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Numerous studies have demonstrated that depression is associated with a decreased expression of brain-derived neurotrophic factor (BDNF). BDNF shows antidepressant-like effects in animal models. Therefore, we tested the hypothesis that BDNF might be a peripheral marker for the mechanism of action of antidepressant agents in humans. Thirty-two patients meeting the DSM-IV criteria for major depressive disorder and 50 normal control subjects were recruited for this study. Plasma BDNF levels and Hamilton Depression Rating Scales were measured at baseline and 6 weeks after antidepressant administration. At baseline, the mean plasma BDNF level was lower in the depressive patients (698.1 ± 537.7 pg/ml) than in the control subjects (830.7 ± 624.8 pg/ml), although the difference was not statistically significant (p = 0.33). The plasma BDNF levels in depressive patients significantly increased from 698.1 ± 537.7 to 1,028.9 ± 744.5 after 6 weeks of antidepressant treatment (p = 0.01). Moreover, plasma BDNF levels were significantly increased after 6 weeks of treatment in the responder group, while there was no statistically significant change in the unresponsive group. These results suggest that the therapeutic response after antidepressant administration might be attributable to the increase in BDNF levels. BDNF may play a critical role in the action mechanism of antidepressant drugs. Further studies with a larger number of subjects are needed to verify these findings.

This study investigated clinical and genetic predictors of increasing suicidal ideation during antidepressant treatment. A total of 131 depressed outpatients were allocated to four antidepressants (paroxetine, venlafaxine, clomipramine or nefazodone) in a sequential step procedure until remission. Suicidality was assessed using the 10th item of the Montgomery-–Asberg Depression Rating Scale (MADRS). A total of 11 candidate genes involved in different mechanisms of antidepressant action were selected for association with increasing suicidality. Increasing suicidality correlated with depression severity and higher antidepressant blood levels. Risk of increasing suicidal ideation was higher in subjects taking antidepressants other than paroxetine (odds ratio: 1.11). The strongest genetic predictor was found to be rs1360780 within the gene (p = 2.9 ×× 10 ), followed by 2677G>T in the gene. The rs130058 SNP within the gene demonstrated a differential association with increasing suicidal ideation depending on antidepressant type. Increasing suicidal ideation might be an adverse effect of antidepressants. The involvement of indicates that dysregulation of the hypothalamic-–pituitary-–adrenal axis is involved in treatment increasing suicidal ideation. Original submitted 12 October 2010; Revision submitted 18 November 2010.

Purpose To assess the effects of venlafaxine extended-release (XR) capsules and desvenlafaxine extended-release (XR) tablets upon indinavir pharmacokinetic properties when co-administrated to healthy volunteers. Methods This was an open-label, two-period, fixed-dose study conducted at the clinical research unit located on a university campus. Twenty-four healthy volunteers enrolled in the study (mean age 28.3 ± 8.0 years). Each subject received a single dose of indinavir 800 mg on day 1. Subsequently, subjects were then randomly assigned to either the venlafaxine XR group ( N  = 12) or the desvenlafaxine XR group ( N  = 12). Starting on day 2, venlafaxine XR was dosed at 37.5 mg/day for 4 days and increased to 75 mg/day for 6 days. Desvenlafaxine XR was dosed at 50 mg/day for 10 days. On day 12, indivanvir 800 mg was co-administered to both the venlafaxine XR and the desvenlafaxine XR groups. The pharmacokinetics of indinavir were determined both before and at the end of antidepressant dosing. Plasma indinavir, venlafaxine, and desvenlafaxine concentrations were assayed by high-performance liquid chromatography with ultra-violet (UV) detection. Indinavir pharmacokinetic parameters were calculated by noncompartmental analysis using validated computer software. Results Venlafaxine XR and desvenlafaxine XR did not produce any significant changes in indinavir disposition. Both antidepressants were well tolerated by the subjects with only minor adverse side effects. Conclusions No pharmacokinetic drug-drug interaction was demonstrated between venlafaxine XR and indinavir or between desvenlafaxine XR and indinvair. The lack of interaction could be due to the venlafaxine and desvenlafaxine extended-release formulation.

Purpose The aim of the present study was to investigate the effect of age on venlafaxine and escitalopram serum concentrations in various cytochrome P450 (CYP) 2D6 and CYP2C19 genotype subgroups. Methods Serum concentration measurements from CYP- genotyped patients treated with venlafaxine ( n  = 255) or escitalopram ( n  = 541) were collected retrospectively from a therapeutic drug monitoring database. Patients were divided into three CYP2D6 (venlafaxine) or CYP2C19 (escitalopram) phenotype subgroups according to inherited genotype, i.e., poor metabolizers (PMs), heterozygous extensive metabolizers (HEMs), and extensive metabolizers (EMs), and subsequently distributed into three age groups, i.e., <40 (control), 40–65, and >65 years. The effect of age on dose-adjusted serum concentrations (i.e., nmol/L/mg/day) of venlafaxine and escitalopram in each of the phenotype subgroups was evaluated by separate multivariate mixed model analyses. Results In CYP2D6 PMs, the mean dose-adjusted serum concentration of venlafaxine was 8-fold higher in patients >65 years compared with those <40 years ( p  < 0.001). In comparison, the respective age-related differences in mean dose-adjusted serum concentrations of venlafaxine were much less pronounced in CYP2D6 HEMs and EMs (<2-fold differences between age groups). A similar genotype-related effect of age was not observed for escitalopram (<1.5-fold age differences in all CYP2C19 subgroups). Conclusion This study suggests that the effect of age on serum concentration of venlafaxine is dependent on CYP genotype, in contrast to escitalopram. Thus, to prevent potential side effects, it might be particularly relevant to consider CYP2D6 genotyping prior to initiation of venlafaxine treatment in older patients.

We present a fatal drug poisoning case involving venlafaxine (VEN). The deceased took his medication regularly (including 150mg VEN twice daily), and nothing in the case or autopsy findings pointed towards suicide. The toxicological assessment concluded that the cause of death was most likely due to a poisoning with a combination of VEN, oxycodone and ethanol, and the manner of death was considered to be an accident. The blood concentration of VEN was high (4.5mg/kg), and the ratio of the VEN metabolite O-desmethylvenlafaxine (ODV) to VEN was exceptionally low (0.006). Mechanistic pharmacokinetic simulations suggested that the low metabolite ratio was the result of combined poor metabolizer (PM) status of cytochrome P450 (CYP) 2C19 and CYP2D6. This hypothesis was confirmed by genetic analysis. Simulations revealed that it was likely that the combined missing CYP2D6 and CYP2C19 activity would cause higher concentrations of VEN, but the simulations also suggested that there could be additional reasons to explain the high VEN concentration found in this case. Thus, it seems likely that the potentially toxic VEN concentration was caused by reduced metabolic capacity. The simulations combined with genotyping were considered very useful in this fatal drug poisoning case.

Dried blood spot (DBS) sampling and quantitative analyses of many current therapeutic drug monitoring (TDM)-guided drugs are advantageous because of the minimal invasive sampling strategy. Here, a fast and robust LC-MS/MS method was developed and analytically validated for simultaneous determination of venlafaxine (VEN) and O -desmethylvenlafaxine (ODV) in DBS. Six-millimeter circles were punched out from DBS collected on Whatman DMPK-C paper, and the DBS was extracted with acetonitrile/methanol at 1:3. The total run time was 4.8 min. The assay was linear in the range of 20–1,000 μg/L for both VEN and ODV. Assay accuracy and precision was well within limits of acceptance (LLOQ = 20 μg/L). Normal hematocrit concentrations (0.30–0.50) did not influence the results neither did a normal spot volume (40–80 μL). Punch position at the perimeter instead of the center of the blood spot gave a bias ranging from 2.4 to 10.4 %. Correlation between plasma and spiked DBS samples was high. The concentrations found in spiked DBS samples were higher than those in plasma, indicating that a conversion factor for translation of DBS to plasma values is needed. This analytically validated method is suitable for determination of VEN and ODV in DBS and applicable for TDM. The method will be used for TDM of VEN in the Dutch CYSCE multicenter trial (NCT01778907).

To investigate the effects of Chinese herb Danzhi Xiaoyao pills on the pharmacokinetics of venlafaxine and its metabolites O-desmethylvenlafaxine (ODV) and N-desmethylvenlafaxine (NDV) in beagles by using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Six beagles (half male, half female) were chosen to test, being fasted before the experiment but having free access to drinking water 1 day before being fed drugs. After oral administration of venlafaxine hydrochloride tablets (10.28 mg/kg), the blood samples were collected in succession at different points in time. After 1-week washout period, Danzhi Xiaoyao pills (0.6g/kg) were given through oral administration to the six beagles every morning until the 7th day, venlafaxine hydrochloride tablets (10.28 mg/kg) were given after feeding Danzhi Xiaoyao pills (0.6g/kg) half an hour and blood samples were collected continuously at different points. All samples were analyzed by UPLC-MS/MS, and the main pharmacokinetic parameters of venlafaxine, ODV and NDV were computed by DAS 2.0. The C of the venlafaxine group (control group) and the combination group (experimental group) were (2267.26±252.89) ng/mL and (1542.64±190.73) ng/mL, respectively. The AUC of the two groups were (13,934.79±3609.23) ng·h/mL and (8001.91±2167.58) ng·h/mL, respectively. The ODV C of the two groups were (2253.80±215.81) ng/mL and (2721.37±118.20) ng/mL, and AUC were (13,974.99±2784.04) ng·h/mL and (17,539.44±1894.29) ng·h/mL, respectively. The NDV C of the two groups were (50.98±5.76) ng/mL and (58.74±12.33) ng/mL, and AUC were (179.26±34.94) ng·h/mL and (220.68±51.41) ng·h/mL, respectively. After administration of Danzhi Xiaoyao pills, the C and AUC of venlafaxine decreased significantly, indicating that the plasma exposure of venlafaxine decreased. The increase of C and AUC of ODV and NDV indicated a rise in plasma exposure. Danzhi Xiaoyao pills can accelerate the metabolism of venlafaxine in beagles. In clinical, when venlafaxine was co-administrated with Danzhi Xiaoyao pills, dose adjustment of venlafaxine should be taken into account.

Introduction Serotonin and norepinephrine reuptake inhibitors (SNRIs) are antidepressants which have high affinity to both serotonin transporter (SERT) and norepinephrine transporter (NET). In studies in vitro, SNRIs have been reported to show a large variability in the affinity ratio between SERT and NET. For instance, the reported affinity ratio is about 30 for venlafaxine and 1.6 for milnacipran. In this study in nonhuman primates, we aimed to investigate the relationship between SERT and NET affinity by measuring the in vivo occupancy at both transporters of venlafaxine and milnacipran. Methods PET measurements with [ 11 C]MADAM and [ 18 F]FMeNER-D 2 were performed in two female cynomolgus monkeys at baseline and after pretreatment with venlafaxine and milnacipran, respectively. Relationships between dose, plasma concentration, and transporter occupancy were evaluated by saturation analysis using a hyperbolic function. Binding affinity (Kd plasma ) was expressed by the dose or plasma concentration at which 50 % of the transporter was occupied. Results SERT and NET occupancy by venlafaxine and milnacipran increased in a dose and plasma concentration-dependent manner. The Kd plasma ratio of SERT to NET was 1.9 for venlafaxine and 0.6 for milnacipran. Conclusions In this nonhuman primate PET study, the affinity in vivo for SERT and NET, respectively, was shown to be at a similar level for venlafaxine and milnacipran. Both drugs were found to produce balanced inhibition of SERT and NET binding. This observation is not consistent with previous in vitro binding data and illustrates the need to characterize antidepressants at in vivo condition.

Serotonin-active drugs are detected relatively frequently in Victorian deaths. During 2002–2008, there were 1123 fatalities where one or more of the serotonin-active drugs tramadol, venlafaxine, fluoxetine, sertraline, citalopram, paroxetine and MDMA, were detected. These deaths were reviewed using pathology, toxicology and police reports, to determine the contribution of these drugs to the cause of death, particularly if serotonin toxicity was the mechanism of death. There were 28 cases of most interest to this research because of the presence of the target drugs and the circumstances suggesting the likelihood of serotonin toxicity involvement in death. There were 5 cases of reported serotonin toxicity and 23 other deaths suspected to have involved this form of toxicity. Tramadol featured most commonly out of the seven target drugs and was frequently detected in combination with serotonergic antidepressants. MDMA was also detected relatively commonly and was associated with moclobemide in 4 cases of confirmed serotonin toxicity. There were an additional 1095 cases where natural disease, external injury or the misuse of other drugs caused death, of which 2 reported the incidental contribution of serotonin toxicity.