Citalopram concentrations and response in obsessive-compulsive disorder. Preliminary results

Pharmacokinetics of serotonergic drugs: focus on OCD

INTRODUCTION

Although the treatment of obsessive-compulsive disorder (OCD), a common, chronic, and disabling psychiatric condition, has significantly improved in the last decades, with the demonstration of the specific effectiveness of serotonin reuptake inhibitors (SRIs), a large proportion of patients still show high relapse rates. In addition, pharmacological treatments should be maintained for years, so that the clinicians should take into account the pharmacokinetic changes in the long-term, which may be responsible for dangerous side effects or interactions. Areas covered: The aim of this paper was to review the literature on the pharmacokinetics of SSRIs and clomipramine, and on their pharmacokinetic parameters in OCD patients. Expert opinion: Although the literature on the pharmacokinetics of both clomipramine and SSRIs is consistent, data on pharmacokinetic parameters in OCD patients are very few. Given the impact of OCD, its chronicity requiring long-term treatments, together with the need to increase the clinical response rate, more studies in this field are urgently required.

The Selective Serotonin Reuptake Inhibitor Citalopram Decreases Human Immunodeficiency Virus Receptor and Coreceptor Expression in Immune Cells

BACKGROUND

This study investigated whether the selective serotonin reuptake inhibitor (SSRI) citalopram downregulates the expression of the human immunodeficiency virus (HIV) receptor cluster of differentiation 4 (CD4) and coreceptors chemokine receptor type 5 and chemokine-related receptor type 4 (CCR5 and CXCR4) on peripheral blood mononuclear cells (PBMCs) and macrophages ex vivo as a potential mechanism of reducing susceptibility to HIV infection.

METHODS

The sample included 150 participants 18-58 years old (59% women, 65% African American, 61% with depression). Monocyte-depleted PBMCs were treated with phytohemagglutinin for 72 hours and then cultured in the presence of interleukin-2 with vehicle control or the SSRI (10(-6) mol/L) for 2 hours. To generate monocyte-derived macrophages, monocytes were cultured for 7 days, after which either vehicle control or SSRI (10(-6) mol/L) was added for 2 hours. RNA was collected from both cell types, and messenger RNA expression of CD4, CCR5, and CXCR4 was measured by real-time polymerase chain reaction.

RESULTS

In PBMCs, SSRI treatment decreased expression of CD4 (p = .009), CCR5 (p = .008), and CXCR4 (p < .0001). In monocyte-derived macrophages, SSRI treatment decreased expression of CD4 (p < .0001) and CXCR4 (p = .0003), but not CCR5 (p = .71). The suppressive effects of the SSRI on receptor expression did not differ as a function of depression diagnosis or depressive symptom severity.

CONCLUSIONS

Treatment with the SSRI at a physiologic dose decreased CD4, CCR5, and CXCR4 expression on PBMCs and macrophages ex vivo. These findings suggest that SSRI treatment, independent of depression status, downregulates HIV receptor and coreceptor expression and may reduce susceptibility of immune cells to HIV infection and decrease inflammation. If clinical trials confirm the present findings, ultimately there may be a role for using SSRI treatment adjunctively in HIV and acquired immunodeficiency syndrome.

ABCB1 gene polymorphisms are associated with the severity of major depressive disorder and its response to escitalopram treatment

OBJECTIVE

ATP-binding cassette, sub-family B (MDR/TAP), member 1 (ABCB1) is a drug transporter protein expressed on the epithelial cells of the intestine and the endothelial cells of the blood-brain barrier. Intestinal ABCB1 actively transports drugs from the cell membrane and prevents them from entering the blood stream whereas the blood-brain barrier ABCB1 prevents drugs from entering the central nervous system. In this study, we tested whether genetic polymorphisms within the ABCB1 gene are associated with the severity of depression and the effectiveness of the antidepressant, escitalopram (S-CIT), in treating major depressive disorder (MDD).

METHODS

Twenty single nucleotide polymorphisms in the ABCB1 gene were selected and genotyped in 100 MDD patients who had undergone S-CIT treatment continuously for 8 weeks. The serum concentrations of S-CIT and its metabolites (S-desmethylcitalopram and S-didesmethylcitalopram) were then measured at weeks 2, 4, and 8.

RESULTS

The ABCB1 genotypes of rs1922242 (P=0.0028) and rs1202184 (P=0.0021) showed significant association with the severity of depressive symptoms as assessed by the Hamilton Rating Scale for Depression adjusted with Hamilton Rating Scale for Anxiety. The haplotype block, rs1882478-rs2235048-rs2235047-rs1045642-rs6949448 (from intron 27 to intron 26), of ABCB1 was found strongly associated with the remission rate (global P=0.003, d.f.=69) in which haplotype T-T-T-C-C was associated with a slower remission rate on S-CIT treatment (P=0.001). The haplotypes may not be indicators of the severity of depression or anxiety.

CONCLUSION

Our findings suggest that single nucleotide polymorphisms in the ABCB1 gene may be indicators of the severity of depression and of the likely S-CIT treatment remission response in MDD.

Open-label study of high (30 mg) and moderate (20 mg) dose escitalopram for the treatment of obsessive-compulsive disorder

This study sought to investigate the efficacy of escitalopram at different dosages for the treatment of obsessive-compulsive disorder (OCD). Thirty individuals were enrolled in a 16-week, open-label trial of escitalopram and randomly assigned to the 20 or 30 mg study arm. Study measures assessing OCD symptoms, anxiety, depression, and quality of life were administered at baseline and weeks 2, 4, 8, 12, and 16. For the 23 study completers, pretreatment and posttreatment analyses revealed significant improvements (P<0.05) on clinician-rated and self-rated measures of OCD symptoms, quality of life, anxiety, and depression. Approximately half of the sample (n = 12) satisfied full medication response criteria and less than one-quarter (n = 5) were partial medication responders. Intention-to-treat analyses showed similar improvements (P<0.05) on all study measures. At study completion, a superior responder rate and more improvement on the Yale-Brown Obsessive Compulsive Scale (P<0.05) was reported for those in the 30 versus 20 mg study arm. The difference between the two groups, however, disappeared when initial differences in baseline depression and anxiety scores were used as analysis covariates. These results suggest that the 30 mg (vs. 20 mg) dose of escitalopram may provide a superior reduction in OCD symptoms for those sufferers with comorbid depression and/or anxiety.

Selective serotonin reuptake inhibitor and substance P antagonist enhancement of natural killer cell innate immunity in human immunodeficiency virus/acquired immunodeficiency syndrome

BACKGROUND

Natural killer (NK) cells play an important role in innate immunity and are involved in the host defense against human immunodeficiency virus (HIV) infection. This study examines the potential role of three underlying regulatory systems that have been under investigation in central nervous system research as well as immune and viral research: serotonin, neurokinin, and glucocorticoid systems.

METHODS

Fifty-one HIV-seropositive subjects were recruited to achieve a representative sample of depressed and nondepressed women. The effects of a selective serotonin reuptake inhibitor (SSRI), a substance P (SP) antagonist, and a glucocorticoid antagonist on NK cell function were assessed in a series of ex vivo experiments of peripheral blood mononuclear cells from each HIV-seropositive subject.

RESULTS

Natural killer cell cytolytic activity was significantly increased by the SSRI citalopram and by the substance P antagonist CP-96345 relative to control conditions; the glucocorticoid antagonist, RU486, showed no effect on NK cytotoxicity. Our results suggest that the effects of the three agents did not differ as a function of depression.

CONCLUSIONS

Our findings provide evidence that NK cell function in HIV infection may be enhanced by serotonin reuptake inhibition and by substance P antagonism. It remains to be determined if HIV-related impairment in not only NK cytolytic activity but also NK noncytolytic activity can be improved by an SSRI or an SP antagonist. Clinical studies are warranted to address these questions and the potential roles of serotonergic agents and SP antagonists in improving NK cell immunity, delaying HIV disease progression, and extending survival with HIV infection.

Obsessive-compulsive disorder: an open-label pilot trial of escitalopram

INTRODUCTION

Selective serotonin reuptake inhibitors are considered the most effective and well-established pharmacotherapy for the treatment of obsessive-compulsive disorder (OCD), a chronic and disabling condition. However, approximately 40% of patients do not have a significant improvement, suggesting that new medications are needed. This study was designed to investigate the treatment response to escitalopram in OCD patients.

METHODS

This open-label study involved 11 adult OCD outpatients diagnosed with the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Axis I Disorders. Data were collected and the treatment response was assessed by an experienced psychiatrist by using the Yale-Brown Obsessive-Compulsive Scale. Subjects received escitalopram 30 mg/day for 12 weeks starting at 10 mg/day. Dosage adjustments were made within 2 weeks, depending on the tolerability of the patient.

RESULTS

Six of the 11 patients (54.5%) presented a reduction of at least 40% in the baseline total Yale-Brown Obsessive-Compulsive Scale scores.

CONCLUSION

Despite the small sample size and the open-label nature of this trial, these data suggest that escitalopram may be a useful option for patients with OCD.

Pharmacotherapy of obsessive-compulsive disorder and obsessive-compulsive spectrum disorders

This article reviews new developments of pharmacotherapy in obsessive-compulsive disorder (OCD) and OC spectrum disorders of the past five years. New developments primarily involved the ex-tension of evidence of efficacy of serotonin reuptake inhibitors(SRIs), the use of atypical antipsychotics in addition to SRIs for treatment refractory patients, the combination of pharmacotherapy with behavior therapy, and studies assessing predictors of response. Today, frontline pharmacological treatment of OCD still consists of drugs with potent serotonin reuptake inhibition proper-ties. In case of non-response, treatment options comprise adding another drug, increasing the dose, switching drugs, or changing the mode of delivery.

Serotonin transporter imaging with [123I]beta-CIT SPECT before and after one year of citalopram treatment of obsessive-compulsive disorder

BACKGROUND

Two thirds of patients with obsessive-compulsive disorder (OCD) respond to treatment with selective serotonin reuptake inhibitors (SSRIs). The neurobiological mechanisms of SSRI action and failure to respond to SSRI treatment remain to be elucidated.

OBJECTIVES

The aim of this pilot study was to quantify changes in the availability of serotonin transporter (SERT) in the course of SSRI treatment and to relate these changes to improvements of clinical symptoms.

METHODS

Ten patients with OCD were investigated at baseline and 5 of them after 1 year of SSRI treatment with citalopram 60 mg per day using brain single photon emission computed tomography and [123I]beta-CIT. Specific-to-nondisplaceable [123I]beta-CIT binding ratios (V3'') were calculated in SERT-rich brainstem, midbrain and thalamus using a magnetic resonance imaging-based region of interest (ROI) analysis. Symptom severity was evaluated with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS).

RESULTS

V3'' differed significantly between pretreatment and follow-up scans in all three brain regions, thalamus, midbrain as well as in brainstem. In thalamic ROI, differ ences in SERT availability and Y-BOCS ratings correlated. In midbrain, a trend toward a significant association was found. In brainstem, no relationship was revealed.

CONCLUSIONS

Higher occupancy of SERT by citalopram seems to be associated with better clinical response after 1 year of SSRI treatment of patients with OCD.

Predictors of pharmacotherapy response in anxiety disorders

Although treatment with different compounds such as tricyclic antidepressants, selective serotonin reuptake inhibitors, high-potency benzodiazepines, and monoamine oxidase inhibitors has been proven effective in anxiety disorders, 20% to 40% of patients are nonresponders. Given the limited efficacy, the delayed onset of response (it takes several weeks before a clinical effect can be seen for most of these drugs), and the occurrence of side effects associated with pharmacotherapy, predicting response in anxiety disorders would be immensely valuable. This review surveys the literature over the past years on predictors of response to pharmacotherapy in obsessive-compulsive disorder, social anxiety disorder, panic disorder, and posttraumatic stress disorder. Prediction of treatment response may be founded on demographic and clinical variables, neurochemical and electrophysiologic parameters, imaging studies, and genetic markers.

Obsessive-compulsive disorder: a critical review of therapeutic perspectives

OBJECTIVE

Obsessive-compulsive disorder (OCD) is a chronic disabling disease with profound implications for social functioning. Thirty per cent of all patients with OCD show insufficient improvement with state-of-the-art treatment. Conventional treatment and alternative treatment options for this population were investigated.

METHOD

A selective review of the relevant scientific literature on OCD treatment and treatment resistance was conducted.

RESULTS

In addition to serotonin reuptake inhibitors (SRIs) and cognitive-behavioural therapy, alternative monotherapies, SRI augmentation strategies with a variety of drugs and electroconvulsive therapy have shown results in individual cases, but no conclusive evidence has been found in placebo-controlled trials. While studies investigating neurosurgery for refractory OCD show positive results, most of these studies have methodological shortcomings.

CONCLUSION

Novel approaches currently under investigation that have shown promising effects for treatment-resistant OCD include SRI augmentation with atypical antipsychotics and chronic deep brain stimulation, a new surgical technique. Placebo-controlled trials for both treatment options will be needed to confirm preliminary findings.