentiation of fluoxetine by aminoglutethimide, an adrenal steroid suppressant, in obsessive-compulsive disorder resistant to SSRIs: a case report

1. The role of serotonin in the aetiology of obsessive compulsive disorder (OCD) has been established through considerable indirect evidence (Landry and Chouinard, 1990). The strongest evidence comes from the fact that drugs known to be serotonin-selective reuptake inhibitors (SSRIs) have been found to be useful in the pharmacotherapy of OCD (Landry and Chouinard, 1990). 2. The authors investigated a new treatment approach by adding an adrenal steroid suppressant to a SSRI, fluoxetine, in the case of a severe obsessive-compulsive patient who was drug-resistant to clomipramine and SSRIs. 3. We found that the combination of aminoglutethimide 250 mg qid and fluoxetine 40 mg die significantly improved the patient's condition. Moreover, during a four and a half year period, each time we tried to decrease either fluoxetine or the steroid suppressant, the patient started to relapse, suggesting that the adrenal steroid suppressant had a potentiating effect on the SSRI.

Sleep EEG of patients with obsessive-compulsive disorder

Twenty-two patients suffering from an obsessive and compulsive disorder (OCD) according to DSM-III-R were investigated by polysomnographic sleep EEG recordings under drug-free conditions and compared to age- and sex-matched healthy controls. Sleep efficiency was significantly lower and wake % SPT was significantly increased in the patient group compared to healthy subjects. Sleep architecture did not differ among the two samples. Especially REM sleep measures, in particular, REM latency did not differ among the groups. No positive correlation was found between sleep variables and rating inventories for obsession and compulsions (Y-BOCS), depression (Hamilton) and anxiety (CAS). A secondary depression did not influence sleep EEG variables. The results of this study contradict the assumption that OCD patients show REM sleep and slow wave sleep abnormalities similar to those shown by patients with primary depression.

Pharmacologic therapy of obsessive compulsive disorder

OCD is an anxiety disorder that was once viewed as rare and very difficult to treat. Although the first evidence that a serotonergic drug, clomipramine, might be effective in treating symptoms of OCD was published by Fernandez-Cordoba and Lopez-Ibor Alino in 1967, controlled trials demonstrating the efficacy of pharmacologic treatments in OCD did not appear until the 1980s. The availability of potentially effective treatments, combined with the awareness of prevalence rates for the disorder that are higher than previously believed, led to considerable interest in OCD. Numerous studies have been undertaken to investigate the biology of OCD. The observation that drugs that act by inhibiting serotonin uptake, such as clomipramine, fluvoxamine, sertraline, and fluoxetine, are effective in treating symptoms of OCD has resulted in intense interest in the relationship between serotonin and this disorder. Several lines of investigation support a serotonergic hypothesis for the pathophysiology and treatment of this disorder. Clomipramine, a tricyclic antidepressant that is a potent serotonin uptake inhibitor, was the first pharmacologic treatment for OCD to be studied in large multicenter trials. The successful outcome of these studies resulted in marketing approval by the United States Food and Drug Administration in 1989. Subsequently, similar multicenter trials have been undertaken with the selective serotonin uptake inhibitors fluvoxamine, sertraline, and fluoxetine. Results from these multicenter trials indicate that all these drugs are more effective than placebo in treating OCD. However, meta-analytic techniques applied to the data from controlled trials of these drugs suggest that the effect size for clomipramine is somewhat larger than that of the selective serotonin uptake inhibitors. A number of other drugs that affect serotonin through mechanisms other than uptake inhibition have been tried as treatments for OCD. Because of the small size of many of these studies, it is difficult to evaluate them in the context of the multicenter trials that studied hundreds of patients. Nevertheless, there may be a role for other serotonergic drugs in the treatment of OCD, particularly as adjunctive treatments used to enhance the effect of the serotonin uptake inhibitors. The data supporting the use of adjunctive treatment are limited and cannot be considered to demonstrate definitively the value of augmentation strategies with adjunctive treatment. Nevertheless, the serotonin uptake inhibitors, although effective in a large number of patients, do not appear to provide adequate symptom relief for some patients. Furthermore, among the patients who do respond to serotonin uptake inhibitors, complete remission in uncommon, which leaves a need for improvement of therapies.(ABSTRACT TRUNCATED AT 400 WORDS)

Exposure with response prevention and serotonergic antidepressants in the treatment of obsessive compulsive disorder: a review and implications for interdisciplinary treatment

A comprehensive review of controlled investigations examining the effectiveness of exposure with response prevention (ERP) and clomipramine (CMI), as well as other serotonergic anti-depressants, in the treatment of Obsessive Compulsive Disorder (OCD) was conducted. Overall, findings suggested that ERP is more effective than CMI, particularly in alleviating rituals, but CMI may be more effective in reducing obsessive compulsive behavior among individuals with concomitant severe depression, obsessions only, and overvalued ideation. In addition, the literature favors ERP in terms of side-effects and risks, dropout, and maintenance, while one advantage of drug therapy is that less time and effort are required by the therapist and patient. Directions for interdisciplinary treatment are discussed.

The benefits of clomipramine-fluoxetine combination in obsessive compulsive disorder

We report the benefits of clomipramine-fluoxetine combination in four cases of severe obsessive compulsive disorder. In two cases, the combination was effective when either drug used singly was ineffective. In the other two cases, fluoxetine adjunct produced benefits with no additional side effects.

Fenfluramine stimulation of prolactin in obsessive-compulsive disorder

The success of serotonergic reuptake inhibitors in the treatment of obsessive-compulsive disorder (OCD) has suggested that serotonergic neurotransmission may play a role in the pathogenisis of this disorder. Prolactin responses to a 60-mg oral dose of fenfluramine in 26 medication-free patients with a DSM-III-R diagnosis of OCD were compared with those of 20 controls subjects. Fenfluramine produced a significant elevation of prolactin levels in both OCD patients and controls. Prolactin responses were significantly blunted in OCD patients compared with responses in control subjects. Female subjects in both groups showed greater prolactin responses to fenfluramine than did their male counterparts. There was a significant interaction between sex and the presence of OCD such that female patients had lower prolactin responses than their controls, while the difference between male patients and controls was not significant. Prolactin responses were not correlated with age, weight, drug level, depression, anxiety, or degree of OCD symptoms. The results are consistent with a relative reduction in serotonergic efficacy in the setting of OCD.

Fluoxetine treatment of obsessive-compulsive disorder

Two patients suffering from severe obsessive-compulsive disorder which had proven refractory to clomipramine and/or phenelzine treatment were successfully treated with fluoxetine, a new drug with a strong serotonin uptake inhibiting action. Outcome of treatment was measured on psychometric tests including the Leyton Obsessive Inventory, Hopkins Symptom Checklist-90, Beck Depression Inventory, and daily self-reports of the duration and degree of discomfort of their most severe obsessions. The delay in responding to fluoxetine, the continuing improvement even after one year on the drug, and the prompt relapse with abrupt withdrawal of treatment were noted.

Spontaneous alternation behavior: an animal model for obsessive-compulsive disorder?

This study entailed the adoption of a well-established behavioral paradigm, spontaneous alternation, as a possible animal model for some of the symptoms observed in obsessive-compulsive disorder (OCD) in humans. Food-deprived rats were run in a T-maze in which both a black and a white goal box were equally baited with a small amount of chocolate milk. Each rat was given 7 trials every other day during which it was placed in the start box and allowed to make a choice. The mean number of choices until an alternation occurred was recorded. After a stable baseline of spontaneous alternation was achieved the effects of manipulating the serotonergic system were tested. Both the nonselective 5-HT agonist 5-MeODMT (1.25 mg/kg) and the more selective 5-HT1A agonist 8-OH-DPAT (2 mg/kg) disrupted spontaneous alternation. A course of chronic treatment (2 x 5 mg/kg for 21 days) with the selective 5-HT uptake blocking agent fluoxetine had a protective effect on the 5-MeODMT-induced disruption of spontaneous alternation behavior. Serotonergic manipulations of spontaneous alternation may be a simple animal model for the perseverative symptoms or indecisiveness seen in people diagnosed with OCD.

Platelet imipramine binding and serotonin uptake in obsessive-compulsive patients

Platelet imipramine binding was measured in 16 drug-free nondepressed patients (aged 20-61 years, mean +/- SD 35 +/- 8) suffering from obsessive-compulsive disorder (OCD) and in 16 sex-, race- and age-matched healthy controls. Imipramine binding capacity and affinity were not different in the 2 groups. Platelet serotonin (5-HT) uptake capacity, Vmax, was also measured in 15 of these patients and their matched controls. Vmax was significantly higher in the patients (309 +/- 149 pmol/10(9) cells/min) than in the controls (181 +/- 110). An increase in platelet 5-HT uptake supports the involvement of 5-HT in OCD and may suggest that a hyperactive serotonergic system is present in this disorder.

Effects of chronic fluoxetine treatment on behavioral and neuroendocrine responses to meta-chlorophenylpiperazine in obsessive-compulsive disorder

To investigate the effect of fluoxetine on serotonergic sensitivity in obsessive-compulsive disorder (OCD), the partial serotonin agonist metachlorophenylpiperazine (mCPP) was compared to placebo under double-blind conditions in six patients with OCD before and during treatment with fluoxetine. Readministration of oral mCPP (0.5 mg/kg) after at least 12 weeks of fluoxetine treatment did not increase obsessive-compulsive (OC) symptoms, in contrast to exacerbation of OC symptoms produced by mCPP before treatment. Chronic fluoxetine treatment resulted in a significant increase in prolactin and cortisol response to mCPP. This may be accounted for, however, by substantially increased plasma mCPP levels during fluoxetine treatment. Chronic fluoxetine treatment diminished the behavioral sensitivity to mCPP and did not diminish, but may have partially normalized, the neuroendocrine response to mCPP in patients with OCD. These adaptive homeostatic effects may reflect fluoxetine's antiobsessional mechanism.

Neuroendocrine aspects of the serotonergic hypothesis of depression

This review examines the role of serotonin (5-HT) in depression. Dysfunction of serotonergic neurons has been implicated as one of the causes of endogenous depression. Since serotonergic neurons innervate the hypothalamus and these neurons send collaterals to several other brain areas, it is possible that hypothalamic sites which control hormone secretion receive the same serotonergic afferents that innervate other limbic areas in the brain. Several investigators have devised neuroendocrine challenge tests measuring the effect of 5-HT agonists on plasma cortisol and prolactin in depressed patients. These tests help to identify dysfunctional 5-HT neurons, and are a "window into the brain." The secretion of cortisol and prolactin is increased predominantly by 5-HT1 receptors. However, changes in 5-HT2 receptors have also been implicated in depression. Results from our laboratory and by others suggest that brain serotonergic neurons stimulate renin and vasopressin secretion by activation of 5-HT2 receptors. Therefore, the renin and vasopressin response to 5-HT agonists should be included in neuroendocrine tests of serotonergic function in affective disorders. Since antidepressants produce a decrease in the density of 5-HT2 receptors, renin and vasopressin could be used to evaluate the antidepressant potential of new drugs.

Fluoxetine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in depressive illness

Fluoxetine is a new antidepressant which enhances serotoninergic neurotransmission through potent and selective inhibition of neuronal reuptake of serotonin. Metabolism by N-desmethylation occurs in man yielding desmethylfluoxetine, which also inhibits serotonin reuptake. Both the parent compound and metabolite possess elimination half-lives of several days facilitating the maintenance of steady-state plasma concentrations during long term treatment. Fluoxetine has overall therapeutic efficacy comparable with imipramine, amitriptyline and doxepin in patients with unipolar depression treated for 5 to 6 weeks, although it may be less effective than tricyclic antidepressants in relieving sleep disorders in depressed patients. Geriatric patients also responded as well to fluoxetine as to doxepin. The symptomatic improvement in patients with unipolar depression during short term fluoxetine treatment has been satisfactorily maintained when therapy was extended for at least 6 months: the relapse rate was low and similar to that of imipramine. Preliminary data have shown that patients with bipolar depression gained similar therapeutic benefit from fluoxetine or imipramine. Other preliminary trials have indicated that fluoxetine may be useful in obsessive-compulsive disorders. Usual doses of fluoxetine cause significantly fewer anticholinergic-type side effects than tricyclic antidepressants. Nausea, nervousness and insomnia are the most frequently reported fluoxetine-related adverse effects, but these have usually not been severe. Therapeutic doses of fluoxetine do not affect cardiac conduction intervals in patients without pre-existing cardiovascular disease and fluoxetine has been relatively safe in the small number of patients who have taken overdoses. It has not been clearly established whether some types of depression may respond more readily to fluoxetine than other antidepressants, and its overall therapeutic efficacy has not been compared with other second generation antidepressants. Thus, with its different and perhaps improved side effect profile compared with older tricyclic antidepressants, fluoxetine offers properties that could be used to advantage in many patients with depression.