Inverse correlation between clinical response to paroxetine and plasma drug concentration in patients with major depressive disorders

Pharmacokinetics of immediate and sustained-release formulations of paroxetine: Population pharmacokinetic approach to guide paroxetine personalized therapy in chinese psychotic patients

Paroxetine is one of the most potent selective serotonin reuptake inhibitors (SSRIs) approved for treating depression, panic disorder, and obsessive-compulsive disorder. There is evidence linking genetic polymorphisms and nonlinear metabolism to the Paroxetine’s pharmacokinetic (PK) variability. The purpose of the present study was to develop a population PK (PPK) model of paroxetine in Chinese patients, which was used to define the paroxetine’s PK parameters and quantify the effect of clinical and baseline demographic factors on these PK characteristics. The study included 184 inpatients with psychosis (103 females and 81 males), with a total of 372 serum concentrations of paroxetine for PPK analyses. The total daily dosage ranged from 20 to 75 mg. One compartment model could fit the PKs characterize of paroxetine. Covariate analysis revealed that dose, formulation, and sex had a significant effect on the PK parameters of paroxetine; however, there was no evident genetic influence of CYP2D6 enzymes on paroxetine concentrations in Chinese patients. The study determined that the population’s apparent distribution volume (V/F) and apparent clearance (CL/F), respectively, were 8850 and 21.2 L/h. The CL/F decreased 1-2-fold for each 10 mg dose increase, whereas the different formulations caused a decrease in V/F of 66.6%. Sex was found to affect bioavailability (F), which decreased F by 47.5%. Females had higher F values than males. This PPK model described data from patients with psychosis who received paroxetine immediate-release tablets (IR-T) and/or sustained-release tablets (SR-T). Paroxetine trough concentrations and relative bioavailability were different between formulations and sex. The altered serum concentrations of paroxetine resulting from individual variants and additive effects need to be considered, to optimize the dosage regimen for individual patients.

Exploring the metabolic characteristics and pharmacokinetic variation of paroxetine in healthy volunteers using a pharmacometabonomic approach

The pharmacokinetic parameters of paroxetine vary between individuals, leading to differences in efficacy. The focus of our research was to predict responses to paroxetine using a pharmacometabonomic approach combining metabolic phenotypes and pharmacokinetic parameters. The pharmacokinetics of 12 healthy volunteers treated with paroxetine over two cycles was determined using high-performance liquid chromatography tandem mass spectrometry. Metabolic profiling and phenotyping were performed on the blood samples that remained after pharmacokinetic studies, using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry. Thirty-nine metabolites (p < 0.05) increased or decreased after treatment with paroxetine. Vitamin B6 metabolism; valine, leucine, and isoleucine biosynthesis; phenylalanine metabolism; pantothenate and coenzyme A biosynthesis; tyrosine metabolism; and glyoxylate and dicarboxylate metabolism were likely to be relevant for the effects of paroxetine. The two-stage partial least squares (PLS) strategy was used to screen potential biomarkers and predict the pharmacokinetic parameters of paroxetine. An orthogonal PLS discriminant analysis strategy was then applied to separate the high- and low-value groups based on the screened biomarkers. Pearson correlation test and receiver operating characteristic curve analysis confirmed the key prediction biomarkers. Seven common biomarkers were able to predict both the area under the curve (AUC) and the maximum concentration (C_max): cortisone, l-tyrosine, phenylpyruvate, l-valine, 2-oxoglutarate, l-lactate, and glycerate. Furthermore, homoprotocatechuate and l-glutamate were unique biomarkers for AUC, and citicoline and fumarate were unique biomarkers for C_max. The selected biomarkers were able to predict the AUC and C_max and discriminate good responders from poor responders to paroxetine treatment. This trial was registered with http://www.chinadrugtrials.org.cn/ (no. CTR20171590).

Concentration-Effect Relationships of Psychoactive Drugs and the Problem to Calculate Therapeutic Reference Ranges

BACKGROUND

Despite the obvious potential of Therapeutic Drug Monitoring (TDM) as a tool to optimize psychopharmacotherapy, especially treatment with mood-stabilizing, antidepressant and antipsychotic drugs, acceptance of TDM as a routine tool is still limited. A serious scientific argument against the regular use of TDM is the lack of evidence for a concentration-dependent clinical effect. The aim of this review was to highlight methodological problems leading to poor or even negative concentration-effect relationships and to show how therapeutically effective concentrations of psychoactive drugs can be determined using routine TDM databases.

METHODS

Reports on concentration-effect relationships of psychoactive drugs were analyzed with regard to applied methods. From routine TDM databases of patients who had been treated with antidepressant or antipsychotic drugs and whose improvement was measured by the clinical global impressions scale, mean and median drug concentrations were calculated and compared with reference ranges recommended by TDM guidelines.

RESULTS

Few fixed-dose studies with adequate design and data analysis demonstrated a correlation between drug concentration and clinical effect for psychoactive drugs. Most studies, however, mostly retrospective analyses of TDM databases, failed to find significant concentration-effect relationships because of flexible dosing. They were not suitable for the determination of therapeutically effective drug concentrations. Using TDM databases of antidepressant and antipsychotic drug concentrations in blood of patients who were categorized as responders by the clinical global impressions score, the interquartile ranges of drug concentrations (25th-75th percent range) can be shown to be very close to the therapeutic reference ranges recommended in guidelines for TDM in psychiatry.

CONCLUSIONS

This review provides a discussion on why simple correlation analyses of psychoactive drug concentrations in blood and clinical effects are obsolete for flexible-dose studies or TDM databases. TDM databases, however, can and should be used to calculate drug concentrations in blood of patients who had responded to the drugs. Interquartile ranges can be regarded and used as preliminary therapeutic reference ranges.

Effects of personality on the association between paroxetine plasma concentration and response

BACKGROUND

We studied the differences between groups that were divided according to personality characteristics with respect to the relationship between drug concentration and symptom improvement.

METHODS

A total of 120 patients with major depressive disorder were treated with paroxetine for 6 weeks, and 89 patients completed the protocol. The Montgomery-Åsberg Depression Rating Scale (MADRS) was used to evaluate the patients. Patients' paroxetine plasma concentrations at week 6 were measured. Their personalities were evaluated by the Temperament and Character Inventory (TCI) at the first visit. We divided the patients into two groups according to the median of each TCI dimension. We compared the responder rate between "high" and "low" groups in each TCI dimension and analyzed Pearson's correlation coefficients of paroxetine plasma concentration and MADRS-improvement rate.

RESULTS

A total of 62 patients completed the TCI. Low-novelty-seeking, high-harm-avoidance, low-reward-dependence, and low-self-directedness groups exhibited significant negative correlations between paroxetine plasma concentration and MADRS improvement. Among the groups with combined personality traits, the high-harm-avoidance and low-self-directedness groups showed a markedly significant negative correlation.

CONCLUSION

Patients with depression exhibiting specific personality traits, especially those with high harm-avoidance and low self-directedness scores, exhibited a significant negative association between paroxetine plasma concentration and MADRS-improvement rate. Therefore, a lower dose might be suitable for patients with specific personality traits.

A prospective, longitudinal study of platelet serotonin and plasma brain-derived neurotrophic factor concentrations in major depression: effects of vortioxetine treatment

BACKGROUND

Various antidepressants occupy brain serotonin transporter (SERT), decrease platelet serotonin (5-HT) concentration, and normalize reduced plasma brain-derived neurotrophic factor (BDNF) concentrations in depressed patients. Vortioxetine is a recently introduced antidepressant with a multimodal mechanism of action. In addition to SERT inhibition, vortioxetine acts via different 5-HT receptors. To further elucidate its mechanism of action, we have investigated the effects of vortioxetine on platelet 5-HT and plasma BDNF concentrations in patients with major depression.

METHODS

Platelet 5-HT and plasma BDNF concentrations were determined in 44 healthy subjects at baseline and in 44 depressed patients before and after 4 weeks of treatment with vortioxetine (5-15 mg daily). Platelet 5-HT concentration was determined using the ortho-phthalaldehyde-enhanced fluorometric method, and plasma BDNF concentration using a commercial enzyme-linked immunosorbent assay (Quantikine ELISA, R&D Systems).

RESULTS

At baseline, platelet 5-HT concentrations did not differ between depressed and control subjects, but plasma BDNF values were lower (p = 0.011; ω = 0.80) in depressed patients than in healthy subjects. Vortioxetine treatment significantly (p < 0.0001; ω = 0.80) decreased platelet 5-HT concentration and significantly (p = 0.004; ω = 0.80) increased plasma BDNF concentration in depressed patients compared to their baseline values. Age, gender, and smoking were not significantly associated with platelet 5-HT and plasma BDNF concentrations.

CONCLUSION

Despite a novel mechanism of action, vortioxetine shares some common effects with other antidepressants. This study is the first to show that, in addition to clinical improvement, 4 weeks of treatment with vortioxetine (5-15 mg daily), decreased platelet 5-HT and increased plasma BDNF concentrations in depressed patients.

Influence of the cytochrome P450 2D6 *10/*10 genotype on the pharmacokinetics of paroxetine in Japanese patients with major depressive disorder: a population pharmacokinetic analysis

OBJECTIVE

Although the reduced function of the cytochrome P450 2D6*10 (CYP2D6*10) allele is common among Asian populations, existing evidence does not support paroxetine therapy adjustments for patients who have the CYP2D6*10 allele. In this study, we attempted to evaluate the degree of the impact of different CYP2D6 genotypes on the pharmacokinetic (PK) variability of paroxetine in a Japanese population using a population PK approach.

METHODS

This retrospective study included 179 Japanese patients with major depressive disorder who were being treated with paroxetine. CYP2D6*1, *2, *5, *10, and *41 polymorphisms were observed. A total of 306 steady-state concentrations for paroxetine were collected from the patients. A nonlinear mixed-effects model identified the apparent Michaelis-Menten constant (Km) and the maximum velocity (Vmax) of paroxetine; the covariates included CYP2D6 genotypes, patient age, body weight, sex, and daily paroxetine dose.

RESULTS

The allele frequencies of CYP2D6*1, *2, *5, *10, and *41 were 39.4, 14.5, 4.5, 41.1, and 0.6%, respectively. There was no poor metabolizer who had two nonfunctional CYP2D6*5 alleles. A one-compartment model showed that the apparent Km value was decreased by 20.6% in patients with the CYP2D6*10/*10 genotype in comparison with the other CYP2D6 genotypes. Female sex also influenced the apparent Km values. No PK parameters were affected by the presence of one CYP2D6*5 allele.

CONCLUSION

Unexpectedly, elimination was accelerated in individuals with the CYP2D6*10/*10 genotype. Our results show that the presence of one CYP2D6*5 allele or that of any CYP2D6*10 allele may have no major effect on paroxetine PKs in the steady state.

Exposure-outcome analysis in depressed patients treated with paroxetine using population pharmacokinetics

Purpose

This study investigated population pharmacokinetics of paroxetine, and then performed an integrated analysis of exposure and clinical outcome using population pharmacokinetic parameter estimates in depressed patients treated with paroxetine.

Patients and methods

A total of 271 therapeutic drug monitoring (TDM) data were retrospectively collected from 127 psychiatric outpatients. A population nonlinear mixed-effects modeling approach was used to describe serum concentrations of paroxetine. For 83 patients with major depressive disorder, the treatment response rate and the incidence of adverse drug reaction (ADR) were characterized by logistic regression using daily dose or area under the concentration–time curve (AUC) estimated from the final model as a potential exposure predictor.

Results

One compartment model was developed. The apparent clearance of paroxetine was affected by age as well as daily dose administered at steady-state. Overall treatment response rate was 72%, and the incidence of ADR was 30%. The logistic regression showed that exposure predictors were not associated with treatment response or ADR in the range of dose commonly used in routine practice. However, the incidence of ADR increased with the increase of daily dose or AUC for the patients with multiple concentrations.

Conclusion

In depressed patients treated with paroxetine, TDM may be of limited value for individualization of treatment.

Therapeutic reference range for plasma concentrations of paroxetine in patients with major depressive disorders

BACKGROUND

We investigated the relationship between plasma concentrations of paroxetine and the therapeutic effect of the drug, and we evaluated the therapeutic reference range for plasma concentration of paroxetine in patients with major depressive disorders (MDD).

METHODS

In this study, 120 patients with MDD were treated with 10-40 mg/d of paroxetine for 6 weeks, and 89 patients completed the protocol. The Montgomery-Asberg Depression Rating Scale (MADRS) was used to evaluate the patients at 0, 1, 2, 4, and 6 weeks. At the 6-week treatment time point, the patients were divided into 7 groups according to their paroxetine plasma concentrations in increments of 20 ng/mL. We used an analysis of variance and a χ test to define the therapeutic reference range for plasma paroxetine concentrations.

RESULTS

We used 50% as the cutoff values for the percentage of MADRS improvement to determine the responder rates, and we defined remitters as patients with MADRS scores <10 at the 6-week treatment time point. We analyzed the responder and remitter rates of the patients according to their plasma paroxetine concentrations: 20 ng/mL, 40 ng/mL, and 60 ng/mL using the χ test. According to the results of the χ test in the responder rates, the 20-60 ng/mL plasma paroxetine group showed the highest effect size.

CONCLUSIONS

The results of this study suggested that a range of 20-60 ng/mL is the therapeutic reference range for concentrations of paroxetine in plasma in patients with MDD.

Possible impact of the CYP2D6*10 polymorphism on the nonlinear pharmacokinetic parameter estimates of paroxetine in Japanese patients with major depressive disorders

It has been suggested that the reduced function allele with reduced cytochrome P450 (CYP) 2D6 activity, CYP2D6*10, is associated with the interindividual differences in the plasma paroxetine concentrations, but there is no data presently available regarding the influence of the CYP2D6*10 polymorphism on the pharmacokinetic parameters, eg, Michaelis–Menten constant (K_m) and maximum velocity (V_max), in Asian populations. The present study investigated the effects of the CYP2D6 polymorphisms, including CYP2D6*10, on the pharmacokinetic parameters of paroxetine in Japanese patients with major depressive disorders. This retrospective study included 15 Japanese patients with major depressive disorders (four males and eleven females) who were treated with paroxetine. The CYP2D6*2, CYP2D6*4, CYP2D6*5, CYP2D6*10, CYP2D6*18, CYP2D6*39, and CYP2D6*41 polymorphisms were evaluated. A total of 56 blood samples were collected from the patients. The K_m and V_max values of paroxetine were estimated for each patient. The allele frequencies of CYP2D6*2, CYP2D6*4, CYP2D6*5, CYP2D6*10, CYP2D6*18, CYP2D6*39, and CYP2D6*41 were 6.7%, 0%, 10.0%, 56.7%, 0%, 26.7%, and 0%, respectively. The mean values of K_m and V_max were 50.5±68.4 ng/mL and 50.6±18.8 mg/day, respectively. Both the K_m and V_max values were significantly smaller in CYP2D6*10 allele carriers than in the noncarriers (24.2±18.3 ng/mL versus 122.5±106.3 ng/mL, P=0.008; 44.2±16.1 mg/day versus 68.3±15.0 mg/day, P=0.022, respectively). This is the first study to demonstrate that the CYP2D6*10 polymorphism could affect the nonlinear pharmacokinetic parameter estimates of paroxetine in Asian populations. The findings of this study suggest that the CYP2D6*10 polymorphism may be associated with the smaller values of both the K_m and V_max in Japanese patients with major depressive disorders, and these results need to be confirmed in further investigations with a larger number of patients.

The influence of 5-HTTLPR genotype on the association between the plasma concentration and therapeutic effect of paroxetine in patients with major depressive disorder

INTRODUCTION

The efficacy of treatment with selective serotonin reuptake inhibitors in patients with major depressive disorder (MDD) can differ depending on the patient's serotonin transporter-linked polymorphic region (5-HTTLPR) genotype, and the effects of varying plasma concentrations of drugs can also vary. We investigated the association between the paroxetine plasma concentration and clinical response in patients with different 5-HTTLPR genotypes.

METHODS

Fifty-one patients were enrolled in this study. The Montgomery-Asberg Depression Rating Scale (MADRS) was used to evaluate patients at 0, 1, 2, 4, and 6 weeks. The patients' paroxetine plasma concentrations at week 6 were measured using high-performance liquid chromatography. Additionally, their 5-HTTLPR polymorphisms (alleles S and L) were analyzed using a polymerase chain reaction with specific primers. We divided the participants into two groups based on their L haplotype: the SS group and the SL and LL group. We performed single and multiple regression analyses to investigate the associations between MADRS improvement and paroxetine plasma concentrations or other covariates for each group.

RESULTS

There were no significant differences between the two groups with regard to demographic or clinical data. In the SS group, the paroxetine plasma concentration was significantly negatively correlated with improvement in MADRS at week 6. In the SL and LL group, the paroxetine plasma concentration was significantly positively correlated with improvement in MADRS at week 6 according to the results of the single regression analysis; however, it was not significantly correlated with improvement in MADRS at week 6 according to the results of the multiple regression analysis.

CONCLUSION

Among patients with MDD who do not respond to paroxetine, a lower plasma concentration or a lower oral dose of paroxetine might be more effective in those with the SS genotype, and a higher plasma concentration might be more effective in those with the SL or LL genotype.

Factors affecting discontinuation of initial treatment with paroxetine in panic disorder and major depressive disorder

OBJECTIVE

The aims of the present study were to analyze the association between discontinuation of paroxetine (PAX) and the genetic variants of the polymorphism in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) in Japanese patients with panic disorder (PD) and major depressive disorder (MDD).

METHODS

The 5-HTTLPR genotype was determined by polymerase chain reaction method. PAX plasma concentration was measured by high-performance liquid chromatography to confirm adherence.

RESULTS

When comparing between the PD and MDD patients with the chi-square test and Fisher's exact test, the PD patients had a significant and higher discontinuation rate due to non-adherence than did the MDD patients (13.5% [7/52] versus 0% [0/88], respectively; P<0.001). MDD patients had a significant and higher discontinuation rate due to untraceability than PD patients (12.5% [11/88] versus 1.9% [1/52]; P=0.032). Multilogistic regression revealed a tendency for the long/short and short/short genotypes to affect discontinuation due to adverse effects in PD patients (25.0% versus 6.3%, respectively; P=0.054).

CONCLUSION

The results indicate that the 5-HTTLPR genotype might contribute to the discontinuation of initial PAX treatment due to adverse effects in PD patients.

Genome-wide expression profiling of human lymphoblastoid cell lines implicates integrin beta-3 in the mode of action of antidepressants

Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for major depression. However, the link between inhibition of serotonin reuptake and remission from depression remains controversial: in spite of the rapid onset of serotonin reuptake inhibition, remission from depression takes several weeks, presumably reflecting synaptogenesis/neurogenesis and neuronal rewiring. We compared genome-wide expression profiles of human lymphoblastoid cell lines from unrelated individuals following treatment with 1 μM paroxetine for 21 days with untreated control cells and examined which genes and microRNAs (miRNAs) showed the most profound and consistent expression changes. ITGB3, coding for integrin beta-3, showed the most consistent altered expression (1.92-fold increase, P=7.5 × 10(-8)) following chronic paroxetine exposure. Using genome-wide miRNA arrays, we observed a corresponding decrease in the expression of two miRNAs, miR-221 and miR-222, both predicted to target ITGB3. ITGB3 is crucial for the activity of the serotonin transporter (SERT), the drug target of SSRIs. Moreover, it is presumably required for the neuronal guidance activity of CHL1, whose expression was formerly identified as a tentative SSRI response biomarker. Further genes whose expression was significantly modulated by chronic paroxetine are also implicated in neurogenesis. Surprisingly, the expression of SERT or serotonin receptors was not modified. Our findings implicate ITGB3 in the mode of action of SSRI antidepressants and provide a novel link between CHL1 and the SERT. Our observations suggest that SSRIs may relieve depression primarily by promoting neuronal synaptogenesis/neurogenesis rather than by modulating serotonin neurotransmission per se.